Cost-effective solar collectors using heat pipes. Final technical report, July 1979-August 1981

Abstract

The objective of the program is the demonstration of high performance, cost effective, non-concentrating solar collectors using heat pipes. The end product will be directly applicable for efficient use with absorption and Rankine cycle chillers. Evacuated tubular solar collectors were selected as the only economical non-concentrating approach capable of efficient operation of chillers. The General Electric TC family of collectors was chosen because of their high level of performance and compatibility with heat pipe integration. Three heat pipe fluid-vessel combinations were identified and are continuing to be life tested at design and stagnation conditions for time periods exceeding 33,000 hours. Testing was carried out at the lower end of the environmental temperature range by freeze/thaw testing several types of water heat pipes. Two heat pipe collectors were tested using trimethylborate/1010 steel and copper/water heat pipes. Both collectors should improve performance as compared to the standard General Electric TC-100. A cost analysis showed that in volume production the heat pipes could be made for $1.50 each (1978 dollars) and would be cost effective for the performance achieved in collector testing.