A prototype 'trumpet' type nonimaging secondary concentrator was designed and fabricated for use with the Cummins Power Generation (CPG) 7.5 kW_e dish-Stirling system A set of operational tests was carried out with a high temperature heat pipe receiver and gas-gap calorimeter. These tests have successfully alleviated any operational concerns about the effectiveness of active water cooling for such devices. We obtained over two full days of testing with the cavity receiver operating at its design temperature of 660 deg C while the trumpet throat temperature remained approx = or less than 100 deg C. In addition, these tests have shown that the thermal isolation of the trumpet from the hot receiver is very effective. Highly variable insolation, instabilities in the temperature controller on the calorimeter, and a poor match between the optical quality of the primary and the design of the trumpet have made detailed quantitative results difficult to obtain.
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