INVESTIGATION OF PERFORMANCE OF A DOUBLE EXPOSURE SOLAR COLLECTOR

Abstract

Flat—plate solar collectors are most commonly used for the utilization of solar energy. Considerable efforts have been made to improve its performance. The double exposure concept using reflectors is one of them. Conventional design for flat—plate collectors have always followed the pattern of exposing one side to the sun while insulating the otherside•This design permits collection of solar energy from one side of the collector only. A double exposure solar collector absorbs the solar radiations on the back side as well as the front side. The insulation of a conventional collector on the back side is replaced by a plane glass and, reflectors are used to reflect the incident solar radiation onto the collector. In this work, a double exposure collector system was designed and fabricated. The conventional collector was installed at the latitude angle for Roorkee. The performance of double exposure collector relative to conventional (reference) collector has been investigated experimentally. It has been found that the double exposure collector system performance is considerably better th-n the conventional system around noon periods. The perfor-mance factor has been found to have value ranging between 1.33 to 1.60 at noon during mid September to mid October period. However, the performance during off-noon periods is not so encouraging. The performance factor has been seen to be a strong function of solar flux and the time of the day.