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You searched for subject:(Droplet characteristics). Showing records 1 – 2 of 2 total matches.

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NSYSU

1. Lin, Ming-siang. Flow/Heat Transfer Characteristics Analysis of Spray Cooling.

Degree: Master, Mechanical and Electro-Mechanical Engineering, 2016, NSYSU

Spray cooling has been proven to be efficient in managing high power thermal load. Due to the MEMS technology, the spray nozzle plate has been reduced to minute size or even microscale with low power consumption. However, several of the key heat transfer mechanisms are still not well understood. The main goal of this study is to observe the velocity characteristics of the spray field, droplets distribution along the downstream, the boiling/cooling curves and the cooling performance. In this study, we use a commercial PZT nozzle plate with three different nozzle diameters of dj = 7 μm, 10 μm and 35 μm. The corresponding volumetric rate is 3.47 ml/min, 6.53 ml/min and 50 ml/min, respectively. The PZT atomizer is composed of Ni-Co alloy nozzle plate bounded to the PZT ring actuator. The approximate numbers of micro nozzles on a circular Ni-Co plate are 2288 and 1071 corresponding to dj = 7 μm and 35 μm, respectively. We use DI water as working fluid spraying on a copper flat heater which the target surface area is 2x2 cm2 and with a 14.5 mm thickness. The main experimental parameters are the spray height, H (30, 40, 50, 70, 90 mm), the initial temperature of the heater surface, Ts (300, 200, 100 ºC), and nozzle diameter, dj (7, 10, 35 μm). Both a transient and steady boiling curve are obtained as well as the quenching cooling curve. The results show that the average heat transfer coefficient (HTC) and the associated critical heat flux(CHF) could be over 2W/cm-K(HTC) and 200W/cm2(CHF), respectively. Furthermore, by using micro particle image velocimetry (μPIV) and Interferometric particle Imaging (IPI) systems, we could image and analyze the velocity and droplet size of the spray field. Besides, we also study the droplets dynamics to understand the droplet-surface interactions relevant to spray cooling. Advisors/Committee Members: C. J. Ho (chair), Shou-Shing Hsieh (committee member), Chao-Kuang Chen (chair), Chi-Hui Chien (committee member).

Subjects/Keywords: PZT nozzle plate; Droplet characteristics; IPI; μPIV; boiling/cooling curve; Spray cooling

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Lin, M. (2016). Flow/Heat Transfer Characteristics Analysis of Spray Cooling. (Thesis). NSYSU. Retrieved from http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0731116-085423

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, Ming-siang. “Flow/Heat Transfer Characteristics Analysis of Spray Cooling.” 2016. Thesis, NSYSU. Accessed August 20, 2019. http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0731116-085423.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Lin, Ming-siang. “Flow/Heat Transfer Characteristics Analysis of Spray Cooling.” 2016. Web. 20 Aug 2019.

Vancouver:

Lin M. Flow/Heat Transfer Characteristics Analysis of Spray Cooling. [Internet] [Thesis]. NSYSU; 2016. [cited 2019 Aug 20]. Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0731116-085423.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Lin M. Flow/Heat Transfer Characteristics Analysis of Spray Cooling. [Thesis]. NSYSU; 2016. Available from: http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0731116-085423

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


Indian Institute of Science

2. Prasad, Boggavarapu V V S U. Experimental Studies on Biodiesel Spray Characteristics : Effects of Evaporation & Nozzle Cavitation.

Degree: 2016, Indian Institute of Science

Vegetable oil methyl esters obtained by transesterification of vegetable oils are considered to be suitable alternative fuels for diesel engines. However, higher viscosity, surface tension and boiling temperatures of biodiesels may adversely affect spray characteristics as compared to those of diesel. Thus, spray characteristics of Jatropha Methyl Ester (JME) are studied by comparing them to those of diesel in a high-pressure chamber with optical access to simulate the actual in-cylinder conditions. Also, the effect of inner-nozzle cavitation on JME and diesel sprays is studied by utilizing two nozzles, one with sharp entry-radius and the other with larger entry-radius. Finally, spray characteristics of surrogate fuels such as n-dodecane and n-hexadecane are also studied. The first part of the work concerning precise measurements of inner-nozzle geometry revealed that one of the nozzles has a hole diameter of 190-µm and entry-radius of around 70-µm, while the other has a hole diameter of 208-µm and entry-radius of around 10-µm. Injection rate-shape and coefficient of discharge for JME and diesel flow through the two nozzles were then measured. It was observed that while the coefficients of discharge (Cd) are almost identical for JME and diesel, the nozzle with entry radius of 10-µm exhibited around 20% lower Cd than that of the entry-radius of 70-µm. This observation coupled with insight from complementary CFD simulations of inner-nozzle flow showed that the lower Cd of the nozzle with entry-radius of 10-µm could be attributed to inner-nozzle cavitation. The second part of the work involved measurement of non-evaporating spray characteristics including spray-tip penetration, spray-cone angle and droplet size measurement under realistic operating conditions using techniques such as Shadowgraphy and Particle/Droplet Imaging Analysis (PDIA). The non-evaporating spray of the fuels are studied by injecting them using a common-rail fuel injection system into the high-pressure chamber maintained at room temperature. Experimental results show that JME is associated with a slightly faster spray-tip penetration and narrow spray-cone angle indicating inferior spray atomization which is confirmed by around 5% larger droplet sizes. Slower spray-tip penetration, wider spray-cone angle and around 5% smaller droplet sizes are observed for the spray from the cavitating nozzle. Thus, the inner nozzle cavitation is observed to improve the atomization of diesel and JME sprays. The differences in spray characteristics of JME and diesel reduce as the injection pressure increases. The spray-tip penetrations of both surrogates are observed to almost match that of diesel. The third part of the work involved measurements of evaporating spray liquid length, vapour penetration and spread angle for JME, diesel and surrogates at conditions of 50 bar chamber pressure and 900 K temperature. It is observed that the JME exhibits around 16% longer liquid length than that of diesel. The liquid length of n-dodecane is significantly lower than that of… Advisors/Committee Members: Ravikrishna, R V.

Subjects/Keywords: Biodiesel Spray - Evaporation Effect; Biodiesel Spray; Jatropha Methyl Ester (JME); Macroscopic Structure - Droplet Size; Inner-Nozzle Geometry; Inner-nozzle Flow; Particle/Droplet Imaging Analysis (PDIA); Biodiesel Spray Characteristics; Nozzel Cavitation Effect; Mechanical Engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Prasad, B. V. V. S. U. (2016). Experimental Studies on Biodiesel Spray Characteristics : Effects of Evaporation & Nozzle Cavitation. (Thesis). Indian Institute of Science. Retrieved from http://etd.iisc.ernet.in/2005/3738 ; http://etd.iisc.ernet.in/abstracts/4610/G28309-Abs.pdf

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):

Prasad, Boggavarapu V V S U. “Experimental Studies on Biodiesel Spray Characteristics : Effects of Evaporation & Nozzle Cavitation.” 2016. Thesis, Indian Institute of Science. Accessed August 20, 2019. http://etd.iisc.ernet.in/2005/3738 ; http://etd.iisc.ernet.in/abstracts/4610/G28309-Abs.pdf.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Prasad, Boggavarapu V V S U. “Experimental Studies on Biodiesel Spray Characteristics : Effects of Evaporation & Nozzle Cavitation.” 2016. Web. 20 Aug 2019.

Vancouver:

Prasad BVVSU. Experimental Studies on Biodiesel Spray Characteristics : Effects of Evaporation & Nozzle Cavitation. [Internet] [Thesis]. Indian Institute of Science; 2016. [cited 2019 Aug 20]. Available from: http://etd.iisc.ernet.in/2005/3738 ; http://etd.iisc.ernet.in/abstracts/4610/G28309-Abs.pdf.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Prasad BVVSU. Experimental Studies on Biodiesel Spray Characteristics : Effects of Evaporation & Nozzle Cavitation. [Thesis]. Indian Institute of Science; 2016. Available from: http://etd.iisc.ernet.in/2005/3738 ; http://etd.iisc.ernet.in/abstracts/4610/G28309-Abs.pdf

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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