An analysis of effectiveness of air heat pump operation dependent on change of external air temperature

Abstract

Currently, air-to-water heat pumps are more widely used, which due to the high coefficient of performance reduce energy consumption and negative impact on the environment. They decrease the dependency on costs of energy resources. The work is devoted to solving the urgent problem of improving the efficiency of air heat pumps at low temperature of outdoor air in winter. One of the main problems of an air heat pump is the reduction of productivity when the outdoor air temperature decreases in winter. In this paper, the effectiveness of LG Therma V air-to-water heat pump to provide apartments with heating and hot water supply was analyzed. The heat pump is reversive, which can cool or heat a heat carrier. A four-way valve swithes the coolant flows between air exchangers. On the basis of the obtained results, plots of effectivness of the heat pump dependent on outdoor air temperature are built. It is shown that the effectiveness of the heat pump significantly depends not only on the outside temperature but also on the water temperature at the outlet of the heat pump. The use of heat pumps with a high coefficient of performance can significantly reduce energy costs. The most effective are low-temperature heating systems, in which the water temperature does not exceed 45 °C. The example is floor heating, which requires very low temperature of the floor surface – up to 30 °C. At outdoor air temperature not less than milnus 7 °C the heat pump is effective at higher temperature off heat carrier at output – up to 55 °C. To provide the uninterrupted heat supply, an additional air heater is included. It covers heat load during defrosting and very low outdoor air temperature. On the basis of the conducted researches, the directions of the further experimental and field researches are planned.