Modelling of plate finned tube evaporators and condensers working with R134A

A model to predict the behaviour of finned tube evaporators and condensers working with R134a has been developed. For modelling of the refrigerant phase change, evaporation or condensation, the heat transfer and the pressure drop for the two-phase flow have to be calculated. Therefore, a number of correlations, the most recommended ones in the reviewed literature, have been analysed and compared. The results of this comparison are presented for the evaporation and condensation heat transfer coefficients and for the evaporator frictional pressure drop. Once the correlations have been implemented in the model and compared with the experimental results, the ones that work best for the studied heat exchangers have been ultimately selected. The experimental study to validate the model has been carried out in a small air-conditioning unit with cross-how air-refrigerant type heat exchangers. The results are compared with model predictions for thermal capacity, refrigerant superheat or subcooling, and tube-side pressure drop. (C) 1998 Elsevier Science Ltd and IIR. All rights reserved.