The article examines the dependencies describing the influence of the working fluid of a vapor-compression air heat pump (HP) integrated into supply and exhaust ventilation units on its operational characteristics (energy conversion ratio, air heating value, specific volumetric heat capacity, maximum absolute pressure in the refrigeration circuit elements, electrical power consumed by the compressor drive, and compression ratio). The dependencies of approximating curves describing the enthalpy and entropy of refrigerants R22, R32, R134a, R152a, and R410a in the superheated vapor region are presented. For the analysis of integrated heat pump characteristics, the refrigerants R134a, R22, R32, R152a, and R410a were selected. It has been established that refrigerants R32 and R410a are the most favorable for use in an integrated HP due to their relatively high specific heat capacity, which results in lower metal consumption of refrigeration equipment under the constrained conditions of ventilation units. Refrigerants R134a and R152a are characterized by a high compression ratio compared to other freons. Their use in the HP of a supply and exhaust unit configuration with the heat pump evaporator located after the heat recovery unit in the direction of exhaust air requires the organization of two-stage compression under extremely low air temperatures.
M. Petrov (Tue,) studied this question.