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In the modern technologies related to energy transformation, namely in split-conditioners, 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 effectiveness of the use of various refrigerants in split-conditioners. The author's innovation mathematical model for analysis of the work of one-step freon refrigerating machines, which are used in air split-conditioners, according to the exergetic method, is developed. The obtained exergetic output-input ratio (OIR) and losses of exergy in the separate elements on the example of air split-conditioner with nominal cooling capacity of 2800 W of "Daikin" firm in the standard external temperature conditions on the refrigerants R410A, R32 and proposed by the authors for the use in split-conditioners R600A refrigerant are obtained on this model. It was established that by the exergy efficiency, the R600A refrigerant is the most effective. The use of the R600A refrigerant when compared to R410A and R32 has shown the increase of the exergetic efficiency of the split-conditioner in 12.4% and 8.7%, respectively. The losses of exergy having been established in all elements of refrigerating machine of the air split-conditioner 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.

Nowadays, the use of heat pumps (HP) of air split-conditioners in air conditioning and heating systems of small industrial, public and residential facilities is becoming more common. It is known that the nominal heat capacity of HP of air split-conditioners is given in catalogs or reference literature under standard outdoor temperature conditions, namely: outdoor air temperature +7oС, indoor air temperature +21oС. At the same time, manufacturers of air split-conditioners do not ensure that, regardless of the size of heating capacity, all air split-conditioners have the same internal temperature conditions, namely: the evaporation temperature of the refrigerant and its condensation temperature. In this case, the thermodynamic efficiency, which can be best assessed by the exergetic output-input ratio (OIR) of different heating capacity of HP of air split-conditioners, is different; this, in our opinion, is incorrect. However, today there is a lack of mathematical models of bringing the operation of air split-conditioners HP to the similar internal temperature conditions, which will allow us to obtain the same exergetic OIR for different heating capacity of HP. To create the mathematical model of bringing the operation of HP of air split-conditioners to the equal internal temperature conditions, we have proposed them, namely: the evaporation temperature of the refrigerant +0.7oC and its condensation temperature +40oC. Taking these temperatures on the basis of the heat balances of the HP evaporator and HP condenser of air split-conditioners, we obtained the dependences for calculating air flow rates on the evaporator and condenser, which respectively maintain the proposed temperatures.

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