A SURVEY OF CORRELATIONS FOR HEAT TRANSFER AND PRESSURE DROP DURING EVAPORATION IN PLATE HEAT EXCHANGER

With the increased regulations to move towards lower GWP refrigerants, natural fluids and their blends are becoming more favorable. Plate heat exchangers are being used in air-conditioning and refrigeration applications as well as a wide variety of other applications including food processing, chemical industry, and energy generation systems. Plate heat exchangers are favored because of their compactness, close approach temperature pure counter-flow operation, and enhanced heat transfer performance. Plate heat exchangers are increasingly utilized in two-phase flow operations due to their desirable characteristics. In order to achieve a better understanding of the current research status of two-phase flow in plate heat exchangers, this paper presents a literature review of available correlations for heat transfer and pressure drop calculations during evaporation in plate heat exchangers. Generally, research on evaporation heat transfer performance in plate heat exchangers is limited. Correlations on natural refrigerant mixtures are scarce. One recent correlationis proposed in literature for ammonia/water mixtures with specific conditions and mixture concentrations. A comparative evaluation of some of the existing correlations is presented in the light of their applicability to natural refrigerants. Overall, there is a significant gap in the literature regarding evaporation heat transfer and fluid flow characteristics of these types of exchangers.