Middle and low temperature thermal energy widely exists in the natural world and many industrial fields.Unlike fossil fuel power generation systems,the significant feature of middle and low temperature power generatio...Middle and low temperature thermal energy widely exists in the natural world and many industrial fields.Unlike fossil fuel power generation systems,the significant feature of middle and low temperature power generation systems is the temperature constraint of the heat source.Exploring the potential of the cycle within a limited temperature range is key to improve energy utilization efficiency.This study proposes the conception of supercritical organic fluid Brayton cycles (SOFBC) and evaluates the feasibility and application potential.R116,R23,R170 and N_(2)O are selected as the working fluids for cycle analysis based on their thermal properties.Then,thermodynamic models of the supercritical gas Brayton cycle based on simple regeneration and organic Rankine cycles (ORCs) have been established.According to the calculation results,the performances of regenerative Brayton cycles (RBCs) using four working fluids are better than that of CO_(2).The maximum thermal efficiencies of R116,R23,and R170 are 41.9%,20.2%,and 15.3%higher than that of CO_(2)at the highest temperature of 150℃.Even at 300℃,the corresponding values of three organic fluids are 25.6%,13.7%,and 13.7%higher than that of CO_(2).By analyzing the variations in isobaric specific heat capacity (c_(p)) of different working fluids,it is found that the c_(p) difference between the high and low pressure sides in the regenerator of CO_(2) is significantly higher than that of organic working fluids.Additionally,the performance of RBCs using R116 is better than the sub-ORC using R123 and the trans-RORC using R236fa at the same temperature range.The results can demonstrate that the SOFBC is superior in middle and low temperature power generation compared with the sCO_(2) Brayton cycle and ORCs.This study provides preliminary and rough evidence of the feasibility and potential for SOFBCs.展开更多
基金supported by Beijing Natural Science Foundation of China (Grant No.3222025)。
文摘Middle and low temperature thermal energy widely exists in the natural world and many industrial fields.Unlike fossil fuel power generation systems,the significant feature of middle and low temperature power generation systems is the temperature constraint of the heat source.Exploring the potential of the cycle within a limited temperature range is key to improve energy utilization efficiency.This study proposes the conception of supercritical organic fluid Brayton cycles (SOFBC) and evaluates the feasibility and application potential.R116,R23,R170 and N_(2)O are selected as the working fluids for cycle analysis based on their thermal properties.Then,thermodynamic models of the supercritical gas Brayton cycle based on simple regeneration and organic Rankine cycles (ORCs) have been established.According to the calculation results,the performances of regenerative Brayton cycles (RBCs) using four working fluids are better than that of CO_(2).The maximum thermal efficiencies of R116,R23,and R170 are 41.9%,20.2%,and 15.3%higher than that of CO_(2)at the highest temperature of 150℃.Even at 300℃,the corresponding values of three organic fluids are 25.6%,13.7%,and 13.7%higher than that of CO_(2).By analyzing the variations in isobaric specific heat capacity (c_(p)) of different working fluids,it is found that the c_(p) difference between the high and low pressure sides in the regenerator of CO_(2) is significantly higher than that of organic working fluids.Additionally,the performance of RBCs using R116 is better than the sub-ORC using R123 and the trans-RORC using R236fa at the same temperature range.The results can demonstrate that the SOFBC is superior in middle and low temperature power generation compared with the sCO_(2) Brayton cycle and ORCs.This study provides preliminary and rough evidence of the feasibility and potential for SOFBCs.
