Simulation Of Supercritical Carbon Dioxide Brayton Cycle Based On Waste Heat And Solar Power

The supercritical carbon dioxide Brayton cycle has received extensive attention and research in recent years for its potential of high efficiency in nuclear,waste,solar power,and fossil power generation.This paper uses Aspen Plus to establish SCO₂ Brayton cycle power generation systems to analyze and optimize thermal performance.The main research contents are as follows:Firstly,based on the first law of thermodynamics,effects of the cycle parameters including the compressor pressure,cycle temperature and heat exchanger temperature approach were compared and analyzed through the method of controlling local variables.Differing from the conventional refrigerants,the results showed that the thermodynamic performance of SCO₂ Brayton cycle was closely related to key parameters and layout.There was optimal maximum pressure and shunt coefficient to maximize circulation efficiency.The reheating process and intercooling process had beneficial effects on the efficiency of the cycle by increasing average heat absorption temperature and reducing compression power consumption.Secondly,this paper compared the combination of gas turbine waste heat and the SCO₂ Brayton power cycle.The results revealed that the performance of the SCO₂Brayton cycle system determined by the heat source utilization rate and the system cycle efficiency for variable temperature heat sources.The dual recuperated cycle had the highest efficiency and generated net power as 119.93 MW,which was higher than the simple recuperated cycle 37.21%.The reason was that by various stream split and merge,the initial endothermic temperature was reducing.An ideal thermal match was therefore reached.Thirdly,this paper compared the combination of gas turbine waste heat and the SCO₂ Brayton power cycle.The results revealed that the performance of the SCO₂Brayton cycle system was only related to system cycle efficiency without heat source characteristics.The recompression cycle had the highest efficiency and generate net power as 2248.01 k W,which was higher than the simple recuperated cycle 7.52%.The reason was that by various stream split,the initial endothermic temperature and regenerator effectiveness were increasing.Finally,for further improving the cycle efficiency,this paper proposed to recover the heat loss of the cooler in the SCO₂ Brayton cycle by Organic Rankine Cycle as the bottom cycle.The results indicated that ORC cycle could improve 5.26%cycle efficiency and net output power as 284.03 k W.