International Journal of Thermal Sciences最新文献

{"title":"Influence of trailing edge thickness and deflection on the performance of a ram air turbine for hypersonic vehicle power generation","authors":"Shijie Xu ,&nbsp;Yulong Li ,&nbsp;Xingjian Li","doi":"10.1016/j.ijthermalsci.2025.109821","DOIUrl":"10.1016/j.ijthermalsci.2025.109821","url":null,"abstract":"<div><div>A ram air turbine power generation system can address the energy utilization challenges of hypersonic vehicles. However, as the maximal flight Mach number of hypersonic vehicles is constantly increased, the total temperature of the incoming airflow becomes extremely high, making it unsuitable for cooling purposes. Therefore, active cooling of the ram air turbine must be achieved using fuel as a heat sink. Applying active cooling by arranging internal cooling channels at the main hotspot like blade edge may lead to thickening and additional deflection of trailing edge. This study focuses on an impulse ram air turbine stage and introduces a continuous curvature profiling method for ram air turbines. The turbine performance is evaluated by numerical simulations under varying trailing edge thicknesses and deflection. Then, an efficiency correction model that accounts for trailing edge effects is developed based on a classical loss model. The results show that a continuous curvature blade achieves a 1.99 % improvement in stage efficiency compared to a typical blade. Particularly, trailing edge thickening enhances the secondary flows of turbine and significantly reduces the stage efficiency. Reducing the trailing edge deflection results in an initial increase in stage efficiency, which decreases afterward, implying the existence of optimal deflection that maximizes stage efficiency. Specifically, a linear correlation between the optimal deflection and trailing edge thickness is observed. The efficiency correction model is used to predict the efficiency of the GE E3 turbine, and the error is less than 1.5 % compared with experimental data.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"213 ","pages":"Article 109821"},"PeriodicalIF":4.9,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143510539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performance investigation of a heatsink with L-shaped fins on a concentric hollow cylindrical tube attached to a round disk","authors":"Gihyun Song,&nbsp;Seungmin Heo,&nbsp;Hak-Ho Nam,&nbsp;Se-Jin Yook","doi":"10.1016/j.ijthermalsci.2025.109818","DOIUrl":"10.1016/j.ijthermalsci.2025.109818","url":null,"abstract":"<div><div>This study proposed a heatsink design with efficient heat dissipation to ensure optimal operation and longevity of LED lightbulbs. Assuming the typical form of LED lightbulbs, the heatsink was designed with a base consisting of a concentric hollow cylindrical tube attached to the center of a round disk, and multiple L-shaped fins were installed on this structure. To enhance thermal performance of the heatsink with L-shaped fins, simulations were conducted by varying the deletion fin area and the number of fins. It was confirmed that modifying both the deletion fin area and the number of fins within a certain range was advantageous for improving the thermal performance of the designed heatsink. The simulation methods used for investigating the thermal performance were validated through experiments. Variations in thermal performance were examined based on the Rayleigh number, the number of fins, and the installation angle of the heatsink with L-shaped fins. For the same size and shape of the base, that is, a base consisting of a concentric hollow cylindrical tube attached to the center of a round disk, the heatsink with L-shaped fins was compared to heatsinks with rectangular fins, triangular fins, or perforated staggered fins. The results showed that the heatsink with L-shaped fins exhibited generally lower thermal resistance over installation angles ranging from 0° to 180°. Therefore, the L-shaped fin heatsink proposed in this study is expected to significantly contribute to improving the heat dissipation performance of LED lightbulbs.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"213 ","pages":"Article 109818"},"PeriodicalIF":4.9,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143487122","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unlocking the potential of lauric acid: A promising solution for battery thermal management","authors":"Enis Selcuk Altuntop ,&nbsp;Dogan Erdemir ,&nbsp;Yüksel Kaplan ,&nbsp;Veysel Özceyhan","doi":"10.1016/j.ijthermalsci.2025.109822","DOIUrl":"10.1016/j.ijthermalsci.2025.109822","url":null,"abstract":"<div><div>This paper presents a comprehensive experimental investigation into the thermal management of lithium-ion batteries using lauric acid as a phase change material (PCM). The study explores the effectiveness of lauric acid under various design and operating conditions, including different battery pack voltages (12V, 24V, 48V), cell spacing (0.25D, 0.5D, and 1D – D: diameter of battery), discharge rates (1C, 2C, 3C, 4C, and 5C), and the incorporation of active air cooling that uses varying external air velocities (5, 7.5, and 10 m/s). The results demonstrate that the hybrid cooling system can maintain the desired temperature, which is below the melting point of lauric acid (43–45 °C). The hybrid cooling system has successfully reduced the temperature differences within the battery pack, consistently maintaining them below 5 °C. The energy efficiencies exceeded 80 % and approached 90 % in most cases. These observations indicate the capability of lauric acid to maintain battery temperatures within safe operating limits, reduce temperature differences within the pack, and achieve high energy efficiency. This research highlights the potential of lauric acid as a promising, cost-effective, and safe PCM solution for battery thermal management systems, particularly in long-term applications.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"213 ","pages":"Article 109822"},"PeriodicalIF":4.9,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143487123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of parameters affecting the cooling capacity of liquid jets by using OpenFoam as tool to solve the inverse heat transfer problem","authors":"Kaissar Nabbout,&nbsp;Martin Sommerfeld","doi":"10.1016/j.ijthermalsci.2025.109797","DOIUrl":"10.1016/j.ijthermalsci.2025.109797","url":null,"abstract":"<div><div>In this work, some of the parameters influencing the cooling capacity of a liquid jet impinging onto Inconel 718 and C45 plates were experimentally investigated under different conditions. The experiment comprises a high-speed camera to record the dynamics of the jet during the cooling process while an infrared camera was used to record the temperature field at the backward surface of the specimen plate. Jets consisting of water or oil-in-water emulsions were analysed as well as the influence of the oil concentration. Other parameters studied here include initial temperature of the plate, nozzle-to-plate distance, nozzle diameter, jet velocity, and impingement angle. The cooling performance was analysed by solving a full 3D inverse heat transfer problem (IHTP) with the Conjugate Gradient Method (CGM) implemented in a new solver in OpenFoam. The basic organization and implementation of the solver is shown, followed by its validation with a synthetic test case. Finally, the growth of the wetting front was analysed for different oil concentrations and a combination of nozzle diameters and jet velocities for the same flow rate. A linear correlation was observed between the Re and the critical heat flux (CHF) when using the same liquid. Furthermore, the estimation of the CHF when using different plate materials was shown to be possible by scaling it with the thermal effusivity of the materials.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"213 ","pages":"Article 109797"},"PeriodicalIF":4.9,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143487124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gas radiation effect on a turbulent thermal plume in a confined cavity using direct numerical simulation","authors":"Ying Wang ,&nbsp;Anne Sergent ,&nbsp;Didier Saury ,&nbsp;Denis Lemonnier ,&nbsp;Patrice Joubert","doi":"10.1016/j.ijthermalsci.2025.109820","DOIUrl":"10.1016/j.ijthermalsci.2025.109820","url":null,"abstract":"<div><div>Influence of gas radiation on a thermal plume is investigated in a cubical cavity filled with humid air (air/H₂O mixture) by means of Direct Numerical Simulation. In this work, radiation within the fluid is considered by the SLW model developed by Denison and Webb and numerically solved using the Discrete Ordinate Method (S₈ quadrature). The simulations are conducted for humid air with different amounts of water vapor and compared to the case without radiation. Two values of the Rayleigh numbers, <span><math><mrow><mn>2</mn><mo>×</mo><msup><mn>10</mn><mn>6</mn></msup></mrow></math></span> and 10⁹, are considered, corresponding to steady and turbulent flow regimes. Steady solutions show that gas radiation tends to reduce the spatial spreading of the thermal plume and to homogenize the temperature field away from the heat source. Gas radiation also results in an attenuation of the global circulation. It is shown that the radiative fluxes are much higher than convective fluxes on the isothermal walls, and the radiative heat transfer still increases with the water vapor concentration. For the turbulent regime, accounting for radiation leads to a less fluctuating behavior of the plume and induces a global shift of the mean temperature field in most of the cavity, except in the region around the heat source. Regarding the mean flow field, thermal radiation tends to weaken the intensity of flow circulation, but to accelerate the flow velocity along the centerline above the heat source.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"213 ","pages":"Article 109820"},"PeriodicalIF":4.9,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143474479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comprehensive parameter analyses on steam-air condensation at equal-height-difference natural circulation loop under large air mass fraction","authors":"Weixiong Chen ,&nbsp;Han Wang ,&nbsp;Sinian Li ,&nbsp;Hui Kai ,&nbsp;Quanbin Zhao ,&nbsp;Shaodan Li ,&nbsp;Junjie Yan","doi":"10.1016/j.ijthermalsci.2025.109807","DOIUrl":"10.1016/j.ijthermalsci.2025.109807","url":null,"abstract":"<div><div>As the development of small-sized reactors progresses, a passive containment cooling system (PCCS) named equal-height difference natural circulation loop (EHDNCS) has been developed. Experiments were carried out at elevated air mass fractions to assess the condensation heat transfer coefficient (HTC) based on the steam-air mixture pressure, air mass fraction, and wall subcooling. Research indicates that as the air mass fraction increases, the HTC for condensation tends to decrease. Conversely, a higher pressure of the steam-air mixture within the containment leads to an increase in HTC. The condensation HTC increases with increasing wall subcooling; however, when the air mass fraction exceeds 75 %, the condensation HTC remains nearly constant with changes in wall subcooling. A quantitative relationship between the condensation HTC and the height of the PCCS (sum of riser height and 0.5 times heat exchanger height) has been derived by analyzing the driving force and resistance of the cooling water flow within the natural circulation loop. The optimal conditions for adjusting the riser height and the initial riser-to-heat-exchanger height ratio have been determined to enhance the heat transfer performance of the PCCS. Drawing from experimental results, an empirical correlation equation has been formulated to estimate the condensation HTC for PCCS utilizing enhanced heat dissipation through natural circulation systems (EHDNCS), with a prediction deviation within ±31 %.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"213 ","pages":"Article 109807"},"PeriodicalIF":4.9,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143480282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancement of heat transfer by inclined holes through perforated heat sinks","authors":"O. Goktan Yildirim,&nbsp;Gokturk M. Ozkan","doi":"10.1016/j.ijthermalsci.2025.109810","DOIUrl":"10.1016/j.ijthermalsci.2025.109810","url":null,"abstract":"<div><div>The effects and enhancement of inclination angle (<em>θ</em>) in perforated heat sinks were investigated using Computational Fluid Dynamics (<em>CFD</em>) by implementing the Finite Volume Method for discretization. A perforated heat sink with three holes and varying inclination angles was analyzed to evaluate the impact of inclination angle on heat transfer, case maximum temperature, turbulent kinetic energy, pressure drop, friction factor ratio, and thermal performance factor across the specified Reynolds number range. Reynolds number (3500 ≤ <em>Re</em> ≤ 6500) and inclination angle (<em>θ</em> = 30°, 45°, 135°, 150°) were considered as parameters and inclined holes were compared with straight perforated pins (<em>θ</em> = 0°) to interpret the effect of inclination angle. The validated model showed that heat transfer enhancement increased by 4.2 %–8 % with increasing inclination angle, while the system maximum temperature decreased by 4.5 %–5.6 %. Although the pressure drop was higher compared to straight perforated pins, it was found to be largely unaffected by the inclination angle. However, the inclination angle was observed to increase the friction factor rate by 6.7%–16 % compared to straight perforated pins. Considering the pressure drop alongside enhanced heat transfer, the thermal performance factor (<em>η</em>) demonstrated that inclined holes performed better than straight holes. For thermal applications, the inclination angle of <em>θ</em> = 135° was reported as the optimal value, providing an 8 % increase in the Nusselt number and a 6 % reduction in the maximum system temperature. This improvement, however, was slightly reduced for <em>θ</em> = 150°, indicating that the inclination angle should only be increased up to a certain value. The benefits were attributed to improved turbulent mixing, as the turbulent kinetic energy between the pins was found to increase significantly.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"213 ","pages":"Article 109810"},"PeriodicalIF":4.9,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143480284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Advancing thermal radiation efficiency with hybrid-patterned metasurface emitters in thermophotovoltaic systems","authors":"Ting Cai ,&nbsp;Zhiheng Xu ,&nbsp;Yujie Yi ,&nbsp;Chen Wang ,&nbsp;Baisong Zhou ,&nbsp;Chao Chen ,&nbsp;Yunpeng Liu ,&nbsp;Yuqiao Wang ,&nbsp;Hongbo Lu ,&nbsp;Xiaobin Tang","doi":"10.1016/j.ijthermalsci.2025.109790","DOIUrl":"10.1016/j.ijthermalsci.2025.109790","url":null,"abstract":"<div><div>In thermophotovoltaic systems, it is essential for emitters to effectively convert thermal energy into thermal radiation photons within the useable wavelengths for photovoltaic cells. Metasurface emitters enable broadband emission to efficiently and accurately match photovoltaic cells because of their complex optical properties and adjustable resonance behavior. In this study, a hybrid-patterned metasurface emitter was designed using an inverse neural network and optimized by a genetic algorithm to efficiently match InGaAs cells with different bandgaps. The designed hybrid-patterned metasurface emitter exhibits 90% high in-band emission with near-zero out-of-band emission, and it is angle insensitive and polarization independent. The optical performance of the emitter and the output performance of the radioisotope thermophotovoltaic system were studied at temperatures ranging from 700 K to 1300 K. At 1300 K, the emitter demonstrates an effective spectral efficiency of 69.84%. The radioisotope thermophotovoltaic system with a 0.56 eV InGaAs cell has a maximum output power density of 1.16 W/cm² and an energy conversion efficiency of 20.77%. The mechanism of selective emission was elucidated. Finally, the hybrid-patterned metasurface emitter was fabricated by micro-nano fabrication technology, and its performance was studied. The optimization and fabrication of the hybrid-patterned metasurface emitter provide an important theoretical foundation and practical guidance for enhancing thermal radiation efficiency.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"213 ","pages":"Article 109790"},"PeriodicalIF":4.9,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143480283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental apparatus for radiation characteristics of semi-transparent materials at high temperature:A direct radiometric method","authors":"Yanfen Xu ,&nbsp;Kaihua Zhang ,&nbsp;Longfei Li ,&nbsp;Kun Yu ,&nbsp;Yufang Liu","doi":"10.1016/j.ijthermalsci.2025.109809","DOIUrl":"10.1016/j.ijthermalsci.2025.109809","url":null,"abstract":"<div><div>The accurate determination of radiation characteristics for semi-transparent materials is essential for the transmission of radiation energy and optical signals at high temperatures. However, distinguishing spontaneous, transmitted, and background radiation in the signals received by the detector poses significant challenges due to the inherent properties of semi-transparent materials. To address this, an experimental apparatus based on the direct radiometric method has been established, operating within a temperature range of 473–1473 K and a wavelength range of 3–12 μm. An integrated approach that employs an ancillary blackbody is introduced to simultaneously measure radiation characteristics of semi-transparent materials. The reliability of experimental equipment and method is evaluated through the measurement of radiation characteristics of silicon carbide and sapphire samples. Additionally, the variation of transmissivity, emissivity, and reflectivity of the sapphire sample is analyzed at various temperatures, exploring the trends of these parameters with respect to temperature and wavelength.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"213 ","pages":"Article 109809"},"PeriodicalIF":4.9,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143474599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performances of approximate radiative property models for conditions met in ammonia combustion","authors":"Raghavendran Raman ,&nbsp;Jean-Louis Consalvi ,&nbsp;Stéphane Zaleski ,&nbsp;Guillaume Legros","doi":"10.1016/j.ijthermalsci.2025.109777","DOIUrl":"10.1016/j.ijthermalsci.2025.109777","url":null,"abstract":"<div><div>Recent investigations on ammonia as a sustainable fuel highlight the need for proper modelling of the radiative heat transfer in ammonia–air flames. As a result, the present work reports on spectral databases that have been specifically generated, leading to the development of various spectral models, ranging from narrow band models to global ones. These models have been tested against the exact line-by-line (LBL) model for an extended pressure range (1–50 atm) in both premixed and non-premixed flame configurations. Noticeably, the premixed flame structure, which can be represented by a two-layer system, is a challenging configuration for correlated-k distribution models. For this configuration, a detailed investigation of the spectral models on various flame fields led to the conclusion that in spite of a higher computational cost, the Statistical Narrow Band Correlated k-distribution (SNBCK) models are better suited for modelling the radiative processes compared to the full spectrum models, such as the Rank Correlated Full-Spectrum k-distribution (RCFSK), Multi-Scale Rank Correlated Full-Spectrum k-distribution (MSRCFSK), and Weighted Sum of Grey Gases (WSGG). Considering the computational load, a reduced SNBCK model, referred to as SNBCK25, was developed and demonstrated high agreement with the LBL model. As an illustration, for a spherically expanding premixed flame at 20 atm, the SNBCK model had a mean absolute relative error (MARE) of 1.17%, while the SNBCK25, RCFSK with double integration, MSRCFSK, and WSGG models resulted in MARE of 1.87%, 4.62%, 8.23%, and 34.7%, respectively, against the LBL model. It is worth mentioning that the contributions of <span><math><mi>NO</mi></math></span>, <span><math><msub><mrow><mi>NO</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, and <span><math><mrow><msub><mrow><mi>N</mi></mrow><mrow><mn>2</mn></mrow></msub><mi>O</mi></mrow></math></span> were not significant to the evaluation of the divergence of radiative heat flux in the LBL model. Hence, these three species were ignored in the subsequent radiative computations.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"213 ","pages":"Article 109777"},"PeriodicalIF":4.9,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143474600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}