Indian Journal of Science and Technology

Abstract

Regulations affecting the refrigerant used in automotive air conditioning systems are gradually being made compulsory. The Global Warming Potential (GWP) of R-134a refrigerant, which is typically used for conventional automotive air conditioning, is very high. It was therefore necessary to create a new one with a low GWP value, and R-1234yf refrigerant was the result.The new refrigerant solves the GWP problem (its GWP is much lower); however, when it is used, there is a drop in system cooling performance and efficiency. To solve the performance problem, a new automotive cooling system was developed, based on the inclusion of an Internal Heat Exchanger (IHX). The purpose of this study was to verify the effectiveness of the type of IHX pipe-sections and the shapes of connecters, which are welded on the both ends of the IHX pipes in the newly developed system. In the study of the types of IHX pipe-sections, there was a small difference in the efficiency of the jointed and extruded IHX pipe designs.In the study of the connecter shape, the highest heat-transfer rate was achieved by the connecter with the least width. The heat-transfer volume was 385.68 watts. These results confirm that the connecter shape and width influences the effectiveness of heat transfer, and that this effect is greater than that caused by differences between these two pipe-section types. 
Keywords: Automotive Air Conditioning, Internal Heat Exchanger, Refrigerant, R-134a, R-1234yf