NEW APPROACH TO LOW-COST LARGE AREA SELECTIVE SURFACES FOR PHOTOTHERMAL CONVERSION

In the present study, selective black paint coatings have been prepared by coating reflective metal particles with a layer of selective black material. the coated particles were mixed in a binder and applied easily as a thin layer onto aluminium or galvanized iron (G.I.) sheet. Three selective black materials, namely CuO, CuS and PbS + CuS have been deposited on zinc metal powder, the solar absorptance of the coatings is ±0.95 and the emittance is ±0.4. the thickness of the coatings was about 20 to 30 μm. the emissivity decreases as the thickness increases, while the solar absorptivity does not change appreciably. the improvement in the collector efficiency, which is the ratio of the temperature increase above the temperature of the standard panel to the temperature increase of the standard panel above the ambient temperature, is estimated to be around 11 per cent. the process is potentially a low cost one for large scale application in solar photothermal conversion. Copyright © 1979 John Wiley & Sons, Ltd.