NUMERICAL MODELING OF CONDUCTION EFFECTS IN MICROSCALE COUNTERFLOW HEAT EXCHANGERS

Abstract

This article examines thermal energy transport in a micro counterflow heat exchanger with a numerical model that includes axial conduction. The unique aspect of this work is an analysis that permits end-wall temperature gradients to be determined, thus allowing the conduction heat transfer from the heat exchanger to be assessed. Since there are two unknown initial conditions out of four needed in the set of equations governing the temperature distributions, a two-value shooting approach is needed to solve the problem. Conduction losses are combined with nonunity effectiveness losses to obtain a total normalized heat loss for the system. The results of the study demonstrate the need for using very low thermal conductivity material in the construction of micro counterflow heat exchangers in order to achieve reasonable performance in small devices.