FREE-STREAM COOLING OF A STACK OF PARALLEL PLATES

This paper addresses the fundamental heat transfer augmentation questi on of how to arrange a stack of parallel plates (e.g. fins of heat sin k, printed circuit boards) in a free stream such that the thermal resi stance between the stack and the stream is minimum. It is shown that t he best way of positioning the plates relative to one another is by sp acing them equidistantly. When the overall dimensions of the stack are specified, there is an optimal number of plates for minimum thermal r esistance. The optimal number and minimum resistance are anticipated t heoretically and correlated into compact formulas that agree with nume rical and experimental results in the Re, range 10(2)-10(4). Finally, it is shown that a stack with more plates than the optimal number can be modeled more expediently as a porous block immersed in a free strea m.