International Journal of Scientific and Research Publications, Volume 4, Issue 7, July 2014 1 ISSN 2250-3153 www.ijsrp.org Performance Comparison of Ejector Expansion Refrigeration Cycle with Throttled Expansion Cycle Using R-170 as Refrigerant Gourav Patel * , Dr. Sharad Chaudhary ** * Mechanical Engineering Department, IET DAVV Indore, India ** Mechanical Engineering Department, IET DAVV Indore, India Abstract- Since long time, it has been noticed that refrigerators are the devices which work almost 365 days round the clock; hence objective of energy efficiency improvement attracts much. There are several ways of improving the performance of a vapor compression refrigeration cycle. Use of an ejector as expansion device is one of the alternative way. The advent of new component ‘Ejector’ into refrigeration system opened the new era of research. The vital component, which decides the effective operation of the ejector expansion refrigeration system, is the ejector. Hence, design of an ejector and analyses of its physical and operational parameters have drawn special attention. The thermodynamic analysis of natural refrigerant (R 170) based vapour compression refrigeration cycles is presented in this article using a constant pressure mixing ejector as an expansion device. Using ejector as an expansion device, R 170 yields a maximum COP improvement of 24.12 percent. Index Terms- Coefficient of performance, Comparison, Ejector expansion cycle, R 170, Vapour compression cycle. I. INTRODUCTION he throttling device in a refrigeration system normally serves two purposes. One of the thermodynamics function is expanding the liquid refrigerant from the condenser pressure to the evaporator pressure. The other one is the control function which may involve the supply of the liquid to the evaporator at the rate at which it is evaporated. Irreversibility associated with throttling is major issue in vapour compression refrigeration cycle. There are different ways to reduce the throttling losses in the refrigeration cycles. Use of ejector as an expansion device by replacing the throttling valve in the conventional vapor compression refrigeration cycle is a promising alternative to reduce the throttling losses or the expansion irreversibility in the refrigeration. Because of its simple structure, ease of manufacturing, no moving parts, low cost and low maintenance requirements, the use of two- phase ejector has become an important cycle modification recently. Ejector reduces the compressor work by raising the suction pressure to a level higher than that of which in turn improves COP of the system. It also enables to reduce size of the evaporator. In 1990, an analysis is performed by Kornhouser [1] on the Ejector Expansion refrigeration cycle to investigate the performance improvement on vapor compression refrigeration (VCRC). Eight refrigerants were used, R11, R12, R113, R114, R500, R502, R22 and R717. According to this paper, refrigerant R502 has given the highest coefficient of performance improvement and the COP improvement using R12 was 21% over the basic cycle. In 1995, according to Domanski [2] the theoretical COP of the ejector-expansion refrigeration cycle was very much sensitive to the ejector efficiency. In 1998, Nakagawa and Takeuchi [3] research was concluding that the longer divergent part provides a longer period of time for the two-phase flow to achieve equilibrium. With this result, using longer length of the divergent part of the motive nozzle, higher motive nozzle efficiency was determined. In 2007, based on the second law of thermodynamics Yari and Siriousazar [4] worked on performance of transcritical CO2 refrigeration cycle with ejector- expansion. They found ejector is improving the optimum second- law efficiency by 24.8% as compared to conventional system and 16% as compared to internal heat exchanger system. In 2007, an analysis is given by Deng et al. [5] on a transcritical CO2 ejector- expansion refrigeration cycle that uses an ejector as the main expansion device instead of an expansion valve. He concluded for the given working conditions, the ejector was improving the maximum COP by 18.6% compared to the internal heat exchanger system and 22% compared to the conventional system. In 2007 according to simulation work by Nehdi et al. [6] on performance of the vapour compression cycle using ejector as an expander, it has been found that the geometric parameters of the ejector design have noticeable effects on the system performance. He achieved the maximum COP for Optimum geometric area ratio around 10. For the given operating conditions of evaporator temperature, 5ºC and condenser temperature, 40 ºC, In 2008, Yari, M. [7] conducted Exergetic analysis of the vapour compression refrigeration cycle using ejector as an expander, in this research the effects of evaporating temperature and condensing temperature on the COP, second law efficiency and exergy destruction in various component were calculated, and also summarized that the COP and second law efficiency of the ejector-compression is about 16% greater than that for the vapour compression cycle and total exergy destruction of the vapour compression cycle was about 24 % higher than that for the ejector-compression cycle. According to J Sarkar [8] - [9] research on the performance improvement with three natural refrigerants namely, ammonia, propane and isobutene, it has been determined that maximum performance improvement using ejector can be achieved in the case of isobutane, whereas ammonia giving minimum performance improvement. In 2012, J Sarkar [10] provided a detailed T