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Numerical Simulation of Charging Performance of Combined Sensible-Latent Heat Storage System with a Macro-Encapsulation Method

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Journal of Thermal Science 2023年第6期32卷 2008-2017页

作者： WANG Wei PAN Zhenfei LEI Biao WU Yuting WANG Jingfu MA Chongfang Key Laboratory of Enhanced Heat Transfer and Energy Conservation Ministry of EducationCollege of Energy and Power EngineeringBeijing University of TechnologyBeijing100124China Key Laboratory of Heat Transfer and Energy Conversion Beijing MunicipalityCollege of Energy and Power EngineeringBeijing University of TechnologyBeijing100124China

In recent years,heat storage system combining sensible and latent heat materials has received more and more attentions.In this paper,we proposed the hybrid configuration with a macro-encapsulation,and analyzed its charging performance with different influencing factors by CFD simulation.In the case,the sensible heat storage materials are magnesia brick or HT concrete and the phase change materials(PCMs)are mixed molten salts.Firstly,we analyzed the heat transfer characteristics of the hybrid configuration in charging process.Then,we analyzed the effect of heating power on charging performance.The maximum temperature of the heating surface shall not exceed 500℃as the constraint condition,the heat storage capacity increases at first and then decreases with the heating power.Then,we compared the charging performance of different solid structure and the hybrid configurations.Whether magnesia brick or HT concrete,the charging performance of the solid structure is better than that of the hybrid configuration,because the thermal conductivity of the molten salt is significantly lower than that of the two sensible heat storage materials.Then,we compared the charging performance of different molten salts.The hybrid configuration with lower melting point molten salt has better performance because of more intensity natural convection.Finally,we analyzed the charging performance of the hybrid configuration used the composite phase change material(CPCM)with high thermal conductivity and specific heat.From the result,the charging performance increases by 22.5%compared with the solid structure.These results indicate that the hybrid configuration with the macro-encapsulation method is a potential form of thermal energy storage,but it needs to be further optimized.

关键词： thermal energy storage hybrid configuration natural convection thermophysical property charging performance

Performance evaluation of absorption thermal energy storage/transmission using ionic liquid absorbents

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Energy and Built Environment

Energy and Built Environment 2023年第3期4卷 259-269页

作者： Jintong Gao Zhenyuan Xu Institute of Refrigeration and Cryogenics Shanghai Jiao Tong UniversityShanghai 200240China Engineering Research Center of Solar Power and Refrigeration MOEChina

Efficient thermal energy storage and transmission are considered as two of the most significant challenges for decarbonisation in thermal energy utilization.The liquid-gas absorption thermal energy storage/transmission sys-tem is promising approach to tackle these challenges,owing to the long-term stability,flexibility in heat/cooling output,and liquid medium.At present,the shortcomings of conventional absorption working fluids have trig-gered considerable interest in searching for novel working pairs,such as ionic liquids(ILs).However,it is still unknown whether ILs can work effectively in thermal energy transmission with long distance.In this study,the absorption thermal energy storage/transmission systems using IL absorbents are theoretically investigated.mod-eling frameworks for working pairs screening and performance evaluation are proposed.Results show that the IL-based working pairs present better or comparable performance than conventional working pairs(including H_(2) O/Salts and NH 3/Salts).Among the investigated IL-based working pairs,H_(2) O/[EMIM][EtSO 4]presents high-est COP(around 0.62)and exergy efficiency(around 0.32),and is relatively close to H_(2) O/LiBr.As for energy storage density,H_(2) O/[EMIM][Ac]performs better than H_(2) O/LiBr,presenting 137.4 kWh/m 3 with a desorption temperature of 115°C.The present work provides a straightforward screening of IL absorbents for thermal energy storage and transmission purposes.

关键词： Thermal storage and transmission Ionic liquid Working fluid thermophysical property

CALTPP:A general program to calculate thermophysical properties

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Journal of Materials Science & Technology 2020年第7期42卷 229-240页

作者： Yuling Liu Cong Zhang Changfa Du Yong Du Zhoushun Zheng Shuhong Liu Lei Huang Shiyi Wen Youliang Jin Huaqing Zhang Fan Zhang George Kaptay State Key Lab of Powder Metallurgy Central South UniversityChangshaHunan 410083China Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China School of Mathematics and Statistics Central South UniversityChangshaHunan 410083China School of Materials Science and Engineering Xiangtan UniversityXiangtanHunan 411105China Department of Nanotechnology University of MiskolcH-3515 MiskolcEgyetemvarosHungary

A program CALTPP(CALculation of thermophysical Properties)is developed in order to provide various thermophysical properties such as diffusion coefficient,interfacial energy,thermal conductivity,viscosity and molar volume mainly as function of temperature and composition.These thermophysical properties are very important inputs for microstructure simulations and mechanical property predictions.The general structure of CALTPP is briefly described,and the CALPHAD-type models for the description of these thermophysical properties are presented.The CALTPP program contains the input module,calculation and/or optimization modules and output module.A few case studies including(a)the calculation of diffusion coefficient and optimization of atomic mobility,(b)the calculation of solid/liquid,coherent solid/solid and liquid/liquid interfacial energies,(c)the calculation of thermal conductivity,(d)the calculation of viscosity,and(e)the establishment of molar volume database in binary and ternary alloys are demonstrated to show the features of CALTPP.It is expected that CALTPP will be an effective contribution in both scientific research and education.

关键词： thermophysical property Diffusion coefficient Interfacial energy Thermal conductivity Viscosity Molar volume CALPHAD-type modeling

Tribological behaviors of turbofan seal couples from friction heat perspective under high-speed rubbing condition

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Friction 2016年第2期4卷 176-190页

作者： Siyang GAO Weihai XUE Deli DUAN Shu LI Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

The tribological behaviors of two types of seal coatings, nickel–graphite and aluminum–hexagon-boron nitride (Ni–Cg and Al–hBN, respectively) versus a Ti–6Al–4V blade used in turbofan engines were investigated using a high-speed rubbing test. The wear status and damage mechanism of the friction couples were studied and the abradability of the seal coatings was evaluated. By analysis of the coating properties and damage mechanism of the seal couple, the friction heat effect was identified as the key factor influencing blade wear forms as well as coating abradability. A one-dimensional heat conduction model was established to estimate the effect of increasing temperature on the friction interface. The results indicated that in the Ni–Cg and Ti–6Al–4V seal couple, the temperature rising rate (TRR) of the Ti–6Al–4V blade was faster than that of the Ni–Cg coating, and so the Ti–6Al–4V blade softened earlier than the Ni–Cg coating, causing the blade to suffer severe wear. In the Al–hBN and Ti–6Al–4V seal couple, the TRR of the Ti–6Al–4V blade was slower than that of the Al–hBN coating, and so the Al–hBN coating softened first; thus, blade damage was reduced or even replaced by coating adhesion. The square root ratio of thermal diffusivity between the blade and the coating could be taken as an indicator of the ratio of TRR between the blade and coating to predict blade wear status as well as damage mechanism. The results of the model agreed well with the experiment results of the two seal couples used in this study.

关键词： seal coating high-speed rubbing wear mechanism friction heat thermophysical property

RESEARCH ON MEASURING METHOD OF THE THERMALCONDUCTIVITY FOR HIGHLY POROUS MATERIALS

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Acta Metallurgica Sinica(English Letters) 1997年第3期10卷 213-218页

作者： J Y Wu Z.M. Tang W Shi andR.Z. Wang (Institute of Refrigeration and Cryogenics Engineering, Shanghai Jiao Tong University, Shanghai 200030,China) Shanghai Jiaotong Univ Shanghai China

A transient method with rectangular pulse heating has been developed to measure the thermal conductivity of highly porous materials such as activated carbon, zeolite and silica gel. By this method the thermal conductivity can be measured quickly and accu-rately. In this paper, a set of automatically controlled testing equiptnent is presented.The measuring method is analysed. The thermal conductivities of some samples, such as activated carbon and zeolite, are measured by the equipment. A group of useful data has been obtained.

关键词： thermal conductivity porous material thermophysical property

Study on the influencing factors of rock-soil thermophysical parameters in shallow geothermal energy

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Journal of Groundwater Science and Engineering 2015年第3期3卷 256-267页

作者： ZHU Xi ZHANG Qing-lian WANG Wan-li LIU Yan-guang The Institute of Hydrogeology and Environmental Geology CAGS Shijiazhuang University of Economics

thermophysical parameters are the main parameters affecting the utilization efficiency of shallow geothermal energy. Based on the research and evaluation data of shallow geothermal energy in capital cities of China, this paper analyzes the differences between two testing methods and finds that data measured in in-situ thermal conductivity test is closer to the actual utilization. This paper analyzes the influencing factors of thermophysical parameters from lithology, density, moisture content and porosity: The thermal conductivity coefficient of bedrock is generally higher than Quaternary system loose bed soil; as for the coefficient of bedrock, dolomite, shale and granite are higher while gabbro, sandstone and mudstone are lower; as for the coefficient of loose bed, pebble and gravel are higher while clay and silt are lower. As the particle size of sand decreases, the thermal conductivity coefficient declines accordingly. The thermal conductivity coefficient increases linearly with growing density and decreases in logarithm with growing moisture content as well as porosity; specific heat capacity decreases in logarithm with growing density, increases in power exponent with growing moisture content and decreases linearly with growing porosity. The thermal conductivity coefficient is high when hydrodynamic condition is good and vice versa. The conclusions of this paper have guiding significance for the research, evaluation and development of shallow geothermal energy in other areas.

关键词： Shallow geothermal energy thermophysical property Influencing factor Distribution rule