Theoretical analysis of the effect of a bottom reflector on a vertical multiple-effect diffusion solar still coupled with a basin-type still

Abstract

The effect of a flat plate bottom reflector on a vertical multiple-effect diffusion solar still coupled with a basin-type still is analyzed theoretically at 30°N latitude. The still has a right-angled triangular cross-section consisting of a horizontal basin liner, a sloping double glass cover, and the vertical multiple-effect diffusion still (multiple-effect section) at the vertical rear wall. A geometrical model was constructed to calculate the amount of solar radiation reflected by the reflector and absorbed on both the basin liner and the first partition of the multiple-effect section. The reflected radiation from the reflector can be a thermal input to the multiple-effect section both in cases where the reflected radiation is absorbed on the basin liner and on the first partition. It is predicted that the overall daily productivity of the still can be increased about 16%, 13%, and 29% on the spring and autumn equinoxes, the winter solstice, and the summer solstice, respectively, by adding the external reflector and setting the reflector inclination to the proper angle according to seasons. © 2013 Hiroshi Tanaka.