Two-dimensional fin efficiency with combined heat and mass transfer between water-wetted fin surface and moving moist airstream

Abstract

A two-dimensional model has been developed to analyze the fin performance with combined heat and mass transfer in cooling and dehumidifying processes. The effect of the variations in moist air temperature and humidity on fin performance has been taken into account. The present results vary significantly, especially at low relative humidities, from those of the existing one-dimensional model. This may prove that the assumption of a lumped parameter to model the mass transfer effect is perhaps oversimplified. By means of this model, the fin temperature distribution, fin efficiency, and the properties of air in contact with the fin surface are predicted. The two-dimensional results show that the streamwise variations in moist air properties have a substantial effect on the fin performance and the trend is to further reduce fin efficiency. A nonuniform transverse distribution of outlet air properties is predicted. In other words, the air path line on the psychrometric chart along the fin base is not the same as the along the fin tip, while a simple straight air path line was assumed in the development of conventional one-dimensional fin model. It is also shown that, for a given inlet air dry bulb temperature, partial condensation occurred on the fin surface at low relative humidities, and a totally dry fin surface is formed at certain low relative humidities.