Energy efficiency of the transition to autonomous heat supply from air heat pump units under the climatic conditions of Russia

Abstract

The article addresses matters concerned with the energy and economic efficiency of the transition to the use of autonomous heat supply from air heat pumps under in the climatic conditions of Russia. The reasons why air heat pumps have not found wide use in Russia are analyzed. They include: limitation of efficient heat pump operation as restricted by the outdoor temperature range, a substantial dependence of the heat transformation ratio on the climatic conditions, and a significant difference in the tariffs for electricity and heat. The autonomous series-connected heat supply arrangement from a heat pump and electric boiler is studied. A computational model is proposed, which takes into account the actual climatic conditions in the regions of Russia and the actual tariffs for electricity and heat. It is shown that smaller consumption of electricity can be achieved by providing a margin in the heat pump's nominal heat output. Smaller consumption of electricity is achieved due a larger part of heat load covered by the heat pump and due to a lower amount of energy consumed by the electric boiler. The results of model calculations have shown that, for the regions the estimated outdoor temperature in which is close to the bivalence point temperature, the use of air heat pumps is energy-efficient according to the criterion of achieving the minimal expenditures of standard fuel for generating the consumed electric energy. As regards the financial feasibility of using heat pumps, it is determined by the ratio of tariffs for heat and electricity. The group of heat consumers located in regions with the estimated outdoor temperature ranging from --22 to --33°C (which is significantly lower than the temperature at the bivalence point) is separated. For this group, the consumption of standard fuel commensurable with the consumption of standard fuel in district heating systems is achieved at the heat pump’s rated heat output exceeding the estimated heating load by about 20%. In this case, the amount of money to be paid for the consumed electricity is by 10--40% more than that for thermal energy, depending on the ratio of tariffs for energy carriers.