MODEL VALIDATION FOR LARGE EVAPORITIVE PLATE FRAME HEAT EXCHNAGERS
Plate and frame heat exchangers are commonly used as liquid-coupled evaporators in thermal systems, and there are many studies that examine their performance. However, most of these studies focus on the performance of heat exchangers with a small number of plates, with very few studies using R134a as the evaporating fluid. In addition, some systems require the working fluid to be heated from a subcooled liquid to a superheated vapor in a single device, and none of the prior studies on these heat exchangers study this method of operation. In the present study, data collected on a plate and frame heat exchanger with more than 100 parallel plates are compared to several single-phase and two-phase heat transfer correlations to determine the best combination for use in a discretized thermal resistance network heat transfer model. The counterflow heat exchanger used a propylene glycol-water mixture to evaporate R134a to a superheated vapor from an entering subcooled liquid. Test data were collected at very low mass fluxes (~8 kg m-2 s-1) and moderate saturation temperatures (~25°C). The heat transfer model accuracy was determined by setting the heat transfer rate, calculating the heat transfer area, and comparing it to the actual test heat exchanger area. The results showed that using the Han et al.  and Chisholm and Wanniarachchi correlations  for the two-phase and all single-phase regions, respectively, resulted in the lowest error for the data collected (MAE of 14.8%).