A design method of flat-plate solar collectors based on minimum entropy generation

Abstract

A procedure to establish the optimal performance parameters for the minimum entropy generation during the collection of solar energy, is presented. The Entropy Generation Number, N_s, and the criterion for the optimal thermodynamic operation of a collector under nonisothermally, finite-time conditions, are reviewed. The Mass Flow Number, M, corresponding to the optimum flow of working fluid as a function of the solar collection area, is also considered. A general method for the preliminary solar collector design, based on N_s, M and the “Sun–Air” or stagnation temperature, is developed. This last concept is defined as the maximum temperature that the collector reaches at nonflow conditions for given geographic location, geometry and construction materials. The thermodynamic optimization procedure was used to determine the optimal performance parameters of an experimental solar collector.