Exergy analysis of Unglazed Transpired Solar Collectors (UTCs)

• The exergy analysis performed for this type of solar collector.
• Optimum dimensionless working temperature was found for this type of solar collector.
• A correlation proposed to relate the optimum dimensionless working temperature to the other dimensionless parameters.
• A contour plot proposed to facilitate the thermo-economical design of a UT.

The Unglazed Transpired Solar Collector (UTC) is a suitable device for preheating outside air directly. They are used mostly in preheating ventilation air as well as in heating air for crop drying. The thermal performance of UTC promises its popular usage in near future. A number of large scale installations have been used all over the world since 1990s. In this study, first, the exergy efficiency of UTC is derived. Based on this efficiency, optimization was performed on 200 different cases and finally, a simple but useful correlation was proposed to predict the optimum working temperature. After finding the optimum working temperature, an economic analysis may be performed to determine the most effective and least expensive geometry.