Energy matrices of U-shaped evacuated tubular collector (ETC) integrated with compound parabolic concentrator (CPC)

This paper deals with the detailed thermal modeling of U-shaped evacuated tubular collector (ETC) integrated with compound parabolic concentrator (CPC). Such type of system is very useful in the preheating process for very high temperature industrial applications. The theoretical model have also been experimentally validated. The energy matrices like Energy pay back time (EPBT), Energy production factor (EPF) and Life cycle conversion efficiency (LCCE) for evacuated tubular collectors connected in series without and with concentrator have been evaluated and compared in this paper. For six number of collectors connected in series, the maximum difference water temperature between inlet and outlet in ETC-CPC combination is found to be 24 °C, whereas it is about 17 °C in ETC without CPC. A good agreement between theoretical and experimental results has been observed. The annual thermal energy gain is found to be 1461.63 kW h and 1859.66 kW h for ETC and ETC-CPC system, respectively. The annual exergy gain is found to be 137.5 kW h and 165.9 kW h for ETC and ETC-CPC system, respectively. EPBT is increased by 6.2% and 11.6% and EPF is decreased by 5.7% and 25% on energy and exergy basis respectively for 20 years life of the system when CPC is integrated with ETC.