Heat transfer and pressure drop of perforated surface heat exchanger with passage enlargement and contraction

Abstract A new enhanced surface for forced-convection heat transfer effective in the range of Reynolds numbers lower than 3000 is proposed The surface has many perforations and is bent to form a trapezoidal shape A heat exchanger constructed with these surfaces has enlargement and contraction parts alternately along the flow passages The mechanism of the heat transfer enhancement is studied experimentally by changing the surface geometries and heat exchanger configuration, and, in addition, by flow visualization It is shown that the mechanism of the heat transfer enhancement is due to the secondary flow induced by the suction and injection through the perforations, and to the frequent boundary layer interruptions at each contraction part Dimensionless correlations on the heat transfer and pressure drop are presented.