Plate heat exchangers, GWP, Condensation, Modeling, R134a, Water, R410A
Plate heat exchangers are used in a wide variety of applications from air-conditioning, refrigeration, food processing, and chemical industry to energy generation systems. Plate heat exchangers are favored because of their compactness, flexible thermal sizing, close approach temperature, pure counter-flow operation, and enhanced heat transfer performance. This paper presents a literature review of available correlations for heat transfer and pressure drop calculations during condensation in brazed plates. Condensation heat transfer in plate heat exchangers can be preliminarily evaluated using the classic Nusselt equation for laminar film condensation on a vertical plate. However, condensation performance is influenced by many factors such as fluid properties, plate geometry, and mass flow rate, and therefore, it is difficult to obtain an ideal correlation which accounts for all these factors. The heat transfer coefficients of different refrigerants, including alternative lower GWP refrigerants R32, D2Y60, and L41a, are computed using heat transfer correlations found in literature. Generally, R32 shows the most favorable heat transfer performance, followed by L41a. An overview on an already existing model that is capable of predicting the performance of plate heat exchangers with generalized multi-fluid and multi-pass configurations is also presented. The model is validated against experimental data for water-to-R134a condenser. A total of sixteen experimental datasets are used. The heat capacity predicted by the model is within ±5% of the measured heat capacity, while most of the predicted outlet temperatures are within ±2 K of measured values.