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1. Al-sarraf, Hayder Hasan Jaafar. Modeling Two Phase Flow Heat Exchangers for Next Generation Aircraft.

Degree: MSME, Mechanical Engineering, 2017, Wright State University

URL: http://rave.ohiolink.edu/etdc/view?acc_num=wright1503935509157319

Two-phase heat exchangers offer the potential of
significant energy transfer by taking advantage of the latent heat
of vaporization as the working fluid changes phase. Unfortunately,
the flow physics of the phase change process is very complex and
there are significant gaps in the fundamental knowledge of how
several key parameters are affected by the phase change process.
Therefore, an initial investigation modeling a two-phase flow heat
exchanger has been accomplished. Many key assumptions have been
defined which are critical to modeling two-phase flows. This
research lays an initial foundation on which further investigations
can build upon. Two-phase heat exchangers will be a critical
enabling technology for several key aerospace advancements in the
21st century.In this research, modeling two- phase flow heat
exchangers to be used in modeling of NASA’s next generation
aircraft (N3- X) is accomplished. The heat exchanger model, which
could be a condenser or an evaporator, currently accommodates two
working fluids; kerosene (jet fuel) and a refrigerant (R134a).The
primary goal is to obtain a dynamic, robust model by using
numerical simulation tools (MATLAB/ SIMULINK) which can simulate
the system efficiently and would be used in the conceptual aircraft
(N3-X) model. The final goal of this project is to investigate the
influence of pressure and enthalpy perturbations on the system. In
other words, how quickly this system responds to change to
perturbations, therefore the model will be transient.Two examples
are used for demonstration of the transient response of a two-
phase heat exchanger to a perturbation in pressure and enthalpy.
Initially, pressure perturbation variation effects on how the
quality of R134a effects the magnitude of the two- phase flow heat
transfer coefficient, therefore the two- phase heat transfer rate
calculated. This changing pressure approach used to provide a rapid
thermal response to a rapid thermal load variation. Other
conventional thermal methods (decreasing the temperature of the
cold fluid or increasing the mass flow rate) results in slower
response times than changing the pressure. For this analysis, a
sample time of 0.000001 seconds was used.In addition, an enthalpy
perturbation was investigated. Since, changing pressure suddenly
from higher value (650 kPa) to the lower value (555 kPa) is not a
real, physical scenario in life, the pressure change with transfer
function would be employed to transform the system into first order
system with two different time constants. Eventually, the time
constant of the system plays a significant role in obtaining a
quicker response.
*Advisors/Committee Members: Roberts , Rory (Advisor).*

Subjects/Keywords: Mechanical Engineering; Two-phase heat exchanger; Next Generation Aircraft

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

APA (6^{th} Edition):

Al-sarraf, H. H. J. (2017). Modeling Two Phase Flow Heat Exchangers for Next Generation Aircraft. (Masters Thesis). Wright State University. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=wright1503935509157319

Chicago Manual of Style (16^{th} Edition):

Al-sarraf, Hayder Hasan Jaafar. “Modeling Two Phase Flow Heat Exchangers for Next Generation Aircraft.” 2017. Masters Thesis, Wright State University. Accessed November 24, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1503935509157319.

MLA Handbook (7^{th} Edition):

Al-sarraf, Hayder Hasan Jaafar. “Modeling Two Phase Flow Heat Exchangers for Next Generation Aircraft.” 2017. Web. 24 Nov 2017.

Vancouver:

Al-sarraf HHJ. Modeling Two Phase Flow Heat Exchangers for Next Generation Aircraft. [Internet] [Masters thesis]. Wright State University; 2017. [cited 2017 Nov 24]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=wright1503935509157319.

Council of Science Editors:

Al-sarraf HHJ. Modeling Two Phase Flow Heat Exchangers for Next Generation Aircraft. [Masters Thesis]. Wright State University; 2017. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=wright1503935509157319