International Communications in Heat and Mass Transfer最新文献_第3页

Radiative MHD flow over a vertical permeable surface with synergistic Soret and Dufour effects 辐射MHD流在垂直可渗透表面与协同Soret和Dufour效应

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer

Pub Date : 2026-04-01 Epub Date: 2026-02-12 DOI: 10.1016/j.icheatmasstransfer.2026.110753

Bandita Das , Pranjal Saikia , Sunmoni Mudoi , Bhaskar Kalita

This work investigates the simultaneous influence of Soret (thermo-diffusion) and Dufour (diffusion-thermo) effects on magnetohydrodynamic (MHD) flow past a radiative elongated vertical plate embedded in a permeable medium, considering heat generation, magnetic fields, and chemical reactions. The governing nonlinear partial differential equations for momentum, energy, and concentration transport are transformed into a system of ordinary differential equations using similarity transformations and solved numerically via the MATLAB bvp4c solver, ensuring stability, convergence, and accuracy. Validation against previously published studies demonstrates excellent agreement, confirming the reliability of the present model. The results reveal pronounced parameter sensitivity of velocity, temperature, and concentration distributions. An increase in the magnetic parameter (

M :

0.5 → 1.5) reduces velocity by 12–15% and lowers the wall temperature gradient by ∼7.6% due to Lorentz force resistance, while radiation (

R :

1 → 3) suppresses velocity by 8–10% and decreases the thermal gradient by ∼6.5%, reflecting enhanced radiative losses. Higher Schmidt number (

Sc

: 0 → 1.5) decreases velocity and wall concentration gradient by ∼8% and 10.1%, respectively, whereas the chemical reaction parameter (

Kc

: 1 → 3) increases velocity by ∼7% and enhances the concentration gradient by ∼4.4%. The Dufour and Soret effects exhibit dual roles: while both reduce velocity (by ∼7–9% and ∼ 6–8%), they substantially amplify mass transfer, with wall concentration gradients increasing by 66.7% and 37.5%, respectively. These findings establish that magnetic, radiative, and diffusive mechanisms tend to suppress momentum, heat, and mass transport near the wall, whereas Soret and Dufour effects significantly intensify coupled transport processes. The study not only clarifies the competing influences of thermal, solutal, and electromagnetic mechanisms but also provides valuable guidance for optimizing thermal and mass transfer control in MHD-based engineering and porous media applications.

这项工作研究了Soret（热扩散）和Dufour（扩散热效应）对磁流体动力学（MHD）流动的同时影响，考虑了热的产生、磁场和化学反应。控制动量、能量和浓度输运的非线性偏微分方程使用相似变换转换为常微分方程系统，并通过MATLAB bvp4c求解器进行数值求解，确保了稳定性、收敛性和准确性。对先前发表的研究的验证证明了极好的一致性，确认了本模型的可靠性。结果表明，速度、温度和浓度分布对参数有明显的敏感性。由于洛伦兹力的阻力，磁参数（M: 0.5→1.5）的增加使速度降低了12-15%，使壁温梯度降低了~ 7.6%，而辐射（R:1→3）抑制了速度8-10%，使热梯度降低了~ 6.5%，这反映了辐射损失的增加。较高的施密特数（Sc: 0→1.5）使速度和壁浓度梯度分别降低了~ 8%和10.1%，而化学反应参数（Kc: 1→3）使速度提高了~ 7%，浓度梯度提高了~ 4.4%。Dufour效应和Soret效应表现出双重作用：虽然两者都降低了速度（分别降低了~ 7-9%和~ 6-8%），但它们大大增强了传质，壁浓度梯度分别增加了66.7%和37.5%。这些发现表明，磁、辐射和扩散机制倾向于抑制壁面附近的动量、热量和质量输运，而Soret和Dufour效应则显著增强耦合输运过程。该研究不仅阐明了热、溶质和电磁机制的相互影响，而且为基于mhd的工程和多孔介质应用中优化传热传质控制提供了有价值的指导。

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引用次数: 0

Design and optimization of a biomimetic lymphatic valve baffle flow channel for PEMFC based on a genetic algorithm 基于遗传算法的PEMFC仿生淋巴阀挡板流道设计与优化

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer

Pub Date : 2026-04-01 Epub Date: 2026-02-13 DOI: 10.1016/j.icheatmasstransfer.2026.110761

Haifu Qin, Fayi Yan, Shijie Feng, Yongzhi Su, Xinhai Li

The design and optimization of the flow channel structure have a significant impact on the performance of a proton exchange membrane fuel cell (PEMFC). Inspired by lymphatic valves, this study proposes a biomimetic lymphatic valve baffle flow channel. A three-dimensional PEMFC numerical model was developed using COMSOL Multiphysics, and the effects of four geometric parameters—baffle angle

β_{a}

, total number of baffles

N

, inlet baffle height

H_{inlet}

, and outlet baffle height

H_{outlet}

—on the current density and cathode pressure drop of the PEMFC were thoroughly analyzed from the perspectives of flow and mass transport. The results indicate that, compared with the conventional single straight flow channel (CSSFC), the biomimetic lymphatic valve baffle flow channel (BLVBFC) exhibits superior mass transfer capability and effectively enhances the overall cell performance. Furthermore, the geometric parameters of the baffles were selected as optimization variables, and the net power density of the PEMFC was used as the optimization objective. Using a genetic algorithm (GA), the optimal parameter combination was obtained. The optimized design shows that when

β_{a}

= 18.3996°,

N

= 25,

H_{inlet}

= 0.5883 mm, and

H_{outlet}

= 0.6683 mm, the PEMFC current density and net power density of the optimal biomimetic lymphatic valve baffle flow channel (OBLVBFC) are improved by 4.79% and 3.73%, respectively. Meanwhile, as the OBLVBFC improves the flow characteristics of the gas, it leads to a 2.98% relative reduction in average liquid water saturation and a 45.06% relative increase in average oxygen concentration at the CGDL-CCL interface.

流道结构的设计与优化对质子交换膜燃料电池（PEMFC）的性能有重要影响。受淋巴阀的启发，本研究提出了一种仿生淋巴阀挡板流道。利用COMSOL Multiphysics软件建立了PEMFC三维数值模型，从流动输运和质量输运的角度深入分析了挡板角βa、挡板总数N、进口挡板高度Hinlet和出口挡板高度houtlet四个几何参数对PEMFC电流密度和阴极压降的影响。结果表明，与传统的单一直流道（CSSFC）相比，仿生淋巴阀挡板流道（BLVBFC）具有更好的传质能力，有效地提高了细胞的整体性能。以挡板的几何参数为优化变量，以PEMFC的净功率密度为优化目标。利用遗传算法（GA），得到了最优的参数组合。优化设计结果表明，当βa = 18.3996°，N = 25, Hinlet = 0.5883 mm, Houtlet = 0.6683 mm时，优化后的仿生淋巴阀挡板流道（OBLVBFC）的PEMFC电流密度和净功率密度分别提高了4.79%和3.73%。同时，由于OBLVBFC改善了气体的流动特性，导致CGDL-CCL界面平均液态水饱和度相对降低2.98%，平均氧浓度相对提高45.06%。

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引用次数: 0

Elliptical cooling zone-induced slag dynamics and multi-source data fusion for thickness prediction in industrial furnace cooling staves 椭圆冷却区诱导炉渣动力学及多源数据融合用于工业炉冷却壁厚度预测

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer

Pub Date : 2026-04-01 Epub Date: 2026-02-13 DOI: 10.1016/j.icheatmasstransfer.2026.110775

Haifeng Chen, Yuling Zhai, Zhouhang Li, Hua Wang

The longevity of high-temperature metallurgical furnaces critically depends on the spatial uniformity of the protective slag layer adhering to cooling staves. Non-uniform slag distribution, especially localized thinning under intense thermal loads, accelerates cooling stave degradation via cracking and deformation. Traditional optimization strategies focusing on maximizing heat transfer inadvertently form elliptical cooling zones at the slag-stave interface, exacerbating such non-uniformity. This study incorporates dynamic slag behavior into computational models, and thermo-mechanical simulations show that increasing furnace gas temperature from 1500 °C to 1750 °C reduces average slag thickness by 86.9%, while cooling stave peak temperature and maximum thermal deformation increase by 529.5% and 497%, respectively. Temperature-driven interfacial dynamics induce a distinct “edge-thin, center-thick” slag morphology with a maximum thickness variation of 7.76 mm. This is attributed to high-efficiency heat transfer tubes, which generate elliptical cooling zones at 1750 °C, causing significant interfacial temperature gradients (ΔT = 784.5 °C, ranging 590.3–1519.55 °C) and thus reducing local slag thickness from 8.70 mm to 0.94 mm. Direct in-situ measurement of the variable slag layer is challenging, as conventional electronic sensors cannot withstand such extreme temperatures. To address this, a multi-source data fusion approach (integrating cooling water thermodynamics, tube wall temperatures, and interfacial heat flux) is adopted, identifying three nonlinear relationships: (1) strong inverse correlation (R² = 0.9989) between average slag thickness and cooling water temperature difference; (2) negative correlation (R² = 0.9973) between average slag thickness and tube wall temperature; (3) localized inverse correlation (R² = 0.9134) between interfacial temperature and slag thickness. These findings provide a reference model for precise control of slag uniformity and for predicting cooling stave cracking and deformation. Furthermore, they clarify the synergistic interactions among slag, furnace walls, and cooling tubes. The results challenge the conventional ‘maximize heat transfer’ approach and advance theoretical frameworks for optimizing kilns and furnaces.

高温冶金炉的寿命关键取决于保护渣层附着在冷却板上的空间均匀性。不均匀的炉渣分布，特别是在强热负荷下的局部变薄，加速了冷却壁的开裂和变形退化。传统的优化策略侧重于最大化传热，无意中在炉渣-壁板界面形成椭圆冷却区，加剧了这种不均匀性。该研究将动态炉渣行为纳入计算模型，热力学模拟结果表明，从1500℃升高至1750℃，炉渣平均厚度降低86.9%，冷却壁峰值温度和最大热变形分别增加529.5%和497%。温度驱动的界面动力学导致了明显的“边薄，中心厚”的渣形态，最大厚度变化为7.76 mm。这要归功于高效的换热管，它在1750°C时产生椭圆冷却区，造成显著的界面温度梯度（ΔT = 784.5°C，范围为590.3-1519.55°C），从而使局部炉渣厚度从8.70 mm减少到0.94 mm。由于传统的电子传感器无法承受如此极端的温度，因此对可变渣层的直接原位测量具有挑战性。为此，采用多源数据融合方法（综合冷却水热力学、管壁温度和界面热流密度），识别出三种非线性关系：(1)平均炉渣厚度与冷却水温差呈强负相关（R2 = 0.9989）；(2)平均炉渣厚度与管壁温度呈负相关（R2 = 0.9973）；(3)界面温度与炉渣厚度之间存在局部负相关（R2 = 0.9134）。这些发现为精确控制炉渣均匀性和预测冷却壁开裂和变形提供了参考模型。此外，它们阐明了炉渣、炉壁和冷却管之间的协同相互作用。研究结果挑战了传统的“最大化传热”方法，并提出了优化窑炉的理论框架。

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引用次数: 0

A data-driven artificial neural network-based Levenberg-Marquardt approach for predicting heat flux in magnetized viscoelastic fluid flow around a solid sphere 基于数据驱动人工神经网络的磁化粘弹性流体绕固体球体流动热通量预测方法

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer

Pub Date : 2026-04-01 Epub Date: 2026-02-13 DOI: 10.1016/j.icheatmasstransfer.2026.110732

Kezheng Zhang , Khalid Masood , Zeeshan , Nehad Ali Shah

Mixed convection (MC) arises from the mutual effects of buoyancy-driven free convection and externally induced forced convection, both of which significantly influence heat and momentum transport. This study examines MC flow of a viscoelastic fluid across a spherical surface under magnetic and buoyancy effects. This study introduces, for the first time, a hybrid numerical–data-driven framework that integrates the Keller–Box finite-difference method (KBFDM) with a Levenberg–Marquardt–optimized recurrent neural network to accurately model magnetically influenced MC flow (ANN-LMA). The governing nonlinear equations are converted into dimensionless and solved numerically to generate a reliable dataset for training and validation of the ANN model. The influences of key parameters, including the Prandtl number

(1 \leq \Pr \leq 3)

, viscoelastic parameter

(1 \leq K \leq 4)

, mixed convection parameter

(1 \leq λ ₁ \leq 4)

, and magnetic parameter

(0.2 \leq M \leq 1)

, are analyzed through velocity and temperature profiles. Results indicate that increasing Prandtl number reduces both velocity and temperature, while stronger viscoelastic effects suppress velocity and enhance thermal distribution. An upsurge in the MC factor augments both flow and temperature fields. The precision of the hybrid model is verified using mean square error, regression analysis, and error histograms, achieving high precision with errors in the range of 10⁻⁴ to 10⁻⁸.

混合对流（MC）是由浮力驱动的自由对流和外部诱导的强迫对流相互作用产生的，两者对热量和动量输运都有显著影响。本研究考察了粘弹性流体在磁力和浮力作用下在球面上的MC流动。本研究首次引入了一种混合数值数据驱动框架，该框架将Keller-Box有限差分法（KBFDM）与levenberg - marquardt优化的递归神经网络相结合，以精确模拟磁影响MC流（ANN-LMA）。将控制非线性方程转换为无因次方程并进行数值求解，生成可靠的数据集，用于人工神经网络模型的训练和验证。通过速度和温度剖面分析了普朗特数1≤Pr≤3、粘弹性参数1≤K≤4、混合对流参数1≤λ₁≤4、磁参量0.2≤M≤1等关键参数的影响。结果表明，普朗特数的增加使速度和温度降低，粘弹性效应的增强抑制了速度，增强了热分布。MC因子的增加增加了流场和温度场。利用均方误差、回归分析和误差直方图验证了混合模型的精度，误差范围在10−4到10−8之间。

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引用次数: 0

An assessment of performance of bifurcations in thermal systems with new correlations for estimating Nusselt number and loss coefficient 热系统分岔性能的评估与估计努塞尔数和损失系数的新相关性

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer

Pub Date : 2026-03-01 Epub Date: 2025-12-05 DOI: 10.1016/j.icheatmasstransfer.2025.110116

Sarangrab Roy Chowdhury, Kaustav Pradhan

Branching networks are continuously being contemplated for use in compact heat transfer systems. They are constructed by connecting straight tubes through bifurcations. The present study investigates the thermo-hydraulic performance of three different bifurcation geometries, viz. symmetric Y-bifurcation, T-bifurcation and asymmetric Y-bifurcation. The velocity and temperature contours show a complementary nature wherein low velocity regions correspond to high temperatures and vice-versa. New quantitative parameters viz. relative secondary strength (E_s/t), velocity non-uniformity (δ_v), temperature non-uniformity (δ_t) and the performance index (ξ) are introduced to understand the effects of the geometry on the flow field and thermal performance. The T-bifurcation shows the best heat transfer performance, but also the worst hydraulic performance. On the other hand, the asymmetric Y-bifurcation shows the worst heat transfer performance, but the best hydraulic performance. Based on the values of the performance index, it is concluded that the performance of the asymmetric Y-bifurcation is better than that of the symmetric Y-bifurcation, which in turn performs better than the T-bifurcation. However, the non-uniform flow distribution in the asymmetric geometry may lead to issues when such bifurcations are connected in series and parallel to form a distribution network. A comparison of the pressure loss obtained by the CFD simulations with theoretical estimations shows the utility of the comprehensive numerical framework. New correlations are also proposed to determine the Nusselt number and loss coefficient as functions of the bifurcation angle and Reynolds number.

分支网络不断被考虑用于紧凑的传热系统。它们是通过分岔连接直管而构成的。本文研究了对称y分岔、t分岔和非对称y分岔三种不同分岔几何形式的热水力性能。速度和温度等高线显示出互补性质，其中低速区域对应于高温，反之亦然。引入了相对二次强度（Es/t）、速度不均匀性（δv）、温度不均匀性（δt）和性能指数（ξ）等新的定量参数，以了解几何形状对流场和热性能的影响。t型分岔的传热性能最好，但水力性能最差。另一方面，非对称y分叉的传热性能最差，但水力性能最好。根据性能指标的取值，得出非对称y分岔的性能优于对称y分岔，而对称y分岔的性能又优于t分岔。然而，当这些分岔以串并联方式连接形成配电网时，不对称几何结构中不均匀的流量分布可能会导致问题。将CFD模拟得到的压力损失与理论计算结果进行了比较，表明了综合数值框架的有效性。本文还提出了新的关系式来确定努塞尔数和损失系数作为分岔角和雷诺数的函数。

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引用次数: 0

An innovative mixed thermal elastohydrodynamic lubrication modeling of spiral bevel and hypoid gears 一种创新的螺旋锥齿轮和准双曲面齿轮混合热弹流润滑建模方法

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer

Pub Date : 2026-03-01 Epub Date: 2025-12-03 DOI: 10.1016/j.icheatmasstransfer.2025.110175

Wenzhe Zhang , Yanbing Li , Yiru Chen , Feng Yin , Zhenyu Zhou , Qiang Wang , Han Ding

For spiral bevel and hypoid gears under high-speed and heavy-duty conditions, time-varying meshing interface experiences high temperature rises due to thermal elastohydrodynamic lubrication (TEHL) effect. While considering the rough tooth surface asperities, it is easy to break the oil film, and this becomes mixed state easily induces various failures such as pitting, scuffing, and wear. Currently, the mixed TEHL mechanism is a very tough task for spiral bevel and hypoid gears, owing to temperature effect lacking systematic in-depth analysis. In full consideration of time-varying geometric and kinematic characteristics, an innovative mixed TEHL modeling is proposed. This model comprehensively considers many factors such as lubricant temperature rise, solid heat conduction, arbitrary directionality of interface speed, rheological properties of the lubricant, actual surface roughness, and elastic deformation of the tooth surface. In this paper, a semi-system approach is utilized to discretize and solve the Reynolds equation for excellent iterative convergence and high computational efficiency. This approach enables numerical simulation across the entire spectrum, from full-film lubrication to mixed lubrication, and ultimately to boundary lubrication. Comparing with the empirical data, a set of hypoid gears in automobile main reducer transmission system is exercised to validate high precision of this modeling.

对于高速重载工况下的螺旋锥齿轮和准双曲面齿轮，由于热弹流润滑（TEHL）效应，时变啮合界面会出现高温升。同时考虑到粗糙的齿面凹凸不平，容易使油膜破裂，从而变为混合状态，容易诱发点蚀、划伤、磨损等各种失效。目前，螺旋锥齿轮和准双曲面齿轮的温度效应是一项非常艰巨的任务，缺乏系统的深入分析。在充分考虑时变几何和运动特性的基础上，提出了一种新颖的混合TEHL建模方法。该模型综合考虑了润滑剂温升、固体热传导、界面速度的任意方向性、润滑剂的流变性、实际表面粗糙度和齿面弹性变形等因素。本文采用半系统方法对雷诺方程进行离散求解，具有较好的迭代收敛性和较高的计算效率。这种方法可以在整个范围内进行数值模拟，从全膜润滑到混合润滑，最终到边界润滑。以汽车主减速器传动系统的准双曲面齿轮为例，与经验数据进行对比，验证了该模型的精度。

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引用次数: 0

Optimization configuration of cylinder-shaped magnets for augmenting the performance of conical stills 提高锥形蒸馏器性能的圆柱形磁体优化配置

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer

Pub Date : 2026-03-01 Epub Date: 2025-12-02 DOI: 10.1016/j.icheatmasstransfer.2025.110174

Mohammed El Hadi Attia , M. Koraiem M. Handawy , K. Harby , Mohamed Benghanem , Mohamed Abdelgaied

Most countries face increasing challenges in providing drinkable water due to the scarcity of water resources and the high costs of conventional desalination technologies that rely on fossil fuels. Solar stills are considered one of the most important sustainable and low-cost solutions; however, their limited productivity and efficiency restrict large-scale deployment. In this study, a traditional conical solar still (TCSS) was enhanced by incorporating low-cost cylindrical magnets (CSS-CSM&1, CSS-CSM&3, CSS-CSM&5, and CSS-CSM&7) to modify water molecule behavior and improve heat transfer. The systems were evaluated through comprehensive 6E analysis along with two sustainability indicators. The results showed that water productivity increased by 23.3 %, 41.9 %, 64.5 %, and 85.8 % for CSS-CSM&1, CSS-CSM&3, CSS-CSM&5, and CSS-CSM&7, respectively, compared to the TCSS. Thermal efficiency improved from 35.5 % in the TCSS to 45.5 %, 52.0 %, 60.3 %, and 67.9 %, corresponding to relative increases of 28.4 %, 46.5 %, 70.1 %, and 91.5 %. Exergy efficiency rose by 41.8 %, 104.4 %, 176.8 %, and 249.1 %, respectively. The cost of production (CPL) decreased by 12.4 %, 18.3 %, 24.6 %, and 28.9 %, while the payback period was shortened from 76 days (TCSS) to 66, 62, 57, and 54 days. Environmentally, net lifetime CO₂ mitigation increased from 18.8 tons (TCSS) to 24.2, 27.8, 32.1, and 36.1 tons for the modified solar stills, resulting in carbon credit returns of 273.13 $, 351.33 $, 402.66$, 464.94$, and 523.42$, respectively. Furthermore, the Sustainability Index (SI) improved from 1.02 (TCSS) to 1.06 (CSS-CSM&7), while the Improvement Potential (IP) decreased from 2050.23 to 1893.12.

大多数国家在提供饮用水方面面临越来越大的挑战，这是由于水资源短缺和依赖化石燃料的传统海水淡化技术成本高昂。太阳能蒸馏器被认为是最重要的可持续和低成本的解决方案之一；然而，它们有限的生产力和效率限制了大规模部署。在本研究中，通过加入低成本的圆柱形磁体（CSS-CSM&1, CSS-CSM&3, CSS-CSM&；5和CSS-CSM&；7）来改进传统的锥形太阳能still (TCSS)，以改变水分子的行为并改善传热。通过综合6E分析和两个可持续性指标对这些系统进行了评估。结果表明，与TCSS相比，CSS-CSM&1、CSS-CSM&3、CSS-CSM&；5和CSS-CSM&；7的水分生产力分别提高了23.3%、41.9%、64.5%和85.8%。热效率从TCSS的35.5%提高到45.5%、52.0%、60.3%和67.9%，分别相对提高28.4%、46.5%、70.1%和91.5%。能源效率分别提高41.8%、104.4%、176.8%和249.1%。生产成本（CPL）分别下降12.4%、18.3%、24.6%和28.9%，投资回收期由76 d （TCSS）缩短为66、62、57和54 d。在环境方面，改进后的太阳能蒸馏器的净寿命CO₂减少量从18.8吨（TCSS）增加到24.2吨、27.8吨、32.1吨和36.1吨，碳信用回报分别为273.13美元、351.33美元、402.66美元、464.94美元和523.42美元。可持续发展指数（SI）从1.02 （TCSS）提高到1.06 (CSS-CSM&7)，而改善潜力（IP）从2050.23下降到1893.12。

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引用次数: 0

Numerical investigation of nano-PCM latent-sensible thermal energy storage enclosures 纳米pcm潜感热储热罩的数值研究

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer

Pub Date : 2026-03-01 Epub Date: 2026-01-14 DOI: 10.1016/j.icheatmasstransfer.2026.110548

Farooq H. Ali , Qusay Rasheed Al-Amir , Hameed K. Hamzah , Lioua Kolsi

To provide consistent energy supply, solar water heating systems often incorporate both sensible and latent heat storage. The current study corresponds to a numerical investigation of a combined latent-sensible thermal energy storage enclosure using a phase change material (PCM) and water. The PCM domain (latent section) contains a coiled heat transfer tube that provides heat input (simulating solar radiation) and is separated by a solid copper wall from the surrounding water (sensible section). We examine the effect of dispersing copper nanoparticles in PCM on its melting performance. The Simulations are performed using the Galerkin finite element method to couple the heat transfer and fluid flow, using the enthalpy-porosity formulation to model the PCM phase change. An iterative scheme couples the PCM and water domains through the copper interface, and overall energy balance is verified at each time step. All external walls are insulated, and a time-dependent thermal input at the internal tube mimics diurnal solar heating. Results show that the PCM region achieves a significantly higher energy storage capacity than an equal mass of water, underscoring the advantage of latent heat storage. The water's average temperature increased almost linearly during charging, while the PCM's temperature remained nearly constant during the phase change. Adding copper nanoparticles (up to 2% by volume) to PCM provided only a modest improvement in melting rate, and higher nanoparticle concentrations offered no significant enhancement. These findings show that excessive nanoparticle loading yields diminishing returns in PCM thermal performance, consistent with prior studies. Overall, the results demonstrate the effectiveness of the dual PCM-water storage configuration.

为了提供一致的能源供应，太阳能热水系统通常包括显热和潜热储存。目前的研究对应于使用相变材料（PCM）和水的组合潜感热储能外壳的数值研究。PCM区域（潜在部分）包含一个提供热量输入（模拟太阳辐射）的盘状传热管，并由固体铜墙与周围的水（敏感部分）分开。研究了在PCM中分散铜纳米粒子对其熔化性能的影响。采用Galerkin有限元法耦合传热和流体流动，采用焓-孔隙率公式模拟相变过程。一个迭代方案通过铜界面耦合PCM和水域，并在每个时间步验证总能量平衡。所有的外墙都是隔热的，内部管道的时间相关热输入模拟了白天的太阳能加热。结果表明，PCM区域的蓄能能力明显高于同等质量的水，凸显了潜热蓄能的优势。在充电过程中，水的平均温度几乎呈线性上升，而在相变过程中，PCM的温度几乎保持不变。向PCM中添加铜纳米粒子（体积比高达2%）仅对熔化速度有适度的改善，更高的纳米粒子浓度没有显著的增强作用。这些发现表明，过多的纳米颗粒负载会导致PCM热性能的回报递减，这与先前的研究一致。总体而言，结果证明了双pcm -储水配置的有效性。

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引用次数: 0

Experimental investigation on high-pressure gas jet characteristics under high backpressure conditions for hydrogen internal combustion engines 高背压条件下氢气内燃机高压气体喷射特性实验研究

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer

Pub Date : 2026-03-01 Epub Date: 2026-01-14 DOI: 10.1016/j.icheatmasstransfer.2026.110555

Shenghao Yu , Dong Xie , Jin Qian , Jiao Wang , Xiaolu Dong , Jiangshan Jin

Hydrogen internal combustion engines face challenges in achieving efficient fuel-air mixing under high-backpressure conditions, where hydrogen jet diffusion is notably suppressed. This study experimentally investigates gas jet characteristics utilizing a high-pressure constant-volume chamber and high-speed schlieren imaging, employing helium as a validated surrogate to ensure safety. Results demonstrate that increasing backpressure significantly attenuates jet momentum by diminishing the pressure differential and amplifying aerodynamic drag. Specifically, for the 2.5 mm nozzle operating at 1 MPa injection pressure, lowering the backpressure from 0.75 MPa to 0.5 MPa boosted the peak jet tip velocity by 45%. Regarding late-stage development at 1.6 ms after the start of injection, this pressure reduction led to a 27% extension in jet penetration and a remarkable 81.78% increase in entrained gas mass. Furthermore, while larger nozzles enhance peak velocity and overall air entrainment due to higher mass flow rates, they exhibit lower initial tip velocities attributed to inertial delays and increased frontal drag. High backpressure was also found to constrain radial expansion, thereby weakening the influence of nozzle diameter on jet width, and shifted the peak velocity occurrence earlier. Ultimately, low backpressure promotes mixing through stronger velocity gradients, whereas large nozzles maximize air entrainment via expanded jet-air interfaces.

氢气内燃机面临着在高背压条件下实现高效燃料-空气混合的挑战，在高背压条件下，氢气射流扩散受到明显抑制。本研究利用高压等容室和高速纹影成像实验研究了气体射流特性，并采用氦气作为有效的替代剂来确保安全性。结果表明，增加背压可以通过减小压差和增大气动阻力来显著减弱射流动量。具体来说，对于在1 MPa喷射压力下工作的2.5 mm喷嘴，将背压从0.75 MPa降低到0.5 MPa，使峰值射流尖端速度提高了45%。在注入后1.6 ms的后期发展中，压力的降低导致射流侵深延长了27%，夹带气体质量显著增加了81.78%。此外，虽然更大的喷嘴由于更高的质量流量而提高了峰值速度和总体空气夹带，但由于惯性延迟和增加的前缘阻力，它们表现出更低的初始叶尖速度。高背压也抑制了径向膨胀，从而减弱了喷嘴直径对射流宽度的影响，使峰值速度出现的时间提前。最终，低背压通过更强的速度梯度促进混合，而大喷嘴通过扩大的喷气-空气界面最大化空气夹带。

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引用次数: 0

Study on spray cooling heat transfer enhancement mechanisms based on capillary imbibition and evaporation models 基于毛细吸胀和蒸发模型的喷雾冷却强化传热机理研究

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer

Pub Date : 2026-03-01 Epub Date: 2025-12-07 DOI: 10.1016/j.icheatmasstransfer.2025.110245

Qin Ni, Bingqing Liu , Xiang Ling

Building on prior research on spray cooling with vapor–liquid separation structures, this study examines ethanol additives at varying concentrations and their effect on heat transfer across three surfaces (S1, S2, S3) with different copper mesh coverage, using theoretical modeling and experiments. S1 consists of only micropillars, S2 is a semi-micromesh surface that retains part of the mesh for capillary pumping while leaving micropillars exposed for droplet impact and vapor escape, and S3 is a fully-micromesh surface.

Capillary liquid supply is modeled with Darcy's law, while evaporation in the porous medium incorporates diffusion and Stefan convection. A mathematical model describes wicking and evaporation, showing that capillary uptake decreases with microfilm thickness and ethanol concentration. With DI water, initial uptake velocity reaches 150.4 m/s—about 181 times higher than through full-layer penetration and 5.4 times higher than with 60 % ethanol solution. During early phase-change heat transfer, evaporation rate falls with heat flux; when it nears zero, boiling dominates, suggesting a predictor of critical heat flux. Heat transfer curves reveal performance improves with greater mesh coverage. On the fully-micromesh surface, DI water achieves the best results, with maximum heat flux reaching 821.4 W/cm² due to higher uptake rates and latent heat.

基于先前对汽液分离结构喷雾冷却的研究，本研究通过理论建模和实验研究了不同浓度的乙醇添加剂及其对不同铜网覆盖的三个表面（S1, S2, S3）传热的影响。S1仅由微柱组成，S2为半微孔表面，保留了部分微孔用于毛细管泵送，而微柱暴露在外，供液滴撞击和蒸汽逸出，S3为全微孔表面。毛细管供液采用达西定律，多孔介质中的蒸发采用扩散和斯蒂芬对流。一个数学模型描述了吸干和蒸发，表明毛细管吸收量随着微膜厚度和乙醇浓度的增加而减少。使用去离子水时，初始吸收速度达到150.4 m/s，约为全层渗透的181倍，为60%乙醇溶液的5.4倍。在相变传热初期，蒸发速率随热流密度的增大而减小；当它接近零时，沸腾占主导地位，这表明它是临界热通量的预测器。传热曲线显示性能提高与更大的网格覆盖。在全微孔表面，去离子水由于吸收率和潜热较高，达到了821.4 W/cm2的最大热流密度。

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引用次数: 0