Thermodynamic Analysis of Two-Stage Vapour Compression Refrigeration System

2016 ◽  
Vol 8 (3) ◽  
pp. 133
Author(s):  
Ajaz Alam ◽  
Subodh Kumar
2019 ◽  
Vol 27 (02) ◽  
pp. 1930001 ◽  
Author(s):  
Shounak Chowdhury ◽  
Ranendra Roy ◽  
Bijan Kumar Mandal

This paper presents a review on energy and exergy analysis of two-stage vapour compression refrigeration (VCR) system. The use of alternative refrigerants instead of conventional refrigerants has also been addressed. The governing equations for the energetic and exergetic analysis of two-stage VCR system have been identified and presented. Several experimental and numerical investigations and their findings on the performance of the two-stage VCR system available in the literature have been discussed in brief. Some of the results have also been reproduced as case studies.


Author(s):  
Ahmet Selim Dalkilic¸ ◽  
Somchai Wongwises

Single-stage vapour compression refrigeration system was compared with an actual vapour compression cycle, single-stage process with internal heat exchanger, and a two-stage process with economiser using the refrigerants of HCFC-22, CFC-502 and their alternatives such as HFC-134a, HFC-32, HFC-152a, HFC-404A, HFC-407C, HFC-507, HFC-410A. A theoretical performance study on a cascade refrigeration system was performed using two refrigeration cycles connected through the heat exchanger in the middle working as the evaporator for the high pressurized cycle and condenser for the low pressurized cycle. Other performance study was performed using a two-stage cascade refrigeration system having low and high pressure compressors connected through the mixing chamber in the middle. The condensation temperatures were between 30 and 50 °C, evaporation temperatures were between −50 °C and 5 °C and heat exchanger and economiser temperatures were kept as constant for the comparisons. Some of the alternative refrigerants’ coefficients of performance values are found to be higher than their base traditional pure refrigerants. The effects of the main parameters of performance analysis such as refrigerant type, degree of subcooling, and superheating on the performance coefficient, refrigerant charge rate and volumetric refrigeration capacity are investigated for various operating conditions as case studies.


Author(s):  
J S Tiedeman ◽  
S A Sherif

This paper presents the results of an optimization study for a two-stage vapour compression refrigeration system based on the coefficient of performance (COP) and exergetic efficiency. Traditional studies have focused on the first-law performance, while those studies dealing with the second law have primarily been limited to performance analysis as opposed to performance optimization. The results of this study indicate that the use of the common approximation of the geometric mean to find the optimum interstage pressure can lead to significant errors in interstage pressure. However, an optimum COP or exergetic efficiency based on the same interstage pressure has relatively little error. This trend is valid as long as the isentropic compressor efficiencies are ‘reasonable’. Second-law optimization revealed that the optimum data curves themselves have a maxima for each set of conditions tested. This leads to the conclusion that for a given system there is an optimum set of conditions that lead to the lowest amount of exergy destruction for that system. This is shown to occur consistently for reasons that are, as yet, undetermined. Finally, polynomial equations have been fitted to the resultant optimum data for the interstage pressure, COP and exergetic efficiency. These equations allow for the reproduction of optimum points based on high-and low-pressure compressor efficiencies and condenser and evaporator pressures.


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