Transient characteristic of reciprocating compressors in household refrigerators

Reduction in energy consumption associated with household appliances is a challenging subject. One of the appliances with great contribution in energy consumption is the household refrigerators . Among the different components of a refrigerator, the compressor has the most effect on system energy consumption. A knowledge of the transient performance of compressors is vital for reduction of energy consumption and improving the overall performance of a refrigerator. In this paper the M7 model of 1/5 hp Nicchi compressor belonging to 12 ft3 refrigerators with refrigerant R12 is selected as a sample and different tests are carried out to determine its transient behavior. Based on the analysis of experimental results, the governing equations and the simulation program of transient behavior have been developed. Good agreement between theoretical and experimental results means that the simulation model could be an appropriate tool to study the transient behavior of reciprocating compressors in different conditions. Analysis of predicted and experimental results shows that refrigerators consume more power in the transient mode as compared to the steady mode, therefore shortening the transient period can lower the energy consumption of the system. Also an isentropic assumption for the hermetic compressor is not a correct assumption, especially for the transient mode. With appropriate design of compressor inlet which locates it near to the suction valve, the energy efficiency will be improved.