Performances of optimized working temperature for a solar central receiver

摘要

Recently, solar central receiver research has been directed toward high-temperature applications. High temperatures offer improved efficiency in the application process or cycle, or they may be required to initiate a particular chemical reaction. The thermal power for these high-temperature receivers could be supplied by a solar central receiver system, but, in the present time, the existing solar systems work at relative moderate temperature (up 800K). The disadvantages associated with high-temperature applications include greater receiver thermal loss per unit area. Thermal radiation and convection from a high-temperature receiver significantly decrease the receiver thermal efficiency. Therefore, in order to prevent this decreasing, a special construction of the receiver must be used: so named volumetric receiver provided with a receiver concentrator in front of this receiver seems to be able to use most efficiently the solar energy that enters receiver. One of the most advanced receivers was proposed by Karni et al. (1997), capable to achieve a temperature over 1500K. In order to decrease the reradiation losses, this receiver has a relative small aperture, the capability for collection of solar energy being improved by a relative large opening to the heliostat field. A concentrator type CPC (Welford and Winston, 1989) provides the optimal connection between this opening and the receiver aperture.