The energetic, exergetic, and mechanical comparison of two structurally optimized non-concentrating solar collectors for intermediate temperature applications

Abstract

The highly efficient non-concentrating solar collector is a key component for increasing solar energy penetration at the district level, thereby achieving the “carbon neutrality” goal. The non-concentrating vacuum-type solar collector used for intermediate temperature (100–200 °C) applications is a promising technology that has not been sufficiently explored. In this paper, two structurally optimized non-concentrating solar collectors have been meticulously analyzed from the perspective of structure, energy, exergy, surface stress, etc. Firstly, an outdoor experiment is executed to exhibit their thermodynamic behavior. Thermal resistance networks before and after their structural optimization are formed and the results indicate the thermal resistance that impedes solar collector heat loss has been enhanced by 3.83 and 4.17-fold, respectively. Next, energy and exergy flow charts are established to explain the thermal performance difference and the solar energy conversion in their respective internal components. Finally, the potential room for performance enhancement is further studied via the advanced exergy analysis method which reveals that the exergy destruction can be reduced by 17.74% and 13.90%, respectively. The results are essential for the further development of non-concentrating solar collectors in intermediate temperature applications, and it is also instrumental to realizing the decarbonization in district energy supplements.