EFFECT OF THERMAL CONTACT RESISTANCE ON THE HEAT TRANSFER IN PLATE FINNED TUBE HEAT EXCHANGERS

Plate fin-and-tube heat exchangers are made by inserting oval tubes through sheet metal strips with stamped holes and then expanding the tubes slightly to cause pressure at the tube-to-strip contacts. The gap between the fin base and the outer tube surface may be filled with air or corrosion products causing a decline in the ability of plate fins to transfer heat. The contact resistance must be accounted for in the design and performance calculations of heat exchangers. In this paper, the thermal contact resistance of the fin-to-tube attachment is estimated from the condition that the dimensionless correlations for the Colburn j-factors obtained from two different methods are in good agreement. The first method is based on the experimental data, while the second one on the CFD simulation of the flow and heat transfer in the heat exchanger