The Effectiveness of Using Air-to-Water Heat Pumps under Russian Climatic Conditions

The energy efficiency of a combined heat-supply system constructed on the basis of an air-to-water heat pump and an additional heat source (an electric boiler) for its operation under different climatic conditions of Russia is studied using the simulation method. The considered subject is of issue because the answer to the question about the effectiveness of using air-source heat pumps depends on many factors, which may influence the effectiveness in different ways. These factors include, in particular, essentially different climatic conditions in different regions and specific consumption of fuel for supply of electricity and heat and different ratios between the tariffs for heat and electricity. A procedure for estimating the effectiveness of an autonomous space-heating system constructed on the basis of a heat pump as a function of the share of the heat-pump unit's nominal heat output in the design heating load is proposed. The procedure is based on using the relative expenditures of energy carriers (reference fuel) and financial expenditures for them in autonomous heat-supply systems on the basis of a heat pump and district heating. The results from calculations of relative consumption of fuel and energy resources and relative operating costs for certain regions of Russia having different climatic conditions are given. The calculations were carried out using generalized characteristics of heat pumps from different manufacturers, actual climatic data for three heating seasons, and ratios between the specific reference fuel consumptions for generation of electricity and heat and tariffs for energy carriers. It is shown that, in the case of using air-to-water heat pumps, the optimal ratio between the nominal heat output of heat-pump units and the design heating load is in the range from 1.0 to 1.4 depending on the design outdoor air temperature. In this case, the expenditures of fuel and energy resources and the financial expenditures for them are commensurable with the costs for district heating.