The supercritical CO_(2)(S-CO_(2)) Brayton cycle is expected to replace steam cycle in the application of solar power tower system due to the attractive potential to improve efficiency and reduce costs.Since the conce...The supercritical CO_(2)(S-CO_(2)) Brayton cycle is expected to replace steam cycle in the application of solar power tower system due to the attractive potential to improve efficiency and reduce costs.Since the concentrated solar power plant with thermal energy storage is usually located in drought area and used to provide a dispatchable power output,the S-CO_(2) Brayton cycle has to operate under fluctuating ambient temperature and diverse power demand scenarios.In addition,the cycle design condition will directly affect the off-design performance.In this work,the combined effects of design condition,and distributions of ambient temperature and power demand on the cycle operating performance are analyzed,and the off-design performance maps are proposed for the first time.A cycle design method with feedback mechanism of operating performance under varied ambient temperature and power demand is introduced innovatively.Results show that the low design value of compressor inlet temperature is not conductive to efficient operation under low loads and sufficient output under high ambient temperatures.The average yearly efficiency is most affected by the average power demand,while the load cover factor is significantly influenced by the average ambient temperature.With multi-objective optimization,the optimal solution of designed compressor inlet temperature is close to the minimum value of35℃ in Delingha with low ambient temperature,while reaches 44.15℃ in Daggett under the scenario of high ambient temperature,low average power demand,long duration and large value of peak load during the peak temperature period.If the cycle designed with compressor inlet temperature of 35℃ instead of 44.15℃ in Daggett under light industry power demand,the reduction of load cover factor will reach 0.027,but the average yearly efficiency can barely be improved.展开更多
Supercritical CO_(2)Brayton cycle has high efficiency,compactness,and excellent power generation potential.In the design of the cycle,some parameters,such as recuperator pinch point temperature difference(ΔTrec,pp),t...Supercritical CO_(2)Brayton cycle has high efficiency,compactness,and excellent power generation potential.In the design of the cycle,some parameters,such as recuperator pinch point temperature difference(ΔTrec,pp),turbine inlet temperature(Ttur,in),and maximum cycle pressure(pmax),are often preset without optimization.Furthermore,different preferences on efficiency and cost tradeoff can significantly affect the optimal design of the cycle,and the influence of different parameters on the design condition and the optimum cycle configuration becomes unclear as the preference changes.In this study,different preferences on efficiency and cost tradeoff are considered,and the effects of cycle configuration and optimization parameter addition on the tradeoff are investigated.In addition,four configurations under different preferences on tradeoff are recommended.Results show that the design condition parametersΔT_(rec,pp) decrease and T_(tur,in) and pmax increase as the preference of thermal efficiency(W_(th))increases.Different optimized parameters affect the results of the design point and cycle performance.In addition,the simple recuperative cycle and reheating cycle are recommended when low cycle initial cost dominates(W_(th)<0.598),and the recompression cycle and intercooling cycle are recommended when high cycle thermal efficiency dominates(W_(th)>0.701).The decision maker can select appropriate configuration according to specific preferences.展开更多
基金supported by Beijing Natural Science Foundation (Grant No.3202014)。
文摘The supercritical CO_(2)(S-CO_(2)) Brayton cycle is expected to replace steam cycle in the application of solar power tower system due to the attractive potential to improve efficiency and reduce costs.Since the concentrated solar power plant with thermal energy storage is usually located in drought area and used to provide a dispatchable power output,the S-CO_(2) Brayton cycle has to operate under fluctuating ambient temperature and diverse power demand scenarios.In addition,the cycle design condition will directly affect the off-design performance.In this work,the combined effects of design condition,and distributions of ambient temperature and power demand on the cycle operating performance are analyzed,and the off-design performance maps are proposed for the first time.A cycle design method with feedback mechanism of operating performance under varied ambient temperature and power demand is introduced innovatively.Results show that the low design value of compressor inlet temperature is not conductive to efficient operation under low loads and sufficient output under high ambient temperatures.The average yearly efficiency is most affected by the average power demand,while the load cover factor is significantly influenced by the average ambient temperature.With multi-objective optimization,the optimal solution of designed compressor inlet temperature is close to the minimum value of35℃ in Delingha with low ambient temperature,while reaches 44.15℃ in Daggett under the scenario of high ambient temperature,low average power demand,long duration and large value of peak load during the peak temperature period.If the cycle designed with compressor inlet temperature of 35℃ instead of 44.15℃ in Daggett under light industry power demand,the reduction of load cover factor will reach 0.027,but the average yearly efficiency can barely be improved.
基金supported by the Beijing Natural Science Foundation(Grant No.3202014).
文摘Supercritical CO_(2)Brayton cycle has high efficiency,compactness,and excellent power generation potential.In the design of the cycle,some parameters,such as recuperator pinch point temperature difference(ΔTrec,pp),turbine inlet temperature(Ttur,in),and maximum cycle pressure(pmax),are often preset without optimization.Furthermore,different preferences on efficiency and cost tradeoff can significantly affect the optimal design of the cycle,and the influence of different parameters on the design condition and the optimum cycle configuration becomes unclear as the preference changes.In this study,different preferences on efficiency and cost tradeoff are considered,and the effects of cycle configuration and optimization parameter addition on the tradeoff are investigated.In addition,four configurations under different preferences on tradeoff are recommended.Results show that the design condition parametersΔT_(rec,pp) decrease and T_(tur,in) and pmax increase as the preference of thermal efficiency(W_(th))increases.Different optimized parameters affect the results of the design point and cycle performance.In addition,the simple recuperative cycle and reheating cycle are recommended when low cycle initial cost dominates(W_(th)<0.598),and the recompression cycle and intercooling cycle are recommended when high cycle thermal efficiency dominates(W_(th)>0.701).The decision maker can select appropriate configuration according to specific preferences.
