Mathematical modeling of an air split-conditioner heat pump operation for investigation its exergetic efficiency

In the modern technologies related to energy transformation, namely in the field of heat pumps of air split-conditioners (“air-to-air”), an important place is occupied by apparatuses and processes, which energy perfection can be objectively evaluated only on the basis of analysis of their exergy efficiency. This allowed substantiating the actuality of the research task due to insufficient information on the exergy efficiency of the use of heat pumps of air split-conditioners and their elements. The author’s innovation mathematical model for the analysis of the operation of one-step freon heat pumps, which are used in air split-conditioners, according to the exergetic method, is developed. In this article analyzes the exergetic output-input ratio (OIR) and the losses of exergy in the separate elements of heat pumps of air split-conditioners on the example heat pumps of air split-conditioners with a nominal heating capacity of 2500, 2840, 3580, 5620, 6400W by “Daikin” firm in the standard external temperature conditions on the refrigerant R410A are obtained on this model. It has been determined that, by exergy efficiency, heat pumps of air split-conditioners with higher heat capacity have lower exergy efficiency. In our opinion, this is due to the incorrect acceptance of air flow rates on the evaporator and condenser, which do not correspond to the heat balances of these apparatuses and the same internal temperature regime for different heat capacity heat pumps of air split-conditioners. An example is the Grassman’s diagram of the heat pump of air split-conditioner with the heat capacity of 2500W. The losses of exergy having been established in all elements of heat pumps of air split-conditioners indicate that the air split-conditioner parts should be improved to reduce the losses of exergy in them and to increase its exergetic OIR in general.

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Mathematical Modeling and Computing, Vol. 7, No. 1, pp. 169–178 (2020)