You searched for subject:(Critical heat flux CHF ).
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University of New Mexico
1.
Lee, Soon Kyu.
Experimental Investigation of Steady-state and Transient Flow Boiling Critical Heat Flux.
Degree: Nuclear Engineering, 2019, University of New Mexico
URL: https://digitalrepository.unm.edu/ne_etds/86 
► The Critical Heat Flux (CHF) causes a rapid reduction of heat transfer coefficient with a rapid increase of cladding temperature, which may induce physical…
(more)
▼ The
Critical Heat Flux (
CHF) causes a rapid reduction of
heat transfer coefficient with a rapid increase of cladding temperature, which may induce physical failure of the heated material. Understanding
CHF phenomena and reliable prediction of the boiling behavior are needed to design a
heat transfer system including nuclear reactors. Due to the complex nature of
CHF, it is still an active research topic of interest. With an increasing interest in Accident Tolerant Fuel (ATF),
CHF of ATF is essential topic of study for the detailed design of the fuel – cladding element and for the reactor safety analysis.
In this study, flow boiling experiments were conducted at atmospheric pressure with deionized water in an internal-tubular channel with a uniformly heated surface. With this
heat flux controlled system, steady-state and transient
CHF experiments were performed to gain a mechanistic understanding of the boiling nature. The experiments were conducted under the following conditions: (1) mass
flux, G of 200 - 2000, (2) inlet subcooling of 54, 34, and 10, (3) atmospheric pressure of 84 kPa. Experiments at low mass
flux were repeated on the same specimen to observe the effect of the surface characteristic change on
CHF. Despite the notable changes in surface wettability and roughness, change in flow
CHF was not observed, which implies the limited significance of surface characteristic on
CHF under flow condition. To mechanistically understand observed
CHF differences among the tested materials, material thermal parameters were considered. In addition, a statistical approach was made to analyze
CHF differences among the tested materials covering a wide range of mass flow rate, which demonstrated a reducing relative
CHF differences with increasing mass flow rate. It implies limited significance of material-sensitivity for the design of fuel and cladding and steady-state safety. Yet, observed
CHF differences at low mass
flux require a more detailed thermal-hydraulic material-sensitivity study at it may play an immense role under the accident scenarios where mass flow is limited. Lastly, transient boiling
CHF experiments were carried out to enhance cladding behavior with a pulsed power insertion under flow condition. With measurable values from the transient boiling experiments, boiling curve construction method is presented.
Advisors/Committee Members: Anil Prinja, Youho Lee, Amir Ali, Nicholas Brown.
Subjects/Keywords: Flow Boiling; Critical Heat Flux; Accident Tolerant Fuel; Steady-state CHF; Transient CHF; FeCrAl; Nuclear Engineering
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APA (6th Edition):
Lee, S. K. (2019). Experimental Investigation of Steady-state and Transient Flow Boiling Critical Heat Flux. (Doctoral Dissertation). University of New Mexico. Retrieved from https://digitalrepository.unm.edu/ne_etds/86
Chicago Manual of Style (16th Edition):
Lee, Soon Kyu. “Experimental Investigation of Steady-state and Transient Flow Boiling Critical Heat Flux.” 2019. Doctoral Dissertation, University of New Mexico. Accessed January 25, 2021.
https://digitalrepository.unm.edu/ne_etds/86.
MLA Handbook (7th Edition):
Lee, Soon Kyu. “Experimental Investigation of Steady-state and Transient Flow Boiling Critical Heat Flux.” 2019. Web. 25 Jan 2021.
Vancouver:
Lee SK. Experimental Investigation of Steady-state and Transient Flow Boiling Critical Heat Flux. [Internet] [Doctoral dissertation]. University of New Mexico; 2019. [cited 2021 Jan 25].
Available from: https://digitalrepository.unm.edu/ne_etds/86.
Council of Science Editors:
Lee SK. Experimental Investigation of Steady-state and Transient Flow Boiling Critical Heat Flux. [Doctoral Dissertation]. University of New Mexico; 2019. Available from: https://digitalrepository.unm.edu/ne_etds/86
University of North Texas
2.
Altalidi, Sulaiman Saleh.
Two-Phase Spray Cooling with HFC-134a and HFO-1234yf for Thermal Management of Automotive Power Electronics using Practical Enhanced Surfaces.
Degree: 2017, University of North Texas
URL: https://digital.library.unt.edu/ark:/67531/metadc1011876/
► The objective of this research was to investigate the performance of two-phase spray cooling with HFC-134a and HFO-1234yf refrigerants using practical enhanced heat transfer surfaces.…
(more)
▼ The objective of this research was to investigate the performance of two-phase spray cooling with HFC-134a and HFO-1234yf refrigerants using practical enhanced
heat transfer surfaces. Results of the study were expected to provide a quantitative spray cooling performance comparison with working fluids representing the current and next-generation mobile air conditioning refrigerants, and demonstrate the feasibility of this approach as an alternative active cooling technology for the thermal management of high
heat flux power electronics (i.e., IGBTs) in electric-drive vehicles. Potential benefits of two-phase spray cooling include achieving more efficient and reliable operation, as well as compact and lightweight system design that would lead to cost reduction. The experimental work involved testing of four different enhanced boiling surfaces in comparison to a plain reference surface, using a commercial pressure-atomizing spray nozzle at a range of
liquid flow rates for each refrigerant to determine the spray cooling performance with respect to
heat transfer coefficient (HTC) and
critical heat flux (
CHF). The heater surfaces were prepared using dual-stage electroplating, brush coating, sanding, and particle blasting, all featuring "practical" room temperature processes that do not require specialized equipment. Based on the obtained results, HFC-134a provided a better
heat transfer performance through higher HTC and
CHF values compared to HFO-1234yf at all tested surfaces and flow rates. While majority of the tested surfaces provided comparable HTC and modestly higher
CHF values compared to the reference surface, one of the enhanced surfaces offered significant
heat transfer enhancement.
Advisors/Committee Members: Bostanci, Huseyin, Shenoda, Michael, Wang, Shuping.
Subjects/Keywords: Spray cooling; Enhanced surface; Critical heat flux (CHF); Heat transfer coefficient (HTC); refrigerants; Temperature; Pressure; Experiment; electronics.
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University of Michigan
3.
Liu, Qingqing.
Post-CHF Heat Transfer Experiments and Modeling at Subcooled and Low-quality Conditions.
Degree: PhD, Nuclear Engineering & Radiological Sciences, 2020, University of Michigan
URL: http://hdl.handle.net/2027.42/162896
► During postulated large break loss of coolant accidents (LB-LOCAs) in a water-cooled nuclear reactor, the reactor is expected to shut down but the fuel cladding…
(more)
▼ During postulated large break loss of coolant accidents (LB-LOCAs) in a water-cooled nuclear reactor, the reactor is expected to shut down but the fuel cladding temperature would still increase due to the release of the stored energy in the fuel and decay energy of fission products. To prevent the cladding from overheating, the Emergency Core Cooling System will start up to inject makeup water into the reactor core, during which post-
critical heat flux (post-
CHF) flow regimes could dominate the
heat transfer from the cladding to the coolant. The
heat transfer characteristics in the post-
CHF flow regimes are important for reactor design and safety.
In this research, a Post-
CHF Heat Transfer (PCHT) test facility was designed and constructed to perform high-pressure (up to 1,000 psi or 6.8 MPa) post-
CHF heat transfer experiments at high mass fluxes (up to 2,000 kg/m2-s) with large inlet subcooling values (up to 50 ºC). A COMSOL multiphysics model was developed to inform the test section design. All the instrumentation in the test facility to measure the temperature, pressure, pressure differential, flow rate, void fraction, and flow topology have been tested to ensure their functionality. Shakedown tests have been performed in the test facility, including hydrostatic leak test, pressure control test, subcooled boiling test, hot patch test, gamma densitometer test, and X-ray radiography system test.
Reflooding and dry patch tests have been performed to study the wall
heat transfer characteristics in the post-
CHF flow regimes. In the reflooding tests, the quench curve indicates that the wall temperature has a rapid decrease in the quenched region, during which the
heat (stored energy) release from the test section plays a significant role in the total wall
heat flux to the fluid. Based on the convective
heat transfer coefficient profile, it is believed that inverted annular film boiling (IAFB) regime exists right downstream of the quench front. In the dry patch tests, the convective
heat transfer coefficient for the dry patches is larger than those calculated by three
heat transfer correlations for IAFB in the literature, especially for conditions of relatively low wall superheats, which indicates that the motion of the dry patch along the heated surface enhances the
heat transfer.
In addition to the experimental study, some closure models in the two-fluid model for the IAFB regime are benchmarked and improved. A correlation for the liquid-side Nusselt number is developed based on a parametric study performed in this research. A laminar vapor film model and nine existing correlations for the interfacial friction factor are evaluated based on the IAFB experimental data. The comparisons suggest that the interfacial friction factor in the smooth IAFB region is primarily dependent on the gas Reynold number and vapor film thickness and that in the wavy IAFB region, it is dominantly affected by the interfacial waves. To predict the flow regime transition from IAFB to ISFB, a correlation for the
critical Weber number is…
Advisors/Committee Members: Sun, Xiaodong (committee member), Pipe, Kevin Patrick (committee member), Kelly, Joseph M. (committee member), Manera, Annalisa (committee member), Petrov, Victor (committee member).
Subjects/Keywords: Post-critical heat flux (Post-CHF); Post-CHF Heat Transfer (PCHT) test facility; Inverted annular film boiling (IAFB); Two-fluid model; Reactor thermal hydraulics; Nuclear Engineering and Radiological Sciences; Engineering
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APA (6th Edition):
Liu, Q. (2020). Post-CHF Heat Transfer Experiments and Modeling at Subcooled and Low-quality Conditions. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/162896
Chicago Manual of Style (16th Edition):
Liu, Qingqing. “Post-CHF Heat Transfer Experiments and Modeling at Subcooled and Low-quality Conditions.” 2020. Doctoral Dissertation, University of Michigan. Accessed January 25, 2021.
http://hdl.handle.net/2027.42/162896.
MLA Handbook (7th Edition):
Liu, Qingqing. “Post-CHF Heat Transfer Experiments and Modeling at Subcooled and Low-quality Conditions.” 2020. Web. 25 Jan 2021.
Vancouver:
Liu Q. Post-CHF Heat Transfer Experiments and Modeling at Subcooled and Low-quality Conditions. [Internet] [Doctoral dissertation]. University of Michigan; 2020. [cited 2021 Jan 25].
Available from: http://hdl.handle.net/2027.42/162896.
Council of Science Editors:
Liu Q. Post-CHF Heat Transfer Experiments and Modeling at Subcooled and Low-quality Conditions. [Doctoral Dissertation]. University of Michigan; 2020. Available from: http://hdl.handle.net/2027.42/162896
University of Missouri – Columbia
4.
Feng, Xin, 1978-.
Experimental and analytical study on two-phase impingement cooling with and without electric field.
Degree: PhD, 2007, University of Missouri – Columbia
URL: http://hdl.handle.net/10355/4853
► Among the thermal management solutions for power electronics, two-phase jet or spray impingement cooling are two promising candidates. In this study, electrohydrodynamic atomization (EHDA) method…
(more)
▼ Among the thermal management solutions for power electronics, two-phase jet or spray impingement cooling are two promising candidates. In this study, electrohydrodynamic atomization (EHDA) method is used to generate spray and jet from the same capillary. This approach enables us to compare the
heat transfer coefficient and
critical heat flux (
CHF) in consistent conditions. Two nondimensional parameters are first developed to lay out the various EHDA modes of ethanol. The experimental results show that the EHDA cooling could enhance the
heat transfer coefficient in most conditions, while it could not benefit
CHF because the electric repulsive force causes a wide spray angle and less impinging mass
flux on the surface. Single and multi micro jet impingement cooling (MJIC) are investigated. Based on the experimental observation and analytical works, a semi-theoretical
CHF correlation is proposed based on force and energy balance. The experimental data of water and ethanol are predicted very well by the new model. It also shows the potential to explain the unique feature on the
CHF curves of saturated HFE7000 and subcooled ethanol. By using multi MJIC,
heat transfer coefficient and
CHF might be improved, which mainly depend on fluids and testing conditions.
Advisors/Committee Members: Bryan, James E., 1964- (advisor).
Subjects/Keywords: electrohydrodynamic atomization (EHDA); critical heat flux (CHF); electrohydrodynamic atomization (EHDA); critical heat flux (CHF); Power electronics; Heat flux; Heat – Transmission
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APA (6th Edition):
Feng, Xin, 1. (2007). Experimental and analytical study on two-phase impingement cooling with and without electric field. (Doctoral Dissertation). University of Missouri – Columbia. Retrieved from http://hdl.handle.net/10355/4853
Chicago Manual of Style (16th Edition):
Feng, Xin, 1978-. “Experimental and analytical study on two-phase impingement cooling with and without electric field.” 2007. Doctoral Dissertation, University of Missouri – Columbia. Accessed January 25, 2021.
http://hdl.handle.net/10355/4853.
MLA Handbook (7th Edition):
Feng, Xin, 1978-. “Experimental and analytical study on two-phase impingement cooling with and without electric field.” 2007. Web. 25 Jan 2021.
Vancouver:
Feng, Xin 1. Experimental and analytical study on two-phase impingement cooling with and without electric field. [Internet] [Doctoral dissertation]. University of Missouri – Columbia; 2007. [cited 2021 Jan 25].
Available from: http://hdl.handle.net/10355/4853.
Council of Science Editors:
Feng, Xin 1. Experimental and analytical study on two-phase impingement cooling with and without electric field. [Doctoral Dissertation]. University of Missouri – Columbia; 2007. Available from: http://hdl.handle.net/10355/4853
INP Toulouse
5.
Gourbil, Ange.
Etude expérimentale de l'ébullition convective en milieu poreux : assèchement et flux critique : Experimental study of flow boiling in porous media : dryout and critical heat flux.
Degree: Docteur es, Energétique et Transferts, 2017, INP Toulouse
URL: http://www.theses.fr/2017INPT0053
► Cette thèse est motivée par le besoin de compléter les connaissances actuelles des phénomènes ayant lieu lors d’un renvoi d’eau dans un lit de débris…
(more)
▼ Cette thèse est motivée par le besoin de compléter les connaissances actuelles des phénomènes ayant lieu lors d’un renvoi d’eau dans un lit de débris radioactifs, opération appelée « renoyage » et qui intervient dans une séquence d’accident grave où un cœur de réacteur nucléaire est dégradé suite à une perte prolongée de refroidissement primaire. Notre étude, de nature expérimentale, vise à mieux caractériser la crise d’ébullition en convection forcée, dans un milieu poreux chauffant. Le cœur du dispositif expérimental est un milieu poreux modèle quasibidimensionnel, composé de 276 cylindres disposés entre deux plaques de céramique distantes de 3 mm, dont l’une, transparente, permet de visualiser les écoulements. Les cylindres, de 2 mm de diamètre, sont des sondes thermo-résistives qui ont une double fonction : elles sont utilisées comme éléments chauffants et comme capteurs de température. Une boucle fluide permet de contrôler le débit d’injection de liquide dans la section test, la température d’injection ainsi que la pression. La section test est placée verticalement, le liquide est injecté par le bas à une température proche de la saturation. Dans une première série d’expériences, la puissance thermique dissipée globalement par un ensemble de cylindres chauffants est augmentée de façon progressive jusqu’à atteindre l’assèchement d’une zone du milieu poreux. Les résultats montrent deux types de phénoménologies dans le déclenchement de la crise d’ébullition. Pour des débits d’injection faibles (densités de
flux massique de l’ordre de 4 kg.m^-2.s^-1 maximum), l’atteinte de la puissance d’assèchement se traduit par un lent recul du front diphasique jusqu’à sa stabilisation en haut de la zone chauffée ; en aval de la zone chauffée, l’écoulement est monophasique vapeur. Pour des débits d’injection plus élevés, la crise d’ébullition apparaît autour d’un des éléments chauffants, conduisant à une ébullition en film localisée, tandis qu’un écoulement diphasique liquide-vapeur continue de parcourir l’aval de la section test. Les visualisations de ces expériences permettent d’identifier qualitativement la structure des écoulements. D’autres expériences consistent à mesurer le
flux critique local autour d’un cylindre choisi, pour différentes configurations d’écoulements. Le débit d’injection est fixé. Une puissance de chauffe est imposée à une ligne horizontale de cylindres en amont du cylindre choisi. Les résultats montrent que le
flux critique sur ce cylindre diminue en fonction de la puissance délivrée à la ligne chauffée. La distance du cylindre étudié à la ligne chauffée semble avoir peu d’influence sur le
flux critique. Des visualisations expérimentales sont utilisées pour caractériser l’écoulement diphasique en aval de la ligne chauffée, dans le but de mettre en relation le
flux critique local avec des paramètres hydrodynamiques (saturations, vitesses des phases). Les images obtenues sont difficiles à exploiter. Afin de calibrer les paramètres des algorithmes de traitement d’images, nous avons reproduit une cellule…
Advisors/Committee Members: Prat, Marc (thesis director), Duru, Paul (thesis director).
Subjects/Keywords: Flux critique; Milieu poreux; Ébullition convective; Écoulement diphasique; Sûreté nucléaire; Critical Heat Flux (CHF); Porous media; Flow boiling; Two-phase flow; Nuclear safety
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APA (6th Edition):
Gourbil, A. (2017). Etude expérimentale de l'ébullition convective en milieu poreux : assèchement et flux critique : Experimental study of flow boiling in porous media : dryout and critical heat flux. (Doctoral Dissertation). INP Toulouse. Retrieved from http://www.theses.fr/2017INPT0053
Chicago Manual of Style (16th Edition):
Gourbil, Ange. “Etude expérimentale de l'ébullition convective en milieu poreux : assèchement et flux critique : Experimental study of flow boiling in porous media : dryout and critical heat flux.” 2017. Doctoral Dissertation, INP Toulouse. Accessed January 25, 2021.
http://www.theses.fr/2017INPT0053.
MLA Handbook (7th Edition):
Gourbil, Ange. “Etude expérimentale de l'ébullition convective en milieu poreux : assèchement et flux critique : Experimental study of flow boiling in porous media : dryout and critical heat flux.” 2017. Web. 25 Jan 2021.
Vancouver:
Gourbil A. Etude expérimentale de l'ébullition convective en milieu poreux : assèchement et flux critique : Experimental study of flow boiling in porous media : dryout and critical heat flux. [Internet] [Doctoral dissertation]. INP Toulouse; 2017. [cited 2021 Jan 25].
Available from: http://www.theses.fr/2017INPT0053.
Council of Science Editors:
Gourbil A. Etude expérimentale de l'ébullition convective en milieu poreux : assèchement et flux critique : Experimental study of flow boiling in porous media : dryout and critical heat flux. [Doctoral Dissertation]. INP Toulouse; 2017. Available from: http://www.theses.fr/2017INPT0053
Virginia Tech
6.
Thompson, Jordan Lee.
Direct Measurement of Boiling Water Heat Flux for Predicting and Controlling Near Critical Heat Flux.
Degree: MS, Mechanical Engineering, 2013, Virginia Tech
URL: http://hdl.handle.net/10919/23091
► A novel method for measuring heat flux of boiling water is designed and built to study critical heat flux (CHF) and observe the response of…
(more)
▼ A novel method for measuring
heat flux of boiling water is designed and built to study
critical heat flux (
CHF) and observe the response of a
heat flux sensor when
CHF occurs. A high temperature
heat flux sensor is embedded in the wall of a pipe to get a direct measurement of the surface
heat flux and sensor temperature. By submerging the pipe in water and applying a controlled
heat flux to the inside diameter over the area where the sensor is located, boiling is created on the outer surface while measuring the
heat flux. The
heat flux is gradually increased up to
CHF and the
heat flux response is observed to determine if the
heat flux sensor could sense
CHF when it occurred. The
heat flux sensor is able to consistently measure the value for
CHF, which is approximately 510 kW/m" for this system. It is also observed during the experiments that the
heat flux response undergoes an inflection of the
heat transfer coefficient at a consistent temperature just before reaching
CHF. This observed inflection caused the
heat flux response to deviate from its cubic relationship with the temperature and drastically increase for a very small change in temperature. This inflection response can be used as an indication for approaching
CHF and can also be used to approximate its value without prior knowledge of when it occurs.
Advisors/Committee Members: Kornhauser, Alan A. (committeechair), Diller, Thomas E. (committee member), Huxtable, Scott T. (committee member).
Subjects/Keywords: heat flux sensor; boiling; critical heat flux
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APA (6th Edition):
Thompson, J. L. (2013). Direct Measurement of Boiling Water Heat Flux for Predicting and Controlling Near Critical Heat Flux. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/23091
Chicago Manual of Style (16th Edition):
Thompson, Jordan Lee. “Direct Measurement of Boiling Water Heat Flux for Predicting and Controlling Near Critical Heat Flux.” 2013. Masters Thesis, Virginia Tech. Accessed January 25, 2021.
http://hdl.handle.net/10919/23091.
MLA Handbook (7th Edition):
Thompson, Jordan Lee. “Direct Measurement of Boiling Water Heat Flux for Predicting and Controlling Near Critical Heat Flux.” 2013. Web. 25 Jan 2021.
Vancouver:
Thompson JL. Direct Measurement of Boiling Water Heat Flux for Predicting and Controlling Near Critical Heat Flux. [Internet] [Masters thesis]. Virginia Tech; 2013. [cited 2021 Jan 25].
Available from: http://hdl.handle.net/10919/23091.
Council of Science Editors:
Thompson JL. Direct Measurement of Boiling Water Heat Flux for Predicting and Controlling Near Critical Heat Flux. [Masters Thesis]. Virginia Tech; 2013. Available from: http://hdl.handle.net/10919/23091
7.
Luitjens, Jeffrey M.
The Development of a Mechanistic Critical Heat Flux Correlation.
Degree: PhD, Nuclear Engineering, 2015, Oregon State University
URL: http://hdl.handle.net/1957/56128
► A mechanistic based critical heat flux (CHF) correlation has been developed derived from a mass, momentum, and energy balance at a nucleation site for water.…
(more)
▼ A mechanistic based
critical heat flux (
CHF) correlation has been developed derived from a mass, momentum, and energy balance at a nucleation site for water. The trigger mechanism for the
CHF condition is postulated to be related to the maximum boiling frequency on a heated surface. It is observed that dependency of results is directly related to the effective cavity size (surface conditions) and as such the effective cavity size is taken to be the single closure coefficient dependent on the system pressure and mass
flux.
The applicable range of the developed model is considered to be with inlet mass fluxes between 128 to 4300 kg/(m²-s), pressures between 4.5 to 15.6 MPa, and
critical qualities between -0.03 to 1.0. The resulting standard error of the mechanistic
CHF model is 12.9% with over 800 experimental data points utilized over these conditions to inform and confirm the development of the model using a bundle geometry.
Advisors/Committee Members: Wu, Qiao (advisor), Reyes, Jose (committee member).
Subjects/Keywords: CHF; Pressurized water reactors – Critical heat flux – Mathematical modeling
…the surface. This heat flux is
referred to as the critical heat flux (CHF). When… …61
3.5 Existing Critical Heat Flux Correlations . . . . . . . . . . . . . . . . . .
3.5.1… …Parameter Effects on Critical Heat Flux
75
4.1 Surface Tension… …TABLE OF CONTENTS (Continued)
Page
6
Proposed Critical Heat Flux Model
103
6.1… …106
107
107
112
6.3 Critical Heat Flux Model…
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APA (6th Edition):
Luitjens, J. M. (2015). The Development of a Mechanistic Critical Heat Flux Correlation. (Doctoral Dissertation). Oregon State University. Retrieved from http://hdl.handle.net/1957/56128
Chicago Manual of Style (16th Edition):
Luitjens, Jeffrey M. “The Development of a Mechanistic Critical Heat Flux Correlation.” 2015. Doctoral Dissertation, Oregon State University. Accessed January 25, 2021.
http://hdl.handle.net/1957/56128.
MLA Handbook (7th Edition):
Luitjens, Jeffrey M. “The Development of a Mechanistic Critical Heat Flux Correlation.” 2015. Web. 25 Jan 2021.
Vancouver:
Luitjens JM. The Development of a Mechanistic Critical Heat Flux Correlation. [Internet] [Doctoral dissertation]. Oregon State University; 2015. [cited 2021 Jan 25].
Available from: http://hdl.handle.net/1957/56128.
Council of Science Editors:
Luitjens JM. The Development of a Mechanistic Critical Heat Flux Correlation. [Doctoral Dissertation]. Oregon State University; 2015. Available from: http://hdl.handle.net/1957/56128
University of Houston
8.
Lu, Yi.
Electrowetting Enhancement of Critical Heat Flux.
Degree: PhD, Mechanical Engineering, 2017, University of Houston
URL: http://hdl.handle.net/10657/4614
► Critical heat flux (CHF) represents the upper limit of nucleate boiling heat transfer, beyond which boiling transitions to the inefficient film boiling regime. Potentially catastrophic…
(more)
▼ Critical heat flux (
CHF) represents the upper limit of nucleate boiling
heat transfer, beyond which boiling transitions to the inefficient film boiling regime. Potentially catastrophic burnout conditions may ensue and endanger the safe and reliable operation of the boiling device. Thus, it is highly desirable to augment
CHF in order to boost the thermal performance of various energy-intensive applications that rely on boiling to transport a large amount of thermal energy.
In this work,
CHF enhancement was explored both theoretically and experimentally by capitalizing on the ability of electrowetting (EW) to modulate the liquid-vapor interfacial stabilities and the liquid-vapor-solid three-phase contact line motion. To do so, a Leidenfrost drop (i.e., a liquid drop hovering over a highly superheated solid surface) was first employed as a model system, due to its simplicity and close connection to film boiling and
CHF, to investigate the effect of the electric field on the dynamics of the vapor film that separates the drop from the hot surface. It was found that the electrostatic attraction force alone cannot destabilize the vapor film, instead, it is the accelerated vapor flow that changes the
critical wavelength of the Kelvin-Helmholtz instability, thus causing the film to collapse. The results show that, without the need for any complicated surface micro/nanostructures, the Leidenfrost point (LFP) temperature of water can be increased from 200°C to 380°C with a moderate voltage of 56 V a frequency of 50 Hz.
Subsequently, to better understand the impact of EW on the liquid-vapor interfacial behaviors, the dynamics of EW-induced motion of both liquid droplets and vapor bubbles was studied. Computational fluid dynamics models were developed by using the Volume of Fluid (VOF)-Continuous Surface Force (CSF) method to scrutinize the response of a droplet when
subject to EW actuating signals. In particular, a dynamic contact angle model based on the molecular kinetic theory was implemented as the boundary condition at the moving contact line, which considers the effects of both the contact line friction and the pinning force. The droplet shape evolution and the interfacial resonance oscillation were investigated in detail. On the bubble aspect, the nucleation, growth and departure of vapor bubbles on a hydrophilic surface, a hydrophobic surface both with and without the influence of EW, were compared, which revealed the significant effect of the EW force on the contact line and, therefore, on the bubble dynamics.
Lastly, to demonstrate the EW enhancement of
CHF, a synchronized high-speed optical imaging and infrared (IR) thermographic technique was used to characterize boiling
heat transfer at the
CHF conditions. Simultaneous measurements of the bubble dynamics and the wall temperature and
heat flux distributions on the boiling surface were acquired. The results showed that
CHF can be enhanced by 133% by the use of EW. Additionally, by considering the force balance at the contact line of a nucleate…
Advisors/Committee Members: Liu, Dong (advisor), Ruchhoeft, Paul (committee member), Mavrokefalos, Anastassios (committee member), Ghasemi, Hadi (committee member), Yu, Cunjiang (committee member).
Subjects/Keywords: Electrowetting; Critical heat flux; Boiling
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APA (6th Edition):
Lu, Y. (2017). Electrowetting Enhancement of Critical Heat Flux. (Doctoral Dissertation). University of Houston. Retrieved from http://hdl.handle.net/10657/4614
Chicago Manual of Style (16th Edition):
Lu, Yi. “Electrowetting Enhancement of Critical Heat Flux.” 2017. Doctoral Dissertation, University of Houston. Accessed January 25, 2021.
http://hdl.handle.net/10657/4614.
MLA Handbook (7th Edition):
Lu, Yi. “Electrowetting Enhancement of Critical Heat Flux.” 2017. Web. 25 Jan 2021.
Vancouver:
Lu Y. Electrowetting Enhancement of Critical Heat Flux. [Internet] [Doctoral dissertation]. University of Houston; 2017. [cited 2021 Jan 25].
Available from: http://hdl.handle.net/10657/4614.
Council of Science Editors:
Lu Y. Electrowetting Enhancement of Critical Heat Flux. [Doctoral Dissertation]. University of Houston; 2017. Available from: http://hdl.handle.net/10657/4614
9.
Kim, Seung Jun.
An experimental study of critical heat flux with surface modification and its analytic prediction model development.
Degree: PhD, 0139, 2012, University of Illinois – Urbana-Champaign
URL: http://hdl.handle.net/2142/34324
► The critical heat flux (CHF) condition causes a drastic reduction of heat transfer coefficient and sometimes involves physical failure of the heating surface in heat…
(more)
▼ The
critical heat flux (
CHF) condition causes a drastic reduction of
heat transfer coefficient and sometimes involves physical failure of the heating surface in
heat flux-controlled systems. Understanding of
CHF phenomena and reliable
CHF prediction model development are necessary to design various
heat transfer systems including nuclear fission reactors, fossil-fueled boilers, thermo-nuclear fusion reactors, etc. Many aspects of
CHF phenomena are well understood and reasonable prediction models have been developed. However, due to the complex natures of phenomena,
CHF in sub-cooled flow boiling is still an active research topic. This experimental study examines the effects of various operating system conditions including; system pressure, mass flow rate, sub-cooled temperature, and surface wettability upon
CHF under sub-cooled flow boiling conditions. An analytical
CHF prediction model also has been proposed using the bubble force balance. Sub-cooled flow boiling is generally characterized by high
heat transfer rate and low wall superheat, which is essential for cooling applications requiring high
heat transfer rates, such as in nuclear reactors and fossil power plants.
In this study, sub-cooled flow boiling tests were conducted using R-134a coolant in a rectangular channel (half inch by half inch) with one uniformly heated surface. This is a surface
heat flux controlled system. This refrigerant is selected as a stimulant fluid for water due to its small surface tension, low latent
heat, and low boiling temperature. The experiments were conducted under the following conditions: (1) inlet pressure (P) of 400 ~ 800 KPa, (2) specific mass flow rate (G) of 124 ~ 248 kg/m2-s, (3) inlet sub-cooling enthalpy ( ) of 9 ~ 45kJ/kg. By varying experimental operating conditions,
CHF was identified by monitoring a sudden rise in heated wall temperature. It was found that
CHF in a rectangular channel increases with increasing mass flow rate, increasing inlet sub-cooling, and increasing system pressure. The parametric trend of the
CHF data using R-134a in a rectangular channel is consistent with classic understanding of
CHF in round tubes using water in relatively low pressure (less than 0.2 reduced pressures). In addition, a Fluid-to-Fluid scaling model was utilized to convert the test data obtained in the simulant fluid (R-134a) into the prototypical fluid (water). The comparison between the converted
CHF of equivalent water and
CHF look-up table with same operation conditions were conducted, and show good agreement.
In order to investigate heating surface feature effects on
CHF, surface modification, applying Atmospheric Pressure Plasma (AP-Plasma) coating, was performed on the copper heating block. It is considered that the AP-Plasma treated surface does not affect boiling
heat transfer directly, but rather via change in microscopic surface parameters such as wettability and static contact angle, parameters that the proposed
CHF prediction model incorporates. The surface oxidation coating with AP-Plasma makes the surface…
Advisors/Committee Members: Jones, Barclay G. (advisor), Jones, Barclay G. (Committee Chair), Jones, Barclay G. (committee member), Axford, Roy A. (committee member), Uddin, Rizwan (committee member), Newell, Ty A. (committee member).
Subjects/Keywords: Critical heat flux (CHF); Sub-cooled flow boiling; surface wettability; correlation development
…1
1.2
Critical heat flux (CHF) in Sub-cooled Flow Boiling… …74
4.1
Critical heat flux (CHF) Measurement and Parametric Trend Study… …forced convection and critical heat flux (CHF) have been
drawing significant… …flow boiling conditions.
1.2
Critical heat flux (CHF) in Sub-cooled Flow Boiling… …Critical Heat Flux (CHF), which is also known as burnout, dry-out, and boiling crisis…
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APA (6th Edition):
Kim, S. J. (2012). An experimental study of critical heat flux with surface modification and its analytic prediction model development. (Doctoral Dissertation). University of Illinois – Urbana-Champaign. Retrieved from http://hdl.handle.net/2142/34324
Chicago Manual of Style (16th Edition):
Kim, Seung Jun. “An experimental study of critical heat flux with surface modification and its analytic prediction model development.” 2012. Doctoral Dissertation, University of Illinois – Urbana-Champaign. Accessed January 25, 2021.
http://hdl.handle.net/2142/34324.
MLA Handbook (7th Edition):
Kim, Seung Jun. “An experimental study of critical heat flux with surface modification and its analytic prediction model development.” 2012. Web. 25 Jan 2021.
Vancouver:
Kim SJ. An experimental study of critical heat flux with surface modification and its analytic prediction model development. [Internet] [Doctoral dissertation]. University of Illinois – Urbana-Champaign; 2012. [cited 2021 Jan 25].
Available from: http://hdl.handle.net/2142/34324.
Council of Science Editors:
Kim SJ. An experimental study of critical heat flux with surface modification and its analytic prediction model development. [Doctoral Dissertation]. University of Illinois – Urbana-Champaign; 2012. Available from: http://hdl.handle.net/2142/34324
McMaster University
10.
BEHDADI, AZIN.
MECHANISTIC MODELLING OF CRITICAL HEAT FLUX ON LARGE DIAMETER TUBES.
Degree: PhD, 2015, McMaster University
URL: http://hdl.handle.net/11375/18045
► Heavy water moderator surrounding each fuel channel is one of the important safety features in CANDU reactors since it provides an in-situ passive heat sink…
(more)
▼ Heavy water moderator surrounding each fuel channel is one of the
important safety features in CANDU reactors since it provides an
in-situ passive heat sink for the fuel in situations where other
engineered means of heat removal from fuel channels have failed.
In a critical break LOCA scenario, fuel cooling becomes severely
degraded due to rapid flow reduction in the affected flow pass of
the heat transport system. This can result in pressure tubes
experiencing significant heat-up during early stages of the
accident when coolant pressure is still high, thereby causing
uniform thermal creep strain (ballooning) of the pressure tube
(PT) into contact with its calandria tube (CT). The contact of the
hot PT with the CT causes rapid redistribution of stored heat from
the PT to CT and a large heat flux spike from the CT to the
moderator fluid. For conditions where subcooling of the moderator
fluid is low, this heat flux spike can cause dryout of the CT.
This can detrimentally affect channel integrity if the CT
post-dryout temperature becomes sufficiently high to result in
continued thermal creep strain deformation of both the PT and the
CT.
A comprehensive mechanistic model is developed to predict the
critical heat flux (CHF) variations along the downward facing
outer surface of calandria tube. The model is based on the
hydrodynamic model of which considers a
liquid macrolayer beneath an elongated vapor slug on the heated
surface. Local dryout is postulated to occur whenever the fresh
liquid supply to the macrolayer is not sufficient to compensate
for the liquid depletion within the macrolayer due to boiling on
the heating surface. A boundary layer analysis is performed,
treating the two phase motion as an external buoyancy driven flow,
to determine the liquid supply rate and the local CHF. The model
takes into account different types of flow regime or slip ratio.
It is applicable for a calandria vessel as well, under a sever
accident condition where a thermal creep failure is postulated to
occur if sustained CHF is instigated in the surrounding shield
tank water. Model shows good agreement with the available
experimental CHF data. The model has been modified to take into
account the effect of subcooling and has been validated against
the empirical correction factors.
Dissertation
Doctor of Philosophy (PhD)
Advisors/Committee Members: LUXAT, JOHN C., Engineering Physics and Nuclear Engineering.
Subjects/Keywords: CRITICAL HEAT FLUX; TWO PHASE FLOW
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APA (6th Edition):
BEHDADI, A. (2015). MECHANISTIC MODELLING OF CRITICAL HEAT FLUX ON LARGE DIAMETER TUBES. (Doctoral Dissertation). McMaster University. Retrieved from http://hdl.handle.net/11375/18045
Chicago Manual of Style (16th Edition):
BEHDADI, AZIN. “MECHANISTIC MODELLING OF CRITICAL HEAT FLUX ON LARGE DIAMETER TUBES.” 2015. Doctoral Dissertation, McMaster University. Accessed January 25, 2021.
http://hdl.handle.net/11375/18045.
MLA Handbook (7th Edition):
BEHDADI, AZIN. “MECHANISTIC MODELLING OF CRITICAL HEAT FLUX ON LARGE DIAMETER TUBES.” 2015. Web. 25 Jan 2021.
Vancouver:
BEHDADI A. MECHANISTIC MODELLING OF CRITICAL HEAT FLUX ON LARGE DIAMETER TUBES. [Internet] [Doctoral dissertation]. McMaster University; 2015. [cited 2021 Jan 25].
Available from: http://hdl.handle.net/11375/18045.
Council of Science Editors:
BEHDADI A. MECHANISTIC MODELLING OF CRITICAL HEAT FLUX ON LARGE DIAMETER TUBES. [Doctoral Dissertation]. McMaster University; 2015. Available from: http://hdl.handle.net/11375/18045
INP Toulouse
11.
Scheiff, Valentin.
Etude expérimentale et modélisation du transfert de chaleur de l'ébullition transitoire : Experimental study of heat transfer during transient boiling.
Degree: Docteur es, Energétique et Transferts, 2018, INP Toulouse
URL: http://www.theses.fr/2018INPT0145
► L’étude de l’ébullition transitoire est un enjeu important pour la sureté nucléaire. Un tel phénomène peut se produire lors d’un accident de type RIA (Reactivity…
(more)
▼ L’étude de l’ébullition transitoire est un enjeu important pour la sureté nucléaire. Un tel phénomène peut se produire lors d’un accident de type RIA (Reactivity Initiated Accident)dans un réacteur nucléaire où le pic de puissance au niveau d’un crayon de combustible peut déclencher une ébullition transitoire conduisant à une forte augmentation de la température de la gaine et à un risque de rupture. Plusieurs études en conditions réacteurs ont permis d’obtenir des courbes d’ébullition transitoires mais la modélisation qui en découle manque encore de fiabilité. Dans le cadre d’une collaboration avec l’Institut de Radioprotection et de Sûreté Nucléaire (IRSN), une expérience modèle a été construite à l’Institut de Mécanique des Fluides de Toulouse (IMFT). Elle génère un écoulement de réfrigérant HFE7000 dans un canal de section semi-annulaire, simulant l’écoulement autour d’un crayon de combustible, dont la partie intérieure, composée d’une feuille de métal, est chauffée rapidement par effet Joule, simulant l’échauffement de la gaine du crayon. La thermographie infra-rouge permet de mesurer la température de la paroi externe du métal. L’application d’une peinture noire sur le métal augmente son émissivité mais aussi la résistance thermique de la paroi. La précision de la mesure de la température d’intérêt a été optimisée en fonction de l’épaisseur de peinture et une correction sur le bilan d’énergie prend en compte ce paramètre. Ces mesures sont couplées avec une caméra rapide qui permet de visualiser les régimes d’ébullition et d’obtenir des tailles de bulles à l’aide de la mise en place d’algorithmes de traitement d’image. On représente sur un diagramme
flux-température les transferts thermiques lors des différents régimes en stationnaire et en transitoire. Chaque régime d’ébullition, en conditions stationnaire ou transitoire, est alors passé en revue : la convection, le déclenchement de l’ébullition, l’ébullition nucléée, la crise d’ébullition, l’ébullition en film et le remouillage. Les régimes stationnaires sont correctement modélisés par des corrélations usuelles. La convection transitoire est caractérisée sur toute la paroi et son évolution se rapproche de la solution quasistationnaire. Il est montré que les transferts thermiques lors du passage vers l’ébullition nucléée sont dépendants de la formation d’une importante poche de vapeur qui se propage sur la paroi. Une étude locale de cette propagation est alors nécessaire. Afin de simuler des transitoires de température durant l’ébullition nucléée, un système d’asservissement de type P.I.D. permet d’imposer des créneaux ou des rampes de températures (de 5 à 500 K.s 1 ). Les résultats en ébullition nucléée sont conformes avec ceux de la littérature, tant en conditions stationnaire que transitoire. L’expérience permet d’étudier le transfert de chaleur lorsqu’un film de vapeur se forme et isole la paroi. Ce régime d’ébullition en film, pendant la chauffe ou le refroidissement de la paroi peut ainsi être stabilisée pendant plusieurs secondes avec ce système. On…
Advisors/Committee Members: Colin, Catherine (thesis director), Sebilleau, Julien (thesis director).
Subjects/Keywords: Accident d’insertion de réactivité (RIA); Échanges thermiques transitoires; Convection; Déclenchement de l’ébullition; Ébullition nucléée; Crise d’ébullition; Flux critique; Ébullition en film; Remouillage; Thermographie infrarouge; SCANAIR; Reactivity Initiated Accident (RIA); Transient boiling; Convection; Onset of nucleate boiling (ONB); Nucleate boiling; Boiling crisis; Critical heat flux (CHF); Film boiling; Rewetting; Infrared thermography; SCANAIR
Record Details
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APA ·
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MLA ·
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Export
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APA (6th Edition):
Scheiff, V. (2018). Etude expérimentale et modélisation du transfert de chaleur de l'ébullition transitoire : Experimental study of heat transfer during transient boiling. (Doctoral Dissertation). INP Toulouse. Retrieved from http://www.theses.fr/2018INPT0145
Chicago Manual of Style (16th Edition):
Scheiff, Valentin. “Etude expérimentale et modélisation du transfert de chaleur de l'ébullition transitoire : Experimental study of heat transfer during transient boiling.” 2018. Doctoral Dissertation, INP Toulouse. Accessed January 25, 2021.
http://www.theses.fr/2018INPT0145.
MLA Handbook (7th Edition):
Scheiff, Valentin. “Etude expérimentale et modélisation du transfert de chaleur de l'ébullition transitoire : Experimental study of heat transfer during transient boiling.” 2018. Web. 25 Jan 2021.
Vancouver:
Scheiff V. Etude expérimentale et modélisation du transfert de chaleur de l'ébullition transitoire : Experimental study of heat transfer during transient boiling. [Internet] [Doctoral dissertation]. INP Toulouse; 2018. [cited 2021 Jan 25].
Available from: http://www.theses.fr/2018INPT0145.
Council of Science Editors:
Scheiff V. Etude expérimentale et modélisation du transfert de chaleur de l'ébullition transitoire : Experimental study of heat transfer during transient boiling. [Doctoral Dissertation]. INP Toulouse; 2018. Available from: http://www.theses.fr/2018INPT0145
Rochester Institute of Technology
12.
Jaikumar, Arvind.
Multiscale Mechanistic Approach to Enhance Pool Boiling Performance for High Heat Flux Applications.
Degree: PhD, Microsystems Engineering, 2017, Rochester Institute of Technology
URL: https://scholarworks.rit.edu/theses/9636
► The advent of cloud computing and the complex packaging architecture of next generation electronic devices drives methods for advanced thermal management solutions. Convection based…
(more)
▼ The advent of cloud computing and the complex packaging architecture of next generation electronic devices drives methods for advanced thermal management solutions. Convection based single-phase cooling systems are inefficient due to their large pressure drops, fluid temperature differences and costs, and are incapable of meeting the cooling requirements in the high power density components and systems. Alternatively, phase-change cooling techniques are attractive due to their ability to remove large amounts of
heat while maintaining uniform fluid temperatures. Pool boiling
heat transfer mechanism centers on the nucleation, growth and departure of a bubble from the
heat transfer surface in a stagnant pool of liquid. The pool boiling performance is quantified by the
Critical Heat Flux (
CHF) and
Heat Transfer Coefficients (HTC) which dictate the operating ranges and efficiency of the
heat transfer process. In this work, three novel geometries are introduced to modify the nucleation characteristics, liquid pathways and contact line motion on the prime heater surface for a simultaneous increase in
CHF and HTC.
First, sintered microchannels and nucleating region with feeder channels (NRFC) were developed through the mechanistic concept of separate liquid-vapor pathways and enhanced macroconvection
heat transfer. A maximum
CHF of 420 W/cm2 at a wall superheat of 1.7 °C with a HTC of 2900 MW/m2°C was achieved with the sintered-channels configuration, while the NRFC reached a
CHF of 394 W/cm2 with a HTC of 713 kW/m2°C. Second, the scale effect of liquid wettability, roughness and microlayer evaporation was exploited to facilitate capillary wicking in graphene through interlaced porous copper particles. A
CHF of 220 W/cm2 with a HTC of 155 kW/m2°C was achieved using an electrodeposition coating technique. Third, the chemical heterogeneity on nanoscale coatings was shown to increase the contribution from transient conduction mechanisms. A maximum
CHF of 226 W/cm2 with a HTC of 107 kW/m2°C was achieved. The enhancement techniques developed here provide a mechanistic tool at the microscale and nanoscale to increase the boiling
CHF and HTC.
Advisors/Committee Members: Satish G. Kandlikar.
Subjects/Keywords: Boiling; Critical heat flux; Enhancement; Heat transfer coefficient; Thermal management
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APA (6th Edition):
Jaikumar, A. (2017). Multiscale Mechanistic Approach to Enhance Pool Boiling Performance for High Heat Flux Applications. (Doctoral Dissertation). Rochester Institute of Technology. Retrieved from https://scholarworks.rit.edu/theses/9636
Chicago Manual of Style (16th Edition):
Jaikumar, Arvind. “Multiscale Mechanistic Approach to Enhance Pool Boiling Performance for High Heat Flux Applications.” 2017. Doctoral Dissertation, Rochester Institute of Technology. Accessed January 25, 2021.
https://scholarworks.rit.edu/theses/9636.
MLA Handbook (7th Edition):
Jaikumar, Arvind. “Multiscale Mechanistic Approach to Enhance Pool Boiling Performance for High Heat Flux Applications.” 2017. Web. 25 Jan 2021.
Vancouver:
Jaikumar A. Multiscale Mechanistic Approach to Enhance Pool Boiling Performance for High Heat Flux Applications. [Internet] [Doctoral dissertation]. Rochester Institute of Technology; 2017. [cited 2021 Jan 25].
Available from: https://scholarworks.rit.edu/theses/9636.
Council of Science Editors:
Jaikumar A. Multiscale Mechanistic Approach to Enhance Pool Boiling Performance for High Heat Flux Applications. [Doctoral Dissertation]. Rochester Institute of Technology; 2017. Available from: https://scholarworks.rit.edu/theses/9636
Rochester Institute of Technology
13.
Raghupathi, Pruthvik A.
On Contact Line Region Heat Transfer, Bubble Dynamics and Substrate Effects during Boiling.
Degree: PhD, Engineering, 2018, Rochester Institute of Technology
URL: https://scholarworks.rit.edu/theses/9849
► Rapid advancement of electronics used in domestic, commercial and military applications has necessitated the development of thermal management solutions capable of dissipating large amounts…
(more)
▼ Rapid advancement of electronics used in domestic, commercial and military applications has necessitated the development of thermal management solutions capable of dissipating large amounts of
heat in a reliable and efficient manner. Traditional methods of cooling, including air and liquid cooling, require large fluid flow rates and temperature differences to remove high
heat fluxes and are therefore unsuited for many advanced applications. Phase change
heat transfer, specifically boiling, is capable of dissipating large
heat fluxes with low temperature gradients and hence is an attractive technique for cooling high
heat flux applications. However, due to the complex interactions between the fluid dynamics,
heat transfer, and surface chemistry, the fundamental physics associated with boiling is not completely understood.
The focus of this work is to get a better understanding of the role played by a nucleating bubble in removing the
heat from the substrate. The interfacial forces acting on a bubble, contact line motion, and the thermal interaction with the heater surfaces are some of the important considerations which have not been well understood in literature. The work reported in this dissertation is divided into three parts. In the first part, an analytical study of the effect of evaporation momentum force on bubble growth rate and bubble trajectory was conducted. It was shown that the trajectory of a bubble can be controlled by creating an asymmetric temperature field. This understanding was used to develop a bubble diverter that increased the
Critical Heat Flux (
CHF) over a horizontal tubular surface by 60% and improved the
heat transfer coefficient by 75%. In the second part of the work, additional contact line regions were generated using microgrooves. This enhancement technique increased the
CHF with water by 46% over a plain copper surface to 187 W/cm2. Finally, the effect of the heater properties and surface fouling during boiling was evaluated. This included a study on the effect of thermophysical properties of the heater surface on
CHF and an investigation of fouling over a heater surface during boiling of seawater.
Advisors/Committee Members: Satish G. Kandlikar.
Subjects/Keywords: Boiling; Bubble dynamics; Contact line heat transfer; Critical heat flux; Seawater
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APA ·
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MLA ·
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Export
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APA (6th Edition):
Raghupathi, P. A. (2018). On Contact Line Region Heat Transfer, Bubble Dynamics and Substrate Effects during Boiling. (Doctoral Dissertation). Rochester Institute of Technology. Retrieved from https://scholarworks.rit.edu/theses/9849
Chicago Manual of Style (16th Edition):
Raghupathi, Pruthvik A. “On Contact Line Region Heat Transfer, Bubble Dynamics and Substrate Effects during Boiling.” 2018. Doctoral Dissertation, Rochester Institute of Technology. Accessed January 25, 2021.
https://scholarworks.rit.edu/theses/9849.
MLA Handbook (7th Edition):
Raghupathi, Pruthvik A. “On Contact Line Region Heat Transfer, Bubble Dynamics and Substrate Effects during Boiling.” 2018. Web. 25 Jan 2021.
Vancouver:
Raghupathi PA. On Contact Line Region Heat Transfer, Bubble Dynamics and Substrate Effects during Boiling. [Internet] [Doctoral dissertation]. Rochester Institute of Technology; 2018. [cited 2021 Jan 25].
Available from: https://scholarworks.rit.edu/theses/9849.
Council of Science Editors:
Raghupathi PA. On Contact Line Region Heat Transfer, Bubble Dynamics and Substrate Effects during Boiling. [Doctoral Dissertation]. Rochester Institute of Technology; 2018. Available from: https://scholarworks.rit.edu/theses/9849
Penn State University
14.
Almudhhi, Turki Khalid.
EXPERIMENTAL STUDY OF HEAT TRANSFER DURING QUENCHING OF A HEATED ROD.
Degree: 2017, Penn State University
URL: https://submit-etda.libraries.psu.edu/catalog/14854tka5098
► Quenching experiments of a cylindrical rod were conducted in a distilled water pool in order to study the behavior of the critical heat flux (CHF)…
(more)
▼ Quenching experiments of a cylindrical rod were conducted in a distilled water pool in order to study the behavior of the
critical heat flux (
CHF) and the minimum
heat flux (MHF). The effects of liquid subcooling, initial rod temperature, and surface condition on
CHF and MHF were investigated during the quench process. The test specimen is a hollow stainless steel rod. The tip of the specimen is welded to prevent any water leakage inside the rod. The specimen has two thermocouples, one at the inner diameter and the other embedded in the wall. Both thermocouples are located at the same axial elevation. During the experiment, all thermocouple readings were taken by a data acquisition system. In addition, a video was recorded by a high-speed video camera for visualization of the boiling phenomenon. The surface
heat flux was calculated using a 1-D inverse
heat conduction code at each location.
It has been found that the MHF and
CHF were significantly influenced by the degree of subcooling. However, the MHF and
CHF values were almost independent of initial rod temperature and surface condition. The calculated surface
heat flux based on each thermocouple location was found to be consistent during the film boiling regime. The inconsistency in the evaluated surface
heat fluxes at both locations begins after the MHF point and reaches a maximum near the
CHF. After the
CHF point, the inconsistency decays dramatically. The inconsistency in
CHF values could be related to the axial conduction effect due to the large temperature gradient above and below the quench front.
Advisors/Committee Members: Fan-Bill B Cheung, Thesis Advisor/Co-Advisor.
Subjects/Keywords: Pool boiling; Heat transfer; Quenching; critical heat flux
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APA (6th Edition):
Almudhhi, T. K. (2017). EXPERIMENTAL STUDY OF HEAT TRANSFER DURING QUENCHING OF A HEATED ROD. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/14854tka5098
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Almudhhi, Turki Khalid. “EXPERIMENTAL STUDY OF HEAT TRANSFER DURING QUENCHING OF A HEATED ROD.” 2017. Thesis, Penn State University. Accessed January 25, 2021.
https://submit-etda.libraries.psu.edu/catalog/14854tka5098.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Almudhhi, Turki Khalid. “EXPERIMENTAL STUDY OF HEAT TRANSFER DURING QUENCHING OF A HEATED ROD.” 2017. Web. 25 Jan 2021.
Vancouver:
Almudhhi TK. EXPERIMENTAL STUDY OF HEAT TRANSFER DURING QUENCHING OF A HEATED ROD. [Internet] [Thesis]. Penn State University; 2017. [cited 2021 Jan 25].
Available from: https://submit-etda.libraries.psu.edu/catalog/14854tka5098.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Almudhhi TK. EXPERIMENTAL STUDY OF HEAT TRANSFER DURING QUENCHING OF A HEATED ROD. [Thesis]. Penn State University; 2017. Available from: https://submit-etda.libraries.psu.edu/catalog/14854tka5098
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Lund
15.
Cao, Zhen.
Pool Boiling on Structured Surfaces: Heat Transfer and
Critical Heat Flux : -Experiments and Mechanistic
Modelling.
Degree: 2019, University of Lund
URL: https://lup.lub.lu.se/record/4476ab29-a1b6-41e6-9446-771360de710c
;
https://portal.research.lu.se/ws/files/70150598/Thesis_Zhen.pdf
► In this thesis, pool boiling heat transfer was experimentally studied on structured surfaces with dielectric liquids (HFE-7200, NOVEC-649, FC-72), organic liquids (Acetone, Pentane) and deionized…
(more)
▼ In this thesis, pool boiling heat transfer was
experimentally studied on structured surfaces with dielectric
liquids (HFE-7200, NOVEC-649, FC-72), organic liquids (Acetone,
Pentane) and deionized water.In the first step, nanoparticle
coatings on copper surfaces were prepared by an electrophoretic
deposition method, with Cu-Zn nanoparticles (100 nm) and Cu
nanoparticles (150 nm). Two types of nanoparticle-coating surfaces
were prepared, namely nanoparticle coatings uniformly deposited on
smooth surfaces and nanoparticle coatings partially deposited on
smoothsurfaces. Pool boiling of HFE-7200 and acetone was tested on
the coating surfaces. It is found that pool boiling heat transfer
coefficients are significantly enhanced by nanoparticle coatings.
However, the uniform coating cannot enhance the critical heat flux,
while the partially-deposited coating can enhance critical heat
flux. Mechanistic heat transfer models were developed to predict
the heat transfer coefficients, considering natural convection,
transient heat conduction, microlayer evaporation and micro
convection, while the critical heat flux was analyzed from the
point of wickability and hydrodynamic instability.In the following
step, microporous coatings on copper surfaces were generated by an
electrochemical deposition method, with electrolyte solutions
(CuSO4+H2SO4). Pool boiling of HFE-7200, NOVEC-649 and water was
tested. The results show that heat transfer coefficients and
critical heat flux are enhanced, and the heat transfer coefficients
are obviously dependent on deposition-relevant parameters, like
deposition time and electrolyte concentration. Heat transfer
coefficients were discussed mechanistically and empirically by a
mechanistic model and correlations, while the critical heat flux
was predicted by a modified force balance model which considers the
forces exerted on vapor and assumes occurrence of the critical heat
flux when the vapor expands on surfaces.Finally, hybrid micro/nano
structures were fabricated on copper surfaces by femtosecond laser
machining and electrophoretic deposition, and on silicon wafers by
dry etching and electrostatic deposition. Pool boiling of acetone
and FC-72 was investigated on the copper surfaces and the silicon
wafers, respectively. It is found that the hybrid structures induce
higher heat transfer coefficients than sole structures and
wickability plays an important role on enhancement of the critical
heat flux.
Subjects/Keywords: pool boiling; heat transfer; critical heat flux; bubble dynamics; surface modification
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APA (6th Edition):
Cao, Z. (2019). Pool Boiling on Structured Surfaces: Heat Transfer and
Critical Heat Flux : -Experiments and Mechanistic
Modelling. (Doctoral Dissertation). University of Lund. Retrieved from https://lup.lub.lu.se/record/4476ab29-a1b6-41e6-9446-771360de710c ; https://portal.research.lu.se/ws/files/70150598/Thesis_Zhen.pdf
Chicago Manual of Style (16th Edition):
Cao, Zhen. “Pool Boiling on Structured Surfaces: Heat Transfer and
Critical Heat Flux : -Experiments and Mechanistic
Modelling.” 2019. Doctoral Dissertation, University of Lund. Accessed January 25, 2021.
https://lup.lub.lu.se/record/4476ab29-a1b6-41e6-9446-771360de710c ; https://portal.research.lu.se/ws/files/70150598/Thesis_Zhen.pdf.
MLA Handbook (7th Edition):
Cao, Zhen. “Pool Boiling on Structured Surfaces: Heat Transfer and
Critical Heat Flux : -Experiments and Mechanistic
Modelling.” 2019. Web. 25 Jan 2021.
Vancouver:
Cao Z. Pool Boiling on Structured Surfaces: Heat Transfer and
Critical Heat Flux : -Experiments and Mechanistic
Modelling. [Internet] [Doctoral dissertation]. University of Lund; 2019. [cited 2021 Jan 25].
Available from: https://lup.lub.lu.se/record/4476ab29-a1b6-41e6-9446-771360de710c ; https://portal.research.lu.se/ws/files/70150598/Thesis_Zhen.pdf.
Council of Science Editors:
Cao Z. Pool Boiling on Structured Surfaces: Heat Transfer and
Critical Heat Flux : -Experiments and Mechanistic
Modelling. [Doctoral Dissertation]. University of Lund; 2019. Available from: https://lup.lub.lu.se/record/4476ab29-a1b6-41e6-9446-771360de710c ; https://portal.research.lu.se/ws/files/70150598/Thesis_Zhen.pdf
Rochester Institute of Technology
16.
Shukla, Maharshi Y.
Influence of Liquid Height on Pool Boiling Heat Transfer.
Degree: MS, Mechanical Engineering, 2020, Rochester Institute of Technology
URL: https://scholarworks.rit.edu/theses/10649
► As technology advances due to continuous research, devices are becoming more compact, efficient, and powerful. Therefore, heat rejection from such devices becomes ever so…
(more)
▼ As technology advances due to continuous research, devices are becoming more compact, efficient, and powerful. Therefore,
heat rejection from such devices becomes ever so
critical to maximizing their potential. Compared to other
heat extraction methods, boiling provides one of the highest
heat transfer coefficients. The
heat extraction due to the boiling process is limited to the
Critical Heat Flux (
CHF). At
CHF, an insulating layer of escaping bubbles forms upon the surface to prevent boiling continuity. Subsequently, the surface temperature increases uncontrollably, leading to a system failure. Hence, the elevation of
CHF is
critical to boiling enhancement. Improvements to the
heat transfer process can be made with either surface manipulation or liquid manipulation. Based on previous studies, it is found that the removal of bubbles from the heater surface is
critical to enhancing performance. Therefore, it is hypothesized that if a bubble can be encouraged to reach liquid-gas the interface quickly, gains in the boiling performance can be achieved. Due to the vapor bubble's movement in liquid bulk, it becomes
critical to understand the influence of liquid height on pool boiling for enhancement. While pool boiling enhancement using heating surface modification is extensively studied and documented, there is a research gap between understanding the effect of liquid height at high
heat fluxes. Thus, this study tries to evaluate the influence of liquid height on pool boiling performance at higher
heat fluxes and identify the underlying bubble movement mechanism. It is observed that as
CHF increases with liquid height. Moreover, it is observed that bubble movement is more effortless at low liquid height resulting in higher HTC. On the other hand, larger liquid height provides improved rewetting of the surface resulting in higher
CHF. Upon analysis of high-speed recording of the escaping bubbles, it was observed that the maximum
heat transfer coefficient is observed when the liquid height is about four times the height of the departing bubble diameter.
Advisors/Committee Members: Satish Kandlikar.
Subjects/Keywords: Critical heat flux; Heat transfer coefficient; Pool boiling
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APA (6th Edition):
Shukla, M. Y. (2020). Influence of Liquid Height on Pool Boiling Heat Transfer. (Masters Thesis). Rochester Institute of Technology. Retrieved from https://scholarworks.rit.edu/theses/10649
Chicago Manual of Style (16th Edition):
Shukla, Maharshi Y. “Influence of Liquid Height on Pool Boiling Heat Transfer.” 2020. Masters Thesis, Rochester Institute of Technology. Accessed January 25, 2021.
https://scholarworks.rit.edu/theses/10649.
MLA Handbook (7th Edition):
Shukla, Maharshi Y. “Influence of Liquid Height on Pool Boiling Heat Transfer.” 2020. Web. 25 Jan 2021.
Vancouver:
Shukla MY. Influence of Liquid Height on Pool Boiling Heat Transfer. [Internet] [Masters thesis]. Rochester Institute of Technology; 2020. [cited 2021 Jan 25].
Available from: https://scholarworks.rit.edu/theses/10649.
Council of Science Editors:
Shukla MY. Influence of Liquid Height on Pool Boiling Heat Transfer. [Masters Thesis]. Rochester Institute of Technology; 2020. Available from: https://scholarworks.rit.edu/theses/10649
Kansas State University
17.
Dahariya, Smreeti.
High-pressure
pool-boiling heat transfer enhancement and mechanism on engineered
surfaces.
Degree: PhD, Department of Mechanical and
Nuclear Engineering, 2020, Kansas State University
URL: http://hdl.handle.net/2097/40311
► Boiling has received considerable attention in the technology advancement of electronics cooling for high-performance computing applications. Two-phase cooling has an advantage over a single-phase cooling…
(more)
▼ Boiling has received considerable attention in the
technology advancement of electronics cooling for high-performance
computing applications. Two-phase cooling has an advantage over a
single-phase cooling in the high
heat removal rate with a small
thermal gradient due to the latent
heat of vaporization. Many
surface modifications have been done in the past including surface
roughness, mixed wettability and, porous wick copper play a crucial
role in the liquid-vapor phase change
heat transfer. However, the
mechanisms of high-pressure pool-boiling
heat transfer enhancement
due to surface modifications has not been well studied or
understood. The properties of water, such as the latent
heat of
vaporization, surface tension, the difference in specific volume of
liquid and vapor, decrease at high-pressure. High-pressure
pool-boiling
heat transfer enhancement is studied fundamentally on
various engineered surfaces. The boiling tests are performed at a
maximum pressure of 90 psig (620.5 kPa) and then compared to
results at 0 psig (0 kPa). The results indicate that the pressure
influences the boiling performance through changes in bubble
dynamics. The bubble departure diameter, bubble departure
frequency, and the active nucleation sites change with pressure.
The pool-boiling
heat transfer enhancement of a Teflon© coated
surface is also experimentally tested, using water as the working
fluid. The boiling results are compared with a plain surface at two
different pressures, 30 and 45 psig. The maximum
heat transfer
enhancement is found at the low
heat fluxes. At high
heat fluxes, a
negligible effect is observed in HTC. The primary reasons for the
HTC enhancement at low
heat fluxes are active nucleation sites at
low wall superheat and bubble departure size. The Teflon© coated
surface promotes nucleation because of the lower surface energy
requirement.
The boiling results are also obtained for wick
surfaces. The wick surfaces are fabricated using a sintering
process. The boiling results are compared with a plain surface. The
reasons for enhancements in the pool-boiling performance are
primarily due to increased bubble generation, higher bubble release
frequency, reduced thermal-hydraulic length modulation, and
enhanced thermal conductivity due to the sintered wick layer. The
analysis suggests that the Rayleigh-
critical wavelength decreases
by 4.67 % of varying pressure, which may cause the bubble pinning
between the gaps of sintered particles and avoids the bubble
coalescence. Changes in the pitch distance indicate that a
liquid-vapor phase separation happens at the solid/liquid
interface, which impacts the
heat-transfer performance
significantly.
Similarly, the role of the high-pressure over the
wicking layer is further analyzed and studied. It is found that the
critical flow length, λu reduces by three times with 200 μm
particles. The results suggest that the porous wick layer provides
a capillary-assist to liquid flow effect, and delays the surface
dry out. The surface modification and the pressure amplify the
boiling
heat…
Advisors/Committee Members: Amy R. Betz.
Subjects/Keywords: Critical
Heat Flux; Heat
Transfer Coefficient;
Thermal-Hydraulic;
Rayleigh-Critical Wavelength; Pinning
Mechanism; Capillary
Pressure
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MLA ·
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Manager
APA (6th Edition):
Dahariya, S. (2020). High-pressure
pool-boiling heat transfer enhancement and mechanism on engineered
surfaces. (Doctoral Dissertation). Kansas State University. Retrieved from http://hdl.handle.net/2097/40311
Chicago Manual of Style (16th Edition):
Dahariya, Smreeti. “High-pressure
pool-boiling heat transfer enhancement and mechanism on engineered
surfaces.” 2020. Doctoral Dissertation, Kansas State University. Accessed January 25, 2021.
http://hdl.handle.net/2097/40311.
MLA Handbook (7th Edition):
Dahariya, Smreeti. “High-pressure
pool-boiling heat transfer enhancement and mechanism on engineered
surfaces.” 2020. Web. 25 Jan 2021.
Vancouver:
Dahariya S. High-pressure
pool-boiling heat transfer enhancement and mechanism on engineered
surfaces. [Internet] [Doctoral dissertation]. Kansas State University; 2020. [cited 2021 Jan 25].
Available from: http://hdl.handle.net/2097/40311.
Council of Science Editors:
Dahariya S. High-pressure
pool-boiling heat transfer enhancement and mechanism on engineered
surfaces. [Doctoral Dissertation]. Kansas State University; 2020. Available from: http://hdl.handle.net/2097/40311
McMaster University
18.
Gocmanac, Marko.
Critical Heat Flux for a Downwards Facing Disk in a Subcooled Pool Boiling Environment.
Degree: MASc, 2011, McMaster University
URL: http://hdl.handle.net/11375/11813
► An experimental investigation of the physical feasibility of thermal creep failure of the Calandria Vessel under a severe accident load is presented in this…
(more)
▼ An experimental investigation of the physical feasibility of thermal creep failure of the Calandria Vessel under a severe accident load is presented in this thesis. Thermal creep failure is postulated to occur if film boiling is instigated in the Shield Tank Water surrounding the Calandria Vessel. The objective of this experimental study is to measure the Critical Heat Flux (CHF) for a representative geometry in environmental conditions similar to those existing in the CANDU Calandria Vessel and Shield Tank Water. Two geometries of downwards facing surfaces are studied. The first is termed the ‘confined’ study in which bubble motion is demarcated to the heated surface. The second is termed the ‘unconfined’ study where individual bubbles are free to move along the heated surface and vent in any direction. The method used in the confined study is novel and involves the placement of a lip surrounding the heated surface. The level of confinement is adjusted by varying the inclination angle. Data has been obtained for Bond Numbers (Bo) 0, 1.5, 3, 3.6 and 11.8 with corresponding qCHF 596, 495, 295, 223, and 187 kW/m2, respectively. A correlation relating the CHF to level of confinement is stated. The CHF results are in good agreement with Theofanous et. al. (1994), as is the observation that a transition angle is observed in the correlation. The transition angle in this study is found to be ~5.5°. The obtained nucleate boiling curves are compared to Su et. al. (2008) data for similar Bo and excellent agreement is achieved in the medium to high heat flux regions. The unconfined study consists of a downward facing plate in a pool of subcooled water. The obtained nucleate boiling curve is compared with the Stephan-Andelsalam correlation and agreement is not observed. There were visibly different trends in the convective heat transfer coefficient with a mean difference of 31%. The experimental data is compared to data obtained by Nishikawa et. al. (1984) and is found to be in acceptable agreement. The power requirement to instigate film boiling was not met, meaning that the CHF is greater than 1 MW/m2. Visual observations are made and an argument is based on the premise that the phenomenon of dryout for a downwards facing surface is similar to that of an upwards facing surface. The theory and current acceptance of CHF for an upwards facing surface is discussed—in particular Zuber’s “Hydrodynamic Limit” of 1.1 MW/m2, Dhir (1992) and recent experimental evidence from Theofanous et. al. (2002). These three studies were found to be in agreement with results presented here. The experimental evidence presented herein supports the statement that thermal creep failure of the Calandria Vessel is physically unreasonable under analyzed severe accident loads.
Master of Applied Science (MASc)
Advisors/Committee Members: Luxat, John C., Novog, David, Novog, David, Engineering Physics.
Subjects/Keywords: Critical Heat Flux Pool Boiling; Heat Transfer, Combustion; Nuclear Engineering; Heat Transfer, Combustion
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APA (6th Edition):
Gocmanac, M. (2011). Critical Heat Flux for a Downwards Facing Disk in a Subcooled Pool Boiling Environment. (Masters Thesis). McMaster University. Retrieved from http://hdl.handle.net/11375/11813
Chicago Manual of Style (16th Edition):
Gocmanac, Marko. “Critical Heat Flux for a Downwards Facing Disk in a Subcooled Pool Boiling Environment.” 2011. Masters Thesis, McMaster University. Accessed January 25, 2021.
http://hdl.handle.net/11375/11813.
MLA Handbook (7th Edition):
Gocmanac, Marko. “Critical Heat Flux for a Downwards Facing Disk in a Subcooled Pool Boiling Environment.” 2011. Web. 25 Jan 2021.
Vancouver:
Gocmanac M. Critical Heat Flux for a Downwards Facing Disk in a Subcooled Pool Boiling Environment. [Internet] [Masters thesis]. McMaster University; 2011. [cited 2021 Jan 25].
Available from: http://hdl.handle.net/11375/11813.
Council of Science Editors:
Gocmanac M. Critical Heat Flux for a Downwards Facing Disk in a Subcooled Pool Boiling Environment. [Masters Thesis]. McMaster University; 2011. Available from: http://hdl.handle.net/11375/11813
NSYSU
19.
Liu, Hao-hsiang.
Spray Heat Transfer with Different Nanofluids.
Degree: Master, Mechanical and Electro-Mechanical Engineering, 2015, NSYSU
URL: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0621115-133426
► This study aims to establish a spray cooling system with nanofluids and investigate its heat transfer performance. In previous study of spray cooling, nozzle diameter…
(more)
▼ This study aims to establish a spray cooling system with nanofluids and investigate its
heat transfer performance. In previous study of spray cooling, nozzle diameter (dj), volumetric flow rate(Q), distance(Z) between nozzle and test surface, and subcooling temperature(Tsub) and so on will influence
heat transfer performance. However, in our study, foucs on
heat transfer performance enhancement by nanofluids, so all of mentioned parameter above are constant, which dj is 270(μm), Q is 0.36(L/min), Z is 30(mm) and (Tsub) is 72(â). A brass block was used as the test surface in the experiment. This study then added different nanoparticles (silver, carbon nanotube, aluminum, titanium dioxide, silicon dioxide, aluminum oxide, and ferric ferrous oxide) into the deionized water to produce the nanofluids. The nanofluids were later atomized with nozzle and sprayed on the test surface to improve the
heat dissipation capability of the spray cooling system. Using steady-state method and transient method in the experiment, this study observed the boiling phenomenon when spraying the deionized water and different nanofluids with different concentration on the test surface, and recorded the temperature variation on the test surface. The results were presented in the boiling curve graph and the cooling curve graph. The ultimate objective of this study is to compare the
heat dissipation performance of the nanofluids made of major nanoparticles available in the market with that of the deionized water and make an in-depth analysis, hoping the results can be applied to electronic component
heat sinks and to solve the problem of rapid increase of thermal power on the electronic componentsâ unit areas.
Advisors/Committee Members: Mei-Ling Wu (chair), Shou-Shing Hsieh (committee member), Chi-Hui Chien (chair), Cheng-Tsung Liu (chair).
Subjects/Keywords: nanofluid; spray cooling; cooling curve; boiling curve; critical heat flux
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Manager
APA (6th Edition):
Liu, H. (2015). Spray Heat Transfer with Different Nanofluids. (Thesis). NSYSU. Retrieved from http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0621115-133426
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Liu, Hao-hsiang. “Spray Heat Transfer with Different Nanofluids.” 2015. Thesis, NSYSU. Accessed January 25, 2021.
http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0621115-133426.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Liu, Hao-hsiang. “Spray Heat Transfer with Different Nanofluids.” 2015. Web. 25 Jan 2021.
Vancouver:
Liu H. Spray Heat Transfer with Different Nanofluids. [Internet] [Thesis]. NSYSU; 2015. [cited 2021 Jan 25].
Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0621115-133426.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Liu H. Spray Heat Transfer with Different Nanofluids. [Thesis]. NSYSU; 2015. Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0621115-133426
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
NSYSU
20.
Lin, Jhen.
Analysis of Flow Field and Heat Transfer Characteristics of Spray Cooling through A Twin-fluid Nozzle.
Degree: Master, Mechanical and Electro-Mechanical Engineering, 2018, NSYSU
URL: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0715118-082448
► This experiment mainly discusses the twin-fluid nozzle with the diameter of 1.6 mm by changing different experimental parameters, such as the spray height (H=40 mm,…
(more)
▼ This experiment mainly discusses the twin-fluid nozzle with the diameter of 1.6 mm by changing different experimental parameters, such as the spray height (H=40 mm, 50 mm, 60 mm), the mass ratio of air to liquid (R = 0.145, 0.194, 0.242, 0.259 , 0.323) and the surface temperature (Tw = 25 °C, 75 °C, 125 °C) to observe the flow field and temperature field.
In the experiment, the heater system consisted of the copper block and heating rods, DI water is used as the working fluid. The velocity distribution is observed by μPIV and the dimension of the particle is observed by IPI; the temperature field measurements, using the thermocouple (K-Type) for the cooling experiment, calculate and analysis to obtain the optimal
critical heat flux (
CHF).
The experimental results show the optimal
critical heat flux and the smallest particle size occurs when the spray height of 50 mm and the gas-liquid ratio of 0.242.
Advisors/Committee Members: Ru Yang (committee member), Chao-Kuang Chen (chair), Shou-Shing Hsieh (committee member), C.J. Ho (chair).
Subjects/Keywords: Twin-fluid nozzle; Spray cooling; Critical heat flux; μPIV; IPI
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APA ·
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Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Lin, J. (2018). Analysis of Flow Field and Heat Transfer Characteristics of Spray Cooling through A Twin-fluid Nozzle. (Thesis). NSYSU. Retrieved from http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0715118-082448
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Lin, Jhen. “Analysis of Flow Field and Heat Transfer Characteristics of Spray Cooling through A Twin-fluid Nozzle.” 2018. Thesis, NSYSU. Accessed January 25, 2021.
http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0715118-082448.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Lin, Jhen. “Analysis of Flow Field and Heat Transfer Characteristics of Spray Cooling through A Twin-fluid Nozzle.” 2018. Web. 25 Jan 2021.
Vancouver:
Lin J. Analysis of Flow Field and Heat Transfer Characteristics of Spray Cooling through A Twin-fluid Nozzle. [Internet] [Thesis]. NSYSU; 2018. [cited 2021 Jan 25].
Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0715118-082448.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Lin J. Analysis of Flow Field and Heat Transfer Characteristics of Spray Cooling through A Twin-fluid Nozzle. [Thesis]. NSYSU; 2018. Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0715118-082448
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Univerzitet u Beogradu
21.
Pezo, Milada L.
Numerička simulacija krize ključanja u isparivačkim
cevima.
Degree: Mašinski fakultet, 2013, Univerzitet u Beogradu
URL: https://fedorabg.bg.ac.rs/fedora/get/o:6576/bdef:Content/get
► Mašinstvo - Termoenergetika / Mechanical engineering - Thermal energetics
Predmet ovog rada je numerička simulacija i analiza trodimenzionalnog dvofaznog strujanja i istraživanje mehanizama krize ključanja…
(more)
▼ Mašinstvo - Termoenergetika / Mechanical
engineering - Thermal energetics
Predmet ovog rada je numerička simulacija i analiza
trodimenzionalnog dvofaznog strujanja i istraživanje mehanizama
krize ključanja u isparivačkim cevima. Kriza ključanja je
nepovoljna pojava. Nagli porast temperature zida cevi izaziva
termomehanička naprezanja, koja mogu dovesti do pojave prskotina i
pucanja cevi pod pritiskom. Razvijen je matematički model dvofaznog
strujanja u isparivačkoj cevi,koji se sastoji od jednačina održanja
mase, količine kretanja i energije za obe faze. Sastoji se od
sistema parcijalnih diferencijalnih jednačinakoje su rečavane za
definisane granične uslove.Bilo je neophodno uvesti i modeliranje i
numeričku simulaciju na mikro nivou, jer je bilo potrebno ispitati
i proces pojave i rasta mehura, kao i ponašanje dvofazne mešavine
na zagrejačkoj površini na makroskopskom nivou. Rezultati
numeričkih simulacija su upoređeni sa raspoloživim eksperimentalnim
rezultatima.
Advisors/Committee Members: Stevanović, Vladimir, 1960-.
Subjects/Keywords: boiling; critical heat flux; boiling crises; numerical
simulation
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APA ·
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Manager
APA (6th Edition):
Pezo, M. L. (2013). Numerička simulacija krize ključanja u isparivačkim
cevima. (Thesis). Univerzitet u Beogradu. Retrieved from https://fedorabg.bg.ac.rs/fedora/get/o:6576/bdef:Content/get
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Pezo, Milada L. “Numerička simulacija krize ključanja u isparivačkim
cevima.” 2013. Thesis, Univerzitet u Beogradu. Accessed January 25, 2021.
https://fedorabg.bg.ac.rs/fedora/get/o:6576/bdef:Content/get.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Pezo, Milada L. “Numerička simulacija krize ključanja u isparivačkim
cevima.” 2013. Web. 25 Jan 2021.
Vancouver:
Pezo ML. Numerička simulacija krize ključanja u isparivačkim
cevima. [Internet] [Thesis]. Univerzitet u Beogradu; 2013. [cited 2021 Jan 25].
Available from: https://fedorabg.bg.ac.rs/fedora/get/o:6576/bdef:Content/get.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Pezo ML. Numerička simulacija krize ključanja u isparivačkim
cevima. [Thesis]. Univerzitet u Beogradu; 2013. Available from: https://fedorabg.bg.ac.rs/fedora/get/o:6576/bdef:Content/get
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Illinois – Urbana-Champaign
22.
Bottini, Joseph Larkin.
Influence of wettability on boiling heat transfer and critical heat flux in vertical flow boiling.
Degree: MS, Nuclear, Plasma, Radiolgc Engr, 2018, University of Illinois – Urbana-Champaign
URL: http://hdl.handle.net/2142/101070
► The critical heat flux (CHF) marks the upper limit of safe operation of heat transfer systems that utilize two-phase boiling heat transfer. In a heat-flux-controlled…
(more)
▼ The
critical heat flux (
CHF) marks the upper limit of safe operation of
heat transfer systems that utilize two-phase boiling
heat transfer. In a
heat-
flux-controlled system, exceeding the
CHF results in rapid temperature excursions which can be catastrophic for system components. In nuclear power generation, the initiation of a
CHF event may cause fuel damage through fuel melting or through zircaloy oxidation.
CHF marks the upper limit for safe reactor operation in light-water reactor systems. The understanding of the physical triggering mechanisms for
CHF and the accurate prediction of
CHF values is important not only for safe reactor operation, but also for efficient plant design and effective fuel utilization. Gamma radiation present in commercial nuclear reactors may affect the surface wettability of fuel rods through the Radiation Induced Surface Activation (RISA) effect, and present power limits on nuclear reactors may be underestimated. Recent studies have focused on the influence of surface wettability on the departure from nucleate boiling (DNB) through surface modifications and coatings, though many of these studies are limited to pool boiling systems.
In this thesis, the surface wettability influence is studied on the boiling curves and specifically the point of DNB. A femtosecond laser is used to texture the surface to change the wettability from hydrophilic to hydrophobic. A parametric study is performed with mass
flux, pressure, and inlet subcooling in a vertical rectangular channel that is heated from one side.
CHF excursions are triggered under various system conditions and are compared with existing models. For the experimental conditions considered, the hydrophobic surface showed delayed onset of nucleate boiling compared to the hydrophilic surface, shifting the boiling curves to higher wall superheat. The hydrophobic surface also showed significantly lower
CHF for the same system conditions and less sensitivity to changes in subcooling. Few models accurately predicted the initiation of
CHF, and a more conservative model is needed that more accurately incorporates the effect of surface wettability.
Advisors/Committee Members: Brooks, Caleb S (advisor), Kozlowski, Tomasz (committee member).
Subjects/Keywords: Critical Heat Flux; Wettability; Flow Boiling; Departure from Nucleate Boiling
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APA (6th Edition):
Bottini, J. L. (2018). Influence of wettability on boiling heat transfer and critical heat flux in vertical flow boiling. (Thesis). University of Illinois – Urbana-Champaign. Retrieved from http://hdl.handle.net/2142/101070
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Bottini, Joseph Larkin. “Influence of wettability on boiling heat transfer and critical heat flux in vertical flow boiling.” 2018. Thesis, University of Illinois – Urbana-Champaign. Accessed January 25, 2021.
http://hdl.handle.net/2142/101070.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Bottini, Joseph Larkin. “Influence of wettability on boiling heat transfer and critical heat flux in vertical flow boiling.” 2018. Web. 25 Jan 2021.
Vancouver:
Bottini JL. Influence of wettability on boiling heat transfer and critical heat flux in vertical flow boiling. [Internet] [Thesis]. University of Illinois – Urbana-Champaign; 2018. [cited 2021 Jan 25].
Available from: http://hdl.handle.net/2142/101070.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Bottini JL. Influence of wettability on boiling heat transfer and critical heat flux in vertical flow boiling. [Thesis]. University of Illinois – Urbana-Champaign; 2018. Available from: http://hdl.handle.net/2142/101070
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
23.
Morovati, Mostafa.
Impact of self-rewetting aqueous solutions on boiling with advanced heat transfer applications.
Degree: Master of Engineering (M.E.), Mechanical Engineering, 2011, City University of New York
URL: https://academicworks.cuny.edu/cc_etds_theses/54
► "Pool boiling experiments have been conducted with self-rewetting fluids consisting of aqueous butanol and pentanol solution to study the boiling heat transfer enhancement at pressures…
(more)
▼ "Pool boiling experiments have been conducted with self-rewetting fluids consisting of aqueous butanol and pentanol solution to study the boiling heat transfer enhancement at pressures of 1 ~ 4 bars. Although self-rewetting fluids have been used to enhance the performance of heat pipes, boiling heat transfer characteristics are yet to be fully understood especially at pressures above atmospheric. Pool boiling experiments with aqueous butanol and pentanol solutions were performed using an electrically heated platinum wire to obtain pool boiling heat transfer data up to the Critical Heat Flux (CHF). Aqueous solutions with butanol concentrations 2-7% showed enhanced heat transfer coefficients and CHF data at various pressure levels. Pentanol aqueous solutions were also tested on the heated wire to observe the consistency for reduce in size of the nucleated bubbles. In comparison to water, butanol aqueous solutions showed 20-270% higher values of CHF at pressures up to 4 bars. The bubble sizes were also observed to be significantly smaller in self-rewetting fluids compared to those in water at the same pressure. This observation was consistent even at higher pressures. However, for higher concentrations (i.e. butanol 5% and 7%), the CHF enhancement was diminished at higher pressures."
Subjects/Keywords: Aqueous Solutions; Critical heat flux; pressure; Engineering; Mechanical Engineering
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APA (6th Edition):
Morovati, M. (2011). Impact of self-rewetting aqueous solutions on boiling with advanced heat transfer applications. (Thesis). City University of New York. Retrieved from https://academicworks.cuny.edu/cc_etds_theses/54
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Morovati, Mostafa. “Impact of self-rewetting aqueous solutions on boiling with advanced heat transfer applications.” 2011. Thesis, City University of New York. Accessed January 25, 2021.
https://academicworks.cuny.edu/cc_etds_theses/54.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Morovati, Mostafa. “Impact of self-rewetting aqueous solutions on boiling with advanced heat transfer applications.” 2011. Web. 25 Jan 2021.
Vancouver:
Morovati M. Impact of self-rewetting aqueous solutions on boiling with advanced heat transfer applications. [Internet] [Thesis]. City University of New York; 2011. [cited 2021 Jan 25].
Available from: https://academicworks.cuny.edu/cc_etds_theses/54.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Morovati M. Impact of self-rewetting aqueous solutions on boiling with advanced heat transfer applications. [Thesis]. City University of New York; 2011. Available from: https://academicworks.cuny.edu/cc_etds_theses/54
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of California – Berkeley
24.
Lu, Ming-Chang.
Exploring the Limits of Boiling and Evaporative Heat Transfer Using Micro/Nano Structures.
Degree: Mechanical Engineering, 2010, University of California – Berkeley
URL: http://www.escholarship.org/uc/item/5rf0n0cq
► This dissertation presents a study exploring the limits of phase-change heat transfer with the aim of enhancing critical heat flux (CHF) in pool boiling and…
(more)
▼ This dissertation presents a study exploring the limits of phase-change heat transfer with the aim of enhancing critical heat flux (CHF) in pool boiling and enhancing thermal conductance in heat pipes. The state-of-the-art values of the CHF in pool boiling and the thermal conductance in heat pipes are about two orders of magnitudes smaller than the limits predicted by kinetic theory. Consequently, there seems to be plenty of room for improvement. Pool boiling refers to boiling at a surface immersed in an extensive motionless pool of liquid. Its process includes heterogeneous nucleation, growth, mergence and detachment of vapor bubbles on a heating surface. It is generally agreed that the high heat transfer coefficient of boiling could be explained by the concept of single-phase forced convection, i.e., the motion of bubbles agitating surrounding liquid is similar to the process in single-phase forced convection. The occurrence of CHF results from a formation of a vapor film on the heater surface, which reduces the thermal conductance drastically and causes a huge temperature rise on the surface. Over the past few decades, researchers were struggling to identify the exact mechanism causing CHF. General observations are that both surface properties and pool hydrodynamics could affect the values of CHF. Nanowire array-coated surfaces having a large capillary force are employed to enhance the CHF. It has been shown that CHFs on the nanowire array-coated surface could be doubled compared to the values on a plain surface. The obtained CHF of 224 ± 6.60 W/cm2 on the nanowire-array coated surface is one of the highest values reported in the boiling heat transfer. To further enhance CHF, the mechanisms that govern CHF have been systematically explored. Experimental results show that the CHF on the nanowire array-coated surface are not limited by the capillary force. Instead, the CHF are dependent on the heater size. Corresponding experiments on plain surfaces with various heater sizes also exhibits similar heater-size dependence. The CHFs on nanowire array-coated surfaces and plain surfaces are consistent with the predictions of the hydrodynamic theory while a higher CHF is obtained on the nanowire array-coated surface as compared to the plain Si surface. This suggests that the CHFs are a result of the pool hydrodynamics while surface properties modify the corresponding hydrodynamic limits. A heat pipe is a device that transports thermal energy in a very small temperature difference and thereby producing a very large thermal conductance. It relies on evaporation of liquid at the heated end of the pipe, flow of vapor between the heated and cooled end, condensation at the other end, and capillary-driven liquid flow through a porous wick between the condenser and the evaporation. The large latent heat involved in evaporation and condensation leads to very large heat flows for a small temperature drop along the heat pipe. Despite the large thermal conductance, their operation is limited by such factors as capillary…
Subjects/Keywords: Mechanical Engineering; Critical Heat Flux; Heat Pipe; Nano Wires; Pool Boiling; Wick
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APA ·
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CSE |
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APA (6th Edition):
Lu, M. (2010). Exploring the Limits of Boiling and Evaporative Heat Transfer Using Micro/Nano Structures. (Thesis). University of California – Berkeley. Retrieved from http://www.escholarship.org/uc/item/5rf0n0cq
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Lu, Ming-Chang. “Exploring the Limits of Boiling and Evaporative Heat Transfer Using Micro/Nano Structures.” 2010. Thesis, University of California – Berkeley. Accessed January 25, 2021.
http://www.escholarship.org/uc/item/5rf0n0cq.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Lu, Ming-Chang. “Exploring the Limits of Boiling and Evaporative Heat Transfer Using Micro/Nano Structures.” 2010. Web. 25 Jan 2021.
Vancouver:
Lu M. Exploring the Limits of Boiling and Evaporative Heat Transfer Using Micro/Nano Structures. [Internet] [Thesis]. University of California – Berkeley; 2010. [cited 2021 Jan 25].
Available from: http://www.escholarship.org/uc/item/5rf0n0cq.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Lu M. Exploring the Limits of Boiling and Evaporative Heat Transfer Using Micro/Nano Structures. [Thesis]. University of California – Berkeley; 2010. Available from: http://www.escholarship.org/uc/item/5rf0n0cq
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of California – Berkeley
25.
Armijo, Kenneth Miguel.
Heat Pipe Performance Enhancement with Binary Mixture Fluids that Exhibit Strong Concentration Marangoni Effects.
Degree: Mechanical Engineering, 2011, University of California – Berkeley
URL: http://www.escholarship.org/uc/item/0f86g1pf
► This research investigates the impact of Marangoni phenomena, with low mixture concentrations of alcohol and water, to enhance thermal transport capability of gravity-assisted heat pipes.…
(more)
▼ This research investigates the impact of Marangoni phenomena, with low mixture concentrations of alcohol and water, to enhance thermal transport capability of gravity-assisted heat pipes. The use of binary mixture working fluids in gravity-assisted heat pipes are shown to improve the critical heat flux (CHF) and operating performance, more so than with pure fluids. The CHF is responsible for dryout when the pumping rate of a liquid flow structure is not sufficient to provide enough fluid to the evaporator section. In the first study, heat pipe performance experiments were conducted for pure water and 2-propanol solutions with varying concentrations. Initial tests with pure water determined the optimal working fluid charge for the heat pipe; subsequent performance tests over a wide range of heat input levels were then conducted for each working fluid at this optimum value. The results indicated that some mixtures significantly enhance the heat transfer coefficient and heat flux capability of the heat pipe evaporator. For the best mixture tested, the maximum evaporator heat flux carried by the coolant without dryout was found to be 52% higher than the value for the same heat pipe using pure water as a coolant under comparable conditions. Peak evaporator heat flux values above 100 W/cm2 were achieved with some mixtures. Evaporator and condenser heat transfer coefficient data are presented and the trends are examined in the context of the expected effect of the Marangoni mechanisms on heat transfer. Analytical modeling effort was also conducted investigating the impact of Marangoni phenomena for low concentrations of 2-propanol/water and methanol/water mixtures. In real systems the addition of small levels of surface-active contaminants can affect the surface tension of the liquid-vapor interface and thermodynamic conditions in this region. Analysis was performed for three widely accepted binary mixture correlations to predict heat flux and superheat values for subatmospheric experimental data using bulk fluid and film thermodynamic properties. Due to the non-ideal nature of these alcohol/water mixtures, this study employs an average pseudo single-component (PSC) coefficient in place of an ideal heat transfer coefficient (HTC) to improve the correlation predictions. This investigation evaluates the ability for these correlations to predict strong Marangoni effects of mixtures that have large surface tension variation with concentration under subatmospheric conditions. It is not always clear that evaluation of bulk fluid properties will satisfactorily account for Marangoni effects. Analysis is also performed to assess correlation predictions for interfacial film properties rather than that of the bulk fluid. The results indicate that the use of film properties along with the PSC coefficient improves heat flux model predictions of subatmospheric experimental data by as much as 59.3% for 0.015M 2-propanol and 49.1% for 0.04M methanol/water mixtures, where strong Marangoni effects are believed to be more evident. …
Subjects/Keywords: Engineering; Energy; Chemical engineering; Critical Heat Flux; Heat Pipes; Marangoni Effects; Solar Energy
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APA ·
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APA (6th Edition):
Armijo, K. M. (2011). Heat Pipe Performance Enhancement with Binary Mixture Fluids that Exhibit Strong Concentration Marangoni Effects. (Thesis). University of California – Berkeley. Retrieved from http://www.escholarship.org/uc/item/0f86g1pf
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Armijo, Kenneth Miguel. “Heat Pipe Performance Enhancement with Binary Mixture Fluids that Exhibit Strong Concentration Marangoni Effects.” 2011. Thesis, University of California – Berkeley. Accessed January 25, 2021.
http://www.escholarship.org/uc/item/0f86g1pf.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Armijo, Kenneth Miguel. “Heat Pipe Performance Enhancement with Binary Mixture Fluids that Exhibit Strong Concentration Marangoni Effects.” 2011. Web. 25 Jan 2021.
Vancouver:
Armijo KM. Heat Pipe Performance Enhancement with Binary Mixture Fluids that Exhibit Strong Concentration Marangoni Effects. [Internet] [Thesis]. University of California – Berkeley; 2011. [cited 2021 Jan 25].
Available from: http://www.escholarship.org/uc/item/0f86g1pf.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Armijo KM. Heat Pipe Performance Enhancement with Binary Mixture Fluids that Exhibit Strong Concentration Marangoni Effects. [Thesis]. University of California – Berkeley; 2011. Available from: http://www.escholarship.org/uc/item/0f86g1pf
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Rochester Institute of Technology
26.
Mehta, Jeet.
Enhanced pool boiling of water with open microchannels over cylindrical tubes.
Degree: MS, Mechanical Engineering, 2013, Rochester Institute of Technology
URL: https://scholarworks.rit.edu/theses/6956
► Pool boiling is a stable and efficient method for transferring large quantities of heat. It is employed in a wide range of applications, including…
(more)
▼ Pool boiling is a stable and efficient method for transferring large quantities of
heat. It is employed in a wide range of applications, including steam generation in boilers, petrochemical, pharmaceutical, cryogenic and many other industrial processes. The objective of this work was to investigate the augmentation in the boiling
heat transfer rates with an array of open microchannels over a cylindrical tube. In order to develop high performance surfaces, rectangular and V-groove cross-sectional geometry microchannels were fabricated and tested over tubular test sections. These microchannels were manufactured in two configurations: circumferentially around the test section and axially along the length. The effects of the microchannel geometric parameters on pool boiling performance were studied under horizontal and vertical orientations. Twenty uniquely modified microchannel surfaces were designed, fabricated and tested. The best performance was obtained with a circumferential rectangular microchannel test section in the horizontal orientation. A maximum
heat transfer coefficient of 129 kW/m2*K was achieved at a
heat flux of 1095 kW/m2, while maintaining a wall superheat of 8.5 K. The overall enhancement factors obtained at the maximum
heat flux condition, ranged between 1.9 and 3.4 in the horizontal orientation, and 2.1 and 3.1 in the vertical orientation. The
critical heat flux for almost all the designed test surfaces was increased by a factor of at least 1.6 over a plain tube. Area normalized results indicated that factors other than area enhancement are responsible for augmenting the
heat transfer performance. High-speed videography of bubbles nucleating, growing and departing from the heated surface was performed. The bubble behavior over these open microchannels was analyzed to understand the fundamental mechanism during pool boiling. The bubble interactions in and over the open microchannels, and the liquid rewetting phenomenon greatly influence the
heat transfer performance for these surface.
Advisors/Committee Members: Kandlikar, Satish.
Subjects/Keywords: Bubble dynamics; Critical heat flux; Heat transfer enhancement; Open microchannels; Pool boiling; Tube orientation
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APA (6th Edition):
Mehta, J. (2013). Enhanced pool boiling of water with open microchannels over cylindrical tubes. (Masters Thesis). Rochester Institute of Technology. Retrieved from https://scholarworks.rit.edu/theses/6956
Chicago Manual of Style (16th Edition):
Mehta, Jeet. “Enhanced pool boiling of water with open microchannels over cylindrical tubes.” 2013. Masters Thesis, Rochester Institute of Technology. Accessed January 25, 2021.
https://scholarworks.rit.edu/theses/6956.
MLA Handbook (7th Edition):
Mehta, Jeet. “Enhanced pool boiling of water with open microchannels over cylindrical tubes.” 2013. Web. 25 Jan 2021.
Vancouver:
Mehta J. Enhanced pool boiling of water with open microchannels over cylindrical tubes. [Internet] [Masters thesis]. Rochester Institute of Technology; 2013. [cited 2021 Jan 25].
Available from: https://scholarworks.rit.edu/theses/6956.
Council of Science Editors:
Mehta J. Enhanced pool boiling of water with open microchannels over cylindrical tubes. [Masters Thesis]. Rochester Institute of Technology; 2013. Available from: https://scholarworks.rit.edu/theses/6956
Rochester Institute of Technology
27.
Negi, Akshat.
Characterization of Boiling Sound at Conditions Approaching Critical Heat Flux.
Degree: MS, Mechanical Engineering, 2019, Rochester Institute of Technology
URL: https://scholarworks.rit.edu/theses/10285
► In industry, boiling heat transfer is extensively used to efficiently dissipate high heat fluxes from heated substrates. Such industrial applications of boiling include cooling…
(more)
▼ In industry, boiling
heat transfer is extensively used to efficiently dissipate high
heat fluxes from heated substrates. Such industrial applications of boiling include cooling of reactor cores in nuclear power plants, steam generation in industrial boilers, and cooling of high
heat flux generating electronic equipment. The maximum
heat flux dissipated during boiling is limited by
critical heat flux (
CHF). At
CHF, due to very high bubble generation and coalescence rates, a stable insulating vapor film is formed on the heated surface that leads to very high surface temperatures in a short time. The sudden temperature overshoot causes thermal breakdown, and therefore
CHF is disastrous in all industrial applications. Owing to limited visualization of the boiling surfaces and dependence on temperature monitoring only, boiling systems are run at relatively low
heat fluxes, ~50% of
CHF limit due to safety considerations. The study presented here is focused on developing a method for identifying and analyzing acoustic signatures in the nucleate boiling regimes and using acoustic mapping as a monitoring tool to detect impending
CHF. Initially, the sound waves generated through bubble coalescence and bubble collapse during boiling are captured for the plain copper chip. It is observed that the boiling sound is dominant in the frequency range of 400-500 Hz, while additional amplitude peaks in the frequency range of 100-200 Hz are also observed at higher
heat fluxes (>100 W/cm²). Further, it is observed that just before
CHF, there is a sudden drop in amplitude in the frequency range of 400-500 Hz. A similar study was performed on two additional microporous surfaces and similar acoustic trends as that of the plain copper chip was observed for both the chips. Coupling these observations with high speed visualization, the study indicates that a continuous acoustic mapping during boiling can be used as a tool to predict the impending
CHF in boiling systems.
Advisors/Committee Members: Satish G. Kandlikar.
Subjects/Keywords: Acoustics; Boiling heat transfer; Boiling sound; Bubble oscillation; Coalescence; Critical heat flux
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APA (6th Edition):
Negi, A. (2019). Characterization of Boiling Sound at Conditions Approaching Critical Heat Flux. (Masters Thesis). Rochester Institute of Technology. Retrieved from https://scholarworks.rit.edu/theses/10285
Chicago Manual of Style (16th Edition):
Negi, Akshat. “Characterization of Boiling Sound at Conditions Approaching Critical Heat Flux.” 2019. Masters Thesis, Rochester Institute of Technology. Accessed January 25, 2021.
https://scholarworks.rit.edu/theses/10285.
MLA Handbook (7th Edition):
Negi, Akshat. “Characterization of Boiling Sound at Conditions Approaching Critical Heat Flux.” 2019. Web. 25 Jan 2021.
Vancouver:
Negi A. Characterization of Boiling Sound at Conditions Approaching Critical Heat Flux. [Internet] [Masters thesis]. Rochester Institute of Technology; 2019. [cited 2021 Jan 25].
Available from: https://scholarworks.rit.edu/theses/10285.
Council of Science Editors:
Negi A. Characterization of Boiling Sound at Conditions Approaching Critical Heat Flux. [Masters Thesis]. Rochester Institute of Technology; 2019. Available from: https://scholarworks.rit.edu/theses/10285
Rochester Institute of Technology
28.
Liu, Felix.
A Study of Sintered Copper Porous Surfaces for Pool Boiling Enhancement.
Degree: MS, Mechanical Engineering, 2016, Rochester Institute of Technology
URL: https://scholarworks.rit.edu/theses/9321
► Miniaturization in microelectronics demands effective thermal management from high energy density devices. While current cooling solutions employ single-phase heat transfer, they are often limited…
(more)
▼ Miniaturization in microelectronics demands effective thermal management from high energy density devices. While current cooling solutions employ single-phase
heat transfer, they are often limited by high fluid temperature differences and pressure drops. Alternatively, two-phase cooling schemes offers attractive solutions to dissipate high
heat fluxes at small temperature differences. Specifically, pool boiling has the potential to dissipate high
heat fluxes without using pumps and other complex header configurations.
Two performance criterion that govern the
heat transfer in pool boiling systems are the (i)
Critical Heat Flux (
CHF), and the (ii)
Heat Transfer Coefficient. The
CHF is the upper limit in nucleate boiling, while the
Heat Transfer Coefficient dictates the efficiency of the process. The current thesis work relates to increasing the aforementioned parameters through copper porous coatings. In this work, copper substrates were coated with 3M copper powders using a drop coating and screen printing technique. Substrate bonding was achieved by sintering at elevated temperatures. The coated substrates were characterized using Scanning Electron Microscopy and Laser Confocal Microscopy which revealed the different geometrical parameters (pore sizes and coating thickness etc.) associated with the coatings. Pool boiling tests were conducted with distilled and degassed water at atmospheric pressure. A highest
Critical Heat Flux (
CHF) of 303 W/cm2 was obtained on a test sample corresponding to a coating thickness of 447 µm. This translated to a
CHF enhancement of ~135 % when compared to a plain copper surface. The effect of coating thickness on pool boiling performance was studied. High speed visualization was conducted on the test samples to identify underlying boiling mechanisms. The effect of additional nucleation sites, and wickability were evaluated in this study. The experimental observations were supplemented with analytical equations available in literature to identify driving mechanisms with the thin and thick porous coatings.
Advisors/Committee Members: Satish Kandlikar.
Subjects/Keywords: Critical heat flux; Heat transfer performance; Pool boiling; Sintered porous surface; Wickability; Wicking rate
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APA (6th Edition):
Liu, F. (2016). A Study of Sintered Copper Porous Surfaces for Pool Boiling Enhancement. (Masters Thesis). Rochester Institute of Technology. Retrieved from https://scholarworks.rit.edu/theses/9321
Chicago Manual of Style (16th Edition):
Liu, Felix. “A Study of Sintered Copper Porous Surfaces for Pool Boiling Enhancement.” 2016. Masters Thesis, Rochester Institute of Technology. Accessed January 25, 2021.
https://scholarworks.rit.edu/theses/9321.
MLA Handbook (7th Edition):
Liu, Felix. “A Study of Sintered Copper Porous Surfaces for Pool Boiling Enhancement.” 2016. Web. 25 Jan 2021.
Vancouver:
Liu F. A Study of Sintered Copper Porous Surfaces for Pool Boiling Enhancement. [Internet] [Masters thesis]. Rochester Institute of Technology; 2016. [cited 2021 Jan 25].
Available from: https://scholarworks.rit.edu/theses/9321.
Council of Science Editors:
Liu F. A Study of Sintered Copper Porous Surfaces for Pool Boiling Enhancement. [Masters Thesis]. Rochester Institute of Technology; 2016. Available from: https://scholarworks.rit.edu/theses/9321
Texas A&M University
29.
Roy, Ronita.
Hydrodynamic and Thermal Analyses of Pool Boiling Data Obtained from Experiments Performed on Flat Horizontal Heaters with Conventional and Nano-Structured Surfaces.
Degree: MS, Mechanical Engineering, 2017, Texas A&M University
URL: http://hdl.handle.net/1969.1/173269
► Pool boiling phenomena on different types of heater configurations have been explored in the heat transfer literature. Pool boiling experiments on heaters with nanostructured surfaces…
(more)
▼ Pool boiling phenomena on different types of heater configurations have been explored in the
heat transfer literature. Pool boiling experiments on heaters with nanostructured surfaces have gained popularity in contemporary literature for microchip cooling application. The thermal management challenges for cooling of electronic chips have become more acute with decrease in the size for these microchips with concomitant increase in device density and
heat flux. Pool boiling is expected to provide appropriate technology solutions to meet these challenges for high
heat flux cooling at low temperature differentials.
In this study, results obtained from pool boiling experiments were analyzed. The experiments were performed using heaters with plain surfaces (copper and silicon) and nanostructured surfaces (Anodic Aluminum Oxide/AAO). In these experiments, high speed digital image acquisition apparatus was used to record bubble dynamics (nucleation, growth and departure) for both nucleate and film boiling regimes. The videos were used to obtain the bubble diameter at departure, bubble growth rates (bubble height as a function of time) and bubble departure frequency. The objective of these experiments was to explore the change in bubble dynamics for different heater configurations in order to ascertain their role in the observed changes in the values of pool boiling
heat flux as a function of wall superheat (i.e., from the boiling curves obtained in these experiments). These experiments were performed for saturated boiling conditions as well as for liquid subcooling of 5 °C and 10 °C. The test fluid was PF-5060 (Manufacturer: 3M Corp.). The experimental apparatus utilized in this study consisted of a visualization chamber, cartridge heaters, power supply, high speed digital data acquisition system and chiller unit. Temperature nanosensors (Thin Film Thermocouples/ TFT) as well as wire bead thermocouples were used for measurement of wall superheat. Micro/ nano-fabrication techniques were utilized in this study for realizing the test surfaces integrated with temperature nanosensors.
The data gleaned from these experiments were compiled to obtain a correlation for the optimal
heat transfer for different heater surface configurations. Literature review was also performed in this study to compare the experimental results with correlations for bubble dynamics available in the literature. The experimental results for bubble dynamics show that while silicon and copper surfaces have similar values for bubble departure diameter, the variability in the bubble departure frequency values for copper heater experiments were larger than that of silicon heaters. This trend is potentially due to large variation in surface roughness on copper heaters compared to that of silicon wafers (which are single crystal silicon substrates and therefore are atomically smooth at the commencement of the experiments). Heaters with nanostructured surfaces (e.g., for AAO heaters) were observed to yield smaller bubble departure diameters and higher bubble…
Advisors/Committee Members: Banerjee, Debjyoti (advisor), Kirkland, Karen (committee member), Felts, Jonathan (committee member).
Subjects/Keywords: Pool boiling; Nanostructures; Critical Heat Flux; Heat Transfer; Boiling Curve; Departure diameter; Departure frequency
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APA (6th Edition):
Roy, R. (2017). Hydrodynamic and Thermal Analyses of Pool Boiling Data Obtained from Experiments Performed on Flat Horizontal Heaters with Conventional and Nano-Structured Surfaces. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/173269
Chicago Manual of Style (16th Edition):
Roy, Ronita. “Hydrodynamic and Thermal Analyses of Pool Boiling Data Obtained from Experiments Performed on Flat Horizontal Heaters with Conventional and Nano-Structured Surfaces.” 2017. Masters Thesis, Texas A&M University. Accessed January 25, 2021.
http://hdl.handle.net/1969.1/173269.
MLA Handbook (7th Edition):
Roy, Ronita. “Hydrodynamic and Thermal Analyses of Pool Boiling Data Obtained from Experiments Performed on Flat Horizontal Heaters with Conventional and Nano-Structured Surfaces.” 2017. Web. 25 Jan 2021.
Vancouver:
Roy R. Hydrodynamic and Thermal Analyses of Pool Boiling Data Obtained from Experiments Performed on Flat Horizontal Heaters with Conventional and Nano-Structured Surfaces. [Internet] [Masters thesis]. Texas A&M University; 2017. [cited 2021 Jan 25].
Available from: http://hdl.handle.net/1969.1/173269.
Council of Science Editors:
Roy R. Hydrodynamic and Thermal Analyses of Pool Boiling Data Obtained from Experiments Performed on Flat Horizontal Heaters with Conventional and Nano-Structured Surfaces. [Masters Thesis]. Texas A&M University; 2017. Available from: http://hdl.handle.net/1969.1/173269
University of Toronto
30.
Nejad, Saman Shaban.
Bubble Formation in a Horizontal Channel at Subcooled Flow Condition.
Degree: 2013, University of Toronto
URL: http://hdl.handle.net/1807/42917
► Bubble nucleation at subcooled flow boiling condition in a horizontal annular channel with a square cross section by the use of high-speed camera is investigated.…
(more)
▼ Bubble nucleation at subcooled flow boiling condition in a horizontal annular channel with a square cross section by the use of high-speed camera is investigated. The channel represents a scaled-down version of a single rod of CANDU reactor core. The experiments were performed by the use of water at pressures between 1-3 atm, constant heat flux of 0.124 MW/m2, liquid bulk subcooling of 32-1 °C and mean flow velocities of 0.3-0.4 m/s. Bubble lift-off diameters were obtained from direct high speed videography. The developed model for the bubble lift-off diameter was obtained by analyzing the forces acting on a bubble. Furthermore, a model for the bubble growth rate constant was suggested. The proposed model was then compared to experimental data and it has shown a good agreement with the experimental data. Additionally, the effects of liquid bulk subcooling, liquid pressure and mean flow velocity on bubble lift-off diameter were investigated.
MAST
Advisors/Committee Members: Nasser, Ashgriz, Mechanical and Industrial Engineering.
Subjects/Keywords: Subcooled two phase flow; Bubble nucleation; Critical Heat Flux; Heat transfer; 0548
Record Details
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Record Details
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APA ·
Chicago ·
MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Nejad, S. S. (2013). Bubble Formation in a Horizontal Channel at Subcooled Flow Condition. (Masters Thesis). University of Toronto. Retrieved from http://hdl.handle.net/1807/42917
Chicago Manual of Style (16th Edition):
Nejad, Saman Shaban. “Bubble Formation in a Horizontal Channel at Subcooled Flow Condition.” 2013. Masters Thesis, University of Toronto. Accessed January 25, 2021.
http://hdl.handle.net/1807/42917.
MLA Handbook (7th Edition):
Nejad, Saman Shaban. “Bubble Formation in a Horizontal Channel at Subcooled Flow Condition.” 2013. Web. 25 Jan 2021.
Vancouver:
Nejad SS. Bubble Formation in a Horizontal Channel at Subcooled Flow Condition. [Internet] [Masters thesis]. University of Toronto; 2013. [cited 2021 Jan 25].
Available from: http://hdl.handle.net/1807/42917.
Council of Science Editors:
Nejad SS. Bubble Formation in a Horizontal Channel at Subcooled Flow Condition. [Masters Thesis]. University of Toronto; 2013. Available from: http://hdl.handle.net/1807/42917
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