Process heating constitutes a significant share of final energy consumption in the industrial sector around the world.In this paper,a high-temperature heat pump(HTHP)using flash tank vapor injection technology(FTVI)is...Process heating constitutes a significant share of final energy consumption in the industrial sector around the world.In this paper,a high-temperature heat pump(HTHP)using flash tank vapor injection technology(FTVI)is proposed to develop low-temperature geothermal source for industrial process heating with temperature above 100°C.With heat sink output temperatures between 120°C and 150°C,the thermo-economic performance of the FTVI HTHP system using R1234ze(Z)as refrigerant is analyzed and also compared to the single-stage vapor compression(SSVC)system by employing the developed mathematical model.The coefficient of performance(COP),exergy efficiency(ηexe),net present value(NPV)and payback period(PBP)are used as performance indicators.The results show that under the typical working conditions,the COP andηexe of FTVI HTHP system are 3.00 and 59.66%,respectively,and the corresponding NPV and PBP reach 8.13×106 CNY and 4.13 years,respectively.Under the high-temperature heating conditions,the thermo-economic performance of the FTVI HTHP system is significantly better than that of the SSVC system,and the larger the temperature lift,the greater the thermo-economic advantage of the FTVI HTHP system.Additionally,the FTVI HTHP system is more capable than the SSVC system in absorbing the financial risks associated with changes of electricity price and natural gas price.展开更多
目的探讨7.0 T磁共振上三维血管壁成像技术(DANTE-FLASH)进行ApoE-/-小鼠颈动脉粥样硬化斑块成像的可行性。方法通过数值仿真优化成像参数,实现血管腔-壁对比度最大化。6只ApoE-/-小鼠和3只野生型小鼠在7.0 T MRI均行DANTEFLASH和流入...目的探讨7.0 T磁共振上三维血管壁成像技术(DANTE-FLASH)进行ApoE-/-小鼠颈动脉粥样硬化斑块成像的可行性。方法通过数值仿真优化成像参数,实现血管腔-壁对比度最大化。6只ApoE-/-小鼠和3只野生型小鼠在7.0 T MRI均行DANTEFLASH和流入流出饱和带的多层2D RARE(2D-IOSB-RARE)两种扫描。在管壁信噪比(SNRwall)、管腔信噪比(SNRlumen)、壁-腔对比噪声比(CNR)、管腔面积(LA)、和管壁面积(WA)方面分别对2D-IOSB-RARE和DANTE-FLASH序列进行比较。对于LA与WA,使用线性回归分析评估MR图像与病理图像测量结果的相关性。结果根据数值仿真结果,小鼠实验的DANTE模块采用了15°翻转角与150脉冲链。相较于2D-IOSB-RARE,DANTE-FLASH的CNR轻微降低(P<0.001),但层分辨率显著提高。组内相关系数(LA:ICC=0.94,P<0.001;WA:ICC=0.93,P<0.001)和Bland-Altman图显示出DANTE-FLASH和2DIOSB-RARE在评估LA和WA测量结果方面具有良好的一致性。MR图像与病理图像在定量测量LA(P<0.0001)和WA(P<0.0001)中呈现较强相关性。结论在7.0 T磁共振上,三维DANTE-FLASH黑血MR序列,可实现各向同性高空间分辨率成像,有利于ApoE-/-小鼠颈动脉粥样硬化病变的灵活显示和定量评估。展开更多
The aim of this work is to investigate the flow instabilities in a baffled, stirred tank generated by a single Rushton turbine by means of large eddy simulation （LES）. The sliding mesh method was used for the coupli...The aim of this work is to investigate the flow instabilities in a baffled, stirred tank generated by a single Rushton turbine by means of large eddy simulation （LES）. The sliding mesh method was used for the coupling between the rotating and the stationary frame of references. The calculations were carried out on the ＂Shengcao-21C＂ supercomputer using a computational fluid dynamics （CFD） code CFX5. The flow fields predicted by the LES simulation and the simulation using standard κ-ε model were compared to the results from particle image velocimetry （PIV） measurements. It is shown that the CFD simulations using the LES approach and the standard κ-ε model agree well with the PIV measurements. Fluctuations of the radial and axial velocity are predicted at different frequencies by the LES simulation. Velocity fluctuations of high frequencies are seen in the impeller region, while low frequencies velocity fluctuations are observed in the bulk flow. A low frequency velocity fluctuation with a nondimensional frequency of 0.027Hz is predicted by the LES simulation, which agrees with experimental investigations in the literature. Flow circulation patterns predicted by the LES simulation are asymmetric, stochastic and complex, spanning a large portion of the tanks and varying with time, while circulation patterns calculated by the simulation using the standard κ-ε model are symmetric. The results of the present work give better understanding to the flow instabilities in the mechanically agitated tank. However, further analysis of the LES calculated velocity series by means of fast Fourier transform （FFT） and/or spectra analysis are recommended in future work in order to gain more knowledge of the complicated flow phenomena.展开更多
Based on the analysis of factors affecting transient temperature field of aircraft fuel tank and coupled heat transfer mechanism, a mathematical model of transient coupled heat transfer, including the dynamic- chan...Based on the analysis of factors affecting transient temperature field of aircraft fuel tank and coupled heat transfer mechanism, a mathematical model of transient coupled heat transfer, including the dynamic- change of fuel quality, the internal heat transfer, the external aerodynamic convection and the radiation heat transfer, is established. Taking the aerodynamic convection and radiation heat transfer outside the tank as the third kinds of thermal boundary conditions for the thermal analysis of the fuel tank, calculation of internal and external coupling heat of fuel tank is decoupled. Ther^nal network method combined with hierarchical dynamic- grid is used to deal with the fuel consumption, and carry on the heat transfer analysis of the fuel tank. The numerical method for the transient temperature field of aircraft fuel tank is established. Through the simulation calculation, the transient temperature distribution of the fuel tank under different flight conditions is obtained, and the influence of the fuel mass and the external thermal environment on the temperature field is analyzed.展开更多
Italian Trade Commission (I.C.E) joined Ornella Bignami releasing the FABRIC FASHION FLASH AUTUMN-WINTER 2011-2012, in Intertex Shanghai, October.Enriched by an uninterrupted dialogue within the profession for over 25...Italian Trade Commission (I.C.E) joined Ornella Bignami releasing the FABRIC FASHION FLASH AUTUMN-WINTER 2011-2012, in Intertex Shanghai, October.Enriched by an uninterrupted dialogue within the profession for over 25 years, through a fine tuned skill in deciphering major trends and social changes, Ornella Bignami has earned a wide credibility in the field of textile industry, fashion and home textile products.展开更多
为解决低温余热资源过剩与高温用热需求紧缺之间的矛盾,设计了一套基于准二级压缩的高温热泵机组,理论分析循环流程并进行优化设计,采用闪蒸器与回热器组合提高机组性能,开展了机组的性能实验,以制热量、制热COP、[火用]效率、冷凝压力...为解决低温余热资源过剩与高温用热需求紧缺之间的矛盾,设计了一套基于准二级压缩的高温热泵机组,理论分析循环流程并进行优化设计,采用闪蒸器与回热器组合提高机组性能,开展了机组的性能实验,以制热量、制热COP、[火用]效率、冷凝压力、排气温度为性能指标,在冷凝器出水温度为85~120℃,蒸发器进水温度为50、60、70℃工况下,对机组性能进行分析。实测机组性能与理论计算结果吻合,蒸发器进水温度为49.8℃,冷凝器出水温度为118.1℃,机组制热量可达916.3 k W,制热COP为2.51,[火用]效率为46.3%,机组冷凝压力为1.8 MPa,排气温度为137℃,符合机组安全运行的要求。展开更多
基金supported by the Carbon Peak and Carbon Neutralization Science and Technology Innovation Special Fund of Jiangsu Province,China(No.BE2022859)Natural Science Foundation of Guangdong Province,China(No.2021A1515011763).
文摘Process heating constitutes a significant share of final energy consumption in the industrial sector around the world.In this paper,a high-temperature heat pump(HTHP)using flash tank vapor injection technology(FTVI)is proposed to develop low-temperature geothermal source for industrial process heating with temperature above 100°C.With heat sink output temperatures between 120°C and 150°C,the thermo-economic performance of the FTVI HTHP system using R1234ze(Z)as refrigerant is analyzed and also compared to the single-stage vapor compression(SSVC)system by employing the developed mathematical model.The coefficient of performance(COP),exergy efficiency(ηexe),net present value(NPV)and payback period(PBP)are used as performance indicators.The results show that under the typical working conditions,the COP andηexe of FTVI HTHP system are 3.00 and 59.66%,respectively,and the corresponding NPV and PBP reach 8.13×106 CNY and 4.13 years,respectively.Under the high-temperature heating conditions,the thermo-economic performance of the FTVI HTHP system is significantly better than that of the SSVC system,and the larger the temperature lift,the greater the thermo-economic advantage of the FTVI HTHP system.Additionally,the FTVI HTHP system is more capable than the SSVC system in absorbing the financial risks associated with changes of electricity price and natural gas price.
文摘The aim of this work is to investigate the flow instabilities in a baffled, stirred tank generated by a single Rushton turbine by means of large eddy simulation （LES）. The sliding mesh method was used for the coupling between the rotating and the stationary frame of references. The calculations were carried out on the ＂Shengcao-21C＂ supercomputer using a computational fluid dynamics （CFD） code CFX5. The flow fields predicted by the LES simulation and the simulation using standard κ-ε model were compared to the results from particle image velocimetry （PIV） measurements. It is shown that the CFD simulations using the LES approach and the standard κ-ε model agree well with the PIV measurements. Fluctuations of the radial and axial velocity are predicted at different frequencies by the LES simulation. Velocity fluctuations of high frequencies are seen in the impeller region, while low frequencies velocity fluctuations are observed in the bulk flow. A low frequency velocity fluctuation with a nondimensional frequency of 0.027Hz is predicted by the LES simulation, which agrees with experimental investigations in the literature. Flow circulation patterns predicted by the LES simulation are asymmetric, stochastic and complex, spanning a large portion of the tanks and varying with time, while circulation patterns calculated by the simulation using the standard κ-ε model are symmetric. The results of the present work give better understanding to the flow instabilities in the mechanically agitated tank. However, further analysis of the LES calculated velocity series by means of fast Fourier transform （FFT） and/or spectra analysis are recommended in future work in order to gain more knowledge of the complicated flow phenomena.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51676055 and 51536001)
文摘Based on the analysis of factors affecting transient temperature field of aircraft fuel tank and coupled heat transfer mechanism, a mathematical model of transient coupled heat transfer, including the dynamic- change of fuel quality, the internal heat transfer, the external aerodynamic convection and the radiation heat transfer, is established. Taking the aerodynamic convection and radiation heat transfer outside the tank as the third kinds of thermal boundary conditions for the thermal analysis of the fuel tank, calculation of internal and external coupling heat of fuel tank is decoupled. Ther^nal network method combined with hierarchical dynamic- grid is used to deal with the fuel consumption, and carry on the heat transfer analysis of the fuel tank. The numerical method for the transient temperature field of aircraft fuel tank is established. Through the simulation calculation, the transient temperature distribution of the fuel tank under different flight conditions is obtained, and the influence of the fuel mass and the external thermal environment on the temperature field is analyzed.
文摘Italian Trade Commission (I.C.E) joined Ornella Bignami releasing the FABRIC FASHION FLASH AUTUMN-WINTER 2011-2012, in Intertex Shanghai, October.Enriched by an uninterrupted dialogue within the profession for over 25 years, through a fine tuned skill in deciphering major trends and social changes, Ornella Bignami has earned a wide credibility in the field of textile industry, fashion and home textile products.
文摘为解决低温余热资源过剩与高温用热需求紧缺之间的矛盾,设计了一套基于准二级压缩的高温热泵机组,理论分析循环流程并进行优化设计,采用闪蒸器与回热器组合提高机组性能,开展了机组的性能实验,以制热量、制热COP、[火用]效率、冷凝压力、排气温度为性能指标,在冷凝器出水温度为85~120℃,蒸发器进水温度为50、60、70℃工况下,对机组性能进行分析。实测机组性能与理论计算结果吻合,蒸发器进水温度为49.8℃,冷凝器出水温度为118.1℃,机组制热量可达916.3 k W,制热COP为2.51,[火用]效率为46.3%,机组冷凝压力为1.8 MPa,排气温度为137℃,符合机组安全运行的要求。
