Application of heat pumps in systems for maintaining the microclimate of high-rise buildings

In the present study, the relevance of microclimate considerations in the residential premises of high-rise buildings is considered. The application of a natural exhaust ventilation system without forced air removal leads to a deterioration in the quality of the indoor air environment, including suboptimal temperature and humidity conditions, an increase in CO2 and dust concentration, as well as the development of pathogenic microorganisms. A transition from a natural ventilation system to one using air recuperative heat exchangers to reuse recyclable heat is proposed. In conditions of low winter temperatures, the prob-lem of freezing in plate heat exchangers leads to a decrease in their energy efficiency. The main content of the study for the operating air supply and exhaust unit with a plate recuperator involves an analysis of methods for preventing freezing and a comparative calculation of energy costs. Three options for pre-venting freezing are considered: the use of an electric air heater prior to the recuperator for heating air to -14 ºC (the freezing condition for this heat exchanger); the use of a bypass to defrost the heat exchanger; the use of a heat pump to transfer heat energy from the exhaust to the supply air. In the developed ex-perimental model with a heat pump, Freon R410A is used as a heat carrier. The calculated data indicate the total energy consumption at -36 ºC to comprise 20.4, 21.3 and 13.5 kW when using an electric air heater, a recuperator with a bypass and a heat pump, respectively. Additionally, the dependences of the change in relative humidity on temperature are derived. Summarising the obtained results, it is possible to use a heat pump for rationalising thermal and electric energy spent on building heating and maintain-ing the indoor microclimate.