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Review on heat-to-power conversion technologies for hypersonic vehicles

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Chinese Journal of Aeronautics 2024年第5期37卷 148-179页

作者： Yinke QI Xiaofeng MA peixue jiang Yinhai ZHU key laboratory for {2. Science and power Engineering of ministry of education Department of Energy and Power EngineeringTsinghua UniversityBeijing 100084China beijing key {2. of CO_(2.Utilization and Reduction Technology Department of Energy and Power EngineeringTsinghua UniversityBeijing 100084China

Hypersonic vehicles have enormous military and economic value,while their power and thermal protection demands will increase substantially with the rise in Mach number and *** the tremendous high-quality heat on the vehicle surface and engine wall into electrical energy through heat-to-power technologies will not only play a role in thermal protection,but also supply power for the *** paper provides a comprehensive review of heat-to-power conversion technologies on hypersonic vehicles,including the indirect conversion of Brayton and Rankine cycles,direct conversion of thermoelectric materials,and combined *** the open Brayton cycle with hydrocarbon fuel as the working fluid,the power-to-Weight Ratio(PWR)can achieve the highest,at around 1.8,due to the high PWR of the hydrocarbon fuel turbine and the few components of the ***,its work capacity is limited by the flow rate of the supplied *** closed Brayton cycle can maintain a relatively high PWR,ranging from 0.2.to 0.8,while achieving relatively high output power and conversion *** Rankine cycle has a higher PWR,its range is close to that of the closed Brayton cycle,peaking at about *** thermoelectric materials technology has a small power generation level,making it more suitable for scenarios with low power *** review provides a basis for selecting and developing heat-to-power conversion technologies on hypersonic vehicles.

关键词： Hypersonic vehicles Heat-to-power conversion Brayton cycle Rankine cycle Thermoelectric materials

thermal conductivity of nanoscale thin nickel films

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Progress in Natural Science:Materials International 2005年第10期 60-67页

作者： YUAN Shiping and jiang peixue ({2. laboratory of thermal Science and power Engineering, department of thermal Engineering, tsinghua university, beijing 100084, china) key laboratory of {2. Science and power Engineering Department of Thermal Engineering Tsinghua University Beijing 100084 China

The inhomogeneous non-equilibrium molecular dynamics (NEMD) scheme is applied to model phonon heat conduction in thin nickel films. The electronic contribution to the thermal conductivity of the film is deduced from the electrical conductivity through the use of the Wiedemann-Franz law. At the average temperature of T = 300 K, which is lower than the Debye temperature (?)= 450 K, the results show that in a film thickness range of about 1 -11 nm, the calculated cross-plane thermal conductivity decreases almost linearly with the decreasing film thickness, exhibiting a remarkable reduction compared with the bulk value. The electrical and thermal conductivities are anisotropic in thin nickel films for the thickness under about 10 nm. The phonon mean free path is estimated and the size effect on the thermal conductivity is attributed to the reduction of the phonon mean free path according to the kinetic theory.

关键词： nanoscale nickel films thermal conductivity electrical conductivity.

Experimental and molecular dynamics study of gas flow characteristics in nanopores

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Chinese Science Bulletin 2012年第13期57卷 1488-1493页

作者： liu qixin {2. peixue xiang heng key laboratory for {2. Science and power Engineering of ministry of education Beijing Key Laboratory of CO_(2)Utilization and Reduction TechnologyDepartment of Thermal EngineeringTsinghua UniversityBeijing 100084China

Gas flow characteristics in nanopores were investigated experimentally and numerically using molecular dynamics (MD) simulations with an emphasis on the friction factor and gas viscosity. The results show that the viscosity and the friction factor in nanopores are much lower than those in macroscale channels. The actual viscosities obtained from the MD studies showed that the gas viscosity in nanopores is less than the macroscale viscosity because collisions between gas molecules are less frequent in high Knudsen number flows and there are more collisions with the wall. The MD simulations show that the velocity profile is composed of two parts, with a much steeper velocity gradient near the wall.

关键词：气体流动特性分子动力学特性实验纳米孔 Knudsen数气体粘度数值模拟摩擦系数

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纳米受限效应下流体自扩散机理及规律研究

工程热物理学报 2024年第3期45卷 778-784页

作者：曾克成姜培学胥蕊娜热科学与动力工程教育部重点实验室清华大学能源与动力工程系北京100084

当固体壁面间距仅有几个纳米时,纳米受限效应使得流体自扩散系数降低12.数量级,孔径、温度和压力的影响显著且复杂。分析受限流体扩散机理和规律,建立简洁的关联式具有重要意义。本研究从分子模拟出发,经过仔细计算和分析,获得了大量... 详细信息

当固体壁面间距仅有几个纳米时,纳米受限效应使得流体自扩散系数降低12.数量级,孔径、温度和压力的影响显著且复杂。分析受限流体扩散机理和规律,建立简洁的关联式具有重要意义。本研究从分子模拟出发,经过仔细计算和分析,获得了大量纳米孔隙中流体自扩散系数数据。分析了壁面吸附作用对流体扩散的影响机理和规律,提出了可简单描述流体扩散行为的无量纲扩散系数,从而与努森数建立相应关联式,具有较强的适用性。

关键词：纳米受限流体扩散分子动力学

Theoretical and experimental study of the thermal conductivity of nanoporous media

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Science china(Technological Sciences) 2012年第8期55卷 2140-2147页

作者： jiang peixue {2. heng XU RuiNa key laboratory for {2. Science and power Engineering of ministry of education Beijing 100084China beijing key {2. of CO2.Utilization and Reduction Technology Beijing 100084China department of thermal Engineering Tsinghua UniversityBeijing 100084China

The nanoparticle thermal conductivity and nanoscale thermal contact resistance were investigated by molecular dynamics(MD) simulations to further understand nanoscale porous media thermal *** porous media thermal conductivity models were then revised for nanoporous *** effective thermal conductivities of two packed beds with nanoscale nickel particles and a packed bed with microscale nickel particles were then measured using the Hot *** measured results show that the nano/microscale porous media thermal conductivities were much less than the thermal conductivities of the solid *** of the measured and calculated results shows that the revised combined parallel-series model and the revised Hsu-Cheng model can accurately predict the effective thermal conductivities of micro-and nanoparticle packed beds.

关键词： thermal conductivity nanoparticle nanoporous media molecular dynamics(MD) simulation contact resistance

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陶瓷基复合材料相变发汗冷却实验研究

工程热物理学报 2024年第2期45卷 506-513页

作者：李晓阳李浩姜培学胥蕊娜清华大学能源与动力工程系热科学与动力工程教育部重点实验室北京100084

采用轻质耐高温陶瓷基复合材料和相变冷却剂分别是发汗冷却的重要发展方向,然而两者相结合的发汗冷却研究相对缺乏。本文在超声速风洞中实验研究了C/C-SiC陶瓷基复合材料的相变发汗冷却过程,分析了复合材料孔隙结构对发汗冷却性能的影... 详细信息

采用轻质耐高温陶瓷基复合材料和相变冷却剂分别是发汗冷却的重要发展方向,然而两者相结合的发汗冷却研究相对缺乏。本文在超声速风洞中实验研究了C/C-SiC陶瓷基复合材料的相变发汗冷却过程,分析了复合材料孔隙结构对发汗冷却性能的影响。结果表明,陶瓷基复合材料平板中,非均匀分布的孔隙结构加剧了蒸汽堵塞效应,导致平板存在局部高温且难以随注入率提升而消除;而孔隙结构较为均匀的材料,表面的温度分布均匀性和冷却效率明显提高。与金属烧结多孔材料相比,陶瓷基复合材料渗透率和热导率较低导致相变比例低,发汗冷却效率偏低。未来需要继续对孔隙结构的优化方法进行研究,以进一步提升复合材料相变发汗冷却效率和均匀性。

关键词：发汗冷却复合材料相变超声速

Effect of reactive surface area of minerals on mineralization trapping of CO_2.in saline aquifers

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Petroleum Science 2012年第3期9卷 400-407页

作者： LUO Shu XU Ruina jiang peixue key laboratory for {2. Science and power Engineering of ministry of education Beijing Key Laboratory of CO_(2) Utilization and Reduction TechnologyDepartment of Thermal EngineeringTsinghua UniversityBeijing 100084China

The reactive surface area, an important parameter controlling mineral reactions, affects the amount of mineralization trapping of CO2.which affects the long-term CO2.storage. The effect of the reactive surface area on the mineralization trapping of CO2.was numerically simulated for CO2.storage in saline aquifers. Three kinds of minerals, including anorthite, calcite and kaolinite, are involved in the mineral reactions. This paper models the relationship between the specific surface area and the grain diameter of anorthite based on experimental data from literature （Brantley and Mellott, 2.00）. When the reactive surface areas of anorthite and calcite decrease from 838 to 83.8 m^2.m^3, the percentage of mineralization trapping of CO： after 500 years decreases from 11.8% to 0.65%. The amount of dissolved anorthite and the amounts of precipitated kaolinite and calcite decrease significantly when the reactive surface areas ofanorthite and calcite decrease from 838 to 83.8 m2.m3. Calcite is initially dissolved in the brine and then precipitates during the geochemical reactions between CO2.H2. and the minerals. Different reactive surface areas of anorthite and calcite lead to different times from dissolution to precipitation. The pH of the brine decreases with decreasing reactive surface areas of anorthite and calcite which influences the acidity of the saline aquifer. The gas saturation between the upper and lower parts of the saline aquifer increases with decreasing reactive surface areas of anorthite and calcite. The mass density distribution of brine solution shows that the CO2.＋brine solution region increases with decreasing reactive surface areas ofanorthite and calcite.

关键词： Reactive surface area, mineralization trapping, dissolution precipitation, brine mass density,CO2.geological storage

Pore-scale visualization on a depressurization-induced CO2.exsolution

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Science Bulletin 2017年第11期62卷 795-803页

作者： Ruina Xu Rong Li Feng Huang peixue jiang key laboratory for CO2.Utilization and Reduction Technology of {2. Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Thermal Engineering Tsinghua University Beijing 100084 China

The pore-scale behavior of the exsolved CO_2.phase during the depressurization process in CO_2.geological storage was *** reservoir pressure decreases when the injection stops or when a leaking event or fluid extraction *** exsolution characteristics of CO_2.affect the migration and fate of CO_2.in the storage site ***,a micromodel experimental system that can accommodate a large pressure variation provides a physical model with homogeneous porous media to dynamically visualize the nucleation and growth of exsolved CO_2.*** pressure decreased from 9.85 to 3.95 MPa at different temperatures and depressurization rates,and the behavior of CO_2.bubbles was *** the pore-scale,the nuclei became observable when the CO_2.phase density was significantly reduced,and the pressure corresponding to this observation was slightly lower than that of the severe expansion pressure *** lower temperature and faster depressurization rate produced more CO_2.*** exsolved CO_2.bubble preferentially grew into the pore body instead of the *** progress of smaller CO_2.bubbles merging into a larger CO_2.bubble was first captured,which validated the existence of the Ostwald ripening *** dispersed CO_2.phase after exsolution shows similarity with the residually trapped CO_*** observation is consistent with the low mobility and high residual trapping ratio of exsolved CO_2.measured in the core-scale measurement,which is considered to be a self-sealing mechanism during depressurization process in CO_2.geological storage.

关键词： Depressurization process CO2.exsolution Ostwald ripening CO2.geological storage

A numerical study of segmented cooling-stream injection in supersonic film cooling

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Chinese Journal of Aeronautics 2022年第6期35卷 156-171页

作者： Hang NI Mingjun WANG peixue jiang Wei PENG Yinhai ZHU Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyKey Laboratory of Advanced Reactor Engineering and Safety of Ministry of EducationTsinghua UniversityBeijing 100084China School of Nuclear Science and Technology Xi’an Jiaotong UniversityXi’an 710049China department of Energy and power Engineering Key Laboratory for Thermal Science and Power Engineering of Ministry of EducationTsinghua UniversityBeijing 100084China tsinghua university-Zhang Jiagang Joint Institute for Hydrogen Energy and Lithium-Ion Battery Technology Tsinghua UniversityBeijing 100084China

The present study proposes a segmented cooling-stream injection structure based on a certain coolant mass flow rate,and numerically investigates the effect of segmented cooling-stream injection on supersonic film *** results indicate that without shock-wave impingement and with helium as the coolant,segmented cooling-stream injection can reduce the mixing between the mainstream and the cooling stream to produce better cooling performance than single injection,especially at larger coolant Mach ***,with nitrogen as the coolant,the cooling effect of the segmented-injection system is very close to that of the single-injection *** at the impinging region is enhanced significantly when there is an incident shock *** the shock wave impinges between the two coolant inlets,segmented cooling-stream injection improves film cooling effectiveness in the midstream and downstream regions more than single injection because only part of the cooling stream undergoes the enhanced mixing effect of the shock *** advantage of segmented injection is reduced when the impinging region is behind the second coolant *** further downstream the impinging region,the smaller the associated advantage.

关键词： Film cooling Mach number Segmented injection Shock wave Supersonic flow