Second-law-based thermodynamic analysis of vapor-compression refrigeration cycles

(1992) Second-law-based thermodynamic analysis of vapor-compression refrigeration cycles. Masters thesis, King Fahd University of Petroleum and Minerals.


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Thermodynamic analysis of vapor-compression refrigeration cycles are investigated by both the first law and second law of thermodynamics. Second law analysis (in terms of energy measure of irreversible loss which is typically described as irreversibility) is carried out for both basic as well as tw-stage vapor-compression refrigeration cycles. This analysis basic as well as two-stage vapor-compression refrigeration cycles. This analysis is performed on each of the system components to determine their individual contribution to the overall system losses. It is found that most of the ireeversibility is in the compressor due to low compressor efficiency. Irreversibilities of the expansion valve as well as condenser are also significant. These irreversible losses increases with the increase of condenser and evaporator temperature differences. As the refrigerant, R-12 is the major contributor to the ozone depletion, therefore in this thesis a new refrigerant R-134a is also investigated, which is considered as a leading candidate to replace R-12. Computer subroutines are modified to calculate the properties of the refrigerant R-134a. A comparative study is also done between these two refrigerants which indicate that R-12 can be replaced by R-134a, without any significant loss in overall system performance. The staging of compressors of a refrigerating system produces a saving in work. One of the design parameters of the two-stage refrigeration system is the selection of interstage pressure. In this study, it is found that the optimum interstage pressure for a two-stage, vapor-compression refrigeration cycle is very close to the saturation pressure corresponding to the arithmetic mean of the condensing and evaporating temperatures. These results are compared with the existing practice.

Item Type: Thesis (Masters)
Subjects: Mechanical
Department: College of Engineering and Physics > Mechanical Engineering
Committee Advisor: Zubair, Syed M.
Committee Members: Sahin, Ali and Ali, Iqbal
Depositing User: Mr. Admin Admin
Date Deposited: 22 Jun 2008 13:55
Last Modified: 01 Nov 2019 13:56