International Journal of Thermofluids最新文献

Numerical simulation of flow and mixing in fracture intersections 断口交叉处流动与混合的数值模拟

Q1 Chemical Engineering

International Journal of Thermofluids

Pub Date : 2025-04-24 DOI: 10.1016/j.ijft.2025.101229

Qinjun Kang, Jeffrey D. Hyman, Philip H. Stauffer, Hari Viswanathan

Fluid transport through fractured geological formations is strongly influenced by the redistribution of solutes at fracture intersections. In this study, we perform detailed numerical simulations of flow and scalar transport within the intersection of two smooth, planar fractures. The analysis focuses on the mixing ratio, the proportion of solute flux exiting along the outlet branch aligned with the primary inlet flow direction, relative to the total solute flux at the outlets. We systematically investigate how the mixing ratio varies with four key parameters: Peclet number, Reynolds number, flow rate ratio between outlet branches, and fracture intersection angle. Results show that the mixing ratio decreases with increasing Peclet number and outlet flow rate ratio, consistent with reduced diffusive spreading and enhanced streamline routing. While low Reynolds numbers have minimal impact, inertial effects at higher Reynolds numbers significantly increase the mixing ratio. Additionally, acute and obtuse intersection angles alter flow partitioning and modify the solute distribution at the outlets. These findings provide a quantitative basis for incorporating physically realistic mixing behavior—intermediate between complete mixing and streamline-following assumptions—into network-scale transport models. The results have direct relevance to subsurface energy systems, including geothermal energy production, carbon sequestration, and contaminant remediation.

流体在裂缝性地质构造中的运移受到裂缝交叉处溶质再分布的强烈影响。在这项研究中，我们对两个光滑的平面裂缝相交处的流动和标量输运进行了详细的数值模拟。分析的重点是混合比，即沿与主要进口气流方向一致的出口分支流出的溶质通量相对于出口总溶质通量的比例。我们系统地研究了混合比随四个关键参数（Peclet数、雷诺数、出口分支流量比和裂缝相交角）的变化规律。结果表明：混合比随着Peclet数和出口流量比的增加而减小，与扩散扩散减小和流线走向增强一致；低雷诺数对混合比的影响很小，而高雷诺数下的惯性效应显著提高了混合比。此外，锐角和钝角相交改变了流动分配，并改变了出口的溶质分布。这些发现为将物理上真实的混合行为（介于完全混合和遵循流线假设之间）纳入网络尺度输运模型提供了定量基础。研究结果与地下能源系统直接相关，包括地热能生产、碳封存和污染物修复。

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引用次数: 0

Experimental analysis of hydroxyapatite nanofluid for enhanced thermal performance in solar evacuated tube collectors 羟基磷灰石纳米流体增强太阳能真空管集热器热性能的实验分析

Q1 Chemical Engineering

International Journal of Thermofluids

Pub Date : 2025-04-24 DOI: 10.1016/j.ijft.2025.101230

T. Sathish

Sustainable Development Goals motivated this investigation for effective energy harvesting. Thermal performance enhancement helps sustainable energy practices by minimizing fossil fuel use while establishing cleaner energy technologies. The study uses hydroxyapatite and deionized water as working fluids with the mass flow rate of 0.5–1.5 lit/min to experimentally examine the thermal performance of heat pipe-based solar evacuated tube collectors. Samples of hydroxyapatite nanofluid with varying volume fraction as 0.05 %, 0.1 %, and 0.15 % have been used in deionized water. The structure of hydroxyapatite has been examined using a scanning electron microscope, and its structural characteristics were ascertained using X-ray diffraction. The Zeta potential measurement was performed to assess the permanency of the working fluid samples and revealed that the generated samples were stable for as long as 30 days. It was investigated and discussed how changing concentrations of the nanofluid affected its thermophysical characteristics. An impact mass flow rate and volumetric concentrations for nanofluid were considered when examining the thermal performance of SETC. In contrast with water, the thermal performance has been achieved at higher in SETC as 38.5 % at the volume fraction as 0.15 % at the mass flow rate as 1.5 lit/min. The results indicate that employing nanofluid samples significantly increases the temperature differential and energy gain. Based on research outcomes, these proposed findings are suitable for industrial and household applications.

可持续发展目标推动了这项有效收集能源的调查。热性能的提高有助于减少化石燃料的使用，同时建立更清洁的能源技术，从而实现可持续能源实践。本研究以羟基磷灰石和去离子水为工质，质量流量为0.5 ~ 1.5 lit/min，对热管太阳能真空管集热器的热性能进行了实验研究。在去离子水中使用了体积分数为0.05%、0.1%和0.15%的羟基磷灰石纳米流体样品。用扫描电镜观察了羟基磷灰石的结构，并用x射线衍射确定了其结构特征。Zeta电位测量用于评估工作流体样品的持久性，结果显示生成的样品在长达30天的时间内是稳定的。研究并讨论了纳米流体浓度变化对其热物理特性的影响。在研究SETC的热性能时，考虑了冲击质量流量和纳米流体的体积浓度。与水相比，在体积分数为38.5%时，在质量流量为1.5 lit/min时，其热性能达到了0.15%。结果表明，采用纳米流体样品可以显著提高温差和能量增益。根据研究结果，这些建议的发现适用于工业和家庭应用。

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引用次数: 0

Design and hydrodynamic performance of low head propeller hydro turbine for wide range high efficiency operation 大范围高效运行低水头螺旋桨水轮机的设计与水动力性能

Q1 Chemical Engineering

International Journal of Thermofluids

Pub Date : 2025-04-22 DOI: 10.1016/j.ijft.2025.101228

Thaithat Sudsuansee , Suwat Phitaksurachai , Rudklao Pan-Aram , Noppong Sritrakul , Yodchai Tiaple

The primary aim of this investigation is to examine the design and hydrodynamic efficiency of a low head propeller hydro turbine tailored for efficient functionality within a diverse range of water head conditions, ranging from 3 to 11 m By employing sophisticated computational fluid dynamics (CFD) simulations and meticulous experimentation, the study endeavors to enhance the design parameters of the propeller hydro turbine to ensure peak efficiency and dependability. This investigation thoroughly examines various design factors, including the runner blade's angle, and the guide vane's angle, aiming to identify the most effective configuration that guarantees exceptional performance across various scenarios. The turbine demonstrated exceptional adaptability, achieving peak efficiencies of 76. 40 % at a head of 3 m, 77.34 % at 7 m, and 78.03 % at 11 m, with a maximum power output of 81.09 kW achieved at 11 m and 800 RPM. These results highlight the turbine's ability to maintain high performance across varying hydraulic conditions. Emphasis is particularly placed on establishing accurate boundary conditions, incorporating turbulent modeling through the Shear Stress Transport (SST) k-ω model, and utilizing advanced mesh generation techniques, notably the Poly-Hexcore mesh technology. By integrating advanced simulation approaches and meshing methodologies, this research aims to refine the precision and effectiveness of turbine design procedures, ultimately contributing to the progression of sustainable energy generation technologies. The outcomes of this study are anticipated to make a substantial contribution to the realm of renewable energy production by enhancing the comprehension and enhancement of low head propeller hydro turbine technology for superior performance and sustainability in energy generation.

本研究的主要目的是研究一种低水头螺旋桨水轮机的设计和水动力效率，该水轮机在不同水头条件下（从3到11米）具有高效的功能。通过复杂的计算流体动力学（CFD）模拟和细致的实验，研究努力提高螺旋桨水轮机的设计参数，以确保峰值效率和可靠性。这项研究彻底检查了各种设计因素，包括流道叶片的角度和导叶的角度，旨在确定最有效的配置，保证在各种情况下的卓越性能。涡轮机表现出了卓越的适应性，达到了76的峰值效率。在水头高度为3米时为40%，在水头高度为7米时为77.34%，在水头高度为11米时为78.03%，在11米和800转/分时的最大功率输出为81.09千瓦。这些结果突出了涡轮在不同水力条件下保持高性能的能力。重点是建立准确的边界条件，通过剪切应力传输（SST） k-ω模型结合湍流建模，并利用先进的网格生成技术，特别是Poly-Hexcore网格技术。通过整合先进的仿真方法和网格划分方法，本研究旨在改进涡轮设计程序的精度和有效性，最终为可持续能源发电技术的发展做出贡献。预计本研究的结果将通过提高对低水头螺旋桨水轮机技术的理解和改进，为可再生能源生产领域做出重大贡献，以实现能源发电的卓越性能和可持续性。

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引用次数: 0

A comprehensive review on natural convection in trapezoidal cavities with mono and hybrid nanofluids 单纳米流体和混合纳米流体在梯形空腔中的自然对流综述

Q1 Chemical Engineering

International Journal of Thermofluids

Pub Date : 2025-04-21 DOI: 10.1016/j.ijft.2025.101226

Farhan Lafta Rashid , Zainab Abdul Karim Alkhekany , Muhammad Asmail Eleiwi , Abdallah Bouabidi , Shabbir Ahmad , Atef Chibani , Mohamed Kezzar , Saif Ali Kadhim , Ali Habeeb Askar , Karrar A. Hammoodi

This review synthesises advancements in natural convection within trapezoidal cavities using mono- and hybrid nanofluids, emphasising their geometric advantages for thermal management. Trapezoidal cavities promote asymmetric flow patterns that enhance heat transfer compared to conventional geometries, as demonstrated in applications like solar absorbers and electronic cooling. Through analysis of 50+ previous studies, the review identifies key trends: Hybrid nanofluids like Cu-Al₂O₃/water consistently outperform mono nanofluids in Nusselt number improvement, with gains exceeding 20 %. Inclined walls mitigate stagnant flow zones, though exact reduction rates vary with aspect ratio and nanoparticle concentration. Magnetic fields and porous media further modulate thermal performance, but trade-offs emerge between conductivity enhancement and viscosity penalties. This review provides a framework to optimise trapezoidal cavities with nanofluids for industrial deployment.

这篇综述综合了使用单一和混合纳米流体在梯形腔内自然对流方面的进展，强调了它们在热管理方面的几何优势。与传统的几何形状相比，梯形腔促进了不对称的流动模式，增强了传热，这在太阳能吸收器和电子冷却等应用中得到了证明。通过分析50多个先前的研究，该综述确定了关键趋势：混合纳米流体，如Cu-Al₂O₃/水，在努塞尔数改善方面始终优于单一纳米流体，收益超过20%。倾斜壁面可以缓解停滞流动区，但确切的减少率随长径比和纳米颗粒浓度而变化。磁场和多孔介质进一步调节热性能，但在导电性增强和粘度损失之间存在权衡。本文综述提供了一个框架，以优化梯形腔与纳米流体的工业部署。

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引用次数: 0

Experimental study on flow properties of jojoba oil-diesel fuel blends with/without alcohols additives 加/不加醇类添加剂荷荷巴油-柴油混合燃料流动特性的实验研究

Q1 Chemical Engineering

International Journal of Thermofluids

Pub Date : 2025-04-21 DOI: 10.1016/j.ijft.2025.101227

Mamdouh Ghannam , Mohamed Y.E. Selim , Ahmed Thaher , Budoor Aljneibi , Fajr Alhammadi , Buthaina Albreiki

The flow characteristics of different jojoba oil–diesel fuel blends (JDFBs) with and without additives (diethyl ether or Butanol at 5, 10 or 15 %) were experimentally examined to assess their flow performance in comparison with diesel fuel. The density and kinematic viscosity of jojoba oil, diesel fuel, and their blends were measured using an SVM 3000 Stabinger Viscometer (Anton Paar). Rheograms and viscosity–shear rate profiles were derived using the MCR 92 Modular Compact Rheometer. The density of pure diesel fuel increases slightly upon the addition of jojoba oil. For example, at 40 °C, the density increases from 0.813 g/cm³ for pure diesel to 0.87 g/cm³ for the JDFB with 50 % jojoba oil content. Moreover, the kinematic viscosity increases gradually with jojoba oil content, ranging from 4.06 cSt for pure diesel to 4.76, 9.16, and 20.30 cSt for JDFBs containing 10 %, 25 %, and 50 % jojoba oil at 20 °C, respectively. The power-law model can predict the flow behavior of JDFBs up to 50 % jojoba oil content. The dynamic viscosity increases from 3.60 mPa.s for pure diesel to 4.97, 6.75, and 12.17 mPa.s for JDFBs containing 10 %, 25 %, and 50 % jojoba oil, respectively, at 20 °C. The increase in the viscosity of the blend was managed either by heating and / or adding non-viscous alcohols. At 60 °C, the viscosity reduction reaches approximately 64 % for the JDFB with 50 % jojoba oil content. The viscosity reduction is more notable when using diethyl ether as an additive than when using butanol. For instance, the 15 % of Butanol addition, caused the viscosity of the blend to be very much comparable to the diesel fuel.

实验研究了不同荷荷巴油-柴油混合燃料（JDFBs）在添加和不添加添加剂（乙醚或丁醇5%、10%或15%）的情况下的流动特性，以评估其与柴油燃料的流动性能。利用Anton Paar的SVM 3000 Stabinger粘度计测量了荷荷巴油、柴油及其混合物的密度和运动粘度。流变图和粘剪率曲线是使用MCR 92模块化紧凑型流变仪得出的。加入荷荷巴油后，纯柴油的密度略有增加。例如，在40°C时，密度从纯柴油的0.813 g/cm3增加到含有50%荷荷巴油的JDFB的0.87 g/cm3。此外，随着荷荷巴油含量的增加，运动粘度逐渐增加，在20°C时，纯柴油的运动粘度从4.06 cSt增加到含10%、25%和50%荷荷巴油的jdbs的运动粘度分别为4.76、9.16和20.30 cSt。幂律模型能较好地预测荷荷巴油含量达到50%时JDFBs的流动特性。动态粘度从3.60 mPa开始增加。4.97, 6.75和12.17兆帕的纯柴油。对于含有10%、25%和50%荷荷巴油的JDFBs，分别在20°C下进行处理。通过加热和/或添加非粘性醇来控制混合物粘度的增加。在60°C时，荷荷巴油含量为50%的JDFB粘度降低约64%。使用乙醚作为添加剂时，粘度的降低比使用丁醇时更显著。例如，添加15%的丁醇，导致混合物的粘度与柴油燃料非常相似。

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引用次数: 0

Unsteady Williamson nanofluid flow over a rotating cone: Effects of variable properties, thermal radiation, and chemical reactions 非定常Williamson纳米流体在旋转锥上的流动：可变性质、热辐射和化学反应的影响

Q1 Chemical Engineering

International Journal of Thermofluids

Pub Date : 2025-04-20 DOI: 10.1016/j.ijft.2025.101211

Endale Ersino Bafe, Mitiku Daba Firdi, Lemi Guta Enyadene

This study investigates the unsteady flow of Williamson nanofluid over a vertically rotating cone, incorporating the effects of variable thermophysical properties, chemical reactions, and thermal radiation. A self-similarity transformation reduces the governing PDEs to ODEs. The spectral relaxation method is utilized for numerical solutions under specified wall temperature and concentration (SWTC), as well as specified thermal and solutal flux (STSF) conditions. A grid independence and residual norm analysis confirm the robustness of the numerical scheme, which is further benchmarked against standard solvers. A parametric sensitivity analysis, involving

\pm 20 %

perturbations, identifies the most influential parameters affecting thermal and solutal transport. Results reveal that tangential and azimuthal momentum components exhibit inverse responses to parameter variations. Variable thermal conductivity and solutal diffusivity enhance temperature and concentration fields under SWTC conditions but reduce them in the STSF scenario. A simultaneous increase in variable viscosity and suction/injection parameters significantly elevates the tangential and azimuthal skin friction coefficients. The Nusselt number rises by 58.34% with simultaneous increases in variable thermal conductivity and linear radiation parameters, and by 81.10% when nonlinear radiation parameter is considered instead, highlighting the effectiveness of nonlinear radiation in enhancing thermal performance. Moreover, chemical reactions increase mass transfer, while enhanced variable diffusivity suppresses it. The findings offer practical insights for optimizing heat and mass transfer in rotating systems such as drilling and rotary filtration units.

本研究考察了Williamson纳米流体在垂直旋转锥体上的非定常流动，考虑了不同热物理性质、化学反应和热辐射的影响。自相似转换将控制pde减少为ode。利用谱松弛法求解了特定壁温浓度（SWTC）和特定热通量（STSF）条件下的数值解。网格独立性和剩余范数分析证实了数值格式的鲁棒性，并进一步对标准解进行了基准测试。参数敏感性分析，涉及±20%的扰动，确定了影响热和溶质输运的最具影响力的参数。结果表明，切向和方位角动量分量与参数变化呈反比。热导率和溶质扩散率的变化增强了SWTC条件下的温度和浓度场，而在STSF条件下则降低了温度和浓度场。同时增加可变粘度和吸入/注射参数会显著提高切向和方位角表面摩擦系数。同时增加变导热系数和线性辐射参数时，Nusselt数增加58.34%，考虑非线性辐射参数时，Nusselt数增加81.10%，凸显了非线性辐射增强热性能的有效性。此外，化学反应增加了传质，而增强的可变扩散率抑制了传质。这些发现为优化钻井和旋转过滤装置等旋转系统的传热传质提供了实用的见解。

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引用次数: 0

Heat transfer improvement in turbulent flow using detached obstacles in heat exchanger duct 利用换热器管内分离障碍物改善紊流换热

Q1 Chemical Engineering

International Journal of Thermofluids

Pub Date : 2025-04-18 DOI: 10.1016/j.ijft.2025.101225

Omar Ghoulam , Hind Talbi , Kamal Amghar , Abdel-illah Amrani , Adil Charef , Ismael Driouch

The current study aims to enhance the effectiveness of a cooling system by introducing vertical and detached obstacles within a rectangular channel to create singularities in the flow. This study focuses on a numerical simulation to investigate the effects of these detached obstacles on forced convective airflow (cooling fluid) in a turbulent flow within a heat exchanger's rectangular channel. The mathematical model governing the fluid flow and heat transfer is based on the Finite Volume Method (FVM) and solves the Navier-Stokes equations under the assumption of steady-state, incompressible flow with constant fluid properties. Two types of obstacles were considered: planar (Type A) and diamond-shaped (Type B), with four different spacings (S = s/2, S = s, S = 5s/4, and S = 3s/2). The simulations were carried out for Reynolds numbers (Re) ranging from 20,000 to 35,000. The CFD calculations employed the SIMPLE algorithm with the QUICK scheme for discretizing the governing equations. The analysis included the impact of obstacle geometry and spacing on hydrothermal interactions, focusing on axial velocity, dynamic pressure, local and average Nusselt numbers, friction factor, and thermal enhancement factor. The results show that diamond-shaped obstacles significantly outperform planar obstacles in terms of both hydrothermal performance and thermal enhancement. Additionally, increasing the distance between the detached obstacles leads to a higher average Nusselt number.

目前的研究旨在通过在矩形通道内引入垂直和分离的障碍物来提高冷却系统的效率，从而在流动中产生奇点。本研究主要通过数值模拟来研究这些分离障碍物对换热器矩形通道内湍流中强制对流气流（冷却流体）的影响。控制流体流动和传热的数学模型基于有限体积法（FVM），并在流体性质恒定的稳态不可压缩流动假设下求解Navier-Stokes方程。我们考虑了两种类型的障碍物：平面（A型）和菱形（B型），它们有四种不同的间距（S = S /2, S = S, S = 5s/4和S = 3s/2）。模拟的雷诺数（Re）范围为20,000至35,000。CFD计算采用SIMPLE算法和QUICK格式对控制方程进行离散。分析了障碍物几何形状和间距对热液相互作用的影响，重点分析了轴向速度、动压力、局部和平均努塞尔数、摩擦因子和热增强因子。结果表明，菱形障碍物在水热性能和热增强方面都明显优于平面障碍物。此外，增加分离障碍物之间的距离会导致更高的平均努塞尔数。

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引用次数: 0

Comparative analysis of machine learning models for wind speed forecasting: Support vector machines, fine tree, and linear regression approaches 风速预报机器学习模型的比较分析：支持向量机、精细树和线性回归方法

Q1 Chemical Engineering

International Journal of Thermofluids

Pub Date : 2025-04-18 DOI: 10.1016/j.ijft.2025.101217

Yousef Altork

Wind speed is an important parameter of wind energy conversion, and its forecast is significant for optimal power generation and maintaining the stability of the electricity supply. In this work, three predictive models, namely Fine Tree, Support Vector Machine (SVM), and Linear Regression, are assessed using meteorological data from the National Wind Technology Center (NWTC) in Boulder, Colorado, for the period 2019–2023. The meteorological variables that have been incorporated into the dataset are wind direction, air temperature, relative humidity, atmospheric pressure, precipitation, and wind speed at 50 m height. The evaluation of the performance of the models used Root mean squared error (RMSE), mean squared error (MSE), mean absolute error (MAE), and coefficient of determination (R²). The findings show that the Linear Regression model has the best accuracy (RMSE = 0.29555, MSE = 0.08735, MAE = 0.18061, R² = 0.97), followed by the SVM model (RMSE = 0.32275, R² = 0.96) and then the Fine Tree model (RMSE = 0.44042, R² = 0.93). These results have demonstrated Linear Regression in enhancing wind speed prediction, where future studies should investigate the combination of the forecasted models or other different machine learning models to improve the accuracy of prediction internationally.

风速是风能转换的重要参数，风速的预测对优化发电和保持供电稳定具有重要意义。在这项工作中，使用2019-2023年期间科罗拉多州博尔德国家风能技术中心（NWTC）的气象数据，评估了三种预测模型，即Fine Tree， Support Vector Machine （SVM）和Linear Regression。已纳入数据集的气象变量为风向、气温、相对湿度、大气压、降水和50米高度的风速。使用均方根误差（RMSE）、均方误差（MSE）、平均绝对误差（MAE）和决定系数（R²）对模型的性能进行评价。结果表明，线性回归模型的准确率最高（RMSE = 0.29555, MSE = 0.08735, MAE = 0.18061, R²= 0.97），支持向量机模型次之（RMSE = 0.32275, R²= 0.96），细树模型次之（RMSE = 0.44042, R²= 0.93）。这些结果证明了线性回归在增强风速预测方面的作用，未来的研究应该研究预测模型或其他不同的机器学习模型的组合，以提高国际预测的准确性。

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引用次数: 0

Conjugated role of variant-shaped ternary hybrid nanoparticles in MHD Jeffery–Hamel Water-EG flows: New mathematical model 不同形状三元杂化纳米颗粒在MHD jeffrey - hamel Water-EG流动中的共轭作用：新的数学模型

Q1 Chemical Engineering

International Journal of Thermofluids

Pub Date : 2025-04-17 DOI: 10.1016/j.ijft.2025.101224

Nawel Benaziza , Rania Saadeh , Ayman A. Dawod , N.F.M. Noor , Ahmad Qazza , Mohamed Kezzar , Mohamed. Rafik. Sari

Present investigation uncovers thermal performance of MHD Jeffery-Hamel flows of water-ethylene glycol volume-equivalent mixtures drenched with ternary hybrid moly-alumina-titania nanoparticles of various shapes in the same base fluid (i.e. EG-H₂O〈50 %-50 %〉). The new mathematical model has been proposed to befit thermo-physical characteristics of the ternary nanofluid that encompasses the nanoparticles with distinct viscosities and thermal conductivities. In the primal stage, the governing PDEs are reduced to ODEs using the similarity reformations. In the next stage, the ensuing equations are dealt both numerically by applying the 4th-5th order Runge-Kutta-Fehlberg method and analytically through the adoption of Duan–Rach Adomian approach. The present findings are compared with the results of HAM-based Mathematica BVPh 2.0 package and those available from the literatures for several selected cases. The variations of tested parameter (i.e. Reynolds number Re ∈ [40∶ 274], Hartmann number ‘’Ha ∈ [0∶ 1000] and volume fraction is φ∈ [0∶ 0,08]) in stream and temperature profiles as well as in skin friction and Nusselt number are analyzed under the effects of variant parameters of interest such as nanoparticle volume fraction and nanoparticle shape factor. Finally the significant remarks from the findings are also concluded. The addition of solid nanoparticles to EG-water mixtures increases skin friction, causing a toll on the surface. The Nusselt number reveals unique contributions of each nanoparticle, with increasing MoS₂ or Al₂O₃ nanoparticles deterring heat flux performance. However, adding TiO₂ nanoparticle volume fraction alone boosts heat transfer performance in ternary hybrid water-EG nanoliquids passing through convergent-divergent channels.

目前的研究揭示了MHD杰弗里-哈默尔流动的热性能，该流动是由水-乙二醇体积当量混合物和不同形状的三元杂化钼-铝-二氧化钛纳米颗粒在相同的基液（即EG-H2O < 50% - 50% >）中浸透的。提出了新的数学模型，以适应三元纳米流体的热物理特性，其中包含具有不同粘度和导热系数的纳米颗粒。在初始阶段，利用相似度重构将控制偏微分方程简化为偏微分方程。在下一阶段，将采用4 -5阶Runge-Kutta-Fehlberg方法对随后的方程进行数值处理，并采用Duan-Rach Adomian方法对其进行解析处理。本文的研究结果与基于ham的Mathematica BVPh 2.0软件包的结果以及从文献中获得的结果进行了比较。在纳米颗粒体积分数和纳米颗粒形状因子等不同参数的影响下，分析了被测参数（雷诺数Re∈[40∶274]，哈特曼数Ha∈[0∶1000]，体积分数φ∈[0∶0,08]）在流体和温度剖面中的变化，以及表面摩擦和努塞尔数的变化。最后，对研究结果进行了总结。在鸡蛋水混合物中加入固体纳米颗粒会增加皮肤摩擦，从而对表面造成伤害。Nusselt数揭示了每个纳米颗粒的独特贡献，增加MoS2或Al2O3纳米颗粒会影响热通量性能。然而，单独添加TiO2纳米颗粒体积分数可以提高三元水- eg杂化纳米液体在会聚-发散通道中的传热性能。

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引用次数: 0

Enhancing thermal performance of water-air cross flow heat exchangers through upstream nozzle design and unit division 通过上游喷嘴设计和单元划分提高水气交叉换热器的热工性能

Q1 Chemical Engineering

International Journal of Thermofluids

Pub Date : 2025-04-16 DOI: 10.1016/j.ijft.2025.101223

Mahmoud Khaled

Improving water-air cross-flow heat exchangers' (HXs') thermal performance is essential for raising energy efficiency in a range of industrial applications. In order to accomplish this, prior research has mostly concentrated on altering interior geometries or flow configurations. Nevertheless, scarce are the studies about the possibilities of manipulating external airflow. This work presents and assesses a unique method for externally altering airflow arrangements in order to maximize the thermal performance of water-air cross-flow HXs. In contrast to conventional techniques that focus on internal adjustments, this study suggests a novel exterior approach that divides the HX into several smaller, face-to-face units inside the airflow and uses an upstream nozzle to boost airflow velocity over a smaller region. The goal of this design is to increase thermal efficiency without changing the HX's internal structure. To mimic the operation of a double-passage HX under various circumstances, a two-dimensional computational model was created and verified. The model evaluated the proposed HX designs' and the conventional designs' thermal performance over a variety of water flow rates and air velocities. According to the simulations, the suggested design can increase thermal performance by up to 6.1 % when compared to the conventional HX setup. Interestingly, these improvements are particularly noticeable at greater water flow rates (12,000 L/h) and moderate mean air velocities (6 m/s). Crucially, these enhancements are made without causing extra pressure drop, highlighting the design's potential for real-world uses.

改善水-空气交叉流热交换器（HXs）的热性能对于提高一系列工业应用中的能源效率至关重要。为了实现这一目标，之前的研究主要集中在改变内部几何形状或流动结构上。然而，关于控制外部气流的可能性的研究很少。这项工作提出并评估了一种独特的外部改变气流安排的方法，以最大限度地提高水-空气交叉流HXs的热性能。与专注于内部调整的传统技术相比，这项研究提出了一种新颖的外部方法，将HX分成几个较小的、面对面的气流单元，并使用上游喷嘴来提高较小区域的气流速度。这种设计的目标是在不改变HX内部结构的情况下提高热效率。为了模拟双通道HX在各种情况下的运行，建立了二维计算模型并进行了验证。该模型评估了建议的HX设计和传统设计在各种水流速率和空气速度下的热性能。根据仿真，与传统的HX设置相比，建议的设计可以提高高达6.1%的热性能。有趣的是，这些改进在较大的水流速度（12,000 L/h）和中等平均空气速度（6 m/s）时尤为明显。至关重要的是，这些增强不会造成额外的压降，突出了设计在现实世界中的应用潜力。

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引用次数: 0