International Journal of Thermal Sciences最新文献

Pool boiling enhancement and durability test of dielectric fluids on thermal sprayed aluminum oxide coated surfaces 热喷涂氧化铝表面介质流体的池沸腾增强及耐久性试验

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2026-07-01 Epub Date: 2026-02-04 DOI: 10.1016/j.ijthermalsci.2026.110745

Mubarak Salisu , Shixue Wang , Yu Zhu

The low boiling temperatures of Novec 649 and Novec 7100 dielectric fluids are advantageous for applications in electronic thermal management. This study examined pool boiling on thermal sprayed micro-porous aluminum oxide (Al₂O₃) coatings, which improved fluid imbibition and boiling stability compared to copper surfaces. The coated Al₂O₃ surfaces have higher critical heat fluxes (CHF) and enhanced heat transfer coefficients (HTC) than the plain copper surfaces for both the Novec 649 and Novec 7100 fluids. Novec 649 had up to 130 % higher HTC with a 62 % higher CHF than on a copper surface. Novec 7100 had 150 % higher HTC with a 92 % higher CHF. Boiling stability testing is crucial when developing modified surfaces. These tests showed that the coated surface boiling characteristics were stable with both Novec 649 and Novec 7100 after four days of boiling curve measurements up to CHF with steady boiling for 12 h between each boiling curve test. The CHF superheat was 7 °C higher on the copper surface with Novec 7100 than on the coated surface, indicating a lower HTC, mainly due to oxidation that reduced surface roughness. This study provides a systematic comparison of the performance and aging of thermal sprayed Al₂O₃ coated surfaces with those of copper surfaces. This aging test is vital for practical application, as it establishes the coating as a promising solution for high-performance, durable direct-immersion cooling of electronics using dielectric fluids.

Novec 649和Novec 7100介质流体的低沸点有利于电子热管理的应用。本研究考察了热喷涂微孔氧化铝（Al2O3）涂层上的池沸腾，与铜表面相比，该涂层改善了流体吸胀和沸腾稳定性。对于Novec 649和Novec 7100流体，涂层Al2O3表面比普通铜表面具有更高的临界热通量（CHF）和增强的传热系数（HTC）。与铜表面相比，Novec 649的HTC和CHF分别高出130%和62%。Novec 7100的HTC上涨了150%，瑞士法郎上涨了92%。在开发改性表面时，沸腾稳定性测试是至关重要的。实验结果表明，Novec 649和Novec 7100包覆后的表面沸腾特性稳定，每次沸腾曲线测试之间有12小时的稳定沸腾时间。使用Novec 7100的铜表面的CHF过热度比涂层表面高7°C，这表明HTC较低，主要是由于氧化降低了表面粗糙度。本研究对热喷涂Al2O3涂层表面与铜表面的性能和老化进行了系统的比较。这种老化测试对于实际应用至关重要，因为它确定了该涂层是一种有前途的解决方案，可用于使用介电流体的高性能、耐用的电子设备直接浸入式冷却。

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引用次数: 0

Regulating lithium dendritic evolution at interface by thermal management for ultrafast charging lithium-ion battery 热管理对超快充电锂离子电池界面枝晶演化的调控

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2026-07-01 Epub Date: 2026-02-04 DOI: 10.1016/j.ijthermalsci.2026.110737

Tong Xu , Feng Jiao , Fei Chen , Runlong Li , Xinyi Zou , Jianwei Wang , Weiqing Shi , Shizhao Xiong , Chengwei Ma , Jiangqi Zhou

This study aims to establish a direct link between battery pack thermal management and micro-scale lithium dendrite evolution to mitigate thermal runaway risks during ultrafast charging. Ultrafast charging technology is important to the development of lithium-ion batteries for electric vehicles. However, it also aggravates the risk of thermal runaway of lithium-ion batteries due to the evolution of lithium dendrites on anode caused by cell heat production. It is crucial to regulate the evolution of lithium dendrites at the electrode interface by thermal management. In this work, the structural optimization design of battery packs and the growth of lithium dendrites under ultrafast charging are simulated by thermal management model and phase-filed model, respectively. The batteries achieve the highest heat dissipation (lowest temperature difference) when the cell arrangement angle θ₁ is 50° with a charging rate of 4C. Furthermore, the cooling performance at high charging multiplicity is improved by optimizing the inlet of the thermal management model, resulting in a 45.5 % reduction in temperature difference and supressed growth of lithium dendrites. Optimizing the battery pack structure to control heat dissipation and thus inhibit the growth of lithium dendrites can avoid the risk of thermal runaway in ultrafast charging lithium-ion batteries. A bridge between the electrochemical performance of battery pack and evolution of lihtium dendrite microstructures in batteries is built based on this innovative design, providing valuable theoretical insights for optimizing and managmant of electric vehicle power battery.

本研究旨在建立电池组热管理与微尺度锂枝晶演化之间的直接联系，以减轻超快充电过程中的热失控风险。超快充电技术对电动汽车用锂离子电池的发展具有重要意义。然而，由于电池发热导致阳极上锂枝晶的演化，也加剧了锂离子电池热失控的风险。通过热管理来调控电极界面处锂枝晶的演化是至关重要的。本文分别采用热管理模型和相场模型对电池组结构优化设计和锂枝晶在超快充电条件下的生长进行了模拟。当电池排放角θ1为50°，充电速率为4C时，电池散热效果最佳（温差最小）。此外，通过优化热管理模型的入口，提高了高充电次数下的冷却性能，使温差减小45.5%，抑制了锂枝晶的生长。通过优化电池组结构来控制散热从而抑制锂枝晶的生长，可以避免超快充电锂离子电池热失控的风险。该创新设计为电池组的电化学性能与电池中锂枝晶微结构的演变搭建了桥梁，为电动汽车动力电池的优化和管理提供了有价值的理论见解。

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引用次数: 0

Effect of non-uniform carbon distribution in electrode on carbon segregation during electroslag remelting of W9Cr4V2Mo steel 电极碳分布不均匀对W9Cr4V2Mo钢电渣重熔碳偏析的影响

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2026-07-01 Epub Date: 2026-02-05 DOI: 10.1016/j.ijthermalsci.2026.110730

Huan Cao, Zhongqiu Liu, Wenbin Yang, Yinbo Geng, Xuechi Huang, Baokuan Li

A two-dimensional multi-physics coupled model was developed to investigate carbon segregation during the electroslag remelting (ESR) of W9Cr4V2Mo steel. Three models with different initial carbon distributions were established to investigate their effect on final segregation after ESR: uniform distribution, edge-rich distribution, and center-rich distribution. The results show that the initial carbon distribution directly governs final carbon segregation by altering fluid flow within the mushy zone. Specifically, a center-rich carbon distribution enhances fluid flow in the mushy zone during early solidification, promoting greater solute transport into the molten pool. This leads to increased negative segregation at the ingot bottom. As solidification progresses, the accumulated solute further intensifies positive segregation in the center, resulting in the most severe overall carbon segregation. Quantitative analysis shows that an electrode with center-rich carbon distribution yields a carbon segregation index of approximately −0.086 at the center and −0.350 at the ingot edge during early solidification, representing increases of about 66 % and 9 %, respectively, compared to the electrode with edge-rich distribution. These findings emphasize the critical role of the initial carbon distribution in controlling carbon segregation during the ESR process, providing valuable insights for optimizing the process and improving the quality of W9Cr4V2Mo steel.

采用二维多物理场耦合模型研究了W9Cr4V2Mo钢电渣重熔过程中的碳偏析现象。建立了三种不同初始碳分布模式：均匀分布、富边分布和富中心分布对ESR后最终偏析的影响。结果表明，初始碳分布通过改变糊化区内的流体流动，直接控制最终的碳偏析。具体来说，在凝固早期，中心富碳的分布增强了糊状区的流体流动，促进了溶质向熔池的运移。这导致锭底负偏析增加。随着凝固的进行，累积的溶质进一步加剧了中心的正偏析，导致最严重的整体碳偏析。定量分析表明，与富边分布电极相比，富边分布电极在凝固初期的中心和边缘碳偏析指数分别约为- 0.086和- 0.350，分别提高了约66%和9%。这些研究结果强调了初始碳分布在ESR过程中控制碳偏析的关键作用，为优化工艺和提高W9Cr4V2Mo钢的质量提供了有价值的见解。

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引用次数: 0

Dynamic heat flux analysis in a high-pressure turbine 高压涡轮动态热流密度分析

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2026-07-01 Epub Date: 2026-02-04 DOI: 10.1016/j.ijthermalsci.2026.110724

N. Medina , J. Saavedra , G. Paniagua , F. Lozano

This work explores the unsteady heat flux distribution on a high-pressure turbine vane subjected to periodic fluctuations in inlet total temperature, using computational fluid dynamics (CFD) simulations. The vane experiences sinusoidal fluctuations in temperature, with peak-to-peak amplitudes of 50 K over the investigated frequency range. Unsteady Reynolds-Averaged Navier–Stokes (URANS) simulations are conducted using the

k

–

ω

SST transitional turbulence model, which accounts for turbulent production, dissipation, and convective heat transfer, thereby enabling the prediction of time-resolved stagnation effects on both velocity and thermal boundary layers.

The computational model has been verified by comparing predicted pressure distributions and surface heat fluxes with experimental data obtained from a high-pressure turbine vane. The analysis focuses on the temporal development of near-wall velocity and temperature profiles over the oscillation cycle, highlighting the mechanisms driving the transient heat transfer response. Furthermore, spectral proper orthogonal decomposition is applied to identify the dominant flow and thermal structures controlling the unsteady momentum and heat transfer dynamics. Insights into the evolution of the thermal boundary layer provide guidance for improving flow management and cooling strategies, aiming to mitigate vane thermal loading while reducing coolant requirements.

本文利用计算流体动力学（CFD）模拟研究了受进口总温度周期性波动影响的高压涡轮叶片上的非定常热流密度分布。叶片经历温度的正弦波动，在所研究的频率范围内，峰对峰的振幅为50 K。非定常reynolds - average Navier-Stokes （URANS）模拟使用k -ω海温过渡湍流模型进行，该模型考虑了湍流的产生、耗散和对流换热，从而能够预测速度和热边界层的时间分辨停滞效应。通过将预测的压力分布和表面热通量与高压涡轮叶片的实验数据进行比较，验证了计算模型的正确性。分析的重点是在振荡周期内近壁速度和温度分布的时间发展，突出了驱动瞬态传热响应的机制。此外，采用谱固有正交分解方法识别控制非定常动量和传热动力学的主导流动和热结构。对热边界层演变的深入研究为改进流动管理和冷却策略提供了指导，旨在减轻叶片热负荷，同时减少冷却剂的需求。

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引用次数: 0

A numerical study on cryogenic sprays under different break-up regimes 低温喷雾在不同破碎状态下的数值研究

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2026-07-01 Epub Date: 2026-02-05 DOI: 10.1016/j.ijthermalsci.2026.110749

Mattia Pelosin , Francesco Duronio , Paolo Albertelli , Tommaso Lucchini , Zhifu Zhou , Jiameng Tian , Bin Chen

CFD simulation of cryogenic sprays represents a challenging task that requires an accurate modeling of the specific thermodynamic-induced primary break-up and evaporation rate. This work presents a computational approach based on the Eulerian–Lagrangian framework to simulate cryogenic flashing sprays. Dedicated models are included to account for flash boiling in atomization, nozzle flow and phase change processes, removing the need to tune conventional break-up models to describe the spray evolution when flash boiling atomizing takes place. The proposed methodology is validated using experimental measurements of local spray properties (velocity, droplet diameter and temperature). The proposed model accurately captures the characteristics of the different breakup regimes (mechanical, transient and fully flashing break-up) reproducing experimental data both in terms of spray morphology and the thermophysical evolution of the vapor and liquid phases.

低温喷雾的CFD模拟是一项具有挑战性的任务，需要对特定的热力学诱导的初级破裂和蒸发速率进行精确建模。这项工作提出了一种基于欧拉-拉格朗日框架的计算方法来模拟低温闪光喷雾。包括专用模型来解释雾化，喷嘴流动和相变过程中的闪沸，从而无需调整传统的破裂模型来描述发生闪沸雾化时的喷雾演变。采用局部喷雾特性（速度、液滴直径和温度）的实验测量验证了所提出的方法。所提出的模型准确地捕捉了不同破裂机制（机械、瞬态和完全闪光破裂）的特征，在喷雾形态和汽液相热物理演化方面再现了实验数据。

引用次数: 0

Experimental investigation of axis switching and local heat transfer in multiple elliptical free surface water jet impingement 多椭圆自由表面水射流冲击中轴向切换与局部换热的实验研究

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2026-07-01 Epub Date: 2026-02-04 DOI: 10.1016/j.ijthermalsci.2026.110746

Abhijit Madhav Date, Janani Srree Murallidharan, S.V. Prabhu

The present study experimentally investigates the local and overall heat transfer from multiple elliptical free surface water jets impinging on a thin stainless-steel foil under constant heat flux. Local surface temperatures are measured using infrared thermography to obtain detailed Nusselt number distributions. A symmetric 3

\times

3 jet array with a hydraulic diameter of 3 mm and a pitch of

4 d

is examined for two elliptical orientations, namely streamwise and spanwise. The jets issue from a 2 mm thick orifice plate and impinge on a 0.06 mm thick foil. Experiments are conducted for Reynolds numbers from 1700 to 8500 and

z / d

ratios from 2 to 10.

To the authors’ knowledge, axis switching is experimentally demonstrated for the first time in multiple elliptical free surface jets. The switching direction depends on jet orientation and shows a 90° phase difference between the two configurations. Local Nusselt numbers decrease with spanwise distance, but this decay weakens as Reynolds number increases. The influence of

z / d

on stagnation and spanwise average heat transfer remains within 10–15%, indicating a stronger effect on cooling distribution than on magnitude. Stagnation, spanwise average and overall average Nusselt numbers nearly double over the tested Reynolds number range.

The overall average Nusselt number is nearly identical for both orientations, showing that axis switching mainly affects local heat transfer patterns. Streamwise oriented elliptical jets outperform circular jets reported in the literature, providing 30–45 % higher local Nusselt numbers and 70–100 % higher overall averages at low Reynolds numbers and 45–50 % at higher Reynolds numbers. The proposed cosine-based correlations predict approximately 97 % of the data within 20% accuracy.

实验研究了在恒定热流密度下，多个椭圆自由表面水射流冲击薄型不锈钢箔时的局部和整体换热。局部表面温度测量使用红外热像仪，以获得详细的努塞尔数分布。研究了一个水力直径为3mm、节距为4d的对称3 × 3射流阵列在顺流和展向两个椭圆方向上的分布。射流从2毫米厚的孔板发出，撞击0.06毫米厚的箔片。在雷诺数为1700 ~ 8500，z/d比值为2 ~ 10的条件下进行了实验。据作者所知，轴交换首次在多椭圆自由表面射流中得到实验证明。开关方向取决于射流方向，两种构型的相位差为90°。局部努塞尔数随展向距离的增加而减小，但随雷诺数的增加而减弱。z/d对滞止和展向平均换热的影响保持在10-15%，表明对冷却分布的影响大于对量级的影响。在测试的雷诺数范围内，停滞、展向平均和总体平均努塞尔数几乎翻了一番。两种方向的总体平均努塞尔数几乎相同，表明轴向切换主要影响局部传热模式。流向定向椭圆射流优于文献中报道的圆形射流，在低雷诺数下提供30 - 45%的局部努塞尔数，70 - 100%的总体平均值，在高雷诺数下提供45 - 50%的平均值。所提出的基于余弦的相关性在20%的精度内预测了大约97%的数据。

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引用次数: 0

Thermal-flow characteristics and field synergy principle analysis in pin-fin manifold microchannels 针鳍形微通道热流特性及场协同原理分析

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2026-06-01 Epub Date: 2026-01-09 DOI: 10.1016/j.ijthermalsci.2026.110674

Xilong Zhang , Rui Wang , Beibei Li , Zhicheng Zhou , Wenlin Dong

This study systematically compares six pin-fin configurations (Cases 0–5) in manifold microchannel heat sinks (MMCHS) through numerical simulation and experimental validation: Case 0 serves as the baseline conventional grooved structure, while Cases 1–5 explore novel designs including in-line rectangular pin-fins (Case 1), staggered rectangular pin-fins (Case 2), circular pin-fins with equilateral triangular pitch (Case 3), rhombus-shaped pin-fins rotated 45° (Case 4), and hybrid circular-rhombus configurations (Case 5). The results demonstrate that all pin-fin variants outperform the baseline by reducing fluid velocity and pressure drop, with Case 4 exhibiting the most significant performance enhancement – achieving 81.4 % thermal resistance reduction and 22.8 % higher convective heat transfer coefficient compared to Case 0. The rhombus-shaped pin-fins in Case 4 also demonstrate superior temperature uniformity, supported by field synergy angles that are 17.8 % lower than Case 0. Performance evaluation criterion (PEC) improvements range from 12.6 % for hybrid designs (Case 5) at high flow rates to 35.5 % for the optimal rhombic configuration (Case 4), with Cases 2 and 3 showing intermediate performance. This comprehensive analysis establishes the rhombic pin-fin structure as the most effective solution for simultaneously reducing thermal resistance and pumping power in MMCHS applications.

本研究通过数值模拟和实验验证，系统比较了流形微通道散热器（MMCHS）中6种引脚鳍构型（案例0-5）：案例0是传统槽型结构的基础，而案例1 - 5则探索了新颖的设计，包括直列矩形pin-鳍（案例1）、交错矩形pin-鳍（案例2）、等边三角形节距的圆形pin-鳍（案例3）、旋转45°的菱形pin-鳍（案例4）和圆形-菱形混合配置（案例5）。结果表明，在降低流体速度和压降方面，所有引脚鳍变体的性能都优于基线，其中Case 4表现出最显著的性能增强，与Case 0相比，其热阻降低了81.4%，对流换热系数提高了22.8%。情形4中的菱形引脚鳍也表现出较好的温度均匀性，且场协同角比情形0小17.8%。性能评估标准（PEC）的改进范围从高流量下混合设计的12.6%（案例5）到最佳菱形配置的35.5%（案例4），案例2和案例3表现为中等性能。综合分析表明，在MMCHS应用中，菱形针鳍结构是同时降低热阻和泵送功率的最有效解决方案。

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引用次数: 0

High-fidelity full-scale three-dimensional thermal-hydraulic characteristics analysis of the primary and secondary side in a steam generator 蒸汽发生器一次侧和二次侧的高保真全尺寸三维热工特性分析

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2026-06-01 Epub Date: 2026-01-09 DOI: 10.1016/j.ijthermalsci.2026.110658

Chunjie Zeng , Defang Mu , Hanrui Qiu , Mingjun Wang , Ge Wu , Wenxi Tian , Guanghui Su

The full-scale three-dimensional (3D) distribution characteristics of thermal-hydraulic parameters in a Steam Generator (SG) are crucial for the performance evaluation and safety analysis, which determine the economic efficiency and safety of nuclear power systems under long-term operation. Therefore, improving the prediction accuracy of the SG's 3D thermal-hydraulic field is one of the main development directions for SG analysis codes. A full-scale, tube-level computational model of the 55/19B steam generator (SG) was constructed using STEAM (Steam generator Tube-level thErmal-hydraulic Analysis platforM), a high-fidelity 3D code incorporating a two-fluid model developed by the Nuclear Thermal-hydraulic Laboratory at Xi'an Jiaotong University (XJTU-NuTHeL). Detailed thermal-hydraulic analysis was conducted for both the primary and secondary sides of the SG. Regarding the secondary side fluid domain, the simulation accurately reproduced the low void fraction distribution in the central bending tube region. Furthermore, areas susceptible to flow-induced vibration were pinpointed by analyzing crossflow energy. In the SG primary side flow domain, the characteristics of flow distribution in tube bundles were obtained, with a dimensionless standard deviation of 0.1 for the flow rates of the 4474 tubes. The influence of the channel head structure on flow distribution was also analyzed. Research on the high-fidelity tube-level 3D distribution characteristics of key thermal-hydraulic parameters on both sides of a full-scale SG can provide critical data support for SG flow-induced vibration analysis and design optimization.

蒸汽发生器内热水力参数的全尺寸三维分布特性对核电系统的性能评价和安全分析至关重要，直接关系到核电系统长期运行的经济性和安全性。因此，提高SG三维热液场预测精度是SG分析程序的主要发展方向之一。利用西安交通大学核热工实验室（XJTU-NuTHeL）开发的包含双流体模型的高保真三维代码steam（蒸汽发生器管级热工分析平台）构建了55/19B蒸汽发生器（SG）的全尺寸管级计算模型。对SG主侧和次侧进行了详细的热水力分析。在二次侧流体领域，模拟准确地再现了弯曲管中心区域的低空隙率分布。此外，通过分析横流能，确定了易受流激振动影响的区域。在SG一次侧流域中，得到了管束内的流动分布特征，4474管的流量无因次标准差为0.1。分析了槽头结构对水流分布的影响。研究全尺寸SG两侧关键热工参数的高保真管级三维分布特征，可为SG流激振动分析和设计优化提供关键数据支持。

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引用次数: 0

A pyro-piezo-phototronic regulation strategy for carrier modulation in a GaN PN junction GaN - PN结中载流子调制的热-压电-光电子调节策略

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2026-06-01 Epub Date: 2026-01-10 DOI: 10.1016/j.ijthermalsci.2026.110670

Mingkai Guo , Guoshuai Qin , Chunsheng Lu , Cuiying Fan , Minghao Zhao

The regulation of carrier distributions in piezoelectric semiconductors through piezo-phototronic and pyro-phototronic effects offers a promising pathway for developing tunable optoelectronic devices. In this paper, we propose a nonlinear pyro-piezo-phototronic model that accounts for the combined influences of ultraviolet radiation and externally applied mechanical stress. Unlike previous approaches that consider only piezoelectric or photoexcitation effects, this work extends the perturbation method to include pyroelectric contributions, enabling a comprehensive analysis of electromechanical field distributions under multi-field coupling. Our findings reveal that the polarity and direction of polarization charges at both ends of a GaN PN junction can be reversibly modulated by adjusting ultraviolet irradiation and mechanical loading. This controllable switching of polarized charges highlights a new avenue for functional regulation in piezoelectric semiconductors and expands their potential applications in next-generation optoelectronic and multifunctional devices.

压电半导体中载流子分布通过压电光电子效应和热光电子效应的调控为开发可调谐光电器件提供了一条有前途的途径。在本文中，我们提出了一个非线性的热-压电-光电子模型，该模型考虑了紫外线辐射和外部机械应力的综合影响。与之前只考虑压电或光激发效应的方法不同，这项工作将微扰方法扩展到包括热释电贡献，从而能够全面分析多场耦合下的机电场分布。我们的研究结果表明，GaN - PN结两端极化电荷的极性和方向可以通过调节紫外线照射和机械负载来可逆地调节。这种极化电荷的可控开关为压电半导体的功能调节提供了新的途径，并扩大了其在下一代光电和多功能器件中的潜在应用。

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引用次数: 0

Enhancing thermal properties: Understanding the combined effect of granular phase change materials and graphite in dry mixtures 增强热性能：了解颗粒相变材料和石墨在干燥混合物中的联合效应

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2026-06-01 Epub Date: 2026-01-23 DOI: 10.1016/j.ijthermalsci.2026.110720

Tairu Chen , Wenbin Fei , Guillermo A. Narsilio

The efficiency of both thermal energy storages and borehole ground heat exchangers in shallow geothermal systems depends on the energy storage and heat transfer rate of the backfilling materials used. Phase change materials (PCMs) can store and release heat at a relatively constant temperature (large latent heat). Incorporating PCMs into backfills can improve overall thermal energy density and thus benefit thermal energy storage and shallow geothermal energy systems. However, due to the low thermal conductivity of PCMs, the overall heat transfer rate through these backfill mixtures may be reduced. Therefore, other additives are needed to increase heat transfer efficiency, while maintaining the enhanced thermal storage effect on the backfill material. Graphite is a candidate for this purpose given its superior thermal conductivity. In addition, glass fines are used in this work, to explore a novel approach for recycling glass waste. Dry mixtures are prepared with different proportions of encapsulated PCMs (EPCMs), graphite and glass fines, and their heat capacity and thermal conductivity are measured in the laboratory. Furthermore, the internal structure of the mixture is observed via imagining techniques including scanning electron microscope and computed tomography. Grain-scale numerical simulations based on the obtained images reveals the particle-scale heat transfer pattern in the proposed backfill mixture materials. Experimental results show that incorporating EPCMs and graphite can lead to an average of 40 % increase in heat capacity without sacrificing thermal conductivity. The advanced numerical modelling shows that heat transfer is mainly determined by the contacts and distribution of glass fines in the mixtures, and that EPCMs under phase transition hinder overall heat transfer.

浅层地热系统中储热装置和井下热交换器的效率取决于所使用的回填材料的能量储存和传热速率。相变材料（PCMs）可以在相对恒定的温度（大潜热）下储存和释放热量。将pcm纳入回填体可以提高整体热能密度，从而有利于热能储存和浅层地热能源系统。然而，由于pcm的低导热性，通过这些充填体混合物的总体传热速率可能会降低。因此，需要其他添加剂来提高传热效率，同时保持充填材料增强的蓄热效果。鉴于其优越的导热性，石墨是这一目的的候选者。此外，在这项工作中使用玻璃粉，探索一种回收玻璃废料的新方法。用不同比例的包封pccm （EPCMs）、石墨和玻璃细粒制备干混合物，并在实验室测量其热容量和导热系数。此外，通过扫描电子显微镜和计算机断层扫描等成像技术观察混合物的内部结构。基于所得图像的颗粒尺度数值模拟揭示了所提出的充填体混合材料的颗粒尺度传热规律。实验结果表明，在不牺牲导热系数的情况下，EPCMs和石墨的结合可以使热容量平均增加40%。先进的数值模拟表明，传热主要取决于混合物中玻璃细粒的接触和分布，相变的epcm阻碍了整体传热。

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引用次数: 0