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工程热物理学报

Journal of Engineering Thermophysics

28 February 2025, Volume 46 Issue 3
    

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  • Catalysts Selection Study on Photothermal Degradation of R134a
    WANG Tianhao, XIE Datong, SHI Lin, DAI Xiaoye
    Journal of Engineering Thermophysics. 2025, 46(3): 693-702.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In accordance with international environmental protection conventions, some high GWP HFCs refrigerants are facing obsolescence and destruction. Therefore, it is necessary to develop energy-saving, high-efficiency destruction way. In this paper, the performance differences of various catalysts in the photothermal catalytic degradation of R134a was compared based on existing technical route. Furthermore, the effects of material properties on the reaction rate, such as morphology, band structure and photoelectric properties, were obtained through characterization of catalysts. Based on the law of the effects, anatase TiO2 was selected for modification. The modified catalyst achieved a degradation rate of over 98% within 30 minutes, with the reaction rate increasing by 3.8 times.
  • Investigation Into the Heat Exchange and Catalytic Matching Characteristics in Continuous Conversion Cryogenic Hydrogen gas Heat Exchangers
    WEI Xinyu, FANG Song, TENG Junjie, ZHU Shaolong, WANG Kai, QIU Limin
    Journal of Engineering Thermophysics. 2025, 46(3): 703-713.
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    In hydrogen liquefaction systems, the continuous catalytic conversion of ortho-para hydrogen is recognized as a key technology for achieving low energy consumption. The conversion heat of ortho-para hydrogen, which exhibits temperature dependence, is observed to vary significantly along the course of the heat exchanger, influencing the cooling process of hydrogen gas flow. This study investigates continuous conversion cryogenic hydrogen plate-fin heat exchangers, employing theoretical analysis and the development of a dynamic simulation model to explore the heat exchange and catalytic matching characteristics of such exchangers. Optimal cold fluid flow rates in various temperature zones have been determined. When helium is used as a cold fluid, optimal cold-to-hot mass flow rate ratios of 3.5 in the 80∼60 K range and 4.7 in the 60∼40 K range are identified. The dynamic simulation elucidates the heat transfer-catalytic matching relationship between normal hydrogen conversion and the cooling fluid in hydrogen heat exchangers, offering insights for the design and optimization of hydrogen liquefaction processes. These findings contribute to enhancing process efficiency, reducing energy consumption, and promoting sustainable development in the
    hydrogen energy sector.
  • Photothermal Synergistic Catalysis of CO2 Reduction on Ti3CN/TiO2
    ZHU Chenxuan, YANG Zhongqing, LI Xinghang, WANG Ziqi, GUO Mingnü, RAN Jingyu
    Journal of Engineering Thermophysics. 2025, 46(3): 714-721.
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    Ti3CN MXene exhibits remarkable electrical conductivity and photothermal conversion capabilities, making it a promising co-catalyst for photothermal catalytic CO2 reduction. This study utilizes two-dimensional mono-multilayer structured Ti3CN MXene to in-situ construct heterojunctions. A series of analyses, including AFM, SEM, TEM, XRD, XPS, UV-vis DRS, and i-t tests combined with DFT simulation calculation were conducted. The photothermal catalytic activity of each catalyst was tested under different energy input conditions. We discovered that the bandgap of Ti3CN/TiO2 is narrowed to 2.94 eV compared to that of TiO2, facilitating efficient electron transport from Ti3CN to TiO2 via the NC-Ti-O electron bridge at the interface, which enhances optical absorptivity and carrier mobility. The catalytic performance evaluation revealed a significant photothermal synergistic effect in CO2 reduction with Ti3CN/TiO2, the CO yield reached 8.34 μmol·g−1·h−1, which is 3.83 times greater than that achieved with TiO2 alone. These findings underscore the impact of Ti3CN-supported TiO2 on photothermal synergistic CO2 reduction characteristics
  • Security Analysis of Central Heating System Based on the Vulnerability Index
    TIAN Xingtao, LIN Xiaojie, ZHONG Wei
    Journal of Engineering Thermophysics. 2025, 46(3): 722-729.
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    With the continuous expansion of the scale of central heating system (CHS), the coupling relationship between the variables in CHS has become increasingly complex. Establishing the security analysis method considering variable coupling characteristics is of great significance to improve the security level of CHS operation. A security analysis method for the hydraulic and thermal states of CHS is proposed based on the vulnerability index, which quantitatively analyzes the impact of control variables such as hydraulic resistance, pump head, and heat source heating temperature on the security of state variables such as node pressure and heat load indoor temperature. The vulnerable state variables corresponding to each control variable and the key control variables corresponding to each state variable in CHS are identified based on the vulnerability index matrix. In the CHS case study, the effectiveness of the proposed method is verified by comparing the energy flow calculation results with the analysis results based on the vulnerability index.
  • Multi-energy Co-generation System With Solar Thermochemical Cycle Based on Chemical-looping Cycle Oxygen Removal
    CHEN Jing, KONG Hui, GUO Yongpeng
    Journal of Engineering Thermophysics. 2025, 46(3): 730-736.
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    As concerns about climate change continue to grow, the conundrum of how to produce carbon-neutral fuel needs to be addressed. This paper proposes a multi-energy co-generation system with solar thermochemical cycle based on chemical-looping cycle oxygen removal, which uses chemical-looping cycle to absorb oxygen generated by thermochemical cycle to improve the reduction degree of oxygencarrier Through the combined cooling, heating and power system, the hightemperature thermal energy generated by chemical-looping cycle is utilized in a cascade manner to output electricity, cold energy and low-grade thermal energy. The results show that NiO/Ni is more suitable as oxygencarrier in chemical-looping cycle. When the pressure ratio of chemical-looping cycle is 5 and the thermal chemical cycle reduction temperature is 1500°C, the solar utilization efficiency and exergy efficiency reached 28.5% and 23.5% respectively, and when the reduction temperature rose to 1600°C, these efficiencies rose to 32.2% and 25.5% respectively. The use of multi-energy cogeneration system can save 57.4% of methane and reduce carbon emissions. Theoretical calculation shows that if the energy supply of the multi-energy cogeneration system is completely relied on, the annual energy consumption per capita of Beijing and Shanghai residents needs 12.1 m2 and 7.3 m2 of concentrating area.
  • Study on Thermal Performance of Integrated Collector-storage Vacuum Tube Solar Air Heater based on Lap Joint-type Heat Pipe
    WANG Zeyu, DIAO Yanhua, ZHANG Dengke, PAN Yawen, WANG Xinran, SUN Mengda, DU Peiyuan, ZHAO Yaohua
    Journal of Engineering Thermophysics. 2025, 46(3): 737-743.
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    In this study, a vacuum tube integrated collector-storage solar air heater using lap-jointtype micro-heat pipe arrays and long straight fins as heat exchange component is proposed, and the heat collecting projection area is 0.51 m2. No.52 industrial paraffin is selected as heat storage material and has a mass of 9.8 kg. The design, working principle and thermal responses under the conditions of charging only and discharging only are introduced in detail. In order to meet the practical application requirements of the collector, the experimental conditions are selected in the winter and transition seasons, which are two weather conditions with high heat demand. In addition, the effects of air flow rate and inlet temperature on the discharging performance of the device are also described in detail. The results show that the vacuum tube integrated collector-storage solar air heater has experienced outstanding charging and discharging performance. The average charging and extraction power can reach 294.2 W (576.9 W/m2 of heat collecting area) and 1041.2 W. The total efficiency in the transition season and winter can reach 63.2% and 56.3%.
  • Study on Performance of a Double-stage Compression Auto-cascade Heat Pump
    WANG Lin, GUO Feiyan, TAN Yingying, LI Xiuzhen
    Journal of Engineering Thermophysics. 2025, 46(3): 744-751.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The conventional single-stage compression auto-cascade heat pump (SACHP) has tough issues such as high compressor discharge temperature and low heating efficiency at the low ambient temperature. Therefore, the concept that the graded compression of high and low boiling point component matches with the fractionation of low boiling point component is presented to develop a double-stage compression auto-cascade heat pump (DACHP) with R290/R600 as the working fluid, which helps reduce the compressor discharge temperature and power consumption, and improve the heating performance of the proposed DACHP. Based on the thermodynamic mathematical model, the cycle performance of DACHP is compared with SACHP. The results indicate that there is an optimal composition ratio for DACHP to obtain the highest heating coefficient of performance (COP), with the maximum COP of 2.44 at the R290 mass fraction of 0.61. When the evaporator outlet temperature varies from −24°C to −10°C, the average discharge temperature of DACHP decreases by 24.09°C, and the average compressor power consumption of DACHP reduces by 55.49%, compared with the SACHP. The compressor power consumption of DACHP is 52.82%∼56.61% lower than that of SACHP, while its COP increases by 0.90∼0.95 as compared with DACHP, as the condenser outlet temperature ranges from 50°C to 65°C. Double-stage compression auto-cascade heat pump is suitable for application in cold areas or severe cold areas.
  • Study on the Mechanism of Mixed-phase Ice Accretion in the Variable Speed of Transonic Fan Blade
    REN Huhu, XU Qiangren, WANG Lizhi, LI Guangchao, ZHAO Wei, ZHAO Qingjun
    Journal of Engineering Thermophysics. 2025, 46(3): 752-760.
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    In order to obtain the influence of speed on the mixed-phase ice accretion of transonic fan blade, FENSAP-ICE software was used to carry out numerical simulation research on the ice accretion on the surface of fan blade. The results show that under the condition of high speed, ice accretion of fan blade was mainly generated on the pressure surface, the speed of supercooled water droplets and ice crystals in the flow channel first increased and then decreased from the leading edge to the trailing edge, the collection coefficient increased first from the leading edge to the tail edge, and then decreased, the higher the speed, the centrifugal force and aerodynamic force of the water film increased, and the water film refreezes behind the leading edge, resulting in a thicker ice accretion thickness of the blade than that of the leading edge. In addition, the unmelted ice crystals on the surface are also collected due to the water film formed by supercooled water droplets on the leaves. In the area where the water film does not exist at the trailing edge, the temperature is higher than the freezing point, and the ice crystals are absorbed to the trailing edge to form ice accretion after melting. Through the numerical simulation of high-speed mixed-phase ice accretion of fan blade, this paper provides theoretical support for predicting mixed-phase ice accretion of fan blade during high-altitude flight.
  • Study on the Coupled Dynamic Responses of a Twin-Turbine Floating Wind Power System
    YU Jie, LAI Yongqing, YANG Yang, LI Chun
    Journal of Engineering Thermophysics. 2025, 46(3): 761-767.
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    The twin-turbine floating wind power system is a novel type of offshore wind energy conversion device, where significant interactions exist between two wind turbines and coupling effects with the platform and mooring system. This study conducted a secondary development on OpenFAST and developed a fully coupled simulation model for the twin-turbine floating wind power system. An investigation has been carried out on the dynamic response of a 10 MW semi-submersible twin-turbine floating wind power system under the combined action of turbulent wind and irregular waves, and then compared with the single-turbine model. The results indicate that the twin-turbine model exhibits lower platform translational and rotational angles. Compared to the single-turbine model, the average, maximum and standard deviation of the platform pitch are reduced by 79.62%, 61.87%, and 48.93%, respectively. Additionally, the mooring tension of the twin-turbine model is lower, with a fluctuation amplitude 66.9% lower than that of the single-turbine model. Due to the lower hub height in the twin-turbine model, the overall power generation is 15.64% lower than that of the single-turbine model under the same wind condition. However, the twin-turbine model shows great potential in reducing platform motions, which can lead to significant cost savings in wind energy utilization by reducing material usage for the platform, particularly in deep offshore areas with higher wind shear effect.
  • Performance Analysis on Annular Cross-Wavy Primary Surface Recuperator
    YANG Yanzhao, CHEN Fu, YU Jianyang, SONG Yanping
    Journal of Engineering Thermophysics. 2025, 46(3): 768-776.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The Cross-wavy primary surface recuperator has become the best choice for micro gas turbine regenerative devices due to its compact structure, high efficiency, and low resistance. However, there are few publicly available research results on the inlet and outlet structures of Cross-wavy primary surface recuperator based on heat exchange cores. This article constructs five comparative models based on the heat exchange core: considering the wall model of CW channel structure, not considering the wall model of CW channel structure, and inclination angle α= 60° model, inclination angle α=45° model and inclination angle α=30° model. Inclination angle of inlet and outlet structures α Compare and analyze the thermodynamic performance of CW channel structures, and then investigate the inclination angle α Conduct optimization. The results show that the inclination angle has a small impact on the temperature rise distribution of the CW channel structure, but a significant impact on the pressure drop near its inlet and outlet. By comparing and analyzing the five models from the perspective of the first and second laws of thermodynamics, the optimal tilt angle can be obtained α=45°.
  • Research on Off-design Performance Prediction Method of Diagonal Compressor With Adjustable Guide Vane
    ZHANG Yuxin, ZUO Zhitao, GUO Wenbin, LI Jingxin, CHEN Haisheng, Qin Wei
    Journal of Engineering Thermophysics. 2025, 46(3): 777-789.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The diagonal compressor is one of the important types of combined compressors for large-scale compressed air energy storage system (CAES). The off-design performance prediction is crucial in the research and development of the diagonal compressor. It can not only quickly evaluate the initial design parameters, but also select the overall optimal parameters according to the characteristics of the off-design operation of the compressor in CAES. The accuracy of the performance prediction model is essential. In this paper, a one dimensional performance prediction program for the diagonal compressor of the developing large-scale CAES is established by programming, and the optimal selection result of the loss model combination of the program is given through the design point parameters. Then, the off-design loss model is modified by using the flow coefficient, and the results are verified by CFD. The results show that this method can effectively predict the off-design performance of the diagonal compressor under different guide vane openings.
  • Study on the Suppression Effect of Plasma Actuation on Leakage Flow in High-Temperature Gas Turbine Blade Tip Clearance
    CHEN Bo, WANG, Tianyi, XUAN Yimin
    Journal of Engineering Thermophysics. 2025, 46(3): 790-799.
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    This paper focuses on the leakage flow between high-pressure turbine rotor blades as the research subject. Based on the establishment of computational methods for gas properties in the turbine environment and the calculation of maximum charge density parameters of plasma under variable actuation conditions, numerical simulation analysis is adopted to investigate the impact mechanism of plasma actuation on leakage flow at turbine blade tip clearances under high-temperature gas flow conditions. It explores the effects of different external actuation conditions and the arrangement of the actuation devices, including shroud single-stage actuator and their array configurations, on the suppression of leakage flow. The research indicates that increasing actuation intensity can enhance the suppression effect of actuator on leakage flow. When external actuation is increased from 0 to 200 for a single-stage actuator, the relative leakage reduction is 24.78%. The synergistic effect of multi-stage actuators can further improve the suppression effect. However, the array arrangement of multiple actuators may lead to inter-stage potential interference, altering potential and electric field distributions, generating factors that promote leakage flow, thereby resulting in a relatively smaller improvement in suppression effect compared to single-stage actuator.
  • Influence of Exhaust Plenum Chamber on Surge of Centrifugal Compressor
    GAO Xiaohuan, XI Guang, ZHAO Yang, ZHAO Jiayi, FAN Hongzhou, ZOU Hansen, ZHAO Tianhao
    Journal of Engineering Thermophysics. 2025, 46(3): 800-806.
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    To further study the variation law of aerodynamic parameters in inlet and outlet pipes during the compressor surge process, this paper uses high-frequency hot-wire probes and pressure sensors to obtain the test data of the centrifugal compressor system with or without exhaust pipe plenum chamber during the surge process. According to the analysis, under the condition of the same valve opening, the surge frequency of the compressor system with the exhaust pipe plenum chamber is about 1.168 Hz, and the large negative flow area (backflow) can be detected in both the inlet and outlet pipes, which indicates that the compressor has entered the deep surge condition. The surge frequency of the compressor system without the exhaust gas chamber is about 3.968 Hz, and the large negative flow area (backflow) is only detected at the inlet, which indicates that the compressor is still in a mild surge condition.
  • Design and Flow Analysis of Three-Stage Highly Loaded Compressor
    DENG Hangwen, LUO Lei, MOU Guangyuan, LI Bai, QIN Runxuan, ZHOU Xun
    Journal of Engineering Thermophysics. 2025, 46(3): 807-814.
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    This article is based on the 9FA heavy-duty gas turbine final stage compressor, aiming to improve the pressure ratio, efficiency, and expand the margin. It redesigns a three-stage high-load compressor that breaks through the conventional load. In the design process, three-dimensional blade technology is used in the end region of the stator blades. Comparative analysis was conducted on the changes in key parameters such as efficiency, pressure ratio, and total pressure loss at the outlet of each stage before and after the modification. The results show that, compared to the prototype, the three-dimensional blade technology effectively controls the separation of the stator blade corner by transferring the boundary layer on the wall while maintaining consistent inlet flow angle and outlet Mach number. The modified three-stage high-load compressor achieves an efficiency of 90.08%, a pressure ratio of 1.393, and a surge margin of 25.5% near the design point.
  • Study on the Design of Bionic Volute Inspired by the Nautilus and Its Influence on Aerodynamic Performance of Centrifugal Compressor
    ZHANG Yuhang, LIU Xiaomin, TAN Jiajian, SUN Yongrui
    Journal of Engineering Thermophysics. 2025, 46(3): 815-822.
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    As one of the critical components of a centrifugal compressor, the optimization design of the volute plays a crucial role in improving the aerodynamic performance of centrifugal compressor. Inspired by the spiral profile of the nautilus shell, the reverse design and bionic reconstruction method are used to design the volute of the centrifugal compressor. Internal flow field of the centrifugal compressor are simulated through numerical calculations to analyze the flow characteristics inside the prototype volute and bionic volute, as well as their impact on the pressure ratio and efficiency of the centrifugal compressor. The results show that the bionic design inspired by the nautilus can be used to reduce the total pressure loss of the volute and improve the static pressure recovery coefficient of the volute, which leads to the increase of the aerodynamic performance of centrifugal compressor. At the design condition, compared to the prototype volute, the bionic volute exhibits a 12.3% relative reduction in the total pressure loss coefficient and a 5.4% relative increase in the static pressure recovery coefficient. When the designed bionic volute is used, the centrifugal compressor achieves a maximum increase of 1.42% in the polytropic efficiency and a maximum increase of 0.84% in the pressure ratio compared to the prototype centrifugal compressor.
  • Dynamic Response of a Spra Floating Platform Under the Coupling Effect of Wind, Waves, and Currents
    TIAN Shaochen, LI Zhiguo, XUE Junfang, GAO Zhiying, WANG Jianwen
    Journal of Engineering Thermophysics. 2025, 46(3): 823-829.
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    By combining the fractal dimension with wind field measurements, a turbulent environment was created to analyze the impact of varying wind speed, wave height, and wind-wave misalignment angle on a spar wind turbine. The study revealed that changes in wind speed had the greatest effect on the turbine, leading to increased surge and pitch with sharp fluctuations. Wave height had a lesser effect, but an increase in height led to higher frequency changes and additional fatigue loads. Wind-wave misalignment angle had a slower impact on platform motion when it varied between 0° ∼ 180°. In the same direction, the platform was more affected by the frequency of incoming current, while staggered wind-waves resulted in slightly higher mean values of surge and pitch compared to wind-wave misalignment.
  • The Influence of Blowing Ratio on the Flow Field and Film Cooling in a Labyrinth Seal
    YANG Shaoyun, LUO Qianqian, LUO Lei, DU Wei, WANG Songtao
    Journal of Engineering Thermophysics. 2025, 46(3): 830-836.
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    Installing labyrinth seals on shrouded blade tips effectively reduces leakage losses at the top of the rotor. With the increase in turbine inlet temperatures, it is necessary to employ film cooling technology to ensure the stable operation of shrouded blade tips. This paper employs numerical simulation to investigate the effect of blowing ratio variation on film cooling within a labyrinth seal. All results are obtained at a main passage Reynolds number of 10000. The results indicate that increasing the blowing ratio enhances the sealing characteristics of the labyrinth seal. The film cooling effectiveness at the cavity bottom is determined by the relative strength of the coolant and the recirculation zone. When the coolant momentum is high, the coolant can easily diffuse within the cavity, resulting in higher cooling efficiency. However, when the coolant momentum is low, the coolant is more prone to be entrained by the swirling recirculation, dissipating and leading to lower cooling efficiency.
  • Research on the Dynamic Characteristics of Microjets Ejected From a Dual Channel Pneumatic Needle-free Injection System
    ZENG Dongping, TANG Zheng, WANG Wei, LIU Rui, LIU Zhong, YU Zheqin
    Journal of Engineering Thermophysics. 2025, 46(3): 837-845.
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    Needle-free injection devices have become the focus of research on medical water jet technology as a new type of fluid machinery. The aim of this study is to investigate the dynamic characteristics of the microjet under different driving pressure modes. By comparing the impact pressure results obtained from numerical simulations with experimental tests, the reliability of the numerical simulation model was validated. And then, the distribution characteristics of the flow field inside and outside the nozzle under different driving pressures are analyzed by numerical simulation. Finally, the influence of driving pressure on the penetration and diffusion characteristics of the microjet was investigated. The results show that different driving pressures affect the distribution of the liquid flow inside the nozzle, and a vortex will appear when the driving pressure is greater than 0.50 MPa, and the vortex location is close to the contraction section gradually with the increase of the driving pressure. At the same time, the driving pressure difference and conversion time between the two stages directly affects the morphology of the jet column. Also, compared with the single-channel pneumatic driving mode, the microjet generated from the dual-channel driving pressure mode has a more uniform diffusion pattern in the porous medium. Therefore, the microjet dynamics can be regulated by controlling the characteristics of dual-channel driving pressures. 
  • Investigation on the Catalytic Upgrading of Heavy Oil Using CuSO4/NaOH
    ZHOU Yantao, ZHAO Qiuyang, ZHANG Yanlong, ZHAO Keyu, KE Bowen, JIN Hui, GUO Liejin
    Journal of Engineering Thermophysics. 2025, 46(3): 846-850.
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    The heavy oil has enormous resource potential, but its poor fluidity makes the extraction difficult. The in-situ upgrading technology aims to decrease the heavy oil viscosity and enhance the oil recovery by the hydrothermal cracking reaction. The transition metal was used as catalyst in in-situ upgrading technology. The composite catalyst including inorganic salt and alkali was been proposed based on the mechanism study of hydrothermal cracking reaction. The composite catalyst solve the disadvantages of low catalytic efficiency and have the advantages of low cost and easy injection, which have a wide application prospect. This work used the response surface methodology to analyze the impact of composite catalyst ratio, reaction temperature and pressure. It was found that the response surface methodology can predict the upgrading results accurately, and excessive or insufficient CuSO4 concentration and reaction temperature were not suitable for improving the upgrading efficiency, while increasing NaOH concentration didn’t have a negative impact. 
  • Numerical Simulation of Evaporation From Droplet Impact on Wall Based on the SPH Method
    MA Xiaojing, XIAO Xinpeng, LIAO Haiyan, FAN Mengyao, XI Hu
    Journal of Engineering Thermophysics. 2025, 46(3): 851-858.
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    In order to avoid the pressure oscillation caused by the change of density during the droplet evaporation, based on the smoothed particle hydrodynamics (SPH) method and mass fraction in liquid phase, a numerical model of the droplet evaporation was established combined with the particle merging technique. At the same time, to improve the computing efficiency and stability, the multi-resolution and the density correction techniques were introduced. The non-reflecting boundary was used to reduce the impact of shock wave on wall rebound on the velocity field. Firstly, the space droplet evaporation problem was simulated, and the reliability of the model was verified by comparing the numerical solution with the theoretical solution. And then the numerical model presented in this paper was used to study the evaporation problem of a droplet impinging on the wall. The research results showed that when the difference between the thermal conductivity of droplet and wall surface was large, the common thermal conductivity correction method in SPH method was no longer applicable, and the results closer to the experimental phenomenon could be obtained by using the average thermal conductivity. In the second place, through comparison and analysis with the experimental diagram, the spreading flow pattern of the droplet after impact had a great influence on the evaporation process.
  • Large Eddy Simulation of TiO2 Nanoparticle Synthesis in a Turbulent Diffusion Flame Burner
    HE Song, SHANG Cheng, XU Zuwei, LU Hao, ZHAO Haibo
    Journal of Engineering Thermophysics. 2025, 46(3): 859-865.
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    In the present work, a new simulation approach coupling large-eddy simulation (LES) and monodisperse model for nanoparticle synthesis in turbulent flame is proposed. In particular, the nonlinear LES-partially stirred reactor model (NLES-PaSR) is utilized to simulate the turbulent flame. In addition, the monodisperse particle transport equations are successfully established in the LES framework to describe the spatiotemporally resolved formation and growth of nanoparticles in turbulent flame. The developed LES-monodisperse model successfully simulates the synthesis of TiO2 nanoparticles via TTIP in a turbulent diffusion flame burner. The results show that the proposed model is able to provide precise predictions of the complex processes involved in turbulent flame synthesis of nanoparticles at a relatively low computational cost. Furthermore, the increase of oxygen flow rate can significantly reduce the particle size, and an increase in precursor flow rate leads to an increase in particle size and a transition from soft agglomerates composed of round-shaped primary particles to branched structures with hard sintering necks/bonds.
  • Research on the Effect of Nano Janus Particles on Pool Boiling Heat Transfer
    YANG Yuhao, JI Xianbing, REN Jixing, ZHANG Zhe, XU Jinliang
    Journal of Engineering Thermophysics. 2025, 46(3): 866-871.
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    In order to explore the influence of nano Janus particles on boiling heat transfer, we used Pickering lotion method to prepare Fe3O4-SiO2 Janus nanoparticles and hydrophilic/hydrophobic nanoparticles, then we carried out pool boiling experiments. Research has found that adding Fe3O4-SiO2 nano Janus particles can significantly enhance boiling heat transfer, the superheat degree ΔTstart at the starting point of boiling is 2.7 K, compared to 7.7 K on smooth surface, ΔTstart decreased by 5.0 K, while the critical heat flux (CHF) increased by 54.1%, and the maximum boiling heat transfer coefficient (h) can be increased by 19%. Due to the deposition problem of nanofluids, we conducted pool boiling experiments on the surface with deposition layer. It was found that the boiling heat transfer performance of Janus particle deposition layer was superior to that of smooth surface and hydrophilic/hydrophobic particle deposition layer. Compared to the smooth surface, the CHF of Janus particle deposition layer increased by 38.5%, and h increased by 11%.
  • Investigation on the Movement of the Polymer in Microchannel Based on Dissipative Particle Dynamics
    ZHOU Hao, LI Yifei, FAN Liangliang, ZHAO Liang
    Journal of Engineering Thermophysics. 2025, 46(3): 872-878.
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    This paper employs the method of dissipative particle dynamics to construct a model of long-chain polymer motion within microchannels. The effects of polymer chain confinement, Reynolds number, and channel structure on the conformational changes and motion rules of individual polymer chains are systematically studied. The result shows that, in the Poiseuille flow in the straight channel, the distribution of the polymer chain’s center of mass is bimodal, and the position and peak value of the double peaks are closely related to the degree of confinement and Reynolds number. In addition, the period of different chain length polymers passing through the slit can be controlled by adjusting the slit width of the T-shaped channel. Based on this mechanism, the separation of different chain length polymers can be achieved, which has great potentials in biomedical field.
  • Experimental Study on Heat Transfer Characteristics of Low Temperature Triple Effect Horizontal Tube Falling Film Evaporator
    YANG Luopeng, LI Qiang, GUO Feng, CHEN Xianbing, ZOU Zhiqiang, WANG Zhan, ZHANG Linhua
    Journal of Engineering Thermophysics. 2025, 46(3): 879-883.
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    A low temperature three-effect horizontal falling film evaporator was set up to test the total heat transfer coefficient, water yield and water production ratio under different spray density, evaporation temperature and feed salinity. The research results indicate that the overall heat transfer coefficient shows an increasing trend with the increase of spray density, but decreases with the rise in evaporation temperature and salinity. The water production of the experimental system increases with the increase of spray density and evaporation temperature, with a relatively minor impact on the water production ratio. However, both the water production and water production ratio decrease with the increase of salinity. 
  • Comparative Study of Non-Fourier Heat Conduction in GaN Transistors Using Thermoreflectance Thermal Imaging and Full-band Multiscale Simulation
    LIU Zhike, LI Hanling, SHEN Yang, CAO Bingyang
    Journal of Engineering Thermophysics. 2025, 46(3): 884-889.
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    Research on non-Fourier heat transport in GaN transistors was conducted using both thermoreflectance thermal imaging and full-band multiscale simulations. Different-sized Au heaters are designed and fabricated on GaN epitaxial structures. Leveraging the high spatial resolution advantage of thermoreflectance thermal imaging, temperature field distributions of heat sources as small as 500 nm thermal observed, enabling more direct measurement of sample hot spot temperatures. Simulation results from three-dimensional multiscale simulations based on full-band phonon Monte Carlo and finite element methods are in good agreement with experimental values, indicating that phonon ballistic effects significantly increase hot spot temperatures. As the size of the heat source decreases, deviations from predictions based on Fourier’s law increase, highlighting the importance of combining high-resolution temperature field experiments with full-band multiscale thermal simulations to accurately predict device junction temperatures.
  • Experimental Study on the Cavitation of Nematic Liquid Crystal Under Stokes Flow in a Microchannel
    YU Jiajia, JIANG Luyang, HUANG Li, WU Chunmei, LI Yourong
    Journal of Engineering Thermophysics. 2025, 46(3): 890-896.
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    This paper reports the phenomenon of hydrodynamic cavitation of nematic liquid crystal 5CB flowing past side-by-side two circular pillars in a microchannel. The influence of the side-by-side two circular pillars on the cavitation characteristics of nematic liquid crystal 5CB is experimentally investigated, and the regularity of the in the flow process is explored. The results show that the length and width of the disclination loop behind the side-by-side two circular pillars will decrease with the increase of Reynolds number, and when the Reynolds number is far less than 1, under the Stokes flow, the hydrodynamic cavitation can occur behind the side-by-side two circular pillars; the oscillation behavior of the cavitation domain after the side-by-side two circular pillars is similar to that of the single circular pillar, and the Strauhl number decreases with the increase of the Reynolds number; The differential pressure between the inlet and outlet of the microchannel set up with side-by-side two circular pillars and single circular pillar is linearly related to the Reynolds number.
  • Energy-saving Strategies for Container Plant Factories
    BU Kunlang, SONG Mengxuan, BAO Hua
    Journal of Engineering Thermophysics. 2025, 46(3): 897-901.
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    Plant factory with artificial light (PFAL) has become a potential solution to the food crisis due to their advantages such as high output per unit area. However, PFAL has high energy consumption, resulting in high operating costs. This paper takes the façade design and light period setting of plant factories as design parameters to reduce energy consumption under four representative cities in different climate zones in China (Harbin, Taiyuan, Shanghai, and Guangzhou). Then the impact of improving these design parameters on the energy consumption of plant factories in the four regions is explored. Results have shown that façade design with high thermal conductivity, high solar reflectivity, and low ventilation, as well as setting the dark period during the day, are beneficial to reducing the energy consumption of plant factories. The maximum energy saving rate of the optimized plant factory is 23.9%.
  • Properties of Inositol Capsules Doped With Nano-alumina
    LI Jiaxuan, LI Yuanhong, MO Songping, XIAO Bo, JIA Lisi, CHEN Ying
    Journal of Engineering Thermophysics. 2025, 46(3): 902-908.
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    To address the problems of poor thermal conductivity and large subcooling of phase change microcapsules, in this study, modified silica-encapsulated inositol phase change capsules were prepared by doping highly thermally conductive nano-alumina into the core material inositol using the sol-gel method, and their morphology and structure, phase change properties, thermal stability and thermal conductivity were characterized. The results showed that spherical nanocapsules with welldefined nuclei and shells and uniform particle size were successfully synthesized, and the presence of nano-alumina promoted the crystalline nucleation of inositol, reduced the supercooling, and improved the thermal stability and thermal conductivity of the capsules with a slight decrease in latent heat. 
  • Study on Wellbore Flow and Heat Transfer Model for Underground Gas Storage
    XUE Wendi, WANG Yi, CHEN Zhe
    Journal of Engineering Thermophysics. 2025, 46(3): 909-917.
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    To address the need for new technology in underground gas storage with carbon dioxide as the cushion gas, an improved underground gas storage wellbore flow and heat transfer model and its solution method are proposed in this paper. In terms of the mathematical model, a flow direction factor is introduced to adapt to the alternating gas flow direction in the wellbore for injection and extraction in underground gas storage. An unsteady wellbore thermal conduction model is established, overcoming the limitations of the Ramey’s analytical model. The impact of phase transitions in carbon dioxide flow in the wellbore is also considered. In terms of the solution method, a nonlinear model for wellbore flow pressure drop is proposed. The whole wellbore is solved by Newton iteration method, which solves the instability issues of the conventional point-by-point iteration method and reduces the computation time at least 40%.
  • Fe3O4-modified Biochar for Efficient Solar Interfacial Evaporation
    CHEN Lei, WEI Linjie, DONG Chuanshuai, ZHANG Lizhi
    Journal of Engineering Thermophysics. 2025, 46(3): 918-924.
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    Solar interfacial evaporation is one of the effective ways to solve the freshwater shortage problem. In this study, to address the problems of low solar energy utilization and serious salt accumulation of existing interfacial evaporation materials, a biochar material with porous distribution and unidirectional channels was prepared using balsa wood, based on which in situ loading of Fe3O4 nanoparticles was performed to improve the hydrophilicity and light-absorption properties of the material. The evaporation rate was 1.448 kg·m−2·h−1 under the light intensity of 1 kW/m2, with the photothermal conversion efficiency of 96.1%, achieving a high solar energy utilization efficiency. This research would provide valuable guidance to the design of subsequent interfacial evaporation materials.
  • Temperature Response Spatiotemporal Correlation Model of Heat Transfer System With Unknown Heat Sources
    WANG Guangjun, CHEN Zehong, CHEN Hong, JI Yalan
    Journal of Engineering Thermophysics. 2025, 46(3): 925-932.
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    The temperature field reconstruction problem of the heat transfer system with unknown heat sources involves in widely practical engineering. In order to reconstruct the temperature field of the heat transfer system with unknown heat sources, it is meaningful to quantitatively describe the response spatiotemporal correlation between the temperatures of the spatial points of the heat transfer system. For a linear heat transfer system, the temperature field has a definite unit step response to any heat source. Therefore, there are the definite response spatiotemporal correlation between the temperatures at spatial points, which independents of the heat source intensities. This manuscript establishes a temperature response spatiotemporal correlation model (RSTCM) of the heat transfer system with unknown heat sources, theoretically and quantitatively revealing the inherent spatiotemporal correlation between temperature responses at spatial points of the heat transfer system. The RSTCM is validated by the numerical experiments.
  • Study on Thermal Diagnosis Method of Mini-channels Based on Convolutional Neural Network
    LI Pei1 LIU Xinyi, JIANG Lin, WANG Qiuwang, MA Ting
    Journal of Engineering Thermophysics. 2025, 46(3): 933-937.
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    High power microwave has important application prospects in the field of electronic system damage such as satellite and aircraft. There is strong electromagnetic interference near the electron beam collector, so it is necessary to develop an indirect thermal diagnosis method that can predict the boiling heat transfer performance of mini-channels. In this paper, the sample database was established through the experimental results of mini-channel boiling heat transfer, and then a thermal diagnosis model based on convolutional neural network was proposed for mini-channels. The method was analyzed and validated. The results indicated that the proposed thermal diagnosis method can predict the experimental operating conditions and thermal boundary conditions, and the test accuracy can reach 86%, which can realize the thermal diagnosis of flow and heat transfer parameters.
  • Study on Surface Machining and Wetting Characteristics of Copper-Based Special-Shaped Microstructure by Ion Etching
    DANG Chao, LI Hao, WANG Xiaowei, JIA Li
    Journal of Engineering Thermophysics. 2025, 46(3): 938-944.
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    The machining of special-shaped microstructure on metal surface was of great significance for the manufacture of hydrophobic surface suitable for low surface energy working fluids. In this paper, a machining method of special-shaped microstructure surface was designed based on ion beam etching process. Through the experimental study, the processing technology was optimized and the relationship between the deformation of the top of the microstructure and the diffusion welding pressure was determined. The wetting characteristics of the droplet with varied surface energy were explored on two types of microstructure surfaces. The special-shaped microstructure surfaces could keep the ethanol solution droplets with surface energy as low as 26.72 mN/m hydrophobic. The droplet contact angle on the microstructure surface varied periodically with the increase of droplet volume and decreased with the decreasing surface energy of the working fluids. The surface with channel structure could maintain the hydrophobic state of the droplets with lower surface energy and the wettability was anisotropic. The surface with array structure could make the droplets of a certain volume had higher contact angle and more uniform wettability.
  • Numerical Research on the Core Component of Thermoacoustic Heat Engine
    LIU Xianxian, CHEN Yanyan, HU Jianying, LUO Ercang
    Journal of Engineering Thermophysics. 2025, 46(3): 945-953.
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    Thermoacoustic heat engines are a type of heat engine that utilizes the reciprocating oscillation of compressible gas to achieve the mutual conversion between sound energy and thermal energy. The core components are composed of static high and low temperature heat exchangers and regenerators, with a simple structure. In this paper, a three-dimensional local model is established for the core components of a thermoacoustic engine. In the three-dimensional local model, the heat exchanger uses the tube and sleeve model, and the recuperator uses Porous medium, in which the inertia drag coefficient and viscous drag coefficient of the recuperator are calculated by the pore method. Then, based on this three-dimensional model, this article establishes equivalent Fluent two-dimensional models and Sage one-dimensional models. By comparing the calculation results of the three models, it is found that the CFD calculation model and Sage calculation model are basically similar in capturing the distribution of time average temperature difference and time average heat flux. However, there is a significant difference in the calculation of resistance characteristics between the two, as Sage is a one-dimensional model software that cannot directly capture the local losses caused by complex flow changes. However, by comparing the calculation results of Fluent’s 2D and 3D models, it was found that the calculation results of the two models in terms of resistance characteristics are relatively close. Therefore, in engineering calculations, in order to simplify calculations and save time, a 2D Fluent model with equivalent topology can be used instead of a 3D model.
  • Study on the Mechanism of Liquid Water Transport Within Graded Porous Electrodes
    JIANG Tao, MOU Xinzhu, CHEN Zhenqian
    Journal of Engineering Thermophysics. 2025, 46(3): 954-960.
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    The electrode structure plays a vital role in mass transfer processes within Proton Exchange Membrane Fuel Cell (PEMFC) systems. This study involved the reconstruction of an orderly graded porous micro-porous layer (MPL) and stochastic gas diffusion layers (GDLs), giving rise to a graded mesoporous structure and uniform microporous gas-liquid separation channels in the MPL. Leveraging the Lattice Boltzmann Method (LBM), the Shan-Chen multiphase pseudopotential model was employed to investigate the mechanisms of liquid water transport within the orderly graded porous architecture. Subsequently, the liquid water saturation in the GDL and gas content in the MPL under various operating conditions were examined. The findings revealed that an ordered positive gradient porous structure can efficiently remove liquid water while retaining more reaction gases at appropriate driving pressure differences and flow rates. Conversely, wetting gradient designs struggle to strike a balance between water removal efficiency and gas retention. Consequently, by optimizing operational conditions, an ordered positive gradient MPL can significantly enhance liquid water management in PEMFCs, thereby boosting their electrochemical performance. 
  • Research on the Spatiotemporal Distribution Characteristics of Solar Energy Resources Over East Asia Based on the Fengyun-4 Geostationary Satellite
    HUANG Chunlin, ZHANG Yue, YU Xiaoxiao, LIU Jiemei, CHEN Qixiang, YUAN Yuan
    Journal of Engineering Thermophysics. 2025, 46(3): 961-966.
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    Fengyun-4 (FY-4A) can provide high spatial-temporal and spectral resolution observation data, and has great potential in the field of solar energy resource assessment. In this paper, a total horizontal radiation (FY-GHI) dataset with a resolution of 4 km and 15 minutes is established by using FY-4A visible light channel observation data and semi empirical model. The results show that the correlation coefficient (R), root mean square error (RMSE) and mean deviation (MBE) of hourly FY-GHI were 0.90, 118.8 W/m2 and 2.2 W/m2, respectively. The results of spatial distribution of solar energy resources show that the Qinghai Tibet Plateau, northern and northwestern China have abundant solar energy resources, while the southwest and northeast China are relatively scarce.
  • Modulation of Thermophysical Property of 3D Printing Materials
    SUN Qiangsheng, XUE Zhixiang, XU Shen, ZHANG Jun, YUE Yanan
    Journal of Engineering Thermophysics. 2025, 46(3): 967-974.
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    Based on the decisive relationship between material structure and physical properties, a method for regulating thermal properties of materials was proposed by generating microstructures through 3D printing technology. The 304L stainless steel with different 3D printing scanning speeds was prepared, and the correlation between porosity, thermal conductivity and scanning speed was established by microstructure characterization and thermal property measurement, and the nonlinear relationship equation k = 14.43 + 4.25 exp(−v/1187.7) between thermal conductivity and scanning speed was obtained based on the experiment. The prediction and experimental verification of the thermal conductivity of the new sample with a scanning speed of 1500 mm/s and the error of 0.6% indicates the validity of the above correlation between thermal conductivity and scanning speed. In addition, a two-dimensional heat transfer model of the microporous structure of the 3D printed samples was established, and the effect of the pore structure on the overall thermal properties of the material was investigated in detail.
  • Optimization Design of Flow Field Configuration for a Large-scale Hydrogen Polymer Electrolyte Membrane Fuel Cell
    WANG Yulin, ZHANG Xiaojian, GUAN Chao, SONG Jiaojiao, HE Wei
    Journal of Engineering Thermophysics. 2025, 46(3): 975-981.
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    If the liquid water generated in the proton exchange membrane fuel cell (PEMFC) cannot be discharged in time, it will cause “water flooding”, thus hindering the mass transfer of reactant gas and leading to the degradation of cell performance. Flow field configuration is one of the decisive factors influencing the transport properties of reactants and products. In this study, the overall performance of 108 cm2 large-scale PEMFCs with conventional parallel flow field configuration and modified parallel flow field configuration with divergent design are comparatively analyzed by a three-dimensional two-phase PEMFC numerical model. It is found that the modified parallel flow field configuration enhances the liquid water discharge performance and has a more uniform current density and oxygen distribution, thus enhancing the overall performance of the PEMFC. Compared with the conventional parallel flow field, the power density, current density uniformity, and temperature uniformity of the optimal modified parallel flow field design are improved by 2.31%, 15.31%, and 8.82%, respectively. In addition, a comprehensive evaluation by the entropy weighting method reveals that the optimal modified parallel flow field design improves the comprehensive evaluation index from 0.057 to 0.309.
  • Design of Thermal Cloaks Based on Artificial Neural Network
    SHAN Qingru, DING Yu, WANG Hewen, ZHOU Xinzhi, XU Yunyu, WANG Jun, XIA Guodong
    Journal of Engineering Thermophysics. 2025, 46(3): 982-987.
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    A bilayer thermal cloak consists of an inner layer with very low thermal conductivity and an outer layer with higher thermal conductivity, which can eliminate the external-field distortion. However, the thermal cloak phenomenon could not be achieved for lower surrounding thermal conductivity in the bilayer thermal cloak, because the inner layer could not be completely insulated. In this paper, based on the method of machine learning, the performance of the bilayer thermal cloak has been optimized. An artificial neural network is established to intelligently learn the relation between each layer’s thermal conductivity and the cloaking performances. The optimized parameters for a better performance of the bilayer thermal cloak can be obtained, which is verified by numerical simulations.
  • Laser Ignition and Combustion Characterization Under Ammonia/Hydrogen Flow Condition
    ZHANG Junjie, CHEN Zihao, JIAO Jian, HU Erjiang, HUANG Zuohua
    Journal of Engineering Thermophysics. 2025, 46(3): 988-995.
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    In this paper, based on the flow ignition platform, laser ignition experiments were carried out on NH3/H2 mixtures under different hydrogen doping ratios and equivalent ratios, and the probability of ignition, minimum ignition energy (MIE), and flame development were analyzed under different conditions. It was found that H2 doping can effectively reduce the MIE of the mixture, of which the effect is most obvious when the doping ratio is 10%. But the effect of changing the hydrogen doping ratio on the subsequent development of the flame is not obvious. Increasing the equivalent ratio will make the MIE first decline and then rise. With the equivalent ratio of 0.8, the mixture of the MIE is the lowest. The change of the equivalent ratio has a significant effect on the flame area, the intensity of the flame luminescence and the flame center of gravity. The increase of the equivalent ratio can effectively improve the combustion performance of ammonia flame.
  • Experimental Investigation of the Ignition Characteristics of Ammonia-Coal Mixtures
    YANG Chaoqiang, ZHOU Yuegui, HUANG Guanshuo
    Journal of Engineering Thermophysics. 2025, 46(3): 996-1002.
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    The ignition characteristics of ammonia-coal mixtures with different ammonia blending ratios (0%∼100%) at different oxygen concentrations (5%∼30%) were investigated on a Hencken burner flat flame combustion facility. The changes in the flame morphology of ammonia-coal mixtures under different operating conditions were analyzed based on the combustion flame images. The variation in the ignition delay distance of ammonia-coal mixtures was quantified by the combustion flame light intensity signals. It was found that the ignition of ammonia-coal mixtures was advanced with the increase of ammonia blending ratio from 0% to 20%, while the change of the ignition delay distance showed different characteristics when the ammonia blending ratio was greater than 20%. Finally, the spectral signals of the combustion flame of the ammonia-coal mixture were measured through a fiber optic spectrometer, which showed a strong correlation between the NH∗/OH∗ ratio and the ignition delay distance.
  • Study on Oxygen-rich Combustion Characteristics of Pulverized Coal in Cement Rotary Kiln
    YAN Zhi, YANG Ziyi, NING Kexiang, LEI Ke, NI Jiwei, ZHANG Jinghao, HUANG Xiangyong, GU Mingyan
    Journal of Engineering Thermophysics. 2025, 46(3): 1003-1008.
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    In the context of national energy conservation and carbon peaking and carbon neutrality, energy conservation, emission reduction and carbon reduction in the cement industry is a very important task. Oxy-fuel combustion is beneficial to increase the temperature in the cement rotary kiln, increase the clinker output, reduce coal consumption and improve the adaptability of coal types, but the increase of oxygen concentration increases the NOx emission compared with the conventional oxygen concentration combustion. In this paper, the effects of primary air oxygen concentration, flue gas recirculation rate and excess air coefficient on the oxygen-rich combustion characteristics of pulverized coal in cement rotary kiln were analyzed by numerical simulation method. The results show that with the increase of primary air oxygen concentration, the flame length in the kiln becomes shorter, and when the primary air oxygen concentration increases from 21% to 33%, the maximum temperature in the rotary kiln increases from 1964 K to 2071 K. The addition of circulating flue gas reduces the oxygen concentration in the kiln, makes the combustion performance of volatiles in pulverized coal and coke worse, reduces the combustion effect, and reduces the combustion temperature in the kiln. As the excess air coefficient increases, the temperature in the rotary kiln decreases.
  • Research on Acoustical Suppression of Flame Spread Over Electric Wire in Confined Space
    LÜ Jinglong, XIONG Caiyi, CHEN Guohua
    Journal of Engineering Thermophysics. 2025, 46(3): 1009-1016.
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    This study experimentally investigated the suppressing effect of sound field on fire spread. The extinguishing performance of sound fields with different structures on flame spread over horizontal electrical wires was explored. Results showed that the sound field can both suppresses and facilitates flame spread, as the sound frequencies and sound pressures varying. In addition, the sound field in confined space performs more excellent on flame extinction than free one. Due to the significant enhancement of sound pressure and medium flow velocity (acoustic streaming) caused by sidewall reflection. Moreover, a fire spread model coupling the structure of sound field and acoustic parameters was formulated. The mechanism behind wire fire extinction in sound field was analyzed based on stretch rate. This study can provide valuable insights for suppressing electrical fire spread in buildings without any residue.
  • Study on the Performance of Food Waste Biochar on Remediation of Heavy Metal Pollution
    LIU Liang, LIU Wenbin, QING Mengxia, HE Zihang, LIU Xinyu, YIN Yanshan
    Journal of Engineering Thermophysics. 2025, 46(3): 1017-1025.
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    Due to biochar’s sustainability and low costs, its suitability for use in aqueous solutions and soil treatment has become increasingly concerning. This paper investigates the physical and chemical properties of biochar (FWB-350, FWB-450, and FWB-550) prepared from food waste at different temperatures and its performance in the solidification of heavy metals in aqueous solutions and soil. FWB-450 had a higher pH, the highest density of oxygen-containing functional groups, and the highest specific surface area. The FWB adsorption isotherms for the solution Cu2+ and Cr3+ were closer to the Freundlich model, with maximum adsorption capacities of 40.283 mg·g−1 and 31.310 mg·g−1, respectively. The addition of FWB-450 at 10% reduces the number of heavy metals in the unstable state (sum of acid-soluble and reducible states) of the soil, effectively reducing the mobility and leaching toxicity of heavy metals.

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