International Communications in Heat and Mass Transfer最新文献_第6页

Experimental study of the effect of delayed ignition on the ethanol spill fire behaviour with different channel width in tunnel environment 隧道环境中不同通道宽度下延迟点火对乙醇泄漏火灾行为影响的实验研究

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer

Pub Date : 2024-11-19 DOI: 10.1016/j.icheatmasstransfer.2024.108335

Xue Jing Hu, Cheng Hao Ye, Mei Qing Xia, Jia Xing Li, Pei Hong Zhang

Tanker trucks are susceptible to combustible liquid spill fire after an accident in the transport process. When the spill fire accident occurs in a road tunnel, the coupling of the kinetic properties of the diffused fuel and the heat transfer mechanism of the fire plume to the fuel layer is more complicated under the constraints of the tunnel environment, which can cause serious hazards to the surrounding environment. In this paper, instantaneous ignition and different delayed ignition time such as 10 s, 20 s, and 30 s were tested using ethanol at a spill rate of 78 ml/min on 10 cm, 15 cm, 20 cm, and 30 cm width steel channels in a model tunnel. Parameters such as burning area, spread rate and burning rate were analysed based on electronic balance data, thermocouple data and MATLAB image processing data. The findings show that an increase in substrate width and delayed ignition time results in an increase in the maximum burning area. The flame spread rate decreases with increasing substrate width at the same ignition time and increases with increasing delayed ignition time at the same width substrate. A spread rate prediction model was developed by analysing the forces on the fuel layer during the spread phase. A model for predicting the average burning rate during the spread phase was developed by taking into account the different absorption rates of radiant heat feedback by different fuel layer thicknesses during the spread phase in the tunnel space. A model for predicting the maximum burning area of delayed ignition ethanol spill fire on substrate of different width in tunnel was developed by combining the spread rate model and the burning rate model in the spreading phase. The results of this study are important reference for understanding the spreading and burning characteristics of spill fire accidents during road transport and the associated risk assessment.

油罐车在运输过程中发生事故后，很容易发生可燃液体泄漏起火事故。当泄漏着火事故发生在公路隧道内时，受隧道环境的限制，扩散燃料的动力学特性与着火羽流向燃料层的传热机制的耦合更为复杂，会对周围环境造成严重危害。本文使用乙醇在模型隧道中 10 厘米、15 厘米、20 厘米和 30 厘米宽的钢制通道上以 78 毫升/分钟的溢出率进行了瞬时点火和 10 秒、20 秒和 30 秒等不同延迟点火时间的测试。根据电子天平数据、热电偶数据和 MATLAB 图像处理数据分析了燃烧面积、扩散率和燃烧速率等参数。研究结果表明，基底宽度的增加和点火时间的延迟会导致最大燃烧面积的增加。在相同的点火时间内，火焰蔓延率随基底宽度的增加而降低，而在相同宽度的基底上，火焰蔓延率随延迟点火时间的增加而升高。通过分析燃料层在扩散阶段的受力情况，建立了扩散率预测模型。考虑到隧道空间内不同燃料层厚度在扩散阶段对辐射热反馈的不同吸收率，建立了扩散阶段平均燃烧速率预测模型。通过结合蔓延速率模型和蔓延阶段的燃烧速率模型，建立了用于预测隧道内不同宽度基质上延迟点燃乙醇溢出火的最大燃烧面积的模型。研究结果对了解公路运输过程中泄漏火灾事故的蔓延和燃烧特征以及相关风险评估具有重要参考价值。

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引用次数: 0

Evaluation of flow and heat transfer behavior in parallel flow copper electro-refining cell with different inlet arrangements 评估不同入口布置的平行流铜电解精炼池中的流动和传热行为

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer

Pub Date : 2024-11-19 DOI: 10.1016/j.icheatmasstransfer.2024.108353

Xiaoyu Huang , Mingyue Wang , Xiaoyan Huang , Shan Qing , Zixi Tian

Parallel flow copper electro-refining cell technology has been developed for over a decade, and the flow field in these cells is significantly influenced by the arrangement of the electrolyte inlets. Four computational fluid dynamics models were developed to compare the flow and heat transfer characteristics of the electrolyte under varying electrolyte inlet arrangements. These models include bi-directional parallel flow (BPF), staggered parallel flow (SPF), top inlet unidirectional parallel flow (UPF-T), and bottom inlet unidirectional parallel flow (UPF-B). Flow and heat transfer simulations were conducted for each model. The simulation results indicate that the BPF and SPF electro-refining cells exhibit varying degrees of kinetic energy loss, which leads to lower volume-weighted average velocities and impacts the rapid circulation of the electrolyte. The UPF-B is the most effective in terms of both flow uniformity and flow velocity, with the UPF-T following closely behind. The temperature in the inter-pole area is elevated when the SPF and UPF-T are arranged, which is more conducive to the diffusion of copper ions. The copper cathode production efficiency and deposition uniformity are enhanced by the UPF-B arrangement, which enables the liquid to be supplied to the inter-pole area more rapidly and uniformly.

平行流铜电解精炼池技术已经发展了十多年，这些电解池中的流场受电解液入口布置的影响很大。为了比较不同电解液入口布置下电解液的流动和传热特性，我们开发了四个计算流体动力学模型。这些模型包括双向平行流 (BPF)、交错平行流 (SPF)、顶部入口单向平行流 (UPF-T) 和底部入口单向平行流 (UPF-B)。每个模型都进行了流动和传热模拟。模拟结果表明，BPF 和 SPF 电精炼电池表现出不同程度的动能损失，导致体积加权平均速度降低，影响电解液的快速循环。就流动均匀性和流速而言，UPF-B 最为有效，UPF-T 紧随其后。当布置 SPF 和 UPF-T 时，极间区域的温度升高，这更有利于铜离子的扩散。UPF-B 的布置提高了阴极铜的生产效率和沉积均匀性，使液体能够更快、更均匀地供应到极间区域。

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引用次数: 0

Adjoint shape optimization for enhanced heat transfer in sweeping jet impingement on concave surface 用于增强凹面上横扫射流撞击传热的邻接形状优化技术

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer

Pub Date : 2024-11-18 DOI: 10.1016/j.icheatmasstransfer.2024.108363

Jie Tang , Ziyan Li

The sweeping jet has gained increasing attention in the field of impingement heat transfer due to its unique advantages. Current research primarily focuses on impinging on flat walls, with less attention given to curved wall scenarios. Recent studies have shown that the trapped vortex ring generated by a sweeping jet impinging on a curved surface can limit the effective cooling range. Therefore, modifying the structure of the fluidic oscillator offers considerable potential for enhancing the impingement heat transfer. In this paper, the shape optimization of the conventional fluidic oscillator is performed using an adjoint optimization method. Numerical simulations were first conducted with a jet Reynolds number of 10,308, an impingement distance of four times the jet hydraulic diameter, and an impingement wall radius of ten times the jet hydraulic diameter as the operating conditions. To accurately reproduce the jet dissipation characteristics and the trapped vortex ring structure, the turbulent dissipation rate was modeled with a well calibrated Generalized

k

-

ω

(GEKO) model. The optimized structure aimed to minimize the surface-averaged temperature. The results indicated that the improved structure reduced the jet's oscillation angle, resulting in a more concentrated jet velocity and less dissipation. This intensified the strength of the wall jet in the non-oscillation plane and pushed the trapped vortex ring farther outward, thus increasing the effective cooling range. Time- and surface-averaged results on the impingement wall revealed that the Nusselt number of the improved structure increased by 11.6%, and the temperature decreased by 2.4 K compared to the baseline structure.

扫掠射流因其独特的优势，在撞击传热领域受到越来越多的关注。目前的研究主要集中在平面壁面上的撞击，而较少关注曲面壁面的情况。最近的研究表明，冲击弯曲表面的横扫射流产生的滞留涡环会限制有效冷却范围。因此，改变流体振荡器的结构为增强撞击传热提供了相当大的潜力。本文采用邻接优化法对传统流体振荡器的形状进行了优化。首先以射流雷诺数为 10308、撞击距离为射流水力直径的四倍、撞击壁半径为射流水力直径的十倍为工作条件进行了数值模拟。为了准确再现射流耗散特性和捕获涡环结构，湍流耗散率采用了校准良好的广义 k-ω (GEKO) 模型。优化结构的目的是最大限度地降低表面平均温度。结果表明，改进后的结构减小了射流的摆动角，使射流速度更集中，耗散更少。这增强了非振荡面上壁面射流的强度，并将受困涡旋环向外推得更远，从而扩大了有效冷却范围。撞击壁的时间和表面平均结果显示，与基线结构相比，改进结构的努塞尔特数增加了 11.6%，温度降低了 2.4 K。

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引用次数: 0

Experimental investigation of enhanced heat transfer in plate heat exchanger under heaving and yawing conditions 板式热交换器在翻转和偏航条件下强化传热的实验研究

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer

Pub Date : 2024-11-18 DOI: 10.1016/j.icheatmasstransfer.2024.108307

Dan Hua, Lizeen Zhang, Yi Chen, Jintao Chen, Feng Yao

An investigation into the heat transfer characteristics of plate heat exchangers operating within cooling systems of offshore floating wind turbines under marine sloshing conditions is presented herein. Utilizing a six-degree-of-freedom motion platform in conjunction with a plate heat exchanger performance testing setup, the effects of yawing and heaving motions, mass flow rates, sloshing amplitudes, frequencies, and intensities on the heat transfer characteristics of R134a plate heat exchangers were systematically explored. The Results indicate that both heaving and yawing significantly enhance the heat transfer performance, with heaving conditions showing a more pronounced effect. At a heaving amplitude of 100 mm and a frequency of 0.6 Hz, the convective heat transfer coefficient of R134a can be increased by up to 61.80 %. Heaving amplitude has a more substantial impact on heat transfer performance compared to yawing amplitude. The heat transfer correlation for R134a plate heat exchangers under yawing and heaving conditions has been presented, showing good predictive capabilities with deviations confined within ±15 %.

本文介绍了对海上浮动风力涡轮机冷却系统中的板式热交换器在海洋倾覆条件下的传热特性的研究。利用六自由度运动平台和板式热交换器性能测试装置，系统地探讨了偏航和翻腾运动、质量流量、滑动幅度、频率和强度对 R134a 板式热交换器传热特性的影响。结果表明，翻腾和偏航都能显著提高传热性能，其中翻腾条件的影响更为明显。当翻腾幅度为 100 毫米、频率为 0.6 赫兹时，R134a 的对流传热系数最高可提高 61.80%。与偏航振幅相比，起伏振幅对传热性能的影响更大。研究还介绍了偏航和翻腾条件下 R134a 板式热交换器的传热相关性，结果表明其具有良好的预测能力，偏差限制在 ±15 % 范围内。

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引用次数: 0

An experimental comparative analysis and machine learning prediction on the evaporation characteristics of R1234yf and R290/R13I1 in a plate heat exchanger 板式热交换器中 R1234yf 和 R290/R13I1 蒸发特性的实验对比分析和机器学习预测

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer

Pub Date : 2024-11-18 DOI: 10.1016/j.icheatmasstransfer.2024.108357

Rajendran Prabakaran , Palanisamy Dhamodharan , Thangamuthu Mohanraj , Sung Chul Kim

The present research attempts to comprehensively compare the evaporation characteristics of a novel R290/R13I1 (35/65 % by mass) with R1234yf in an offset-strip fin embedded plate heat exchanger. The impact of various testing phenomena, namely saturation temperature (T_s) (278 to 288 K), heat flux (q) (4000 to 10,000 W m⁻²), entry vapor quality (x_i) (0.1 to 0.8), and mass flux (G) (40 to 80 kg m⁻² s⁻¹) have been explored. Meanwhile, highly potential machine learning algorithms (MLAs) namely Linear Regression (LR), Multi-Layer Perceptron (MLP), and Extreme Gradient Boost regression (XGB) have been employed to predict the evaporation heat transfer coefficient (EHTC) and evaporation frictional pressure drop (EFPD) of the refrigerants. Findings revealed that the EHTC of R290/R13I1 is significantly lower than that of R1234yf by 7.9–38.8 % in the nucleation boiling or low mean vapor quality (x_m) domain, whereas it had superior EHTC by up to 18.2 % in the convective boiling domain (high x_m). Interestingly, there was a dry-out incidence at mid-x_m ranges (0.35–0.5) for both refrigerants, except for R290/R13I1 at a higher G of 80 kg m⁻² s⁻¹. In all cases (except at 10000 W m⁻²), the EFPD of R290/R13I1 increased by 0.3–11.1 % compared to that of R1234yf. The evaporation thermo-hydraulic performance (ETHP) factor analysis revealed that utilizing R290/R13I1 could perform satisfactorily in the convective boiling domain (x_m > 0.5) with an ETHP factor ranging between 0.8 and 1.08, especially at high q, high T_s, and low G conditions. New empirical correlations have been developed based on the experimental dataset for the EHTC and EFPD of the considered refrigerants with an mean absolute error (MAE) of up to 14.7 % and 13.4 %, respectively. Among the three MLAs with different enhancement methods, the EHTC and EFPD predictions using MLP, in combination with principal component analysis and hyperparameter tuning, had superior performance, with MAEs of 0.1119 and 0.0581, respectively, for R1234yf, while they were 0.1726 and 0.0482 for R290/R13I1.

本研究试图全面比较新型 R290/R13I1（质量分数为 35/65%）与 R1234yf 在偏置带翅片嵌入式板式热交换器中的蒸发特性。研究探讨了各种测试现象的影响，即饱和温度 (Ts)（278 至 288 K）、热通量 (q)（4000 至 10,000 W m-2）、入口蒸汽质量 (xi)（0.1 至 0.8）和质量通量 (G)（40 至 80 kg m-2 s-1）。同时，采用了极具潜力的机器学习算法（MLAs），即线性回归（LR）、多层感知器（MLP）和极梯度提升回归（XGB）来预测制冷剂的蒸发传热系数（EHTC）和蒸发摩擦压降（EFPD）。研究结果表明，在成核沸腾或低平均蒸汽质量（xm）域，R290/R13I1 的 EHTC 明显低于 R1234yf，低 7.9-38.8%；而在对流沸腾域（高 xm），R290/R13I1 的 EHTC 则优于 R1234yf，高达 18.2%。有趣的是，两种制冷剂在中等 xm 范围（0.35-0.5）内都出现了干涸现象，只有 R290/R13I1 在 80 kg m-2 s-1 的较高 G 值下除外。在所有情况下（10000 W m-2 除外），R290/R13I1 的 EFPD 比 R1234yf 增加了 0.3-11.1%。蒸发热液性能（ETHP）系数分析表明，R290/R13I1 在对流沸腾域（xm > 0.5）的性能令人满意，ETHP 系数介于 0.8 和 1.08 之间，尤其是在高 q、高 Ts 和低 G 条件下。根据实验数据集，为所考虑制冷剂的 EHTC 和 EFPD 建立了新的经验相关性，其平均绝对误差（MAE）分别高达 14.7 % 和 13.4 %。在采用不同增强方法的三种工作重点中，结合主成分分析和超参数调整使用 MLP 预测的 EHTC 和 EFPD 性能更优，R1234yf 的 MAE 分别为 0.1119 和 0.0581，而 R290/R13I1 的 MAE 分别为 0.1726 和 0.0482。

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引用次数: 0

A novel condensation heat transfer correction based on non-equilibrium film theory and degradation mechanism for zeotropic mixture 基于非平衡膜理论和各向同性混合物降解机理的新型凝结传热修正方法

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer

Pub Date : 2024-11-18 DOI: 10.1016/j.icheatmasstransfer.2024.108342

Zhantao Wu, Yangkai Xia, Xianglong Luo, Yingzong Liang, Jianyong Chen, Zhi Yang, Ying Chen

Energy conversion based on thermodynamic cycle using zeotropic mixtures is an effective strategy for advancing global low-carbon development in the context of carbon neutrality. However, the deficiencies of existing heat transfer mixtures models and the complex condensation mechanisms of zeotropic refrigerants pose significant challenges to the size design and optimization of heat exchangers, which can directly impact the economic efficiency and operational safety of thermodynamic cycle systems. Thus, there is an urgent need for a simplified and universal correction method that incorporates mixing effects to improve prediction accuracy of conventional models. In the present study, a non-equilibrium condensation heat transfer model based on film theory was developed and validated to analyze the influence of various parameters on heat transfer degradation and heat transfer coefficients of zeotropic mixtures inside horizontal circular tubes. Through multi-factor sensitivity analysis and dimensionless method, a degradation factor characterizing the gradient contributions to heat transfer degradation was proposed. Based on the proposed factor, a simplified non-equilibrium model considering mixing effect without complex computations was developed. Using the new developed non-equilibrium model, prediction of a database containing 1813 experimental points was conducted. A deviation of 15.7 % between the predicted values and the experimental values was achieved, demonstrating remarkable predictive accuracy and significant generalizability compared to existing mixture models. Extending this corrective method to various pure substance models resulted in a significant improvement in accuracy.

使用各向同性混合物进行基于热力学循环的能量转换是在碳中和背景下推进全球低碳发展的有效战略。然而，现有传热混合物模型的缺陷和各向同性制冷剂复杂的冷凝机制给热交换器的尺寸设计和优化带来了巨大挑战，会直接影响热动力循环系统的经济效益和运行安全。因此，迫切需要一种包含混合效应的简化通用修正方法，以提高传统模型的预测精度。本研究建立并验证了基于膜理论的非平衡冷凝传热模型，以分析各种参数对水平圆管内各向同性混合物传热降解和传热系数的影响。通过多因素敏感性分析和无量纲方法，提出了表征传热退化梯度贡献的退化因子。根据提出的因子，开发了一个考虑混合效应的简化非平衡模型，无需进行复杂计算。利用新开发的非平衡模型，对包含 1813 个实验点的数据库进行了预测。预测值与实验值之间的偏差为 15.7%，与现有的混合物模型相比，显示出显著的预测准确性和可推广性。将这种校正方法扩展到各种纯物质模型后，准确性有了显著提高。

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引用次数: 0

Wall heat partitioning model with bubble tracking method for nucleate boiling considering conjugate heat transfer coupled with OpenFOAM 考虑共轭传热并与 OpenFOAM 相结合的成核沸腾气泡跟踪法壁热分区模型

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer

Pub Date : 2024-11-18 DOI: 10.1016/j.icheatmasstransfer.2024.108364

Ja Hyun Ku , Heepyo Hong , Jae Soon Kim , Hyoung Kyu Cho

This study aimed to predict boiling heat transfer more accurately by incorporating the bubble tracking method and conjugate heat transfer into the conventional heat partitioning model. The bubble tracking method is developed to predict boiling heat transfer by continuously simulating the size and location of individual bubbles and simulating realistic phenomena in boiling, unlike previous methods for predicting boiling heat transfer. The method considers several factors that were not previously considered, including the stochastic behavior of the boiling process, interaction between bubbles, interaction between nucleation sites, and microlayer evaporation considering the thickness and radius of the microlayer. Additionally, it was validated for pool boiling experiments. In this study, the model was improved by incorporating conjugate heat transfer for the wall temperature variation that was not considered in the previous study, and the method was also validated with the pool boiling experiment. In this validation, the temporal and spatial surface temperature variation seen in the single-bubble experiment was well simulated, and the trends in heat flux observed in the multi-bubble experiment were well predicted.

本研究旨在将气泡跟踪法和共轭传热纳入传统的热分配模型，从而更准确地预测沸腾传热。与以往预测沸腾传热的方法不同，气泡跟踪法是通过连续模拟单个气泡的大小和位置以及模拟沸腾中的真实现象来预测沸腾传热的。该方法考虑了以前未曾考虑的几个因素，包括沸腾过程的随机行为、气泡之间的相互作用、成核点之间的相互作用以及考虑到微层厚度和半径的微层蒸发。此外，该模型还在水池沸腾实验中得到了验证。本研究对模型进行了改进，加入了共轭传热，用于计算之前研究中未考虑的壁面温度变化，并通过水池沸腾实验对该方法进行了验证。在这次验证中，单气泡实验中的表面温度时空变化得到了很好的模拟，多气泡实验中的热通量趋势也得到了很好的预测。

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引用次数: 0

Comparative analysis of diffusion mechanisms inside porous media for steam methane reforming over Ni-Al2O3 catalyst Ni-Al2O3 催化剂蒸汽甲烷转化过程中多孔介质内部扩散机制的比较分析

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer

Pub Date : 2024-11-18 DOI: 10.1016/j.icheatmasstransfer.2024.108322

Igor Karpilov , Viacheslav Papkov , Dmitry Pashchenko

The catalyst particles are widely used in steam methane reforming. The main mass transport mechanism inside the catalyst particles is diffusion. Several diffusion mechanisms are used by researchers for the investigations, and no consensus has been reached on which one is more suitable. This study aims to find the appropriate diffusion mechanism for the steam methane reforming. The effect of various diffusion mechanisms on the predictive performances of the steam methane reforming process was investigated for Ni-Al

_{2}

O

_{3}

catalyst particles. Four diffusion mechanisms were considered: constant diffusion coefficient, Lewis number correlation, kinetic theory, and Bosanquet approximation. The CH

_{4}

conversion, species and temperature distributions were compared for various operating temperatures, residence time, particle diameters, pressure and H

_{2}

O/CH

_{4}

ratio (

β

). For the similar operating and design parameters, CH

_{4}

conversion obtained for Bosanquet approximation and Lewis number correlation showed close to similar results with average deviation of 2%. Other diffusion models have failed to correctly predict the CH

_{4}

conversion. It was shown that the choice of an appropriate diffusion mechanism is important for the numerical prediction of the steam methane reforming performances.

催化剂颗粒广泛应用于蒸汽甲烷转化。催化剂颗粒内部的主要质量传输机制是扩散。研究人员在研究中使用了几种扩散机制，但对于哪种机制更合适尚未达成共识。本研究旨在找到适合蒸汽甲烷转化的扩散机制。针对 Ni-Al2O3 催化剂颗粒，研究了各种扩散机制对蒸汽甲烷转化过程预测性能的影响。考虑了四种扩散机制：恒定扩散系数、路易斯数相关、动力学理论和博桑凯近似。比较了不同操作温度、停留时间、颗粒直径、压力和 H2O/CH4 比率 (β)下的 CH4 转化率、物种和温度分布。对于相似的操作和设计参数，博桑凯特近似法和路易斯数相关法得到的 CH4 转化率显示出接近相似的结果，平均偏差为 2%。其他扩散模型未能正确预测 CH4 转化率。研究表明，选择合适的扩散机制对于蒸汽甲烷转化性能的数值预测非常重要。

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引用次数: 0

Numerical characterisation of the convective heat transfer and fluid flow for inline woven wire meshes in solar volumetric receivers 太阳能容积式接收器中内嵌编织金属丝网的对流传热和流体流动的数值特性分析

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer

Pub Date : 2024-11-18 DOI: 10.1016/j.icheatmasstransfer.2024.108269

Daniel Sanchez-Señoran , Miguel A. Reyes-Belmonte , Meryem Farchado , Marina Casanova , Antonio L. Avila-Marin

In solar tower systems, metallic woven wire meshes following an inline arrangement are a promising geometry for commercial application in open volumetric receivers (OVRs). To assess their potential, two main parameters, with two different methodologies, need to be analysed in depth: the convective heat transfer coefficient (HTC) and the pressure drop per unit length (ΔP/L). In this study, three wire diameters, 0.7, 0.4 and 0.1 mm, with a fixed porosity of 80 %, have been selected to establish a baseline for the HTC and the ΔP/L sensitivity studies. In the HTC methodology, six air inlet velocities between 0.5 and 5 m/s, and constant solid matrix temperatures of 700, 1100 and 1500 K, have been evaluated. For the ΔP/L methodology, six air inlet velocities between 0.5 and 5 m/s and a constant solid matrix temperature of 300 K was used.

For each thermo-fluid-dynamic attribute, HTC and ΔP/L, and each wire diameter (0.7, 0.4 and 0.1 mm) with 80 % porosity, an individual correlation is presented resulting in a total of six individual correlations. In addition, two generalised correlations, one of each thermo-fluid-dynamic attribute, for 80 % porosity and wire diameter ranging from 0.1 to 0.7 mm are shown, taking into account the specific geometrical parameters of the wire mesh lattices. The generalised correlations obtained in the study present deviations under 7 % from the CFD results in both thermo-fluid-dynamic attributes, showing results as good as the ones obtained with the individual correlations. As a result, it is demonstrated that the geometrical parameters must be included in the correlations used to predict the thermo-fluid-dynamic attributes in wire mesh lattices. All the correlations have been validated through porous models with good agreement and they would work for future optimisation studies.

在太阳能塔系统中，金属编织网采用内嵌式布置，是开放式容积式接收器（OVR）中具有商业应用前景的几何形状。为了评估其潜力，需要用两种不同的方法深入分析两个主要参数：对流传热系数（HTC）和单位长度压降（ΔP/L）。在本研究中，我们选择了三种直径（0.7、0.4 和 0.1 毫米）、孔隙率固定为 80% 的金属丝，为 HTC 和 ΔP/L 敏感性研究建立基线。在 HTC 方法中，评估了 0.5 至 5 m/s 之间的六种进气速度，以及 700、1100 和 1500 K 的恒定固体基质温度。对于每种热流体动力属性、HTC 和 ΔP/L，以及孔隙率为 80% 的每种金属丝直径（0.7、0.4 和 0.1 毫米），都提出了一个单独的相关性，从而产生了总共六个单独的相关性。此外，考虑到金属丝网格的具体几何参数，还显示了两个通用相关性，即孔隙率为 80%、金属丝直径为 0.1 至 0.7 毫米时的每个热流体力学属性的一个通用相关性。研究中获得的通用相关性在两个热流体动力属性方面与 CFD 结果的偏差均小于 7%，显示出与使用单个相关性获得的结果一样好的结果。结果表明，用于预测金属丝网网格热流体动力属性的相关性中必须包含几何参数。所有相关性都通过多孔模型进行了验证，结果一致良好，可用于未来的优化研究。

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引用次数: 0

Parameterized physics-informed neural networks for a transient thermal problem: A pure physics-driven approach 针对瞬态热问题的参数化物理信息神经网络：纯物理驱动方法

IF 6.4 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer

Pub Date : 2024-11-18 DOI: 10.1016/j.icheatmasstransfer.2024.108330

Maysam Gholampour , Zahra Hashemi , Ming Chang Wu , Ting Ya Liu , Chuan Yi Liang , Chi-Chuan Wang

Parameterization in computational fluid dynamics is crucial for exploring design ranges and optimizing systems. Traditional methods struggle with efficient parameter variation, requiring multiple simulations and significant computational resources. This study evaluates physics-informed neural networks (PINNs) to address this challenge, highlighting its ability to handle multiple parameter variations, including geometric configurations, Rayleigh, and Prandtl numbers, within different intervals in a single training process. The study focuses on a highly challenging problem in PINNs: transient natural convection, characterized by transient coupled equations with source terms. Although some issues have been previously addressed, applying pure physics-driven PINNs to transient natural convection and parameterization challenges represents a novel approach. The model, benchmarked against finite difference, finite element, and finite volume methods, shows excellent predictive accuracy but surpasses them in versatility and robustness when handling several parameter variations simultaneously. The results show that the computational cost increases by 15 % for parameterizing a single parameter and by 46 % for parameterizing all three parameters simultaneously. Moreover, special normalization techniques for large-scale parameters, such as Rayleigh number, are crucial for parameterized models; without them, the training process may diverge. This paper provides insights and techniques to overcome the challenges in parameterization for coupled problems with source terms.

计算流体动力学中的参数化对于探索设计范围和优化系统至关重要。传统方法难以实现有效的参数变化，需要多次模拟和大量计算资源。本研究评估了物理信息神经网络（PINNs）应对这一挑战的能力，强调其在单次训练过程中处理不同区间内多种参数变化的能力，包括几何配置、瑞利和普朗特数。研究重点是 PINNs 中一个极具挑战性的问题：瞬态自然对流，其特点是带有源项的瞬态耦合方程。虽然之前已经解决了一些问题，但将纯物理驱动的 PINNs 应用于瞬态自然对流和参数化挑战是一种新方法。该模型以有限差分法、有限元法和有限体积法为基准，显示出卓越的预测精度，但在同时处理多个参数变化时，其通用性和鲁棒性超过了这些方法。结果表明，对单个参数进行参数化时，计算成本会增加 15%，而同时对所有三个参数进行参数化时，计算成本会增加 46%。此外，大规模参数（如瑞利数）的特殊归一化技术对参数化模型至关重要；如果没有这些技术，训练过程可能会出现偏差。本文提供了克服带源项耦合问题参数化挑战的见解和技术。

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引用次数: 0