MATHEMATICAL MODEL AND OPTIMIZATION OF GEOTHERMAL HEAT PUMP OPERATION

Abstract

The article considers the issue of increasing the energy efficiency of heat supply systems based on geothermal heat pumps by improving approaches to mathematical modeling and optimizing their operating modes. The features of using low-potential thermal energy of the soil massif are analyzed and the feasibility of using brine-water heat pumps, which are characterized by stability of thermal parameters and low dependence on external climatic conditions, is substantiated.

A generalized mathematical model of the functioning of a geothermal heat pump is developed, which takes into account the relationship between the input, output and control parameters of the heat transfer process. The proposed model allows studying the influence of temperature regimes, coolant consumption, compressor power and thermodynamic perfection coefficient on the efficiency of the installation. The conversion coefficient (COP) is used as a criterion for assessing efficiency, reflecting the ratio between the received thermal energy and electricity consumption.

Based on the calculations, the patterns of changes in the thermal transformation coefficient depending on the temperature of the geothermal heat carrier at the inlet and the temperature of the heat carrier in the heating circuit were established. It was shown that the maximum COP values are achieved under conditions of a minimum temperature difference between the low-potential energy source and the heat supply system, which confirms the effectiveness of the use of low-temperature heating systems.

Special attention was paid to the study of the influence of the degree of refrigerant overheating in the evaporator on the energy performance of the heat pump. It was established that reducing overheating within permissible limits contributes to an increase in the conversion coefficient: up to 25% for low-temperature modes and up to 15% for high-temperature modes. The feasibility of using modern electronic temperature-regulating valves, which provide adaptive regulation of overheating and increase the reliability of compressor equipment, was substantiated.