Analysis, development and testing of a fixed tilt solar collector employing reversible Vee-Trough reflectors and vacuum tube receivers
The Vee-Trough/Vacuum Tube Collector (VTVTC) aimed to improve the efficiency and reduce the cost of collectors assembled from evacuated tube receivers. The VTVTC was analyzed rigorously and a mathematical model was developed to calculate the optical performance of the vee-trough concentrator and the thermal performance of the evacuated tube receiver. A test bed was constructed to verify the mathematical analyses and compare reflectors made out of glass, Alzak and aluminized GEB Teflon. Tests were run at temperatures ranging from 95 to 180 C during the months of April, May, June, July and August 1977. Vee-trough collector efficiencies of 35-40 per cent were observed at an operating temperature of about 175 C. Test results compared well with the calculated values. Test data covering a complete day are presented for selected dates throughout the test season. Predicted daily useful heat collection and efficiency values are presented for a year's duration at operation temperatures ranging from 65 to 230 C. Estimated collector costs and resulting thermal energy costs are presented. Analytical and experimental results are discussed along with an economic evaluation.