Features of modeling a highly efficient multistage vapor compression heat pump unit

The increase in the cost of fuel and energy resource and the deterioration of the environment from the combustion of traditional fossil fuel, have led to a great interest in energy-saving technology by using secondary energy resources in the thermal energy of industrial, housing and communal services using heat pump units in Russia and abroad. This paper analyzes the well-known two-stage heat pump units, and reveals their advantages in comparison with single-stage. The modeling of a highly efficient multistage vapor compression heat pump unit is proposed. Moreover, a method for calculating a multistage heat pump unit with a high coefficient of performance is presented. In addition, an example of calculating the thermodynamic cycle of a four-stage heat pump unit is presented. The influence of the number of stages on the increase in coefficient of performance in relation to a single-stage heat pump unit, the effect of the temperature difference between the temperature of the high-potential heat source and the temperature of the low-potential heat source on the coefficient of performance were analyzed. In addition, the influence of the initial value of the temperature of the high-potential heat source before heating during the course in the heat pump unit on the value of coefficient of performance for a different number of stages is analyzed under the condition of a constant difference between the heating temperature of the high-potential heat source at the outlet of the heat pump unit and the temperature of the low-potential heat source.