Complex Approach to the Conversion of Existing Refrigeration Systems to A2L Group Refrigerants

Modern requirements for refrigeration equipment include the cessation of the use of systems with refrigerants that destroy the ozone layer, as well as a gradual reduction in the use of refrigerants with a high impact on global warming. The current task is to replace an environmentally unacceptable refrigerant with a neutral refrigerant for ozone and with a low global warming potential. The purpose of this paper is to develop and demonstrate a multivariate approach to the analysis of the specified problem – replacing HCFC and HFC refrigerants with refrigerants of the A2L group with a global warming potential below 500. Special attention is paid to the potential for increasing the productivity and energy efficiency of the refrigeration system. The following research tasks are solved in the paper: the impact of refrigerant replacement on the operation of the main elements of the system is determined; means and methods for increasing the cooling capacity of the refrigeration system when replacing the refrigerant are proposed; methods for increasing the energy efficiency of the refrigeration system are developed. The main changes in the operation of a refrigeration machine when replacing with a refrigerant of group A2L are identified in the paper. Namely, it is determined that the compressor performance changes, the lubricant needs to be replaced, it is necessary to take into account the influence of temperature glide, as well as changes in the operation of the condenser and evaporator. To increase the cooling capacity of a refrigeration machine, the following means and methods are proposed: selection of a refrigerant that can provide the required cooling capacity; increasing the compressor capacity either by frequency regulation or by installing an additional compressor; minimizing pressure losses in the hot steam and suction pipelines; reducing the temperature gradient on the condenser and evaporator; reducing the air temperature at the condenser inlet by adiabatic cooling; additional subcooling of the liquid refrigerant; optimizing the operating modes of the unit. The most effective method is determined – reducing the temperature difference between the condensation and boiling temperatures in the largest number of hours of the annual cycle.