The effects of recycle at the ends on the heat and mass transfer through a parallel-plate channel with uniform wall temperature are studied by an orthogonal expansion technique. The heat and mass transfer problem is solved for fully developed laminar velocity profiles in a parallel-plate channel with ignoring axial conduction, and with fluid properties which are temperature independent. Analytical results show that recycle can enhance the heat transfer rate for high Graetz numbers compared with that in an open conduit (without an impermeable plate inserted and without recycle). The preheating and residence-time are the two effects which are in domination of the heat transfer behavior.
International Journal of Heat and Mass Transfer 41(17), pp.2589-2599