General thermal analysis of serpentine-flow flat-plate solar collector absorbers

A thermal analysis is performed on an absorber which has general applicability to the ser-pentine-flow configuration. The heat conduction equation is rendered in nondimensional form for a typ-ical panel-segment of the absorber, and shape factors are introduced for general application to various detailed flow-duct geometries. An analytical solution is obtained for the typical panel in terms of an Effectiveness--NTU relationship for that panel; the series combination of these relationships yields the overall E-NTU relationship for the entire absorber plate, for any number of "panels," or serpentine-flow reversals. The results of the present analysis indicate the expected, axially varying, asymmetry of the temper-ature profile between the flow passes. Performance results are stated in terms of a serpentine relative performance factor, which permits direct comparison to the parallel configuration. The results indicate superior thermal performance of the serpentine-flow absorber, relative to the parallel-flow absorber, for the same number of transfer units