Substantiation of the possibility of gas liquefaction in oil–free low–speed refrigeration compressors

Abstract

BACKGROUND: Existing refrigeration machines contain four main units, i.e., compressor, condenser, expander, and evaporator that perform the refrigeration cycle. Currently, the liquefaction of the refrigerant occurs in the condenser. The creation of the conditions under which condensation of the working fluid would occur in the compressor unit would make the development of a compact refrigeration machine possible by eliminating the condenser from it.
 AIMS: This work aims to investigate the possibility of creating a compact refrigeration machine with the implementation of the condensation process of the working fluid in the compression chamber of the compressor.
 MATERIALS AND METHODS: The object of the study is a low–speed compressor, in which the pressure ratio significantly exceeds known analogs and simultaneously the temperature is significantly lower than that of high–speed machines because of the creation of conditions under which compression occurs with polytropic indicators below 1.08. The research method involves determining the gas temperature at critical pressure and comparing the obtained result with the critical temperature. The system of equations and assumptions used relates to the model with lumped parameters of the working fluid.
 RESULTS: The results obtained on the compression of such refrigerants as ammonia, carbon dioxide, R12, R22, and Freon–134a showed the possibility of obtaining the required pressures in a low–speed machine at temperatures significantly below the critical temperature.
 CONCLUSIONS: This work examines and proposes to study further those working fluids of refrigeration machines that can go into the liquid phase in a low–speed compressor unit because of their characteristics and operating parameters in the refrigeration machine. Further experimental confirmation of this will enable partial or complete elimination of the condenser unit in the refrigeration machine.