CORRELATION OF OPTIMAL SIZES OF BODIES WITH EXTERNAL FORCED-CONVECTION HEAT-TRANSFER

This paper shows how to correlate the optimal sizes of bodies with spe cified external forced convection heat transfer, when the objective is to minimize 1) the total rate of entropy generation, or 2) the total cost. Specific results are reported for the cylinder in cross-flow, th e sphere, and the flat plate in parallel flow. The results are present ed in terms of dimensionless parameters that show that regardless of t he body shape, the optimal size increases monotonically with the heat transfer duty parameter. A universal correlation is obtained by nondim ensionalizing the body size as a Reynolds number based on the transver sal length scale of the flow, and by replacing the body with an equiva lent one in two-dimensional flow. The optimal sizes correlated in this manner can be applied to bodies of other shapes.