Finned Tube Gap Resistance for Compressor Inter-Cooler

Abstract

This paper presents a rational analysis for predicting thermal-contact resistance in the compressor intercoolers where the hot air is on the finned side with cooling water in the tube side. It further includes a derivation of the maximum design temperature for the hot air or fluid for a zero thermal-contractor or gap resistance. At the elevated temperatures, a gap resistance is created by the differential thermal expansion between the fins and the tubes. This expansion completely relaxes the initial fabrication contact pressure that binds the fins to the tubes. The equations derived for the gap resistance and maximum design temperature are quite in good agreement in verifying the results. The results generally show that the gap resistance increases as hot air temperature increase, and that the lower cooling temperatures would tolerate higher design temperatures. It is interesting to note that the initial contact pressure is a major factor in restricting the formation of the gap resistance