Honeycomb devices in flat-plate solar collectors

Abstract The results are presented of a theoretical study on the performance of a flat-plate type solar collector in which a selectively transmitting honeycomb panel is mounted between the absorbing flat plate and the outer glass cover. An analytic study of the natural convection process in such panels has shown that, under certain conditions, natural convection losses can be suppressed. Further, the honeycomb significantly reduces the radiation heat losses from the absorber. If the honeycomb cell walls are sufficiently thin, heat losses by conduction directly through the honeycomb wall material need not be important, and a high transmittance to solar radiation can be achieved. Efficiency curves for this type of collector are given and compared with those of a more convectional design. Higher efficiencies in the 200 to 300 deg F plate-temperature range are predicted. The importance of the honeycomb wall thickness in the overall efficiency is pointed out.