Comparison of potential control strategies for an impinging receiver based dish-Brayton system when the solar irradiation exceeds its design value

Potential control strategies for an impinging receiver based dish-Brayton system have been presented for protecting the key components from the risks of overheating when the solar irradiation exceeds its design value. Two of them are selected for a detailed study: changing the effective diameter of the shading device and changing the inlet temperature. A rope-pulley shading device is developed for controlling the shading area in the center of the dish, and the change of the inlet temperature is achieved by applying a bypass at the cold side of the recuperator for reducing the heat transfer rate. Both control strategies can manage the peak temperature on the absorber surface within 1030 degrees C with an outlet temperature fluctuation between -4.1 and 15.1 degrees C, so that the impinging receiver can work for long time at any solar direct normal irradiance value. Furthermore, the temperature differences on the absorber surface are between 137.1 degrees C and 163.8 degrees C. The cases that are achieved by changing the shield effective diameter are significantly lower (11-26 degrees C) than the corresponding cases that are achieved by changing the inlet temperature.