Development of an Energy Efficient Refrigeration Unit Using Carbon Dioxide as a Natural Refrigerant

Abstract

Refrigeration units, ubiquitous in various industrial applications, necessitate refrigerants for effective heat transfer. The end of service life for these agents, predominantly fluorocarbon-based, poses significant environmental hazards, necessitating safer alternatives. To mitigate fluorine-based environmental pollution, several solutions are under exploration, with a key proposal being the utilization of natural substances, such as carbon dioxide (R744), as refrigerants. This study introduces a novel design for a refrigeration unit operating on carbon dioxide. Distinctively, the proposed unit incorporates a series of nozzles in the refrigerator compartment that spray the refrigerant directly onto the food items, thereby expediting the cooling process. The operation principle of this unit, based on direct contact between carbon dioxide and the food products, is its primary novelty. A calculation technique is proposed for the selection of unit components, enhancing the cooling efficiency by facilitating direct heat exchange between the refrigerant and the product. The design includes a 3D model of the unit, developed in accordance with the sizes of currently manufactured equipment, and a layout that ensures mobility. The implementation of a recuperation principle in the unit allows a 20% reduction in refrigerant mass consumption, while the direct contact method increases the freezing rate by 30%. The proposed utilization of R744 as a refrigerant could significantly attenuate the emission of ozone-depleting substances, thereby contributing positively to the current environmental situation.