Characteristics of Vapor-Compression Cooling System on Multicomponent Working Medium

Author Name(s): Anna V. Pleshka, Arthur R. Valinurov
Author Email: anya.pleshka@mail.ru

Abstract

The article presents the structural diagram of the static mathematical model for vapor compression cooling system (VC CS), which is the sequence of units with known transfer functions of thermal processes and the static mathematical model that allows to calculate the static characteristics of the considered CS in the form of cooling
capacity dependence on the ambient temperature and the mass flow rate of cooling water. The non-azeotropic mixture R423A was chosen as the working agent for static characteristics development, as the most environmentally safe among single-component refrigerants, and with greater energy efficiency for reverse cycles of heat engines. The evaluation criterion was the condition of lower energy consumption for a working agent compression in the compressor at a sufficiently high value of the refrigeration coefficient. The calculation result showed that with the cooling water temperature decrease at the inlet to the condenser tw1 with a constant flow of cooling water Gw, the heat load of the evaporator Qev will increase. A sharp increase of the evaporator heat load Qev was also observed with flow rate increase Gw to 0.4 kg/s, and with a further increase of cooling water flow rate, the heat load of the evaporator gradually increases. The dependence of the heat load of the evaporator Qev on the temperature of the cooling water tw1 is linear.

Introduction

Steam compression chillers are the most common for artificial cooling in the moderate cold area [1]. They are widely used in cryogenic and refrigeration equipment for cooling, freezing and storage due to their energy efficiency
(lower energy consumption as compared to other machines) and less environmental hazard. Currently, refrigeration equipment does not have one-component working substances with simultaneously high thermodynamic, thermophysical and environmental indicators, and in this regard, they started to apply mixtures consisting of one component substances authorized for production and use by the Montreal Protocol.

Conclusion

Thus, the mathematical model was compiled and the static characteristics of the vapor compression refrigeration machine on a multicomponent working agent were calculated. They considered the dependence of the heat load of the evaporator on the flow of cooling water with a changing temperature of the water at the inlet to the condenser and the dependence of the heat load of the evaporator on the temperature of the cooling water at the inlet of the condenser with a changing flow of cooling water. The obtained static model makes it possible to evaluate the
performance parameters of the steam compression cooling system under consideration: mass flow of the working agent, the amount of heat Qи, the heat transfer coefficient in the condenser kK and the heat transfer surface area FK of
the condenser.

 

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