Optimization of an absorber plate fin having a step-change in local thickness

Solar collectors having “tube-and-fin” absorber plates have traditionally used rectangular fins. The introduction of a “step-change” in fin thickness, so that the fin is thinner far from the tube, permits a savings in material content. Through heat transfer analysis, this paper derives an expression for the efficiency of a fin of this step-change shape, and applies it to the problem of finding the savings in material this shape permits. The results indicate that roughly a 20% reduction in fin material is possible.