ABSORPTION OF RADIATION IN SOLAR STILLS

A method of calculating the fraction of incident solar radiation which is productively used in solar stills is presented. The number of variables which can influence this make it necessary to standarize on set values of glass thickness and extinction coefficent and liner reflectance. The variables considered are the day of the year, latitude, cover slope, orientation, percentage diffuse radiation and insolation intermittency. The complexity of the resulting functions, together with the number of varibles, makes it difficult to accurately predict what the still mean effective absorptance will be for a given set of conditions. It is found that insolation intermittency has an insignificant effect and that the greater the daily proportion of diffuse radiation, the lower the absorptance. Using the equations presented, a mean effective absorptance can be calculated for any given combination of the variables. © 1969.