Application of Exergy Concept to the Analysis of Optimum Operating Conditions of Solar Heat Collectors

A linear model was developed to obtain the relationships between the characteristic temperatures of the solar heat collector (e.g., the fluid outlet temperature) and the heat capacitance rate of the heat transfer medium. Combining these relationships and the exergy concept, we derived the optimum operating conditions in a general form to satisfy the requirements for the optimum outlet temperature. The optimum operating conditions can be used as a criterion when an appropriate collector type must be chosen for any particular solar application system. To confirm the analytical results, experiments were carried out with a simple flat-plate type solar collector. Good agreement could be obtained between the theoretical values and the experimental results.