An accurate upper estimate for the transmission of solar radiation in salt gradient ponds

Abstract

The objective of the present work is the estimation of maximum transmission of solar radiation within a body of natural water under the most favorable conditions, with special reference to salt gradient solar ponds. The study, based on recent data, includes two alternative analytical approaches based on the split of the solar spectrum into the appropriate number of spectral bands and numerical calculation of discrete values of integrals according to Beer's law. As far as radiation transmission properties of clear water are concerned, it was found that the broadly used absorption law, which is commonly referred to as an upper transmission limit, is derived from original work by Schmidt[23] and deficient data, employed at the time, are responsible for the appreciably lower theoretical maximum transmission then derived. The accurate upper transmission limit derived now also gives comparative higher heat collection efficiency. Comments have been made for the introduction of a water clarity dimensionless factor in terms of the upper transmission limit, describing the economical operation limits for solar pond water.