Experimental investigation on the heat transfer behavior of water in offset strip fin channels

Abstract

This paper experimentally investigates the heat transfer behavior of water in offset strip fin (OSF) channels. 18 different OSF geometries, which are divided into three groups by the ratio of the front-fin-end area of a single cell to fin thickness squared (Affe/t2), are tested under a constant heat flux. The results show that when the Affe/t2 is large, the high and close-spaced OSFs with small fin length are unsuitable for water heat transfer, while high fin density, small fin height and small fin length can improve the water heat transfer performance for the OSFs with small Affe/t2. Further analysis indicates that there is a negative relationship between the j factor and Prandtl number, as well as between the j factor and fin efficiency. The comparison between the data for water and air reveals that the large difference between the heat transfer coefficient and the heat transmittance coefficient due to the low fin efficiency of water heat transfer makes it difficult to extend air data to water. Moreover, a j correlation of water for the different OSFs is developed based on the regression analysis. The correlation provides the water j factors that fall within the 2σ confidence interval with a standard deviation of 9.63%. The present study not only provides useful data for the design and development of OSF heat exchangers, but also offers strong support for a deeper understanding of liquid heat transfer behavior in OSF channels.