Approximate method for computation of glass cover temperature and top heat-loss coefficient of sola collectors with single glazing

- An improved equation form for computing the glass cover temperature of flat-plate solar collectors with single glazing is developed. A semi-analytical correlation for the factor f - the ratio of inner to outer heat-transfer coefficients - as a function of collector parameters and atmospheric variables is obtained by regression analysis. This relation readily provides the glass cover temperature ([T.sub.g]). The results are compared with those obtained by numerical solution of heat balance equations. Computational errors in [T.sub.g] and hence in the top heat loss coefficient ([U.sub.t]) are reduced by a factor of five or more. With such low errors in computation of [T.sub.g] and [U.sub.t], a numerical solution of heat balance equations is not required. The method is applicable over an extensive range of variables: the error in the computation of [U.sub.t] is within 2% with the range of air gap spacing 8 mm to 90 mm and the range of ambient temperature 0 [degrees] C to 45 [degrees] C. In this extended range of variables the errors due to simplified method based on empirical relations for [U.sub.t] are substantially higher.