Nowadays,the recompression supercritical carbon dioxide(R-SCO_(2))cycle has emerged as a promising option for power conversion systems because of its boundless potential to tackle energy and environmental issues.In th...Nowadays,the recompression supercritical carbon dioxide(R-SCO_(2))cycle has emerged as a promising option for power conversion systems because of its boundless potential to tackle energy and environmental issues.In this study,we examined the performance of the solar parabolic trough collector(SPTC)integrated combined cogeneration system for the purpose of power generation as well as recovery of waste exhaust heat from the R-SCO_(2) cycle with the help of the organic Rankine cycle(ORC).An exergy and energy analysis was performed for a combined recompression cycle(R-SCO_(2)-ORC)by varying the input variables such as intensity of solar irradiation(Gb),pressure at the inlet of SCO_(2) turbine(P_(5)),mass flow rate of SCO_(2)()&mSCO_(2) inlet temperature of SCO_(2) turbine(T5),inlet temperature of main compressor(T_(9))and effectiveness of the high-and low-temperature recuperator( HTR and LTR).Eight organic working fluids were considered for the ORC:R123,R290,isobutane,R1234yf,R1234ze,toluene,isopentane and cyclohexane.The study revealed that R123-based R-SCO_(2)-ORC demonstrates the highest thermal and exergy efficiency:~73.4 and 40.89%at G_(b)=0.5 kW/m^(2);78.8 and 43.9%at P_(5)=14 MPa;63.86 and 35.57%at T5=650 K;74.84 and 41.69%at&mSCO 7kg s;2=/85.83 and 47.82%at T_(9)=300 K;84.57 and 47.11%at HTR 65;=0.85.06 and 47.38%at LTR 65,=0.respectively.Alternatively,R290 showed the minimum value of exergy and thermal efficiency.As can be seen,the maximum amount of exergy destruction or exergy loss occurs in a solar collector field,~58.25%of the total exergy destruction rate(i.e.6703 kW)and 18.99%of the solar inlet exergy(i.e.20562 kJ).Moreover,R123 has the highest net work output,~4594 kJ at T5=650 K and 6176 kJ at T_(9)=300 K.展开更多
超临界二氧化碳(supercritical CO_(2),sCO_(2))三压缩循环(tri-compression,TC)与再压缩循环(recompression cycle,RC)相比有较大的效率提升,为进一步提升燃煤sCO_(2)发电系统效率,有必要构建TC燃煤发电系统.烟气热量全温区吸收是超临...超临界二氧化碳(supercritical CO_(2),sCO_(2))三压缩循环(tri-compression,TC)与再压缩循环(recompression cycle,RC)相比有较大的效率提升,为进一步提升燃煤sCO_(2)发电系统效率,有必要构建TC燃煤发电系统.烟气热量全温区吸收是超临界二氧化碳循环应用于燃煤热源时会面临的关键问题之一,目前主要有两种解决方法,分别为基于能量复叠利用原理构建复合循环(overlap energy utilization,OEU)和尾部烟道添加烟气冷却器(flue gas cooler,FGC).本文以三压缩+再热(tri-compression plus reheating,TC+RH)为基本循环,耦合锅炉水动力模型,基于两种烟气热量全温区吸收方法,构建了OEU和FGC两个燃煤发电系统,针对烟气中低温区余热吸收性能进行对比分析.研究发现,由于FGC系统中温区工质吸热能力不足,并且受限于尾部受热面30°C夹点温差,锅炉排烟温度高达172.6°C,锅炉效率仅为90.64%.对于OEU系统,锅炉排烟温度可降低至126.0°C,对应的锅炉效率为92.85%,满足系统性能的要求.另外,FGC系统烟气中温区和低温区的传热?损均高于OEU系统,说明OEU系统锅炉中低温区的烟气与工质能级更加匹配.展开更多
文摘Nowadays,the recompression supercritical carbon dioxide(R-SCO_(2))cycle has emerged as a promising option for power conversion systems because of its boundless potential to tackle energy and environmental issues.In this study,we examined the performance of the solar parabolic trough collector(SPTC)integrated combined cogeneration system for the purpose of power generation as well as recovery of waste exhaust heat from the R-SCO_(2) cycle with the help of the organic Rankine cycle(ORC).An exergy and energy analysis was performed for a combined recompression cycle(R-SCO_(2)-ORC)by varying the input variables such as intensity of solar irradiation(Gb),pressure at the inlet of SCO_(2) turbine(P_(5)),mass flow rate of SCO_(2)()&mSCO_(2) inlet temperature of SCO_(2) turbine(T5),inlet temperature of main compressor(T_(9))and effectiveness of the high-and low-temperature recuperator( HTR and LTR).Eight organic working fluids were considered for the ORC:R123,R290,isobutane,R1234yf,R1234ze,toluene,isopentane and cyclohexane.The study revealed that R123-based R-SCO_(2)-ORC demonstrates the highest thermal and exergy efficiency:~73.4 and 40.89%at G_(b)=0.5 kW/m^(2);78.8 and 43.9%at P_(5)=14 MPa;63.86 and 35.57%at T5=650 K;74.84 and 41.69%at&mSCO 7kg s;2=/85.83 and 47.82%at T_(9)=300 K;84.57 and 47.11%at HTR 65;=0.85.06 and 47.38%at LTR 65,=0.respectively.Alternatively,R290 showed the minimum value of exergy and thermal efficiency.As can be seen,the maximum amount of exergy destruction or exergy loss occurs in a solar collector field,~58.25%of the total exergy destruction rate(i.e.6703 kW)and 18.99%of the solar inlet exergy(i.e.20562 kJ).Moreover,R123 has the highest net work output,~4594 kJ at T5=650 K and 6176 kJ at T_(9)=300 K.
文摘超临界二氧化碳(supercritical CO_(2),sCO_(2))三压缩循环(tri-compression,TC)与再压缩循环(recompression cycle,RC)相比有较大的效率提升,为进一步提升燃煤sCO_(2)发电系统效率,有必要构建TC燃煤发电系统.烟气热量全温区吸收是超临界二氧化碳循环应用于燃煤热源时会面临的关键问题之一,目前主要有两种解决方法,分别为基于能量复叠利用原理构建复合循环(overlap energy utilization,OEU)和尾部烟道添加烟气冷却器(flue gas cooler,FGC).本文以三压缩+再热(tri-compression plus reheating,TC+RH)为基本循环,耦合锅炉水动力模型,基于两种烟气热量全温区吸收方法,构建了OEU和FGC两个燃煤发电系统,针对烟气中低温区余热吸收性能进行对比分析.研究发现,由于FGC系统中温区工质吸热能力不足,并且受限于尾部受热面30°C夹点温差,锅炉排烟温度高达172.6°C,锅炉效率仅为90.64%.对于OEU系统,锅炉排烟温度可降低至126.0°C,对应的锅炉效率为92.85%,满足系统性能的要求.另外,FGC系统烟气中温区和低温区的传热?损均高于OEU系统,说明OEU系统锅炉中低温区的烟气与工质能级更加匹配.
