Аналіз ефективності ежекторних холодильних машин на різних холодоагентах

Abstract

Modern heat-using ejector refrigeration machines used in heat recovery systems for power plants based on gas turbine engines and internal combustion engines have many advantages over absorption refrigeration machines: smaller dimensions and weight; the ability to obtain lower temperatures. However, they are inferior in energy efficiency, and the thermal coefficient is much lower and can be 0.2…0.4. The efficiency of such refrigeration machines largely depends on the choice of the working fluid (refrigerant). Hence the need to choose a refrigerant that would provide the maximum heat factor, and hence the maximum efficiency of heat recovery. Given the relatively low efficiency of the ejector refrigeration machine, the search for a working fluid that will provide, on the one hand, higher thermal coefficients, and on the other hand high environmental friendliness, is one of the promising areas of development of heat recovery technologies in power plants. The study used the software complex developed by the authors to calculate the refrigeration cycles of heat-using refrigeration machines, taking into account the properties of many modern refrigerants, ejector characteristics, as well as basic heat exchangers (condenser, evaporator, generator). The efficiency of ejector refrigeration machines when working on the following working bodies was analyzed: R142b, R134a, R600, R600a, R1234ze(E), R1233zd(E), R1234yf, R227ea, R236fa, R245fa. R142b, R600, R600a, R245fa have the largest values of thermal coefficients. It is established that the most profitable in terms of environmental friendliness (ODP, GWP) and energy efficiency is the use of refrigerant R245fa, which has a condensation temperature range is 25…35 oC and boiling in the evaporator is 0…15 oC thermal coefficient is 0.40…1.03.