1.lntrodudion
Vapor compression cycles (VCC) are widely used in refrigeration and air conditioning systems, which are considered as one of the most energy-consuming domestic appliances. Refrigerators and air conditioning systems represent 13.7% and 16% respectively of all residential electricity consumption in USA for 2001 [1]. Also, air conditioning systems consume up to 70% of the UAE total energy consumption [2]. Hence. better designs of cooling systems are required to minimize the energy consumption. The trend in electronic industry is towards more compact systems. These systems required more effective cooling as they produce a lot of heat. Therefore, compact vapor compression cycles are sought for portable high-end electronic systems. A study has been done by Trutassanawin et al. [3] to develop a compact refrigeration system prototype to demonstrate its feasibility in electronic cooling applications. The system cooling capacity varied from 121 to 268 W, with a COP of2.8 to 4.7, and with a second-law efficiency ranging from 33% and 52%. A test-bed has been developed by Chang et al. [4] to examine the thermal performance of a miniature vee for electronic cooling purposes. The effect of the compressor speed and the expansion valve opening on the COP of the cycle has been studied. The study concluded that the condensation phenomena were improved when the compressor speed was reduced from 4200 to 3840 RPM.