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Science China(Physics,Mechanics & Astronomy) 2008年第11期51卷 1733-1744页

作者： CAI RuiXian liu qibin Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China

Analytical solutions of governing equations of various phenomena have their irre-placeable theoretical meanings. In addition, they can also be the benchmark solu-tions to verify the outcomes and codes of numerical solutions, and even to develop various numerical methods such as their differencing schemes and grid generation skills as well. A hybrid method of separating variables for simultaneous partial differential equation sets is presented. It is proposed that different methods of separating variables for different independent variables in the simultaneous equa-tion set may be used to improve the solution derivation procedure, for example, using the ordinary separating method for some variables and using extraordinary methods of separating variables, such as the separating variables with addition promoted by the first author, for some other variables. In order to prove the ability of the above-mentioned hybrid method, a lot of analytical exact solutions of two-buoyancy convection in porous media are successfully derived with such a method. The physical features of these solutions are given.

关键词： analytical solution hybrid method of separating variables two-buoyancy natural convection porous me-dium

Nanoparticle-strengthened Ni_(2)CoCrNb_(0.2)medium-entropy alloy with an ultrastrong cryogenic yield strength fabricated by additive manufacturing

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Journal of Materials Science & Technology 2023年第32期163卷 17-31页

作者： Fangping Wang Yaxiong Guo qibin liu Xiaojuan Shang College of Materials and Metallurgy Guizhou UniversityGuiyang 550025China Guiyang Vocational and Technical College Guiyang 550081China Key Laboratory for Modern Manufacturing Technology of Educational Ministry Guiyang 550025China

To improve the yield strength of metallic materials at low temperatures,a strategy of combining the calculation of phase diagrams(CALPHAD)technique with the overall valence electron concentration(OVEC)principle is applied,and a Ni_(2)CoCrNb_(0.2)medium-entropy alloy(MEA)with D022 superlattice(noted as theγ″phase)is *** MEA samples without defects were successfully fabricated using laser additive manufacturing(AM),followed by solution treatment at 1200℃for 1 h and then aging at 650℃for 120 *** nanoscaleγ″phase *** tensile results indicated that the MEA had superior yield strengths of∼1180 MPa and∼1320 MPa and tensile strengths of∼1335 MPa and∼1552 MPa at 293 K and 77 K,*** yield strength obtained was superior to that of currently reported medium/high-entropy alloys and typical advanced cryogenic *** mechanical properties of the Ni_(2)CoCrNb_(0.2)MEA demonstrated a strong temperature dependence,and the increased yield strength was mainly attributed to the increase in lattice friction stress at low *** research provides a new strategy for producing materials with ultrastrong cryogenic yield strengths by AM.

关键词： Additive manufacturing Medium-entropy alloys D0_(22)superlattice Temperature dependence Cryogenic performance

Solar fuel from photo-thermal catalytic reactions with spectrum-selectivity： a review

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Frontiers in Energy 2017年第4期11卷 437-451页

作者： Sanli TANG Jie SUN Hui HONG qibin liu Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing 100190 China University of Chinese Academy of Sciences Beijing 100049 China

Solar fuel is one of the ideal energy sources in the future. The synergy of photo and thermal effects leads to a new approach to higher solar fuel production under relatively mild conditions. This paper reviews different approaches for solar fuel production from spectrum- selective photo-thermal synergetic catalysis. The review begins with the meaning of synergetic effects, and the mechanisms of spectrum-selectivity and photo-thermal catalysis. Then, from a technical perspective, a number of experimental or theoretical works are sorted by the chemical reactions and the sacrificial reagents applied. In addition, these works are summarized and tabulated based on the operating conditions, spectrum-selectivity, materi- als, and productivity. A discussion is finally presented concerning future development of photo-thermal catalytic reactions with spectrum-selectivity.

关键词： photo-thermal catalysis spectrtun-selectivity,solar fuel full-spectrum

Superior piezoelectricity in lead-free barium titanate piezoceramics

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Journal of Materiomics 2024年第3期10卷 694-706页

作者： Enpei Cai Shiqiang Peng qibin liu School of Materials and Metallurgy Guizhou UniversityGuiyang550025China Key Laboratory of Advanced Manufacturing Technology of the Ministry of Education Guiyang550025China

Since the 21st century,increasing environmental protection and human health concern have been the driving force to develop lead-free piezoelectric materials with enhanced performances,and phase en-gineering strategy has been validated to be a viable method in numerous ***,we gained a superb d_(33)~(637±30)pC/N in lead-free(1-x)(Ba_(0.93)Ca_(0.07))(Sn_(0.08)Ti_(0.92))O_(3-x)(Sb_(0.5)Li_(0.5))TiO_(3)[abbreviated as(1-x)BCST-xSLT,0≤x≤0.4%(in mole)]piezoelectrics utilizing chemical *** illustrate the relationship among composition-structure-performance,microstructure characterization,electrical properties measurement,first-principles calculation,and phase-field simulations were ***-resolved polarization mapping of z-contrast imaging manifests the ferroelectric three phases(ReOeT)coexist at the nanoscale with nanoscale polarization switching among *** calculations and simulations confirm that the high-density nano-domain boundary bridges the poly-phase coexisting nano-domains,which makes the polarization reversal easy,thus significantly reducing the energy barrier and polarization anisotropy among different phases.

关键词： Chemical doping Relaxor ferroelectrics Phase-field simulations Phase engineering strategy First-principles calculations

Thermodynamic analysis of auto-thermal chemical looping hydrogen production systems

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Science China Technological Sciences 2024年第12期67卷 3707-3723页

作者： LI PeiJing liu TaiXiu LI JiChao QIN YuanLong liu qibin School of Energy Power and Mechanical Engineering North China Electric Power University Institute of Engineering Thermophysics Chinese Academy of Sciences University of Chinese Academy of Sciences Department of Thermal Science and Energy Engineering University of Science and Technology of China

Chemical looping hydrogen production is of interest because of its ability to simultaneously produce hydrogen and capture CO2at the same time. Achieving an energy balance is crucial in chemical-looping hydrogen production systems. Decreasing the external heat duty can effectively reduce carbon capture and energy conversion efficiency. In this study, two auto-thermal chemical looping H2generation systems are proposed. An adiabatic counter current moving bed chemical looping H2generation system using CH4as fuel and Fe2O3and Al2O3（inert carriers） as oxygen carriers（OC） is proposed to analyse the energy balance and exergy balance of the systems. A parametric analysis was conducted to investigate the influence of the reaction ratio and temperature on the product outcomes, leading to the determination of optimal operating conditions. Subsequently, the impact of hydrogen production efficiency and reduction reactor outlet stream ratio and inert component proportion in the oxygen carrier on the system's thermal balance was analysed under these optimal conditions, culminating in the identification of key parameters for the two auto-thermal systems. Energy balance and exergy balance analyses were employed to compare the energy efficiency and irreversible losses of the autothermal and reference systems. The results demonstrated that the autothermal system enhanced the energy efficiency by 2.5% and the CO2capture rate by 11%（percentage points） compared with the reference system.

关键词： chemical looping hydrogen generation hydrogen production auto-thermal energy balance analysis exergy balance analysis

Performance Enhancement of Parabolic Trough Collector by Using Homogenizer and Spiral

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Journal of Thermal Science 2024年第2期33卷 658-674页

作者： LI Peijing liu Taixiu QIN Yuanlong ZHENG Zhimei ZHAO Kai liu qibin School of Energy Powerand Mechanical EngineeringNorth China Electric Power UniversityBeijing102206China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing100190China University of Chinese Academy of Science Beijing100049China Department of Thermal Science and Energy Engineering University of Science and Technology of ChinaHefei230027China Research Institute of Science and Technology of China Three Gorges Group Corporation Beijing100038China

In conventional parabolic trough collectors(PTCs),sunlight is concentrated at the bottom of the absorber tube,resulting in a significant circumferential temperature gradient across the absorber tube,heat loss and thermal deformation,which affects the safety and thermal performance of *** this study,a new receiver with homogenizer and spiral(RHS) is proposed,achieving the optical and thermal synergy to ameliorate the thermal deformation of the absorber tube and enhance thermal efficiency.A plane structure homogenizer is designed to improve uniformity of the concentrated solar flux of absorber tube through second *** combination with the spiral,it improves the optical-thermal efficiency of the PTC by enhancing heat exchange between the fluid and the backlight side of the absorber *** performance of the collector is numerically studied by building a three-dimensional coupled light-thermal-structure *** results show that the thermal deformation of the RHS is reduced by more than 96% and the optical-thermal efficiency is improved by 1.2%-0.63% compared with conventional receivers(CRs) under the same inlet temperature *** proposed receiver is validated to be effective in reducing thermal deformation and improving optical-thermal efficiency.

关键词： parabolic trough collector homogenizer thermal deformation spiral

Design and performance investigation of modified dual reflector parabolic trough collector with double planar mirrors

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Science China(Technological Sciences) 2024年第3期67卷 902-918页

作者： LI Peijing liu TaiXiu QIN YuanLong LI JiChao liu qibin School of Energy Powerand Mechanical EngineeringNorth China Electric Power University Beijing 226China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Department of Thermal Science and Energy Engineering University of Science and Technology of ChinaHefei 230027China

In a typical parabolic trough collector(PTC), sunlight is concentrated at the bottom of the absorber tube. This concentrated solar flux leads to uneven heat distribution, resulting in high local temperatures and significant thermal stress on the absorber *** limitations have restricted the application of PTCs in solar thermochemistry and other fields and have impacted their safe operation. In this study, a new PTC with dual planar mirrors(DPMS) is proposed to homogenize the circumferential solar flux distribution of the absorber tube. A design method and single-objective optimization of the new PTC with a DPMS are proposed,and an uncertainty analysis of the operational and structural parameters is performed. A coupled light-heat-structure numerical model was developed to study the heat transfer performance and structural mechanical properties. The thermodynamic properties of the PTC with DPMS under different boundary conditions were analyzed. The results show that the circumferential temperature difference of the new PTC is within 2.6 K, and the circumferential thermal deformation is within 0.9 mm under typical working conditions(the inlet velocity of the heat transfer fluid is 3 m/s, inlet temperature is 573.15 K, and the direct normal irradiance is 1000 W/m^(2)). Compared with conventional PTCs, the circumferential temperature difference is reduced by 74%–90%, and the maximum thermal deformation along the y-axis is reduced by more than 95% under all working conditions(1–5 m/s, 373.5–675.15 K, 200–1000 W/m^(2)). The new PTC maintains the uniformity of the circumferential solar flux distribution for different operating parameters(sun incident angle of 0°–3°) and installation errors(±3 mm), is suitable for solar energy applications in various fields, and has the potential for large-scale applications.

关键词： solar thermal energy parabolic trough collector secondary reflector solar flux distribution optical optimization

New operation strategy and multi-objective optimization of hybrid solar-fuel CCHP system with fuel thermochemical conversion and source-loads matching

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Science China(Technological Sciences) 2023年第2期66卷 528-547页

作者： liu TaiXiu ZHENG ZhiMei QIN YuanLong SUI Jun liu qibin Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Department of Thermal Science and Energy Engineering University of Science and Technology of ChinaHefei 230027China

Multi-energy hybrid energy systems are a promising option to mitigate fluctuations in the renewable energy supply and are crucial in achieving carbon ***-fuel thermochemical hybrid utilization upgrades solar energy to fuel chemical energy,thereby achieving the efficient utilization of solar energy,reducing CO_(2)emission,and improving operation *** hybrid solar-fuel thermochemical CCHP systems,conventional integration optimization methods and operation modes do not account for the instability of solar energy,thermochemical conversion,and solar fuel *** improve the utilization efficiency of solar energy and fuel and achieve favorable economic and environmental performance,a new operation strategy and the optimization of a mid-and-low temperature solar-fuel thermochemical hybrid CCHP system are proposed *** system operation modes for various supply-demand scenarios of solar energy input and thermal-power outputs are analyzed,and a new operation strategy that accounts for the effect of solar energy is proposed,which is superior to conventional CCHP system strategies that primarily focus on the balance between system outputs and user *** alleviate the challenges of source-load fluctuations and supply-demand mismatches,a multi-objective optimization model is established to optimize the system integration configurations,with objective functions of system energy ratio,cost savings ratio,and CO_(2)emission savings ratio,as well as decision variables of power unit capacity,solar collector area,and syngas storage *** optimization design of the system configuration and the operation strategy improve the performance of the hybrid *** results show that the system annual energy ratio,cost saving ratio,and CO_(2)emission saving ratio are 52.72%,11.61%,and 36.27%,respectively,whereas the monthly CO_(2)emission reduction rate is 27.3%–47.6%compared with those of reference *** promising results will provide useful gu

关键词： solar thermochemical multi-energy hybrid operation strategy multi-objective optimization CCHP

Relaxor behavior and superior ferroelectricity of Y_(2)O_(3)-doped(Ba_(0.98)Ca_(0.02))(Ti_(0.94)Sn_(0.04)Zr_(0.02))O_(3) lead-free ceramics

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Journal of Rare Earths 2022年第6期40卷 942-951,I0004页

作者： Sifan Wang qibin liu Enpei Cai Fanghui Mou An Xue College of Material and Metallurgy Guizhou UniversityGuiyang 550025China Key Laboratory for Modern Manufacturing Technology of Educational Ministry Guiyang 550025China

To upgrade the electric properties of lead-free piezoceramics,(1-x)(Ba_(0.98)Ca_(0.02)Ti_(0.94)Sn_(0.04)Zr_(0.02))O_(3)-xY_(2)O_(3)(abbreviated as(1-x)BCTSZ-xY,x=0 mol%,0.02 mol%,0.04 mol%,0.06 mol%,0.08 mol%and 0.1 mol%)ceramics were successfully synthesized by traditional solid-state sintering *** phase structure and microstructure of ceramics were investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM)and piezoresponse force microscopyeramics(PFM).The electric properties of ceramics were researched through piezoelectric,dielectric and ferroelectric test *** results show that all samples have pure perovskite structure and favorable electric *** optimal electric properties which especially include superior ferroelectric properties are gained when Y_(2)O_(3)content is 0.06 mol%(d_(33)=419 pC/N,k_(p)=52%,T_(c)=89.5℃,ε_(r)=26900,tanδ=2.86%,P_(r)=14.41μC/cm^(2),Ec=1.8 kV/cm).Moreover,the temperature-dependent dielectricity of samples shows apparent relaxor behavior under different *** Curie-Weiss law further proves that all samples are typical relaxor ferroelectrics,and the relaxor degree of samples decreases with increase of Y_(2)O_(3)*** conclusion,Y_(2)O_(3)plays a significant role in enhancing electric properties of BCTSZ ceramics.

关键词： Lead-free ceramics Y2O_(3)doping Relaxor behavior Ferroelectric properties Rare earths

Integration of a thermochemical energy system driven by solar energy and biomass for natural gas and power production

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Science China(Technological Sciences) 2022年第6期65卷 1383-1395页

作者： WU HaiFeng ZHANG BoWen QU WanJun XU RongJi liu qibin Beijing Engineering Research Center of Sustainable Energy and Buildings Beijing University of Civil Engineering and ArchitectureBeijing 100044China Guangdong Provincial Key Laboratory of Distributed Energy Systems School of Chemical Engineering and Energy TechnologyDongguan University of TechnologyDongguan 523808China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

Energy systems with multi-energy product outputs driven by renewable energy sources are becoming increasingly *** satisfy the diversification of energy use forms in China,this study proposes a new thermochemical energy system driven by solar energy and biomass for natural gas and power *** this system,syngas from solar-driven biomass gasification is used to synthesize natural gas,whereas the unreacted syngas is burned directly in a combined cycle for power *** adjust the production capacity of the system,a shift reaction was used to change the H_(2)/CO ratio in the *** biomass gasification model was experimentally verified,and the thermodynamic performance of the system was studied *** results showed that the production rate of natural gas,with a heat value of 714.88 k J/mol,was approximately 0.306 m^(3)-SNG/kg-bio,and the primary energy efficiency was 47%.The new system showed a good energy-saving potential of 15.29%.Parametric analysis indicated that an increase in the gasification temperature led to a reduction in the natural gas production and an increase in the power output of the system,with a maximum energy efficiency of 66.72%at gasification temperature of 1050°*** an increase in the syngas share entering the transfer reactor,the natural gas production rate and energy efficiency of the system were improved with an optimum share of approximately 0.55,thereby facilitating the development and optimization of operation *** study provides a promising way to increase the share of renewable energy instead of fossil fuels.

关键词： solar energy biomass gasification natural gas thermochemical energy system thermodynamics performance

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