Overall thermal performance oriented numerical comparison between elliptical and circular finned-tube condensers

This paper compares the overall thermal performance of refrigerant-to-air finned-tube condensers with elliptical and circular tubes. A distributed-parameter model of the circular-tube and the elliptical-tube condensers is developed and the prediction agrees well with the experimental data. The two type condensers are compared under different outlet subcoolings, air velocities, circuitries and refrigerants. Further, the condenser model is integrated with other component models to establish a system model, with which the tube shape effect on the system performance is evaluated. The results show that the air pressure drop and the heat transfer rate of elliptical-tube condensers are 20.0%-27.3% lower and -8.3% to 30.9% higher than those of circular-tube condensers, respectively. The superiority of elliptical-tube condensers could vanish if the refrigerant pressure drop is too large. The heat transfer rate improvement of elliptical-tube condensers can be promoted by increasing circuit number only at higher refrigerant pressure drop. Compared to circular-tube condensers, the system capacity improvement using elliptical-tube condensers can be as high as 21.3%-27.5% and the COP improvement ranges from 3.6% to 6.7%. Elliptical-tube condensers using R410A yield higher improvement of condenser heat transfer rate and system capacity than using R22 and R134a, while R134a has the most potential in system COP improvement. (C) 2014 Elsevier Masson SAS. All rights reserved.