Carbon Dioxide and Dimethyl Ether Mixture as a Refrigerant for Air Conditioning Systems for Space Ground-based Infrastructure

摘要

The choice of refrigerants for modem air conditioning systems (ACS) of ground-based infrastructure facilities for administrative and general production purposes for the space industry is a multidisciplinary task. In particular, it is necessary to ensure the required energy efficiency of the refrigeration cycle, environmental safety of the production, operation and disposal of the refrigeration unit. An operating pressure levels in the cycle affect the availability, cost and safety of refrigeration equipment. Fire safety of the working fluid is also important. The history of the issue of environmental protection from emissions of refrigerants causing the destruction of the ozone layer and the greenhouse effect is considered. The restrictions implemented by existing agreements on the use of refrigerants are described. The existing criteria for evaluating the refrigerant in terms of environmental friendliness are described. A brief description of the properties of carbon dioxide (C02) and dimethyl ether (DME) is given, the key features of which are the high-pressure range and temperature glide in the case of C02 and the cost effectiveness, environmental friendliness and fire safety in case of DME. The possibility of using a mixture of C02 and DME in the framework of a vapor-compression refrigerating cycle is considered. Comparative calculations of vapor compression cycles were carried out both for pure DME, R22 and R410A, and for a mixture of DME and C02 at various concentrations. Comparisons are made between the proposed mixture and the refrigerants widely used before the introduction of the protocols (R22 and R410A) for operating pressures. Also made a comparison of the coefficient of performance of the proposed mixture at various concentrations of its components in the selected range. An interval in which the use of the proposed mixture is most optimal from the point of view of refrigerating capacity has been identified.