Most download

  • Published in last 1 year
  • In last 2 years
  • In last 3 years
  • All
  • Most Downloaded in Recent Month
  • Most Downloaded in Recent Year

Please wait a minute...
  • Select all
    |
  • Journal of Engineering Thermophysics. 2021, 42(10): 2481-2490.
  • Journal of Engineering Thermophysics. 2021, 42(12): 3031-3044.
  • YAO Zhaoming, WANG Xun, QI Jian
    Journal of Engineering Thermophysics. 2024, 45(5): 1440-1449.
    The thermal conductivity of soil is a vital parameter in describing its heat transfer properties. Accurate prediction and sensitivity analysis of this parameter can aid in assessing the thermal response in geotechnical engineering and prevent deformation and damage in projects. Based on thermal conductivity experiments by Kersten’s team, we analyzed the factors influencing this parameter. we considered introducing a temperature variable into the traditional empirical formula and conducted validation, resulting in an improved formula with good applicability to clay. Using artificial intelligence algorithms, we established a prediction model for thermal conductivity. The model uses soil type, dry density, water content, and temperature as input variables. Our analysis showed that the Random Forest model, Radial Basis Function Neural Network (RBFNN), and Whale Optimization Algorithm Backpropagation Neural Network (WOA-BP) could all accurately predict thermal conductivity. Among these, the WOA-BP model demonstrated the best performance, followed by Random Forest and RBFNN.We tested the prediction model using a new sample set and found that the model still performed well, indicating a certain level of generalization ability. We employed a Monte Carlo simulation for parameter sensitivity analysis of the improved empirical formula. With the Random Forest model, we ranked feature importance to evaluate the impact of different input variables on model output. Finally, we calculated the sensitivity of influencing factors using a weighted product method combined with WOA-BP. The results from all three methods were consistent. They indicated that the sensitivity of thermal conductivity to changes decreases in the order of water content, dry density, temperature, and soil type.
  • WANG Chenfeng, LI Guoqing, BAI Xiaohui, LI Nianqiang, ZHANG Yanfeng, LU Xingen
    Journal of Engineering Thermophysics. 2025, 46(1): 104-113.
    A total three-dimensional method for calculating mixing loss is proposed in response to the problem that existing methods for evaluating the mixing loss of film cooling cannot accurately calculate the loss between mainstream and coolant in the area affected by passage secondary flow. Film holes with different compound angles are set in the suction surface based on HS1A turbine guide vane. Under the premise of meeting the requirements from film cooling effectiveness, the loss mechanism is analyzed by controlling the mainstream and coolant parameters. Different models are analyzed by using the entropy creation of mixing as the basis for loss evaluation. The results show that film cooling effectiveness is improved by arranging subregional compound angle holes with entropy creation of mixing increasing. And the loss of film deflection caused by passage secondary flow and film detachment can be reduced by setting compound angles.
  • LI Song, SI Tianyu, LIANG Kecheng, ZHANG Han, CHENG Zhilong, WANG Qiuwang
    Journal of Engineering Thermophysics. 2023, 44(10): 2849-2854.
    Porous media play a key role in the fields of energy conversion, thermal management and energy storage due to their outstanding advantages such as large surface area, light weight and complex channels. In this paper, the homogeneous porosity and gradient porosity W type porous structure (porosity ε=0.3∼0.5, hydraulic diameter dh=1.33∼3.86 mm) were customized based on the triply periodic minimal surface (TPMS) method. A computational model of combustion reaction of porous media was established to investigate the range of flame stabilization within the W type porous structure and the SC-BCC cubic lattice structure, and the results showed that the flame blowout of W type structure limitation is higher (equivalence ratio φ=0.65 and inlet velocity Vin=0.6∼2.2 m·s−1). Furthermore, the regulation of combustion and heat transfer processes by the W type porous structure with continuous gradient porosity was investigated, and the results showed that the continuous gradient porous structure would significantly broaden the range of flame stabilization by adaptively modifying the heat rejection rate. 
  • LU Pei, WANG Jin, CHENG Kaihuang, LUO Xianglong, CHEN Jianyong, LIANG Yingzong, CHEN Ying
    Journal of Engineering Thermophysics. 2023, 44(11): 3084-3090.
    Carnot battery (CB) is a novel electricity storage technology which could realize electricity storage and waste heat recovery simultaneously. The thermal integrated CB (TI-CB) only utilizes the waste heat energy during the charging process in previous study. The waste heat energy utilization is insufficient. A CB with thermal integration during charging and discharging process (DTI-CB) is proposed in this paper. The waste heat energy is effectively integrated with DTI-CB in all periods through being coupled to the Organic Rankine cycle (ORC). A thermo-economic evaluation of the proposed DTI-CB is conducted. Compared with TI-CB, the power output capacity could be increased 95.67% and the Levelized cost of storage could be reduced 30.90%. The thermoeconomic performance of the proposed DTI-CB performs better than those of the single ORC and CB under the conditions with relatively higher heat utilization load. 
  • YU Dan, TIAN Zhenyu, DU Lijun, KUANG Jiujie, CHEN Jintao, SU Guanyu
    Journal of Engineering Thermophysics. 2024, 45(6): 1825-1837.
    As a typical kind of air pollutants, VOCs has hazardous effects on both the gas environment and impair human health. Abatement of VOCs is the major requirement of China’s ecological environment. Simultaneously, it is the significant content of China’s 14th five-year plan. Based on the economic development, emission source of VOCs in China has been illustrated. Furthermore, the national, local and industrial regulations of VOCs emissions have been concluded. Abatement techniques of VOCs have been compared and analyzed, including various recovery and destruction techniques. The multi-technique characteristics has been concluded. Finally, the dominant abatement technique in the future was prospected.
  • Journal of Engineering Thermophysics. 2022, 43(1): 43-49.
  • WANG Gang, ZHANG Zhen, JIANG Tieliu
    Journal of Engineering Thermophysics. 2025, 46(1): 35-41.
    In this paper, a new solar photovoltaic/thermal system with parabolic trough concentrator and indium tin oxide/ethylene glycol nano-fluid beam splitting is proposed. Indium tin oxide/ethylene glycol nano-fluid is prepared and tested. The results show that the absorptivity and transmittance of the indium tin oxide nano-fluid are 30.9% and 69.1% in the full wavelength range. The optical behavior of the photovoltaic/thermal system is studied and the overall optical efficiency of the system is 89.38%. When the sun tracking error is less than 0.2 ̊, the photovoltaic/thermal system can have an overall optical efficiency which is greater than 84.14%. The operation performance analysis reveal that the photoelectric efficiency of the photovoltaic subsystem is 29.1%, and the overall photoelectric conversion and thermal efficiencies of the photovoltaic/thermal system are 19.1% and 19%. The thermal efficiency of the system can be improved by increasing the inlet indium tin oxide nano-fluid velocity, or by reducing the inlet indium tin oxide nano-fluid temperature and external convectional heat transfer coefficient.
  • Journal of Engineering Thermophysics. 2021, 42(10): 2681-2685.
  • DAI Zeyu, WANG Zengli
    Journal of Engineering Thermophysics. 2025, 46(1): 144-150.
    To realize reasonable control of the water injection parameters for a single-screw steam compressor, a three-dimensional single screw groove model was established, the numerical simulation of the wall-approaching film formation process of injected water along the wet compression process was carried out, the coverage area of the effective water film formed by the injected cooling water inside the compression channel, as well as the influence laws of the key parameters such as water injection mass flow rate, velocity, angle, and screw rotor rotational speed were analyzed. The results indicate that the injection mass flow rate has the greatest impact on the coverage area of the effective water film with a maximum increase of 6.77×10−4 m2. Within the selected parameter range in the study, the respective increases in the coverage area of the effective water film caused by these factors are 59.85%、50.68% and 47.79% compared to the increase caused by the injection mass flow rate. 
  • YANG Shaoyun, LUO Lei, DU Wei, WANG Songtao
    Journal of Engineering Thermophysics. 2025, 46(1): 138-143.
    The straight-through labyrinth seal is an effective and simple sealing technology which is widely used in gas turbines. In this paper, the effect of rotation on the flow heat transfer in a straight-through labyrinth sealing structure is investigated using numerical simulations. All results are obtained at Reynolds numbers of 6000, 10000 and 15000. The results show that the increase in rotational speed reduces the vortex losses and throttling losses in the labyrinth seal channel, which leads to the increase in the discharge coefficient. With the increase of rotational speed, the heat transfer at the tip wall is enhanced while the heat transfer at the tooth cavity is weakened.
  • YANG Tianlong, ZHANG Jinrui, RAO Qiong, GAI Zhongrui, LI Yang, PAN Ying, JIN Hongguang
    Journal of Engineering Thermophysics. 2024, 45(9): 2551-2557.
    Chemical looping can achieve high product selectivity using lattice oxygen in oxygen carriers for partial oxidation of methane. Oxygen carrier La1−xSrxFe0.8Al0.2O3 was prepared by sol-gel method for chemical looping dry reforming of methane. The reaction performance of the oxygen carrier doped with different proportions of Sr was tested by thermogravimetric and fixed bed reactor. The experimental results showed that the oxygen capacity of x=0.4 oxygen carrier in La1−xSrxFe0.8Al0.2O3 is as high as 1.88 mmol·g−1, with excellent reaction performance and less carbon deposition. The stability of the oxygen carrier La0.6Sr0.4Fe0.8Al0.2O3 was further tested for 20 redox cycles. The oxygen carrier maintained excellent redox performance, achieving 61.2% methane conversion, 97.1% CO selectivity, and 1.81 H2/CO. The material characterization results displayed that the morphology and crystal structure of the oxygen carrier were stable. The results show that La0.6Sr0.4Fe0.8Al0.2O3 is an excellent oxygen carrier suitable for chemical looping dry reforming of methane.
  • ZHANG Hongtao, WU Junhong, PAN Xi, XIE Junlong
    Journal of Engineering Thermophysics. 2025, 46(1): 98-103.
    The compressor is the core component of an air conditioner, and its vibration characteristics play a key role in improving the reliability of the compressor. In order to clarify the effect of the fixing method of air conditioner external pipeline on the compressor’s vibration characteristics, this paper carried out some experimental research on it. Two variable factors, including the location of the constraints and the number of constraints on the air conditioner external pipeline, were taken into account; the vibration acceleration in different directions at each test point of the compressor was recorded during the test at an operating frequency of 30 Hz∼90 Hz. The results of the test show that a moderate increase in the distance between the restraining position and the outdoor unit can lead to a better realization of compressor vibration reduction; Increasing the number of constraints achieves little vibration reduction in the axial direction at the compressor position, but will increases the radial vibration acceleration at the motor position considerably.
  • Journal of Engineering Thermophysics. 2022, 43(2): 472-478.
  • LI Yibo, ZHU Linhang, JIN Yuzhen
    Journal of Engineering Thermophysics. 2023, 44(9): 2423-2430.
    Numerical simulations were performed to study the effects of two factors, water content and contact angle of liquid bridges, on the fluidization characteristics, particle temperature, and particle concentration of wet particles in a spouted bed. Results shows that the number of fluidized particles increases with the height of the spouted bed. When the water content is 0, there is no particle agglomeration in the fountain region; as the water content increases, the flow velocity in the Z direction first increases and then decreases, and obvious agglomeration occurs in the fountain region. When the contact angle increases, the flow velocity in the Z direction first decreases and then increases, with the minimum velocity occurring when the contact angle is 30. The larger the contact angle, the closer the core high-temperature region is to the spout region When the contact angle is 30, the particle movement resistance reaches its maximum value, and the least number of particles escape from the bed layer with the airflow.
  • JIANG Yi, WANG Qian, JIANG Peng, DAI Liming, ZHONG Wenjun, YAO Jiawei
    Journal of Engineering Thermophysics. 2024, 45(3): 915-924.
    In this paper, the in-cylinder combustion characteristics and soot generation processes of diesel blended polyoxymethylene dimethyl ethers (PODE)-gasoline reactivity controlled compression ignition mode were collected on an optical engine using high-speed imaging combined with the two-color method for clean fuel replacement of conventional fuels. The test results showed that with the increase of PODE blending at the same premixed ratio, the peak in-cylinder pressure, peak heat release rate and pressure rise rate were reduced, the ignition delay was extended, the combustion duration was increased, the combustion phase was shifted back and the combustion tended to be gentle. At a premixed ratio of 50%, the total heat release volumes from single cycle combustion of P20D80 and P50D50 as direct injection fuel was 97.89% and 95.39% of the total heat release volumes of direct injected P0D100 respectively, the total soot generation from single cycle was 55.22% and 36.55% of that of direct injected P0D100 respectively, the high temperature region of soot was reduced by 52.9% and 73.32% respectively, the stable values of soot average temperature were reduced by 6.65 K and 20.25 K respectively, and the stable values of soot average KL factors were reduced by 10.35% and 16.12% respectively. In contrast, P50D50 as a direct injection fuel ensured high combustion thermal efficiency and effectively suppress the generation of soot.
  • LI Zhi, LIU Yan, YANG Jinguang
    Journal of Engineering Thermophysics. 2024, 45(8): 2363-2368.
    Turbine design is a complex and empirical process. To reduce the difficulty of turbine design, this paper proposed a method with uniform flux along radial direction and verified its advantages by the design case of E3 turbine. The results show that the through-flow design is basically consistent with the spanwise distribution of parameters in 3D CFD simulation. The results show that the through-flow prediction is basically consistent with the 3D CFD prediction. And the new design scheme reduces the secondary flow loss at the root of the first rotor and increases the turbine efficiency by 0.5%. The proposed through-flow design method has some advantages in improving calculating stability, reducing time cost and improving turbine aerodynamic performance.
  • LI Xin, MA Zhihao, JIN Yifan, WANG Xin, XI Zhideng, HU Shiji, CHU Xianglin
    Journal of Engineering Thermophysics. 2023, 44(7): 1994-2004.
    The ignition delay times of ammonia/methanol mixtures were measured by a shock tube at different equivalence ratios, high temperature and medium-low pressure. A new combined simplification model (NH3-M) was proposed and it can well predict the experimental ignition delay times of ammonia/methanol mixtures, Chemkin-PRO software was used to analyze the chemical reaction kinetics based on NH3-M model. The results show that adding a small amount of methanol can significantly shorten the IDTs of ammonia/methanol mixtures. The ignition delay time satisfies the Arrhenius relation, it is mainly affected by small radicals such as OH, O, HO2 and H. The initial consumption of ammonia and methanol mixtures begins with H-abstraction, R224 is the most sensitive ignition-promoting reaction, it is not R466 and R467 that directly promote ignition but the active substances generated from the intermediates produced by R466 and R467 that facilitate the entire reactions.
  • TIAN Xikun, XU Tianxin, YAN Jun, LIN Shangchao, ZHAO Changying
    Journal of Engineering Thermophysics. 2023, 44(9): 2541-2548.
    Sintering of CaO grains in CaO/CaCO3 thermochemical energy storage system results in the decrease of energy storage performance. In this study, the selection criterion of dopants for material modification is proposed based on lattice energy. High-valence metallic oxides via the phase combination modification mechanism can promote cyclic stabilities of energy storage materials. Using calcium citrate as the precursor and doping with 10% mole fraction of TiO2 make the effective conversion of calcium-based material increase to 0.66 after 15 cycles, which is 2.1 times of raw calcium-based materials. Doping TiO2 results in the partial formation of CaTiO3 during the material preparation process. The modified energy storage material has lower apparent size distribution and retain complex pore structures, causing its high anti-sintering performance.
  • ZHOU Xia, ZHANG Hanwei, RONG Yangyiming, FANG Song, XU Zhuoren, WANG Kai, ZHI Xiaoqin, QIU Limin
    Journal of Engineering Thermophysics. 2023, 44(2): 311-320.
    This article compares three compression heat recovery methods in cryogenic air separation units, including organic Rankine–assisted air compression heat recovery system (ORC-ACS), organic Rankine-electric driven vapor compression-assisted air compression heat recovery system (ORC-VCR-ACS), and organic Rankine-driven vapor compression-assisted compression heat recovery system (ORVC-ACS). The calculation results show that among the three systems, ORVC-ACS has the highest energy-saving efficiency and economic benefits. The system power saving of the ORVC-ACS reaches 1723 kW, which saves about 15.1 GWh/a, and accounts for about 7.5% of the total power consumption of the air compressors. The ORC-VCR-ACS is next, and its highest system power saving is about 1268 kW, while that of the ORC-ACS is about 783 kW. The highest net present value of the ORVC-ACS is about 99 million CNY with an average discounted payback time less than 3.2 years, indicating great economic potential. The maximum net present value and maximum discounted payback periods of the ORC-VCR-ACS and ORC-ACS are approximately 97 million CNY, 3.4 years and 44 million CNY, 4.8 years, respectively. In addition, the three systems can save up to 10.8, 11.4 and 4.9 million tons of carbon dioxide per year, respectively, showing great environmental potential.
  • GUAN Yonggang, ZHOU Tian, WANG Hui, FAN Aoran, WANG Lei
    Journal of Engineering Thermophysics. 2025, 46(1): 1-7.
    The application, screening, evaluation and funding of National Natural Science Foundation of China programs in Engineering Thermophysics and Energy Utilization Discipline in 2024 are summarized and statistically analyzed. The strategic research, funding proposals in the field of energy and power under the carbon peaking and carbon neutrality goals are introduced. The outstanding achievements funded by the discipline in 2024 and future work in 2025 are introduced as well.
  • JIANG Zhongming, OUYANG Yurong, HAN Kewu, TANG Dong
    Journal of Engineering Thermophysics. 2023, 44(12): 3433-3444.
    In order to accurately understand the thermodynamic characteristics of compressed air in a storage cavern of compressed air energy storage(CAES) plants during the first operation cycle, a numerical model for compressed air thermodynamics in storage cavern was eastablished by considering the feature of conjugate heat transfer between fluid and surrounding rock, and the feature of non-isothermal flow. The model was also validated by Huntorf CAES plant data. Based on the comparison analysis of the thermodynamic process of compressed air in the different shape of caverns with the same volume and of the spatial distribution charateristics of temperature, two ways for temperature control of compressed air in the cavern were proposed, and their effects were also explored by numerical method. The research results show that the average temperatures of compressed air in caverns with different profile shape are significantly different, even if the opreation pressures are the same. The cavern shapes also have a significant influence on the spatial distribution characteristics of compressed air temperature. Local high temperature phenomenon occurs in the tunnel type of cavern. For the tunnel type of cavern, the temperature control effect of the measurement such as extending the initial charging time is poor, while the way of reasonable arrangement of the air inlet and outlet positions has a good effect on temperature control.
  • KANG Haopeng, XU Qiang, CAO Zeshui, LU Xuyang, GUO Liejin
    Journal of Engineering Thermophysics. 2023, 44(4): 994-998.
    As a very competitive hydrogen production technology, supercritical water gasification technology has important practical significance in exploring the combination route with hydrogen metallurgy under the carbon peaking and carbon neutrality goals. This paper presents a new technical route: supercritical water gasification for hydrogen production complete the reduction of metal oxide in the same reactor, simplifying the metallurgical process. The feasibility of this technology was verified from thermodynamics and experiment, and Fe3O4, Cu and MoO2 powders could be rapidly reduced to prepare in supercritical water gasification atmosphere with glycerol mass concentrations of 2%, 5% and 10%. Under the mass concentration of formic acid 50%, 60% and 70%, blue tungsten oxide and violet tungsten oxide can be obtained by supercritical water gasification, and under the mass concentration of 50%, the needle structure is obvious and less agglomeration.
  • Journal of Engineering Thermophysics. 2022, 43(5): 1182-1189.
  • ZHENG Jugan, ZHANG Dan, YANG Yue, YANG Qingzhong, YUAN Yang
    Journal of Engineering Thermophysics. 2024, 45(1): 20-31.
    The combination of spray flash and mixing evaporation (FME) was one of the most effective way to process wastewater with high aqueous salt concentration. In this paper, aqueous NaCl solution was selected as working fluid, a comprehensive calculation model for flow field of FME, including movement, evaporation and crystallization of droplets was set up on basis of previous experimental results. Numerical simulation was carried out with initial diameter of droplets between 20 and 200 μm, initial temperature between 100 and 120C, initial mass fraction 0.26, initial speed 20 m·s−1, and air speed of 15 m·s−1, air temperature between 100∼300C, and spray angle between 0 and 90◦ Results suggested that, during the increasing of spray angle from 0 to 90 the main location of crystallization moved from the spray axis to the top of spray plume, making crystal easier to be separated. Besides, with the increasing of spray angle, superheat or air temperature, the average mass fraction of crystallization increased, but the average particle size and crystallization distance decreased. In order to measure the effect of crystallization within a given distance, complete crystallization efficiency was defined as the ratio of the mass flow rate of crystal salt of droplets to the mass flow rate of dissolved salt at inlet. Results suggested that this efficiency could be improved by increasing spray angle or air temperature. A semi-empirical formula for complete crystallization efficiency was proposed, and the main error between its calculated value and the simulated value was in ±35%. Above conclusion could provide technical support for design and operation of industrial desalination system.
  • Journal of Engineering Thermophysics. 2021, 42(12): 3119-3124.
  • FAN Xuanhui, ZHANG Zhongyin, ZHOU Jing, YUAN Kunpeng, ZHU Jie, TANG Dawei
    Journal of Engineering Thermophysics. 2023, 44(10): 2866-2871.
    The thermal properties of ZnO with different crystal orientations were characterized by the time-domain thermoreflectance method combined with a diamond anvil cell and a heating stage in 0∼8 GPa and 300∼873 K. It is found that the thermal conductivity of wurtzite ZnO is anisotropic under both high pressure and high temperature conditions. Meanwhile, the pressure dependence of the thermal conductivity is non-monotonic, while the temperature dependence of the thermal conductivity is monotonic. This research can provide useful insights into the internal heat transport mechanism of wide band-gap semiconductors under high pressure and high temperature, and give ideas for searching for materials with high thermoelectric figure of merit.
  • ZHANG Dibo, SHI Liuliu, ZHANG Wenjie
    Journal of Engineering Thermophysics. 2025, 46(1): 83-91.
    The performance of the PEMFC ejector is influenced by the dimensions of the structure, and there are serious deviations from the design points in the solutions obtained according to the mainstream design methods. Firstly, the initial design of the ejector is based on Соколов’s method and the parameters to be optimised are determined. Secondly, the initial sample points are selected in the design space using the LHS and the response values of the sample points are obtained by CFD. Subsequently, the radial basis function surrogate model is constructed and hyper-parameter tuning is performed to improve the model performance. Then the current surrogate model is optimised by the particle swarm optimisation algorithm to obtain the possible optimal solution of the original optimisation problem. In the optimization process, the internal sample points are gradually added and the surrogate model is updated to improve the approximation accuracy of the surrogate model in the vicinity of the global optimal solution. Finally, a sensitivity analysis is performed on the optimization parameters. The results show that the performance of the ejector at the optimal design point is improved by 22.5%, the nozzle outlet diameter, mixing chamber inlet diameter and the distance between the nozzle and the mixing chamber inlet have a significant impact on the performance of the ejector.
  • Journal of Engineering Thermophysics. 2022, 43(6): 1478-1484.
  • FAN Jumeng, SHEN Ting, LIU Dandan, XIAO Huahua
    Journal of Engineering Thermophysics. 2023, 44(1): 266-273.
    In this paper, the unsteady, fully compressible, reactive Navier-Stokes equations were solved by high-order CFD method to study the effect of composition gradient on the flame acceleration and deflagration to detonation transition (DDT) in a mixture of hydrogen and air. A simplified chemical-diffusive model was developed for non-uniform hydrogen-air mixture. The homogeneous mixture with the highest risk (stoichiometric ratio) was compared with the inhomogeneous mixture with a global equivalence ratio of 1. The results show that although the maximum flame surface area of the inhomogeneous mixture is large, the average total heat release is low and the flame acceleration is weak, which leads to different DDT mechanism and location, and the detonation wave is more easily decoupled. In this paper, DDT is more likely to occur in homogeneous mixtures with stoichiometric ratio than in inhomogeneous mixtures, mainly because of the higher total heat release.
  • Journal of Engineering Thermophysics. 2022, 43(5): 1155-1162.
  • YUAN Xi, ZHANG Kai, XUAN Yimin
    Journal of Engineering Thermophysics. 2024, 45(11): 3415-3426.
    A novel solar energy driven CO2 and H2O conversion system based on concentrated spectral splitting technology is proposed for liquid hydrocarbon fuels production. Concentrated solar energy is divided into two parts via spectral splitting technology. The short-wave segment is utilized for photovoltaic power generation to drive a proton exchange membrane cell, by which water can be split into hydrogen and oxygen, providing the reactant necessary for CO2 hydrogenation into methanol. While, the rest part is converted into heat and stored in heat transfer fluid, and can be used in gaseous reactant preheating, water desalination, and/or direct air carbon dioxide capture, etc. Then, the mathematical theoretical model for this solar energy utilization system is built, and its thermodynamic performance is also investigated. It is found that the system achieves its maximum exergy efficiency of about 23.40%, when the temperature of gallium arsenide photovoltaic panel reaches 105°C, along with a corresponding hydrogen production rate of 2.84 L·min−1. Employing an exhaust gas recirculation reaction mode, the CO2 hydrogenation reactor achieves a hydrogen conversion rate of 68.19%, methanol product selectivity of 97.90%, and methanol yield of 0.91 g·min−1, at reaction pressure of 5 MPa, reaction temperature of 220°C, and a carbon-hydrogen ratio of 1 : 3. The solar energy-to-methanol fuel efficiency of this system is calculated to be 6.08%. This work offers a viable approach for leveraging solar energy to mitigate carbon emissions and advance carbon neutralization technologies.
  • ZENG Kecheng, JIANG Peixue, XU Ruina
    Journal of Engineering Thermophysics. 2024, 45(3): 778-784.
    When the distance between solid walls is only a few nanometers, the self-diffusion coefficient of fluid is reduced by 1∼2 orders of magnitude due to the nanoconfinement effect, and the effects of pore size, temperature and pressure are significant and complex. It is of great significance to analyze the diffusion mechanism and law of nanoconfined fluid and establish a concise correlation formula. In this study, a wide range of fluid self-diffusion coefficient data in nanopores were obtained through careful calculation and analysis based on molecular dynamics simulation. The mechanism and law of the adsorption effect on fluid diffusion were analyzed, and a novel dimensionless diffusion coefficient, which can simply describe the fluid diffusion behavior, was proposed, and the corresponding correlation formula was established with Knudsen number, which has strong applicability.
  • Journal of Engineering Thermophysics. 2022, 43(4): 1097-1107.
  • Journal of Engineering Thermophysics. 2022, 43(2): 296-303.
  • YANG Yong, CHEN Baojun, LI Guangfu, ZHANG Shuai, LIU Jintian, LI Wenfei, KONG Shining, ZHANG Zhao, LIU Hong, SHEN Shengqiang
    Journal of Engineering Thermophysics. 2025, 46(1): 27-34.
    Entransy analytical model of heat transfer process in stacked porous medium is built, and a new utilization efficiency of Entransy is proposed, meanwhile wave function and field function characteristics of Entransy are found. Based on the model, coupling the cooling curve, surface temperature of cooling products in porous medium, internal temperature gradient, convective heat transfer coefficient along quick freezer, entransy dissipation rate during cooling process are predicted for the first time. Mesoscale characteristics of coupled heat transfer for conduction, convection and radiation in heat transfer process in porous medium have been found. Results show that, volume scale of internal heat transfer core and temperature gradient control heat flux and convective heat transfer coefficient on surface, and wavy characteristics of internal temperature difference decreasing rate affect tendency of heat flux convective heat transfer coefficient. Temperature change trend can be predicted accurately based on along heat transfer coefficient. Porous medium can enhance heat transfer, and scaling factor of heat transfer coefficient without and within porous medium is about 0.6, meanwhile radiation and convection have field synergy characteristics.
  • LIN Xiaojie, MAO Yihui, ZHONG Wei
    Journal of Engineering Thermophysics. 2025, 46(1): 20-26.
    District heating system is one of the important carriers for coordinating renewable energy and traditional energy and realizing flexible consumption of renewable energy. Considering the impact of the uncertainty of renewable energy output and user cluster heat load on the dynamic transportation process of district heating network, it is necessary to quantitatively analyze the uncertain variables on both sides of the source and load and the dynamic characteristics of the heating network. This paper first established a dynamic transportation model of the heating network to solve its heat loss and transmission delay characteristics. Secondly, the Gram-Chalier A algorithm was applied to calculate the probability distribution semi-analytical expression of the thermal power of the source and load nodes of the system, and Bayesian credible inference method was used to calculate the fluctuation interval of node thermal power. This paper selected a secondary heating network in Beijing for model accuracy validation and case analysis. The system has 90 nodes and 109 pipes. The results show that the proposed model and algorithm can effectively quantify the fluctuation interval of nodes’ thermal power.
  • LI Bingrui, WANG Wei, WANG Xin, LI Bingxi, SHUAI Yong
    Journal of Engineering Thermophysics. 2024, 45(11): 3440-3445.
    Flash steam is an efficient and rapid phase change process with great engineering applications. In this paper, a pressure-driven Lee phase transition model with variable saturation temperature is established for the flash evaporation process accompanied with flow, and a numerical simulation and mechanism analysis of pure water flash evaporation with inlet superheat of 3∼6 K and initial liquid level height of 0.3∼0.8 m are carried out by combination with the VOF model. The results show that the intense phase change steam generation at the inlet area improves the gas-liquid and temperature distribution in the flash chamber, which is an important factor to increase the steam generation rate and the degree of conversion of water. Within the study scope, an increase in the inlet superheat and a decrease in the initial level height can reduce the non-equilibrium fraction of outlet water by about 55% and 35%, respectively, and an increase in the inlet superheat and the initial level height can increase the steam generation rate by about 292% and 191%, respectively. 
  • LI Zhenxing, CHEN Bo, LIANG Caihang
    Journal of Engineering Thermophysics. 2023, 44(9): 2496-2503.
    Hollow fiber membrane dehumidification technology has been paid more and more attention in recent years, because it avoids the indoor environment pollution caused by gas-liquid entrainment. The hollow fiber membrane is prone to bend and deform under the combined action of liquid gravity and airflow erosion. The vibration and shape change of the membrane tube have effects on fluid flow and heat and mass transfer, but there are few studies on heat and mass transfer of the hollow fiber membrane tube under flow-induced vibration at present. In this study, an arbitrary Lagrange-Euler method is used to establish a two-way fluid-solid coupling heat and mass transfer model of flow-induced vibration, and the effects of the amplitude and frequency of pulsating flow on the heat and mass transfer performance of the hollow fiber membrane are studied. The results show that: When the amplitude of pulsating flow is increased, the vibration amplitude of the membrane in the upstream direction is higher than that in the vertical direction. Compared with the non-flow induced vibration state, the enhancement factors of heat and mass transfer can reach 81.4% and 86.7%. When the mean velocity of the pulsating flow is 1.5 m·s−1 and the pulsating frequency is 10∼40 Hz, the flow-induced vibration can make the enhancement factors of heat and mass transfer up to 68.9% and 96.2%.