CAV2: A PC-based computer program for predicting incident solar flux distributions inside dish cavity receivers

Abstract

The energy flux distribution at the aperture of cavity receivers is an important parameter that characterizes the performance of point-focusing solar concentrators. Together with simplifying assumptions about cavity absorptance, emittance, and convective losses, good estimates of the dish-receiver collection efficiency as a function of incident flux and effective cavity temperature can be obtained. For detailed design of cavity receivers, however, it is necessary to determine the incident flux distribution on the interior surfaces. This information is needed ultimately to determine the resulting energy fluxes to the working fluid, temperature distributions within the cavity, and receiver performance. Knowing the incident flux distributions provides the designer with insights such as where hot-spots are likely to occur, where heat exchange surfaces are needed, and where more detailed analysis might be warranted. Solar receivers are heat exchangers and incident flux distributions are a fundamental aspect of their design. The objective of this effort was to develop a design tool with which the effects of concentrator and receiver geometry on energy distributions could be investigated. The principal interest was in obtaining the overall flux distributions within arbitrarily shaped cavities. CAV was selected as a starting point for this development because of its availability and becausemore » it interfaces with a thermal analysis program called CVT. It also has the advantage that it can accommodate a number of internal surface orientations and has been shown to agree very well with more sophisticated computer programs.« less