Abstract:A new type of trough solarconcentrating carbon dioxide generator was designed. The heat collection and gas production performance of the generator was tested under the tracking and nontracking conditions in Huhhot, and the changing rules of the reactor cavity stagnation temperature, integral water temperature and heatcollecting efficiency with the irradiance at the daylight opening were analyzed, the optimal operation mode of the system was determined and two system performance evaluation indexes of gas loss rate and gas production capacity were proposed. The test results showed that the determination coefficient of the fitting formulas were both greater than 0.998 after the calibration with two thermocouples, and the fitting function had high accuracy. During the test, the fitting curve equation was used to correct each test temperature value. The No.1 thermocouple tested the generator cavity temperature, which was installed in the center of the cavity. The No.2 thermocouple was installed close to the outer wall to test the temperature of the outer wall of the generator. Under the two conditions, the change rules of the system performance parameters were similar, but there were also features in common. The temperature of each test point and gas production capacity had positive correlation with the irradiance. The heat generation efficiency of the system was mainly affected by the initial temperature of the heat storage medium, and the higher the initial temperature of the heat storage medium was, the lower the heatcollecting efficiency of the system would be. When the temperature of the heat storage medium approached the limit temperature, the higher solar irradiance was needed to supply the system heat loss and then continue to enhance its heat storage. Under tracking and nontracking conditions, the maximum stagnation temperatures of the reactor were 107℃ and 92℃, respectively. Compared with the nontracking conditions, the maximum stagnation temperatures of the reactor cavity was increased by 1630% under tracking conditions. Under the conditions of tracking and nontracking, the maximum integral water temperatures of the reactor were up to 94℃ and 83.6℃ and the highest heat concentration efficiency were 38.90% and 20.00%, respectively. Compared with the nontracking conditions, the maximum water temperature in the reactor cavity was increased by 12.44% and the maximum heat concentration efficiency of the system was increased by 94.50% under tracking condition. During the test period, the minimum water temperature in the reactor cavity was 62.4℃, which was higher than the complete decomposition temperature of the reaction raw materials. Integral temperature of reactor was less influenced by ambient temperature. The best operation condition of the system was determined to be tracking model. The heatcollecting efficiency of the system was 31.80% within the gas generation temperature range, and the gas loss rate was 450% during the whole gas production process. When the solar direct irradiance was ranged from 650W/m2 to 850W/m2, the gas generation capacity of the system showed a positive correlation with the solar direct irradiance lower than 700W/m2, the gas production capacity gradually tended to be steady, and the gas loss approached the limit value, and the decomposition speed tended to be stable. The relationship between gas production capacity and solar direct irradiance was obtained. Based on the gas production capacity, the determination method of specific structural parameters of line focus solar carbon dioxide generator under the best mode of operation can be determined. The research result was of great significance for promoting the standardized application of the line focus solar carbon dioxide generator.
