NATURAL CONVECTION CHARACTERISTICS OF FLAT PLATE COLLECTORS.

Local and average heat transfer coefficients for natural convection between parallel plates have been experimentally studied using interferometric techniques. The experimental conditions were similar to these existing in flat-plate solar collectors. Correlations have been developed for the local and average heat transfer Nusselt numbers as functions of tilt angle and Grashof number. The results are useful in determining the top loss coefficient for flat plate collectors and, eventually, for finding means of minimizing these losses.