ASSESSMENT OF BOILING HEAT TRANSFER AND PRESSURE DROP CORRELATIONS OF AMMONIA/ WATER MIXTURE IN A PLATE HEAT EXCHANGER
Abstract Plate heat exchangers are gaining acceptance in absorption refrigeration systems due to their high transfer rates, compactness, and low refrigerant charge. Nevertheless, boiling heat transfer and pressure drop studies with mixtures in plate heat exchangers (PHEs) are scarce. In this study, the experimental data of Taboas et al. (2010) on flow boiling of ammonia/water in a plate heat exchanger are compared with the predicted values using the correlations available in the open literature for the boiling heat transfer coefficient and pressure drop. In addition, this study proposes a new correlation based on a separate model by which to obtain the boiling coefficient. The new correlation uses a transition criterion, divided into an apparent nucleate boiling region where pure convective boiling cannot appear, and a region with competition between convective and apparent nucleate boiling. The correlation proposed can predict 98% of data from Taboas et al. (2010) within 20% error.