压缩空气储能是解决可再生能源发电并网、提高电网稳定性的有效方法。为减少储气库体积、维持系统工况稳定,采用工业流程模拟软件Aspen Plus建立了100 MW×4 h等压压缩空气储能(I-CAES)系统的热力学仿真模型,计算了设计工况下的系...压缩空气储能是解决可再生能源发电并网、提高电网稳定性的有效方法。为减少储气库体积、维持系统工况稳定,采用工业流程模拟软件Aspen Plus建立了100 MW×4 h等压压缩空气储能(I-CAES)系统的热力学仿真模型,计算了设计工况下的系统性能,分析了压缩机出口温度及压缩膨胀级数对系统运行的影响。结果表明,当压缩机出口温度为160℃时,4级压缩-4级膨胀的I-CAES系统储能效率可达62.61%,储能密度为5.99 k W·h/m^(3);压缩机出口温度每升高10℃,储能密度及效率分别增加2.66 k W·h/m^(3),1.49百分点;压缩膨胀级数每增加1,储能密度及效率分别增加6.34 k W·h/m^(3),0.81百分点。展开更多
A heat exchanger’s performance depends heavily on the operating fluid’s transfer of heat capacity and thermal conductivity.Adding nanoparticles of high thermal conductivity materials is a significant way to enhance ...A heat exchanger’s performance depends heavily on the operating fluid’s transfer of heat capacity and thermal conductivity.Adding nanoparticles of high thermal conductivity materials is a significant way to enhance the heat transfer fluid’s thermal conductivity.This research used engine oil containing alumina(Al_(2)O_(3))nanoparticles and copper oxide(CuO)to test whether or not the heat exchanger’s efficiency could be improved.To establish the most effective elements for heat transfer enhancement,the heat exchangers thermal performance was tested at 0.05%and 0.1%concentrations for Al_(2)O_(3)and CuO nanoparticles.The simulation results showed that the percentage increase in Nusselt number(Nu)for nanofluid at 0.05%particle concentration compared to pure oil was 9.71%for CuO nanofluids and 6.7%for Al_(2)O_(3)nanofluids.At 0.1%concentration,the enhancement percentage in Nu was approximately 23%for CuO and 18.67%for Al_(2)O_(3)nanofluids,respectively.At a concentration of 0.1%,CuO nanofluid increased the LMTD and overall heat transfer coefficient(U)by 7.24 and 5.91%respectively.Both the overall heat transfer coefficient(U)and the heat transfer coefficient(hn)for CuO nanofluid at a concentration of 0.1%increased by 5.91%and 10.68%,respectively.The effectiveness(εn)of a heat exchanger was increased by roughly 4.09%with the use of CuO nanofluid in comparison to Al_(2)O_(3)at a concentration of 0.1%.The amount of exergy destruction in DTHX goes down as Re and volume fractions go up.Moreover,at 0.05%and 0.1%nanoparticle concentrations,the percentage increase in dimensionless exergy is 10.55%and 13.08%,respectively.Finally,adding the CuO and Al_(2)O_(3)nanoparticles improved the thermal conductivity of the main fluid(oil),resulting in a considerable increase in the thermal performance and rate of heat transfer of a heat exchanger.展开更多
文摘压缩空气储能是解决可再生能源发电并网、提高电网稳定性的有效方法。为减少储气库体积、维持系统工况稳定,采用工业流程模拟软件Aspen Plus建立了100 MW×4 h等压压缩空气储能(I-CAES)系统的热力学仿真模型,计算了设计工况下的系统性能,分析了压缩机出口温度及压缩膨胀级数对系统运行的影响。结果表明,当压缩机出口温度为160℃时,4级压缩-4级膨胀的I-CAES系统储能效率可达62.61%,储能密度为5.99 k W·h/m^(3);压缩机出口温度每升高10℃,储能密度及效率分别增加2.66 k W·h/m^(3),1.49百分点;压缩膨胀级数每增加1,储能密度及效率分别增加6.34 k W·h/m^(3),0.81百分点。
文摘A heat exchanger’s performance depends heavily on the operating fluid’s transfer of heat capacity and thermal conductivity.Adding nanoparticles of high thermal conductivity materials is a significant way to enhance the heat transfer fluid’s thermal conductivity.This research used engine oil containing alumina(Al_(2)O_(3))nanoparticles and copper oxide(CuO)to test whether or not the heat exchanger’s efficiency could be improved.To establish the most effective elements for heat transfer enhancement,the heat exchangers thermal performance was tested at 0.05%and 0.1%concentrations for Al_(2)O_(3)and CuO nanoparticles.The simulation results showed that the percentage increase in Nusselt number(Nu)for nanofluid at 0.05%particle concentration compared to pure oil was 9.71%for CuO nanofluids and 6.7%for Al_(2)O_(3)nanofluids.At 0.1%concentration,the enhancement percentage in Nu was approximately 23%for CuO and 18.67%for Al_(2)O_(3)nanofluids,respectively.At a concentration of 0.1%,CuO nanofluid increased the LMTD and overall heat transfer coefficient(U)by 7.24 and 5.91%respectively.Both the overall heat transfer coefficient(U)and the heat transfer coefficient(hn)for CuO nanofluid at a concentration of 0.1%increased by 5.91%and 10.68%,respectively.The effectiveness(εn)of a heat exchanger was increased by roughly 4.09%with the use of CuO nanofluid in comparison to Al_(2)O_(3)at a concentration of 0.1%.The amount of exergy destruction in DTHX goes down as Re and volume fractions go up.Moreover,at 0.05%and 0.1%nanoparticle concentrations,the percentage increase in dimensionless exergy is 10.55%and 13.08%,respectively.Finally,adding the CuO and Al_(2)O_(3)nanoparticles improved the thermal conductivity of the main fluid(oil),resulting in a considerable increase in the thermal performance and rate of heat transfer of a heat exchanger.
