Development and testing of low cost solar energy collectors for heating air

Abstract Solar Energy Collector designs utilising plastic films for the absorber and the glazing are developed for air heating applications. The objective is the cost reduction of such collectors with reasonable performance and acceptable life time. The developed collectors were of nonporous as well as porous type, the latter having a special synthetic textile as the absorber. An experimental facility is described to study the performance of the collectors as a function of typical physical parameters and the experimental results are discussed. The collector, with a black porous textile absorber, was found to be much superior to the collector of nonporous type. The thermal performance of the former gets, however, severely affected if the porous absorber is not suitably optimized and if the back of the collector is not properly insulated. Considering life time of a collector as a parameter and taking into account the investment cost, interest rate and the useful energy available from the collector, a simple expression has been developed for rating various collectors. A comparison of the numerical data for the present porous collector and commercially available conventional collector for air heating shows that the present collectors have a better economic potential even if one assigns a short life time to them.