International Journal of Thermal Sciences最新文献_第4页

Thermal modeling of caves ventilated by chimney effect

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2025-02-07 DOI: 10.1016/j.ijthermalsci.2025.109757

Amir Sedaghatkish , Claudio Pastore , Frédéric Doumenc , Pierre-Yves Jeannin , Marc Luetscher

Cave ventilation significantly increases the depth of natural thermal oscillations and decreases the time of propagation compared to heat conduction in the rock mass. This makes it necessary to develop and test thermal models for the prediction of temperature fields in ventilated karst massifs. Here, we develop a thermal model of a single conduit ventilated by chimney effect. The model is based on the diffusion equation in the rock mass coupled to the conservation of energy and water vapor mass in the airflow. The effect of the latent heat of evaporation and condensation is considered. In parallel, the main conduit of a ventilated cave has been equipped with a flowmeter and several temperature sensors. The model is tested against field data collected during a complete year. The relevance of the model assumptions (geometry simplification, initial and boundary conditions, use of transfer coefficients to couple the air and the conduit wall) is thoroughly analyzed. The model correctly predicts the temperature fluctuations at daily and yearly scale, but underestimates the annual mean temperatures inside the cave. A biased assessment of the ground temperature seems to explain this discrepancy. The effect of condensation and evaporation on the cave climate turns out to be low on cave temperature, but significant on air humidity with consequences for ecology or paleoclimatology. This study is a first step towards the elaboration and validation of models providing a quantitative assessment of caves’ thermal response at any location and time scale.

{"title":"Thermal modeling of caves ventilated by chimney effect","authors":"Amir Sedaghatkish , Claudio Pastore , Frédéric Doumenc , Pierre-Yves Jeannin , Marc Luetscher","doi":"10.1016/j.ijthermalsci.2025.109757","DOIUrl":"10.1016/j.ijthermalsci.2025.109757","url":null,"abstract":"<div><div>Cave ventilation significantly increases the depth of natural thermal oscillations and decreases the time of propagation compared to heat conduction in the rock mass. This makes it necessary to develop and test thermal models for the prediction of temperature fields in ventilated karst massifs. Here, we develop a thermal model of a single conduit ventilated by chimney effect. The model is based on the diffusion equation in the rock mass coupled to the conservation of energy and water vapor mass in the airflow. The effect of the latent heat of evaporation and condensation is considered. In parallel, the main conduit of a ventilated cave has been equipped with a flowmeter and several temperature sensors. The model is tested against field data collected during a complete year. The relevance of the model assumptions (geometry simplification, initial and boundary conditions, use of transfer coefficients to couple the air and the conduit wall) is thoroughly analyzed. The model correctly predicts the temperature fluctuations at daily and yearly scale, but underestimates the annual mean temperatures inside the cave. A biased assessment of the ground temperature seems to explain this discrepancy. The effect of condensation and evaporation on the cave climate turns out to be low on cave temperature, but significant on air humidity with consequences for ecology or paleoclimatology. This study is a first step towards the elaboration and validation of models providing a quantitative assessment of caves’ thermal response at any location and time scale.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"212 ","pages":"Article 109757"},"PeriodicalIF":4.9,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143349132","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}

引用次数: 0

Aerothermal characterization of divider wall geometry inside serpentine channel

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2025-02-06 DOI: 10.1016/j.ijthermalsci.2025.109760

Arun Chand, Andallib Tariq

Serpentine channels are integral units to many of the energy, chemical, and biomedical application areas, and its configuration and shape play a critical role in affecting the flow dynamics at the turn. This investigation provides comprehensive insights about flow evolution and thermal characteristics of serpentine channels with different configurations of the divider wall. Two distinct shapes of divider wall (separation wall in-between serpentine channel), i.e., (i) sharp divider wall (SDW) and (ii) smooth-curved divider wall (SCDW) are studied for five divider wall thicknesses,

W_{d}

(= 0.1W, 0.25W, 0.5W, 0.75W and W) combinations through experimentally validated numerical simulations. Effects of divider wall configurations upon main and secondary flow structures and heat transfer distribution pattern upon the bottom wall across the bend section are analyzed for three different flow conditions, i.e., Reynolds numbers, Re = 6500, 13000, 20000. Results are captured across multiple planes along the flow direction to analyze the interactions between main and secondary flows. It was observed that the divider wall configuration significantly affects the flow behavior within the bend region, impacting velocity, recirculation zones, and Nusselt number distribution. With a thicker divider, the serpentine channel with SDW reflects higher mainstream velocity, flow separation, and pressure loss but improved heat transfer in the bend region. Whereas SCDW channel provides a more uniform flow profile, reduces pressure loss, and results in slightly lower heat transfer. The aerothermal characteristics of serpentine channels become identical at thinner divider walls, reducing the influence of wall shape on flow characteristics.

{"title":"Aerothermal characterization of divider wall geometry inside serpentine channel","authors":"Arun Chand, Andallib Tariq","doi":"10.1016/j.ijthermalsci.2025.109760","DOIUrl":"10.1016/j.ijthermalsci.2025.109760","url":null,"abstract":"<div><div>Serpentine channels are integral units to many of the energy, chemical, and biomedical application areas, and its configuration and shape play a critical role in affecting the flow dynamics at the turn. This investigation provides comprehensive insights about flow evolution and thermal characteristics of serpentine channels with different configurations of the divider wall. Two distinct shapes of divider wall (separation wall in-between serpentine channel), i.e., (i) sharp divider wall (SDW) and (ii) smooth-curved divider wall (SCDW) are studied for five divider wall thicknesses, <span><math><msub><mi>W</mi><mi>d</mi></msub></math></span> (= 0.1W, 0.25W, 0.5W, 0.75W and W) combinations through experimentally validated numerical simulations. Effects of divider wall configurations upon main and secondary flow structures and heat transfer distribution pattern upon the bottom wall across the bend section are analyzed for three different flow conditions, i.e., Reynolds numbers, <em>Re</em> = 6500, 13000, 20000. Results are captured across multiple planes along the flow direction to analyze the interactions between main and secondary flows. It was observed that the divider wall configuration significantly affects the flow behavior within the bend region, impacting velocity, recirculation zones, and Nusselt number distribution. With a thicker divider, the serpentine channel with SDW reflects higher mainstream velocity, flow separation, and pressure loss but improved heat transfer in the bend region. Whereas SCDW channel provides a more uniform flow profile, reduces pressure loss, and results in slightly lower heat transfer. The aerothermal characteristics of serpentine channels become identical at thinner divider walls, reducing the influence of wall shape on flow characteristics.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"212 ","pages":"Article 109760"},"PeriodicalIF":4.9,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143218909","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}

引用次数: 0

The modeling of rotational effect on the purge flow cooling coverage of a blade platform

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2025-02-05 DOI: 10.1016/j.ijthermalsci.2025.109723

Hongyu Gao , Yifei Dong , Xueying Li , Jing Ren

Gas turbine operation follows the Brayton cycle, where increasing the turbine inlet temperature enhances efficiency. However, this higher temperature introduces significant thermal stress, necessitating further investigation into endwall cooling techniques. Although gas turbines operate under high rotational speeds, experimental studies are often conducted under stationary conditions due to experimental constraints. This paper discusses the feasibility of using the swirl ratio (SR) under stationary conditions to model rotational effects. To this end, experimental and numerical investigations of endwall flow were conducted for both rotating (with Coriolis force) and non-rotating (without Coriolis force) cases. The Coriolis force alters the structure of the horseshoe vortices, increases turbulence intensity within the blade passages, and promotes a more uniform distribution of the endwall adiabatic cooling effectiveness (ACE). Additionally, the Coriolis force lifts the passage vortex, reducing coolant coverage, particularly in the axial direction, compared to stationary conditions. Moreover, a lower SR yields higher endwall cooling effectiveness compared to a higher SR. Under stationary conditions, optimizing the swirl ratio of the purge flow can significantly improve endwall ACE, making it comparable to that under rotating conditions. The circumferential motion of the purge flow relative to the blade weakens the endwall ACE, while the Coriolis force enhances it, leading to notable differences in cooling distribution between stationary and rotating conditions. This is the fundamental reason for the differences in cooling distribution between stationary and rotating conditions.

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引用次数: 0

Comprehensive evaluation of swirler structural performance in graphitic HCl synthesis combustor based on entropy weight method

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2025-02-05 DOI: 10.1016/j.ijthermalsci.2025.109753

Yuncong Wang , Ming Li , Yan Jiang , Chunwei Zhang , Wei Chang

Insufficient combustion and energy utilization present significant challenges for the HCl synthesis industry. To improve its efficiency, combustors with inlet structures like inner swirlers and porous nozzles have been proposed. However, a comprehensive evaluation of the design parameters of these inlet structures has not been thoroughly investigated, which hinders further optimization of HCl synthesis combustors. This study utilizes numerical simulations to systematically analyze five design parameters of the inner swirler, include swirler length (L), swirler inner diameter (R₁), the swirler hole radius (R₂), the number of swirler holes (n), and the swirler angle (

θ

). A multi-objective evaluation and optimization method for the swirler design based on a combination of Taguchi's experimental method, entropy weight method, and grey correlation analysis is proposed. The result shows that the inner diameter of the swirler is highlighted as the most important structural parameter to consider in the design of swirler-porous nozzle structures. The holistic performance objective (HP) for the combustor and the respective weight values of the structural parameters are proposed based on exergy evaluation analysis. The mathematical expression of HP was calculated as HP = 0.2HCl-0.151H + 0.149

η

+0.137 Q +0.123 Nu −0.096

I

-0.082 TD -0.063

φ

. The optimal combination of parameters is L = 4 %, R₁ = 7 mm, n = 8,

θ

= 80°, R₂ = 99 mm, when the HP reached its highest value. This research offers comprehensive guidelines for the inlet swirler designs of non-premixed combustors with enhanced combustion and exergy efficiency.

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引用次数: 0

Numerical investigation of dynamic arc behavior in K-TIG welding enhanced by an external sinusoidal alternating longitudinal magnetic field

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2025-02-04 DOI: 10.1016/j.ijthermalsci.2025.109744

Jiatong Zhan , Xiongyue Ye , Zhizhong Liu , Shaotao Zhong , Yuchao Zhou , Rong Zhang , Zuxin Liang , Yonghua Shi

A three-dimensional transient numerical model was developed to investigate the K-TIG welding arc plasma at various keyhole depths. The model systematically explored the influence mechanisms of an external sinusoidal alternating longitudinal magnetic field (EMF) on the arc's multiphysical characteristics, including temperature, velocity, and pressure. The results indicated that the EMF significantly reduced the penetration current of the base metal (BM), effectively lowering the welding heat input. First, the EMF induced a sinusoidal variation in the circumferential velocity of the arc plasma, causing it to rotate periodically around its axis. This rotation generated a negative pressure region at the center, resulting in a significant longitudinal pressure gradient and a marked increase in longitudinal velocity. This enhanced velocity amplified the impact on the BM, facilitating the formation of the keyhole. The rotation of the arc plasma also significantly improved the stirring effect on the weld pool, thereby enhancing the fluidity of the molten metal. Subsequently, the influence of the EMF caused the longitudinal velocity to oscillate sinusoidally at a frequency of 80 Hz. This oscillatory effect on the BM contributed to the refinement of the grain structure, thereby improving both the microstructure and the mechanical properties of the weld joint. Finally, the changes in the temperature and velocity fields of the arc plasma generated circumferential plasma drag shear forces and varying Marangoni forces, further amplifying the oscillatory effect on the weld pool. This study reveals the crucial mechanisms through which the EMF influences the K-TIG welding process, providing a theoretical basis and practical guidance for optimizing welding techniques and improving weld quality.

{"title":"Numerical investigation of dynamic arc behavior in K-TIG welding enhanced by an external sinusoidal alternating longitudinal magnetic field","authors":"Jiatong Zhan , Xiongyue Ye , Zhizhong Liu , Shaotao Zhong , Yuchao Zhou , Rong Zhang , Zuxin Liang , Yonghua Shi","doi":"10.1016/j.ijthermalsci.2025.109744","DOIUrl":"10.1016/j.ijthermalsci.2025.109744","url":null,"abstract":"<div><div>A three-dimensional transient numerical model was developed to investigate the K-TIG welding arc plasma at various keyhole depths. The model systematically explored the influence mechanisms of an external sinusoidal alternating longitudinal magnetic field (EMF) on the arc's multiphysical characteristics, including temperature, velocity, and pressure. The results indicated that the EMF significantly reduced the penetration current of the base metal (BM), effectively lowering the welding heat input. First, the EMF induced a sinusoidal variation in the circumferential velocity of the arc plasma, causing it to rotate periodically around its axis. This rotation generated a negative pressure region at the center, resulting in a significant longitudinal pressure gradient and a marked increase in longitudinal velocity. This enhanced velocity amplified the impact on the BM, facilitating the formation of the keyhole. The rotation of the arc plasma also significantly improved the stirring effect on the weld pool, thereby enhancing the fluidity of the molten metal. Subsequently, the influence of the EMF caused the longitudinal velocity to oscillate sinusoidally at a frequency of 80 Hz. This oscillatory effect on the BM contributed to the refinement of the grain structure, thereby improving both the microstructure and the mechanical properties of the weld joint. Finally, the changes in the temperature and velocity fields of the arc plasma generated circumferential plasma drag shear forces and varying Marangoni forces, further amplifying the oscillatory effect on the weld pool. This study reveals the crucial mechanisms through which the EMF influences the K-TIG welding process, providing a theoretical basis and practical guidance for optimizing welding techniques and improving weld quality.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"212 ","pages":"Article 109744"},"PeriodicalIF":4.9,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143135327","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}

引用次数: 0

3D temperature field reconstruction for automotive forging dies based on heterogeneous triocular vision

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2025-02-04 DOI: 10.1016/j.ijthermalsci.2025.109738

Yongshuo She , Zeqi Hu , Hongwei Qi , Yitong Wang , Lin Hua

The temperature distribution on the forging die surface is crucial for the quality of forgings. Traditional thermocouples and thermal imagers are unable to obtain the 3D temperature distribution of the die surface in a comprehensive manner. Responding to these issues, this paper proposes a method for reconstructing the 3D temperature field of automotive forging dies using a heterogeneous triocular vision system, which combines the two-dimensional temperature image with the three-dimensional reconstruction technique to obtain more accurate and comprehensive temperature distribution information. Firstly, a heterogeneous triocular imaging system consisting of two visible light cameras and one infrared thermal imager is constructed. Due to the difference in the spectral range recognizable by the infrared and visible light cameras, a calibration board suitable for both the infrared thermal imager and the visible light camera is designed to conduct a dual target calibration of the visible light and infrared cameras. Then, the images captured by the dual visible light cameras are rectified and stereo-matched to form a three-dimensional point cloud. Finally, based on the matching projection principle, the spatial information of the three-dimensional point cloud is fused with the two-dimensional thermal infrared information to reconstruct the three-dimensional temperature field of the automotive forging die. The experimental results show that, relative to the numerical simulation with temperature error in the range of 5%–10 %, the temperature error of this method is less than 0.3 %, and the reconstruction geometry error is less than 0.15 %. The reconstructed 3D temperature field can accurately display the temperature information and spatial information of the mold with strong robustness.

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引用次数: 0

Simple nanoparticle coating for efficient solar thermal energy harvesting in high-temperature solar receiver

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2025-02-04 DOI: 10.1016/j.ijthermalsci.2025.109746

Taoran Liu , Qing Li , Mingpan Xu , Yu Qiu

Improving operating temperature is a straightforward way to increase the solar-electric efficiency of the concentrating solar power (CSP) through boosting the power cycle efficiency. In this paper, a nanoparticle coating with tungsten (W) nanoparticles is proposed for the next-generation CSP to improve the outlet temperature of the solar receiver to above 700 °C. Firstly, a three-dimensional finite-different time-domain model is developed and validated to analyze the solar absorption process in the coating. Then, the effects of the materials and structural parameters on the spectral selectivity of the coating are investigated, and an optimized coating is recommended. The optimized coating exhibits quite high solar absorptance (α_s) of 0.930 at normal incidence and relatively low total emittances (ε_tot) within 0.093–0.240, achieving high solar-thermal efficiencies (η) of 92.90%–91.21% when the solar concentration and coating temperature are 1000 and 673 K–1073 K, respectively. Then, mechanism analysis indicates that the high α_s of the optimized coating is attributed to the coupling effects of Fabry-Perot resonance and the interaction of the electric field with the free electrons in the nanoparticle. Finally, a sensitivity analysis indicates robust performance across varying polarization angle (0°–90°) and incidence angle (0°–50°). Results from this study offer a promising strategy to boost the operating temperature and efficiency of CSP.

{"title":"Simple nanoparticle coating for efficient solar thermal energy harvesting in high-temperature solar receiver","authors":"Taoran Liu , Qing Li , Mingpan Xu , Yu Qiu","doi":"10.1016/j.ijthermalsci.2025.109746","DOIUrl":"10.1016/j.ijthermalsci.2025.109746","url":null,"abstract":"<div><div>Improving operating temperature is a straightforward way to increase the solar-electric efficiency of the concentrating solar power (CSP) through boosting the power cycle efficiency. In this paper, a nanoparticle coating with tungsten (W) nanoparticles is proposed for the next-generation CSP to improve the outlet temperature of the solar receiver to above 700 °C. Firstly, a three-dimensional finite-different time-domain model is developed and validated to analyze the solar absorption process in the coating. Then, the effects of the materials and structural parameters on the spectral selectivity of the coating are investigated, and an optimized coating is recommended. The optimized coating exhibits quite high solar absorptance (<em>α</em><sub>s</sub>) of 0.930 at normal incidence and relatively low total emittances (<em>ε</em><sub>tot</sub>) within 0.093–0.240, achieving high solar-thermal efficiencies (<em>η</em>) of 92.90%–91.21% when the solar concentration and coating temperature are 1000 and 673 K–1073 K, respectively. Then, mechanism analysis indicates that the high <em>α</em><sub>s</sub> of the optimized coating is attributed to the coupling effects of Fabry-Perot resonance and the interaction of the electric field with the free electrons in the nanoparticle. Finally, a sensitivity analysis indicates robust performance across varying polarization angle (0°–90°) and incidence angle (0°–50°). Results from this study offer a promising strategy to boost the operating temperature and efficiency of CSP.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"212 ","pages":"Article 109746"},"PeriodicalIF":4.9,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143135055","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}

引用次数: 0

Exploring thermal insulation enhancement in differentially heated cavities through topology optimization

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2025-02-04 DOI: 10.1016/j.ijthermalsci.2025.109748

Andrea Fragnito , Casper Schousboe Andreasen , Marcello Iasiello , Gerardo Maria Mauro , Nicola Bianco

The objective of this work is to investigate the optimal distribution of solid material within the cavity that minimizes heat transfer across its vertical boundaries. To this end, we explore the application of topology optimization (TO) – a methodology used to determine the optimal layout of material within a given design domain – to address the challenge of thermal insulation in rectangular cavities subjected to differential heating. By strategically placing material, the aim is to balance the diffusion/convection trade-off between low-velocity air gaps and diffusive solid paths, improving the thermal resistance of the heated cavity. The optimization problem is set based on a conjugate heat transfer formulation, i.e., the governing equations of heat conduction inside solid material, and natural convection inside air domains. Regularization techniques are applied to ensure the obtained solutions possess certain desirable characteristics, e.g., smoothness and discreteness, essential for instance in additive manufacturing for features such as 3D printability. A dimensionless problem is firstly solved to explore how the material distribution changes with the air recirculation magnitude, i.e., changing the Rayleigh number (Ra) value from 10⁵ to 10⁸. Further, the impact of mesh size, objective function selection, and initial design is investigated. Parameters affecting the TO routine are thus calibrated based on these simulations. Resulting designs are compared with baseline solutions consisting of vertical partitions, fixing the same volume of solid material. Material distribution of TO cases strongly differs depending on the Ra value flow strength. Therefore, convective motions are locally obstructed by smart solid features, leading to reduction in the Nusselt number up to 26 % at Ra = 10⁸

{"title":"Exploring thermal insulation enhancement in differentially heated cavities through topology optimization","authors":"Andrea Fragnito , Casper Schousboe Andreasen , Marcello Iasiello , Gerardo Maria Mauro , Nicola Bianco","doi":"10.1016/j.ijthermalsci.2025.109748","DOIUrl":"10.1016/j.ijthermalsci.2025.109748","url":null,"abstract":"<div><div>The objective of this work is to investigate the optimal distribution of solid material within the cavity that minimizes heat transfer across its vertical boundaries. To this end, we explore the application of topology optimization (TO) – a methodology used to determine the optimal layout of material within a given design domain – to address the challenge of thermal insulation in rectangular cavities subjected to differential heating. By strategically placing material, the aim is to balance the diffusion/convection trade-off between low-velocity air gaps and diffusive solid paths, improving the thermal resistance of the heated cavity. The optimization problem is set based on a conjugate heat transfer formulation, <em>i.e.,</em> the governing equations of heat conduction inside solid material, and natural convection inside air domains. Regularization techniques are applied to ensure the obtained solutions possess certain desirable characteristics, <em>e.g.,</em> smoothness and discreteness, essential for instance in additive manufacturing for features such as 3D printability. A dimensionless problem is firstly solved to explore how the material distribution changes with the air recirculation magnitude, <em>i.e.,</em> changing the Rayleigh number (<em>Ra</em>) value from 10<sup>5</sup> to 10<sup>8</sup>. Further, the impact of mesh size, objective function selection, and initial design is investigated. Parameters affecting the TO routine are thus calibrated based on these simulations. Resulting designs are compared with baseline solutions consisting of vertical partitions, fixing the same volume of solid material. Material distribution of TO cases strongly differs depending on the <em>Ra</em> value flow strength. Therefore, convective motions are locally obstructed by smart solid features, leading to reduction in the Nusselt number up to 26 % at <em>Ra</em> = 10<sup>8</sup></div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"212 ","pages":"Article 109748"},"PeriodicalIF":4.9,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143135054","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}

引用次数: 0

Investigation on multi-component gas distribution and the influence on the performance of variable conductance heat pipe

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2025-02-04 DOI: 10.1016/j.ijthermalsci.2025.109758

Jihong Lei , Wen Wang , Sixue Liu , Huizhi Wang , Jianyin Miao , Hongxing Zhang

The variable conductance heat pipe (VCHP) can prevent the operating temperature from changing with heat load varying and employs a better temperature control performance while facing large temperature-changing environments since the filled non-condensable gas (NCG) in VCHP could adjust the temperature distribution along VCHP and the working status through changing the effective heat exchange area. In this study, the steady heat and mass transfer model of VCHP is established, and the operating mechanism and performance of a grooved heat pipe with distinct working fluids and NCGs are studied under different working conditions. It is found that the position of the vapor-NCG interface in VCHP is related to the logarithmic gradients of the heat transfer Pelect number

{P e}_{T}

and the derivative of the mass transfer Peclet number

{P e}_{m}

gradient between species in this region. The effects of heat load, operating temperature, and NCG filling molar amount on the flow and heat transfer mechanism in pipes are discussed. The operating temperature in the evaporation section and position of the vapor-NCG interface change obviously with heat load and NCG filling molar amount.

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引用次数: 0

Multi-objective parameter optimization of U-type air-cooled thermal management system based on a surrogate model

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2025-02-04 DOI: 10.1016/j.ijthermalsci.2025.109707

Han Yang , Ninghao Liu , Mengjie Gu , Qiang Gao , Zhipeng Jiao

The air-cooled battery thermal management system (BTMS) is critical for regulating the temperature of lithium batteries in electric vehicles, thereby ensuring their efficient operation. Optimizing the structural design of the air-cooled BTMS can significantly enhance the cooling performance of the heat dissipation system. This paper investigates a U-type air-cooled BTMS and proposes a method that integrates fluid dynamics with a response surface model to optimize its performance. Initially, a heat-flow coupling model of the BTMS is developed to examine how structural parameters—such as air inlet height (A), air inlet angle (B), secondary vent position (C), longitudinal cell spacing (D), transverse cell spacing (E), and fillet radius (F)—affect the cooling performance metrics of the system. Through orthogonal test polarity analysis, three critical structural parameters are identified as having substantial influence on cooling performance and are selected as design variables. The maximum temperature, maximum temperature difference, and average temperature of the battery pack are used as performance metrics to guide the optimization. The response surface method is employed to model the functional relationships between design variables and performance metrics, and two multi-objective optimization algorithms are applied to drive the optimization process. The CRITIC weight method is utilized for the first time to select the optimal solution, addressing the limitations of subjective decision-making in previous studies. The results demonstrate that the optimized structural parameters markedly enhance the cooling performance of the U-type air-cooled BTMS, reducing the maximum temperature, maximum temperature difference, and average temperature of the battery pack by 11.29 %, 60.75 %, and 5.51 %, respectively, while significantly improving temperature uniformity.

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引用次数: 0