A discussion about the methodology to validate the correlations of heat transfer coefficients and pressure drop during the condensation in a finned-tube heat exchanger

Abstract

The purpose of this work is discuss about the best way for validating a model able to predict the performance of afinned-tube condenser. A simulation tool has been used in order to analyze the effects on the model prediction ofsome correlations intended to the evaluation of the heat transfer coefficients (HTC) and pressure drop (PD) of bothrefrigerant and air side. The discussion is supported by an experimental set of data obtained by testing a traditionalair-to-water heat pump equipped with a finned round tube condenser. The test campaign has been designed in orderto cover a wide range of operating points including different air velocities (from 1.5 m/s to 4 m/s), refrigerant massflow rate (50.4-82.2 kg/h), air inlet temperatures (20-46°C) and subcooling (0-5-10 K). Once defined the classicboundary conditions for validating a model, such as the condenser inlet conditions (temperature and pressure) and themass flow rate, the predicted capacity is compared against the experimental one. In the paper an alternative set ofboundary conditions is proposed and the results have been compared with experimental ones in terms of condensertemperature and capacity. The analysis of statistical parameters such as Mean Error (ME), Standard Deviation (SD)and Mean Square Error (MSE) allows demonstrating how a good combination of inlet parameters and correlationsmakes possible a very good agreement between the model and the experimental data without using any enhancementfactors.