Effects of liquid refrigerant injection on the performance of a refrigeration system with an accumulator heat exchanger

Liquid refrigerant injection technique can be a very effective method for controlling subcooling and the compressor discharge temperature of a refrigeration system at high ambient temperatures. In this study, the effects of liquid refrigerant injection on the performance of a refrigeration system with an accumulator heat exchanger were investigated by varying the liquid injection rate at the conditions of constant expansion valve opening in the evaporator and constant total flow rate. During the tests, the ambient temperature was maintained at 43 °C. With the increase of the liquid injection rate, the subcooling at the inner heat exchanger outlet increased and the superheat at the accumulator outlet decreased. However, unacceptable results such as the increase of the compressor discharge pressure and decrease of the system performance were also observed depending on the control method applied. To obtain high system performance and reliability, optimum control methods for liquid injection in the accumulator heat exchanger are suggested. The liquid injection technique for the refrigeration system with an accumulator heat exchanger was found to be an effective method for controlling adequate subcooling and the compressor discharge temperature of the refrigeration system at high ambient temperatures.     

Quantitative analysis of flow inside the accumulator of a rotary compressor

The flow structure inside the accumulator of a rotary compressor was investigated experimentally using a hybrid particle tracking velocimetry (PTV) velocity field measurement technique. A proto-type accumulator was studied while operating under real working conditions. The flow inside the accumulator was qualitatively visualized using a high-speed camera. The period of one cycle of the rotary compressor was divided into 4 phases and the velocity fields inside the accumulator were measured using a phase-averaging technique. The flow inside the accumulator, especially in the region between the screen holder and tube holder, showed a pulsating periodic flow structure according to the rotational phase of rotary compressor.