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Occurrence and flow Characteristics of Methane in High-Temperature and High-Pressure Nanopores of Deep Shale

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2025年第4期46卷 1200-1204页

作者： Wang, Rui Sun, Chengzhen Yang, Xu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Petroleum Engineering School Southwest Petroleum University Chengdu610500 China

The understanding of gas transport in deep shale nanopores is still not clear. In this study, molecular simulations of methane occurrence and flow in illite slits of deep shales under the condition of high-temperature and high-pressure was carried out. The occurrence, diffusion and flow characteristics of methane molecules were analyzed. The effects of temperature and pressure on methane occurrence and flow were elucidated. The results show that the distribution of methane density in illite slits is nonuniform, and there are density peaks near the wall. Compared with Middle and Shallow shales, more methane molecules can exist in the pores of deep shale, and the diffusion ability is limited. The methane flow flux decreases with the decrease of pressure (5∼80 MPa) and increases with the decrease of temperature (60∼120◦C). Pressure is the main dominating factor of flow flux, and the flow flux decreases gradually during depressurization. © 2025 Science Press. All rights reserved.

关键词： Nanopores

flow and Thermal Analysis of the Transition Scheme between Micro-Channel and Micro-Jet Cooling Solution

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SSRN 2022年

作者： Guo, Yuming Fan, Liang-Liang Zhao, Liang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'An710049 China School of Mechanical Engineering Xi'an Jiaotong University Xi'An China

With the rapid development of high-power electronics, the thermal management of these emerging devices is challenging due to the danger of ultra high heat flux and uneven temperature distribution. In this perspective, as promising cooling technologies, micro-channel and micro-jet cooling designs have been extensively investigated. In the past decade, certain heat-dissipation technologies based on micro-channel and micro-jet cooling have utilized geometrically identical heat sinks;however, their corresponding flow and thermal characteristics are dissimilar including micro-channel cooling technologies often have large temperature gradients as well as high heat transfer coefficients, while microjet technologies are more advantageous in terms of temperature distribution uniformity but larger pressure drop penalty. To characterize the enhanced heat-transfer mechanism driving this dissimilitude, a transition scheme between micro-channel and micro-jet was designed, featuring a gap on the channel fins top to provide extra flow area, and investigated experimentally and numerically. By controlling the volumetric flow ratio of the channel and jet, the flow and thermal characteristics of the transition scheme could be interchangeably transformed between the micro-channel and micro-jet. Moreover, we investigated the effect of the vortex generated by the jet impingement on channel bottom and fins top, an important factor causing the distinctions between the two schemes. The results revealed that the vortex in the stagnation zone enhanced the local heat-transfer coefficient corresponding to the channel bottom and promoted temperature uniformity;however, it caused the thermal boundary layer on the fins top to thicken. Although the vortex was favorable for the forced convection in the acceleration zone, the vortex intersections formed by adjacent jets introduced a greater pressure-drop penalty and flow blockage, which were not conducive to enhancing the heat transfer. Subsequently,

关键词： Vortex flow

Catalytic combustion of methane over a highly active and stable Ni0/Ce02 catalyst

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Frontiers of Chemical Science and engineering 2020年第4期14卷 534-545页

作者： Xiuhui Huang Junfeng Li Jun Wang Zeqiu Li Jiayin Xu School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093China Shanghai MCC20 Construction Co.Ltd Shanghai 201999China

In the last decades,many reports dealing with technology for the catalytic combustion of methane(CH4)have been ***,attention has increasingly focused on the synthesis and catalytic activity of nickel *** this paper,a NiO/CeO2 catalyst with high catalytic performance in methane combustion was synthe-sized via a facile impregnation method,and its catalytic activity,stability,and water-resistance during CH4 com-bustion were investigated.X-ray diffraction,low-tempera-ture N2 adsorption,thermogravimetric analysis,Fourier transform infrared spectroscopy,hydrogen temperature programmed reduction,methane temperature programmed surface reaction,Raman spectroscopy,electron paramag-netic resonance,and transmission electron microscope characterization of the catalyst were conducted to determine the origin of its high catalytic activity and stability in *** incorporation of NiO was found to enhance the concentration of oxygen vacancies,as well as the activity and amount of surface *** a result,the mobility of bulk oxygen in CeO2 was *** presence of CeO2 prevented the aggregation of NiO,enhanced reduction by NiO,and provided more oxygen species for the combustion *** results of a kinetics study indicated that the reaction order was about 1.07 for CH4 and about 0.10 for O2 over the NiO/CeO2 catalyst.

关键词： methane combustion NiO/CeO2 catalyst interaction oxygen vacancy kinetic study

Tuning the local electronic structure of oxygen vacancies over copper-doped zinc oxide for efficient CO_(2) electroreduction

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eScience 2022年第5期2卷 518-528页

作者： Ke Wang Dongyu Liu Limin Liu Jia Liu XiaoFei Hu Ping Li Mingtao Li Andrey S.Vasenko Chunhui Xiao Shujiang Ding Xi'an Key Laboratory of Sustainable Energy Materials Chemistry School of ChemistryEnergy Storage Materials and Chemistry of Shaanxi University Engineering Research CenterXi'an Jiaotong University28 Xianning West RoadXi'an710049China International Research Center for Renewable Energy(IRCRE) State Key Laboratory of Multiphase Flow in Power Engineering(MFPE)Xi'an Jiaotong University28 Xianning West RoadXi'anShaanxi710049China HSE University 101000MoscowRussia College of Materials and Environmental Engineering Hangzhou Dianzi UniversityHangzhou310018PR China CNNC Shaanxi Uranium Enrichment Co. Ltd.HanzhongChina

Oxygen vacancies in metal oxides can serve as electron trap centers to capture CO_(2) and lower energy barriers for the electrochemical CO_(2) reduction reaction(CO_(2)RR).Under aqueous electrolytes,however,such charge-enriched active sites can be occupied by adsorbed hydrogen(H∗)and lose their effectiveness for the CO_(2)***,we develop an efficient catalyst consisting of Cu-doped,defect-rich ZnO(Cu–ZnO)for the CO_(2)RR,which exhibits enhanced CO Faradaic efficiency and current density compared to pristine *** introduced Cu dopants simultaneously stabilize neighboring oxygen vacancies and modulate their local electronic structure,achieving inhibition of hydrogen evolution and acceleration of the CO_(2)*** a flow cell test,a current density of more than 45mAcm^(−2) and a CO Faradaic efficiency of>80%is obtained for a Cu–ZnO electrocatalyst in the wide potential range of−0.76V to−1.06V *** Hydrogen Electrode(RHE).This work opens up great opportunities for dopant-modulated metal oxide catalysts for the CO_(2)RR.

关键词： CO_(2)electroreduction Oxygen vacancy Heteroatom doping Metal oxide catalysts

Steam Entrainment and Heat Transfer Characteristic of Steam Submerged Jet Condensation within Steam-Water Mixture Layer

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SSRN 2022年

作者： Zhao, Quanbin Fu, Pengfei Chong, Daotong Chen, Weixiong Liu, Jiping Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China MOE Key Laboratory of Thermal Fluid Science and Engineering Xi'an Jiaotong University Xi'An710049 China

Steam-water interface and mixture layer are the key window for understanding the heat and mass transfer mechanism of steam submerged jet condensation. In this paper, the steam-water two-phase mixture layer is captured and the interfacial vortex is observed with a quasi-two-dimensional submerged steam jet visualization experimental platform. Then, the volume heat transfer capacity of steam-water mixture layer and heat transfer coefficient with steam-water inner interface are obtained. Furthermore, a new turbulent eddy entrainment model is developed to calculate the local entrainment mass rate and local condensation heat transfer coefficient. Both the local entrainment mass rate and local condensation heat transfer coefficient increases along steam jet direction, and reaches the maximum value at the tail of the mixture layer. The calculated condensation heat transfer coefficient ranges from 0.88 to 2.94 MW·m -2 ·K -1 , which is about the half of the value of hypothetical heat transfer coefficient with inner interfacial area. © 2022, The Authors. All rights reserved.

关键词： Condensation

Neutronic/Thermal-Hydraulic Coupling Analysis of Heat Pipe Reactor Nuster-100 Based on Comsol

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SSRN 2022年

作者： Zhang, Yin Nie, Jingyu Wang, Chenglong Guo, Kailun Tian, Wenxi Su, Guanghui Qiu, Suizheng School of Nuclear Science and Technology Shanxi Key Laboratory of Advanced Nuclear Energy and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China

Heat pipe cooled nuclear reactor plays an important role in future space and ocean exploration missions due to its advantages such as high inherent safety, removability, passive safety. Xi’an Jiatong University proposed a concept design of 100kWe nuclear reactor named NUclear Silent ThermoElectric heat pipe cooled Reactor (NUSTER-100). To explore NUSTER core’s performances, COMSOL are used for neutronic/thermal-hydraulic coupling calculation. Neutron diffusion equations are used to calculate NUSTER’s neutron flux distribution by partial differential equation (PDE) model. Dragon code is used to solve the group constants of neutron diffusion equations. The heat transfer module of COMSOL is used to calculate NUSTER’s temperature distribution. for NUSTER-100, the keff calculated by the neutron diffusion module of COMSOL is 1.0372. The calculation results of three-dimensional NUSTER show that the maximum temperature of heat pipe is 1226.2 K and that of fuel rod is 1447.1K. The calculated temperatures have not exceeded the limit. The unified calculation of neutron physics and temperature distribution is realized in COMSOL platform. This work provides a preliminary basis for neutronic/thermal-hydraulic coupling calculation for heat pipe reactor. © 2022, The Authors. All rights reserved.

关键词： Heat pipes

The Thermal Effect of Flame-Wall Interaction on the Nox Emission Characteristics of Ammonia Swirling Flames in a Model Combustor

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SSRN 2022年

作者： Zhang, Meng Xu, Wanying Wang, Ruixiang Wei, Xutao Wang, Jinhua Huang, Zuohua Tan, Houzhang State Key Laboratory of Multiphase Flow in Power Engineering Xian Jiaotong University Xian710049 China MOE Key Laboratory of Thermo-Fluid Science and Engineering Xian Jiaotong University Xian710049 China

Ammonia (NH 3 ) combustion is regarded as one of the most promising solutions to realize zero CO 2 emission. However, the low reactivity, low heat release result in a strong flame-wall interaction (FWI) which significantly affects the flame stabilization and the NOx emission characteristics. In this study, an air film cooling on the swirling combustion chamber was designed to investigate the thermal effect of the FWI on NOx emission. The flame structure and NO production are measured with the OH-/NO-PLIF techniques. The NOx emission is analyzed by the Gasmet DX4000 Fourier Transform Infrared (FTIR) gas analyzer. Large eddy simulation is also conducted to extend the understandings of experimental findings. For the current combustion chamber, the temperature difference is increasing as downstream location, resulting a larger convection heat loss. The heat loss shows no apparent effect on the flame structure and NO production at the symmetrical plane. The flame tends to be more fragmentized and the NO production is largely decreased at near wall region and the outer recirculation zone with increasing heat loss. This can be understood that NO production rate from the oxidation of NH i by O, H and OH radicals through HNO is largely decreasing in these regions. Therefore, a decreasing NO trend is found at the chamber outlet. NO emission shows a decreasing trend with heat loss at lean condition, which is mainly caused by the decreased NO production at near wall region resulting from the lower combustion efficiency. However, N 2 O, a more serious greenhouse gas, significantly increases as the heat loss increases. This is mainly because that the production of N 2 O from NO is promoted and N 2 O decomposition is suppressed within the thermal boundary. Thus, N 2 O might become a more serious emission component in NH 3 fuelled gas turbines. Moreover, a tradeoff behaviour between NO and N 2 O is observed as increasing heat loss. This study suggests the thermal effect of FWI on t

关键词： Heat losses

Numerical Study on Transverse Mixing Characteristics of flow Sweeping in Helical Cruciform Rod Bundle

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SSRN 2022年

作者： Jiang, Dianqiang Zhang, Dalin Tian, Wenxi Qiu, Suizheng Su, Gguanhui State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi'An710049 China

In the chemical industry, nuclear energy, electronics, and other industries, heat transfer enhancement has been the focus of significant attention. To enhance the flow heat transfer performance of coolant in the nuclear fuel assembly, helical cruciform fuel rods are designed as a foundation fuel element. The transverse mixing characteristics of flow sweeping of heat conduction oil in the present study using the numerical approach in helical cruciform rod bundle. The fluid in the helical cruciform rod bundle exhibits a substantial flow sweeping crossflow phenomena as a result of the impact of the helical structure. The transverse mixing velocity and temperature profiles are analyzed. The subchannel conservation equation is optimized, and the link between flow sweeping mixing parameters and dimensionless local gap width in various Reynolds number ranges is determined by fitting. Furthermore, the turbulent mixing parameters of the cylindrical rod bundle are analyzed. It can be concluded that the helical cruciform rod bundle has considerable transverse mixing, which enhances the flow heat transfer performance of the reactor core. This study provides a guide for the numerical study of flow heat transfer in helical structures, and a foundation for the development of the subchannel mixing model. © 2022, The Authors. All rights reserved.

关键词： Mixing

Evaluation of droplet drag force model on spray and atomization behaviours of R134a flashing spray 14

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Evaluation of droplet drag force model on spray and atomizat...

14th International Conference on Liquid Atomization and Spray Systems, ICLASS 2018

作者： Zhou, Zhi-Fu Lu, Guan-Yu Zhang, Lu Chen, Bin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Flashing spray is of great importance in a variety of engineering fields, which occurs as the pressurized liquid is released into a low-pressure environment below its saturation pressure. This paper conducts a systematically numerical study on the spray and thermal characteristics of R134a flashing spray with high volatility and low saturation temperature, using a modified sprayFoam solver in the open source tool OpenFOAM-2.4.0. key physics involved in the complex process, including droplet flash boiling, evaporation, droplet transport, breakup, heat transfer and interaction between droplet and gas phases are taken into consideration. The emphasis is put on the droplet drag force model and nozzle diameter on flashing spray including spray morphology, droplet diameter, velocity and temperature. The result indicates that most of the drag force models have little effect on droplet diameter, velocity and temperature distributions in flashing spray, except the Khan-Richardson (K-R) model. The K-R model predicts lower temperature, higher velocity and larger size of droplet, compared to other models. The nozzle diameter greatly affects R134a spray morphology and tip penetration, that smaller diameter contributes to a larger radial expansion at the near nozzle region while leading to a much smaller penetration distance. This research give a useful guidance that how people choose the appropriate drag force model for simulation of flashing spray. © 2018 Solar Turbines Incorporated.

关键词： Morphology