Conjugate heat transfer in a total heat exchanger with cross-corrugated triangular ducts in laminar flow

Abstract

Membrane-based total heat exchanger is a device to recover both sensible heat and moisture from exhaust air stream from a building. Heat and mass transfer intensification has been undertaken by using a structure of cross-corrugated triangular ducts. Conjugate heat under laminar flow regime in this total heat exchanger are investigated. Contrary to the traditional methods of assuming a uniform temperature or a uniform heat flux boundary condition, in this study, the real boundary conditions on the exchanger surfaces are obtained by the numerical solution of the coupled equations that govern the transfer of momentum and energy in the two air streams and in the membrane materials. The naturally formed heat boundary conditions are then used to calculate the cyclic mean Nusselt numbers along the exchanger ducts. The data are compared with those results under uniform temperature and uniform heat flux boundary conditions. The heat transfer will change with different thermal wall boundary conditions. Synergy principle is applied to reveal the Nusselt number variation with various thermal wall boundary conditions.