International Journal of Thermofluids最新文献

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Modeling and optimization of thermal conductivity ratio of Al2O3–water nanofluid using artificial neural network and Box-Behnken design based response surface methodology with canonical analysis 基于人工神经网络和典型分析响应面Box-Behnken设计的al2o3 -水纳米流体导热系数建模与优化
International Journal of Thermofluids Pub Date : 2025-09-24 DOI: 10.1016/j.ijft.2025.101426
M․ S․ Alam , M. Masud Parveg Nayon , T. Islam , M. Sajjad Hossain , M․ M․ Rahman
{"title":"Modeling and optimization of thermal conductivity ratio of Al2O3–water nanofluid using artificial neural network and Box-Behnken design based response surface methodology with canonical analysis","authors":"M․ S․ Alam ,&nbsp;M. Masud Parveg Nayon ,&nbsp;T. Islam ,&nbsp;M. Sajjad Hossain ,&nbsp;M․ M․ Rahman","doi":"10.1016/j.ijft.2025.101426","DOIUrl":"10.1016/j.ijft.2025.101426","url":null,"abstract":"<div><div>Superior thermal characteristics, including increased thermal conductivity, enhanced convective performance, and improved thermal stability, make nanofluids attractive substitutes for enhancing the effectiveness of heat transfer. It is therefore possible to circumvent the thermo-physical constraints of regular fluids by scattering appropriate nanoparticles. This study predicts and optimizes the thermal conductivity ratio of water-aluminum oxide nanofluids using statistical response surface methodology (RSM) and artificial neural networks (ANN). A Box-Behnken design (BBD) within the RSM framework was employed to explore the relationship between independent variables, such as nanoparticle concentration (1–4 %), temperature (293-323 K), and surfactant weight (776-3104 mg), and the response function thermal conductivity ratio. Canonical analysis was also conducted to identify significant interactions among variables. For ANN, the Levenberg-Marquardt (LM) algorithm is employed to optimize the network's performance with six neurons in the hidden layer. To create second-order polynomial equations for predictive modeling, a total of 17 experiments were conducted. The accuracy of the predictive performance of RSM and ANN was evaluated using the margin of deviation (MOD), mean squared error (MSE), root mean squared error (RMSE), and coefficient of determination (<em>R²</em>). The optimal ANN configuration exhibited a high <em>R</em><sup>2</sup> (0.9945) and a low MSE error (0.0030) as compared to the RSM model. Moreover, the average error for the ANN was 1.8192 %, which is significantly less than the 3.9773 % error of RSM. Both methods were successful in forecasting the thermal conductivity ratio of aluminum oxide–water nanofluids, although the ANN method was more accurate. According to these results, ANN is a practical and effective tool for evaluating and improving heat transfer systems based on nanofluids in industrial applications.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"30 ","pages":"Article 101426"},"PeriodicalIF":0.0,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145321175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Computational study of steady micropolar hybrid nanofluid flow between permeable walls: Impact of reynolds and peclet numbers using advanced numerical methods 微极性混合纳米流体在可渗透壁间稳定流动的计算研究:用先进数值方法研究雷诺数和小波数的影响
International Journal of Thermofluids Pub Date : 2025-09-24 DOI: 10.1016/j.ijft.2025.101429
Pooriya Majidi Zar , Payam Jalili , Davood Domiri Ganji , Bahram Jalili
{"title":"Computational study of steady micropolar hybrid nanofluid flow between permeable walls: Impact of reynolds and peclet numbers using advanced numerical methods","authors":"Pooriya Majidi Zar ,&nbsp;Payam Jalili ,&nbsp;Davood Domiri Ganji ,&nbsp;Bahram Jalili","doi":"10.1016/j.ijft.2025.101429","DOIUrl":"10.1016/j.ijft.2025.101429","url":null,"abstract":"<div><div>This study investigates the steady, two-dimensional flow of a micropolar hybrid nanofluid between two parallel porous walls under varying Reynolds and Peclet numbers. Advanced numerical techniques, specifically the Akbari-Ganji Method (AGM) and the Homotopy Perturbation Method (HPM), are employed to solve the governing nonlinear differential Eqs.. The effects of key dimensionless parameters, including the Reynolds number, Peclet number, and coupling parameters, on velocity, temperature, and concentration profiles are examined. Results indicate that increasing the Reynolds number reduces the stream function, while a higher Peclet number enhances heat transfer. The influence of suction and injection on fluid dynamics and thermal behavior is also explored, revealing that suction diminishes the dimensionless parameters, whereas injection amplifies them. To enhance thermal and transport performance, Al<sub>₂</sub>O<sub>₃</sub>–SiO<sub>₂</sub> hybrid nanofluids are incorporated into the analysis, combining high thermal conductivity, stability, and biocompatibility with pH sensitivity suitable for tumor environments. These findings offer new insights into the behavior of micropolar hybrid nanofluids in porous media, contributing to the optimization of fluid flow systems in engineering applications. Moreover, due to their ability to model microstructural effects and rotational dynamics, micropolar fluids combined with Al<sub>₂</sub>O<sub>₃</sub>–SiO<sub>₂</sub> hybrids show promising potential in biomedical applications such as targeted drug delivery and cancer therapy, where precise control over transport phenomena is critical.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"30 ","pages":"Article 101429"},"PeriodicalIF":0.0,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Entropy optimization of micropolar nanofluid flow through a porous microchannel with Darcy–Forchheimer phenomenon using differential transform method: An ANOVA–Taguchi approach 微极性纳米流体通过多孔微通道的熵优化及Darcy-Forchheimer现象的微分变换方法:ANOVA-Taguchi方法
International Journal of Thermofluids Pub Date : 2025-09-23 DOI: 10.1016/j.ijft.2025.101428
Pradeep Kumar , Guruprasad M․N․ , Felicita Almeida , Youssef El Khatib , Qasem Al-Mdallal
{"title":"Entropy optimization of micropolar nanofluid flow through a porous microchannel with Darcy–Forchheimer phenomenon using differential transform method: An ANOVA–Taguchi approach","authors":"Pradeep Kumar ,&nbsp;Guruprasad M․N․ ,&nbsp;Felicita Almeida ,&nbsp;Youssef El Khatib ,&nbsp;Qasem Al-Mdallal","doi":"10.1016/j.ijft.2025.101428","DOIUrl":"10.1016/j.ijft.2025.101428","url":null,"abstract":"<div><div>This study systematically investigates the impact of key physical parameters on entropy generation and thermal behaviour in a micropolar nanofluid flowing through a horizontal microchannel using the ANOVA–Taguchi method. The Buongiorno model is employed to represent nanoparticle transport mechanisms accurately, including Brownian motion and thermophoresis. The analysis also incorporates the effects of magnetic field, fluid suction/injection, and wall boundary conditions. The presence of a porous medium is modelled using the Darcy–Forchheimer theory, while micropolar fluid theory accounts for microstructural effects through microrotation and microinertia. The resulting nonlinear governing equations are resolved numerically using the fourth–fifth order Runge–Kutta–Fehlberg method and validated via the differential transform method to ensure accuracy. The findings indicate that the material parameter increases microrotation in the upper region of the channel but reduces in the lower region, whereas the microinertia parameter exhibits the opposite trend. Higher values of the material parameter also lead to reduced entropy generation, indicating improved thermodynamic performance. Optimization analysis identifies a maximum thermal transfer rate of 1.09233 for the system. According to the ANOVA results, the Prandtl number is the most influential parameter, contributing 79.73% to the total effect on entropy generation, while the Darcy number has a minimal influence of 0.07%. These results highlight the significant role of fluid thermal properties and microstructural parameters in controlling entropy generation and heat transfer in micropolar nanofluid flows through porous microchannels.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"30 ","pages":"Article 101428"},"PeriodicalIF":0.0,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145321215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Cattaneo–Christov model for Marangoni convection in Casson fluid with thermal radiation and activation energy under dual-phase heat transfer 双相传热条件下具有热辐射和活化能的Casson流体Marangoni对流Cattaneo-Christov模型
International Journal of Thermofluids Pub Date : 2025-09-20 DOI: 10.1016/j.ijft.2025.101413
D. Prabu , Shajar Abbas , Inamullah Inam , Mustafa Bayram , Barno Abdullaeva , Afnan Al Agha , Hakim AL Garalleh , Ibrahim Mahariq
{"title":"Cattaneo–Christov model for Marangoni convection in Casson fluid with thermal radiation and activation energy under dual-phase heat transfer","authors":"D. Prabu ,&nbsp;Shajar Abbas ,&nbsp;Inamullah Inam ,&nbsp;Mustafa Bayram ,&nbsp;Barno Abdullaeva ,&nbsp;Afnan Al Agha ,&nbsp;Hakim AL Garalleh ,&nbsp;Ibrahim Mahariq","doi":"10.1016/j.ijft.2025.101413","DOIUrl":"10.1016/j.ijft.2025.101413","url":null,"abstract":"<div><div>This study investigates the effect of local thermal non-equilibrium (LTNE) conditions on the flow of Casson fluid under elastic deformation along a stretched boundary. The Cattaneo–Christov flux framework is used to model thermal and mass diffusion, incorporating non-classical effects of thermal and concentration relaxation phenomena. Furthermore, the model accounts for thermal radiation, activation energy, and an internal heat source, offering a more comprehensive representation of energy transfer in non-Newtonian fluid systems. These physical effects are particularly relevant in technical applications that require precise heat transfer control between fluid and solid phases, such as heat exchangers, geothermal systems, and thermal control devices. The model is also applicable in industrial processes that involve viscoplastic or yield-stress fluids, such as polymer extrusion, oil recovery, and food processing. By applying similarity transformations, the governing partial differential equations are reduced to a set of coupled ordinary differential equations, which are numerically solved using MATLAB’s bvp4c solver. The results reveal that increasing the interphase heat transfer coefficient <span><math><mrow><mo>(</mo><msub><mrow><mi>N</mi></mrow><mrow><mi>h</mi></mrow></msub><mo>)</mo></mrow></math></span> from 1.0 to 5.0 causes a 23.7% reduction in the fluid-phase temperature and a 31.4% reduction in the solid-phase temperature at a fixed location. Furthermore, the presence of thermal radiation (<span><math><mrow><mi>R</mi><mi>d</mi><mo>=</mo><mn>2</mn></mrow></math></span>) and internal heat generation (<span><math><mrow><mi>Q</mi><mo>=</mo><mn>1</mn><mo>.</mo><mn>5</mn></mrow></math></span>) amplifies this cooling effect by an additional 12.5% compared to the case without these effects. These findings emphasize the critical role of the LTNE parameters and energy transport mechanisms in optimizing thermal performance in engineering systems.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"30 ","pages":"Article 101413"},"PeriodicalIF":0.0,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145159706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Impacts of nanoparticle shape and periodic heating on entropy generation inside a tilted nanofluid filled rectangular cavity 纳米颗粒形状和周期性加热对倾斜纳米流体填充矩形腔内熵产的影响
International Journal of Thermofluids Pub Date : 2025-09-19 DOI: 10.1016/j.ijft.2025.101424
Md.Aslam Hossain , Md.Rafiqul Islam , Md.Nur Alam , Md. Sagib , M.A.H. Sajib , Chinmayee Podder , Bijan Krishna Saha , Md.Jakir Hossen
{"title":"Impacts of nanoparticle shape and periodic heating on entropy generation inside a tilted nanofluid filled rectangular cavity","authors":"Md.Aslam Hossain ,&nbsp;Md.Rafiqul Islam ,&nbsp;Md.Nur Alam ,&nbsp;Md. Sagib ,&nbsp;M.A.H. Sajib ,&nbsp;Chinmayee Podder ,&nbsp;Bijan Krishna Saha ,&nbsp;Md.Jakir Hossen","doi":"10.1016/j.ijft.2025.101424","DOIUrl":"10.1016/j.ijft.2025.101424","url":null,"abstract":"<div><div>This paper deals with the utilization of <em>TiO</em><sub>2</sub>-water nanofluid to investigate the MHD free convection (FC) flow and entropy generation inside a tilted rectangular cavity in the presence of uniform magnetic field. The bottom and the left vertical walls of the cavity are heated periodically, but the right vertical one is kept cool with a comparatively low temperature. The upper wall is a superb insulator. The walls are in no slip boundary condition. The novelty of this work lies in the fact that, to date, no study has been addressed entropy generation optimization in cavities considering the both effects of inclination and periodic heating, as far as the author know. An analysis is conducted on the optimization of local entropy (LE) that results from the combination of HT and fluid movement throughout FC. The study of temperature distributions in terms of isothermal contours (IC), fluid flow patterns in terms of stream functions (SF) and HT rate in terms of <em>Nu</em> are presented in this investigation. The simulation is carried out for 10<sup>3</sup> ≤ Ra ≤ 10<sup>6</sup>, 0 ≤ φ ≤ 0.04,  30<sup>0</sup> ≤ ω ≤ 90<sup>0</sup>, 0 ≤ <em>Ha</em> ≤ 80 and 0.2 ≤ AR ≤ 0.8. The continuity, momentum and energy equations are solved with the help of finite element Galerkin method after transforming them into non-dimensional form using some non-dimensional variables. The findings reveal that heat transfer and entropy generation in nanofluid-filled tilted cavities are strongly influenced by thermal, magnetic, particulate, and geometric parameters. High Ra and lamina-shaped nanoparticles enhance convection and heat transport, though at the expense of increased irreversibility, while moderate <em>Ha</em> and low-to-moderate particle concentrations (φ ≈ 0.02) provide an optimal balance of efficiency. Geometric optimization, particularly an inclination angle of ω ≈ 60° and aspect ratio AR ≈ 0.4, minimizes entropy generation while maintaining effective circulation. These findings are significant as they establish optimal parameter ranges that enhance heat transfer while maintaining energy efficiency, providing practical design strategies for thermal management. Such insights are highly relevant to applications like electronic cooling, solar collectors, energy storage, and magneto-hydrodynamic systems, where balancing performance with reduced entropy generation is essential for reliable operation.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"30 ","pages":"Article 101424"},"PeriodicalIF":0.0,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145110050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
MHD Casson Nanofluid Flow over a Stretching Rotating Disk with Heat Source and Spatially Varying Magnetic Field MHD卡森纳米流体在具有热源和空间变化磁场的拉伸旋转盘上的流动
International Journal of Thermofluids Pub Date : 2025-09-19 DOI: 10.1016/j.ijft.2025.101422
Talha Anwar , Qadeer Raza , Tahir Mushtaq , Bagh Ali , Ehsanullah Hemati
{"title":"MHD Casson Nanofluid Flow over a Stretching Rotating Disk with Heat Source and Spatially Varying Magnetic Field","authors":"Talha Anwar ,&nbsp;Qadeer Raza ,&nbsp;Tahir Mushtaq ,&nbsp;Bagh Ali ,&nbsp;Ehsanullah Hemati","doi":"10.1016/j.ijft.2025.101422","DOIUrl":"10.1016/j.ijft.2025.101422","url":null,"abstract":"<div><div>This paper investigates the steady magnetohydrodynamic (MHD) flow and heat transfer of a Casson nanofluid over a stretching, rotating disk in the presence of a spatially varying magnetic field and internal heat source. The model incorporates the Buongiorno nanofluid framework, which accounts for nanoparticle motion due to Brownian diffusion and thermophoresis, and includes velocity, thermal, and concentration slip conditions at the disk surface. Unlike traditional studies assuming a uniform magnetic field, the present work considers a magnetic field that decays exponentially away from the disk surface, providing a more realistic representation of applied magnetic fields in practical systems such as electromagnetic processing and rotating machinery. Additionally, the influence of an internal heat generation term is included in the energy equation to simulate thermal sources within the fluid. By applying similarity transformations, the governing nonlinear partial differential equations are reduced to a system of coupled ordinary differential equations. These equations are solved numerically using the bvp4c function in the Matlab computer language. The effects of various physical parameters such as magnetic field strength and gradient, slip coefficients, Casson fluid parameter, and heat source intensity are systematically explored. The results reveal that increasing the magnetic field strength or the heat source significantly enhances the thermal boundary layer, while velocity profiles are suppressed near the disk due to magnetic damping. The presence of multiple slips and the Casson fluid parameter further alter the flow and thermal behavior, making the system tunable for thermal management applications.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"30 ","pages":"Article 101422"},"PeriodicalIF":0.0,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Multi discharge assessment of non-eutectic mixture PCM as excellent candidate for medium temperature thermal storage operation 多放电评价非共晶混合PCM作为中温蓄热运行的优秀候选者
International Journal of Thermofluids Pub Date : 2025-09-19 DOI: 10.1016/j.ijft.2025.101423
Joko Waluyo , Sugeng Priyanto , Robertus Dhimas Dhewangga Putra , Reza Abdu Rahman
{"title":"Multi discharge assessment of non-eutectic mixture PCM as excellent candidate for medium temperature thermal storage operation","authors":"Joko Waluyo ,&nbsp;Sugeng Priyanto ,&nbsp;Robertus Dhimas Dhewangga Putra ,&nbsp;Reza Abdu Rahman","doi":"10.1016/j.ijft.2025.101423","DOIUrl":"10.1016/j.ijft.2025.101423","url":null,"abstract":"<div><div>Mixing polyol-based phase change material (P-PCM) to form non-eutectic mixture (NEM) is performed to reduce the impact of poor crystallization of sorbitol (STL) and high supercooling of mannitol (MTL). A series of experimental evaluations is designed based on various discharge methods commonly used for the application of thermal energy storage (TES) systems. It is the main novelty of this work, as the modification of the TES material is evaluated under different discharge methods, providing more detailed outcomes to understand the impact of material modification and operational conditions on the performance of the TES system. The finding indicates the charging capacity for the produced NEM varies between 430.8 – 486.1 Wh, which is higher than STL (386.2 Wh). Forming NEM with 25 wt% MTL offers a reliable rating charge, which enhances 10.1% than MTL. Active discharge with air yields the highest rating at 1.29°C/min for NEM, which improves under passive operation with liquid by 43.7% relative to STL. Improvement on the solidification mechanism indicates positive outcome according to the average increment of water temperature outlet with maximum improvement around 13.1°C. Rapid discharge by flowing water through the external wall of TES container produces a higher temperature outlet, which improves between 18.5 - 21.3°C. Detailed observation of the heat release profile demonstrates a significant impact on the solidification behavior, implying that the formation of NEM has a better freezing mechanism than the base material. The finding opens up new opportunities to use NEM as a reliable solution to improve the usability of P-PCM for TES systems.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"30 ","pages":"Article 101423"},"PeriodicalIF":0.0,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145119555","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Influence of chemical reaction on convective flow in porous medium with varying viscosity generated by internal heat source in thermal non-equilibrium temperature conditions 热非平衡温度条件下由内热源产生的变粘度多孔介质中化学反应对对流流动的影响
International Journal of Thermofluids Pub Date : 2025-09-18 DOI: 10.1016/j.ijft.2025.101412
Monal Bharty , Atul K. Srivastava , Hrishikesh Mahato , Ashwini Kumar , Mayank Srivastava , Jayant Giri , Eman Ramadan Elsharkawy , Divya Srivastava
{"title":"Influence of chemical reaction on convective flow in porous medium with varying viscosity generated by internal heat source in thermal non-equilibrium temperature conditions","authors":"Monal Bharty ,&nbsp;Atul K. Srivastava ,&nbsp;Hrishikesh Mahato ,&nbsp;Ashwini Kumar ,&nbsp;Mayank Srivastava ,&nbsp;Jayant Giri ,&nbsp;Eman Ramadan Elsharkawy ,&nbsp;Divya Srivastava","doi":"10.1016/j.ijft.2025.101412","DOIUrl":"10.1016/j.ijft.2025.101412","url":null,"abstract":"<div><div>This study investigates the onset of natural convection in a horizontal fluid-saturated porous medium subject to uniform internal heat generation and chemical reactions under local thermal non-equilibrium (LTNE) temperature conditions. The fluid viscosity is assumed to vary nonlinearly with temperature, capturing realistic thermophysical behavior often encountered in high-temperature and chemically reactive porous systems. Such configurations are frequently encountered in engineering applications, including geothermal energy extraction, thermal insulation in buildings, chemical catalytic reactors, nuclear waste disposal, and porous heat exchangers. In these systems, internal heat generation, chemical reactions, and non-equilibrium heat exchange between fluid and solid phases play a critical role in determining thermal stability and efficiency. The present analysis employs linear stability theory using the normal mode technique, and the resulting eigenvalue problem is solved via the Galerkin-weighted residual method. A comparative study is conducted for three thermal boundary conditions: rigid-rigid <span><math><mrow><mo>(</mo><mi>R</mi><mo>/</mo><mi>R</mi><mo>)</mo></mrow></math></span>, rigid-free <span><math><mrow><mo>(</mo><mi>R</mi><mo>/</mo><mi>F</mi><mo>)</mo></mrow></math></span>, and free-free <span><math><mrow><mo>(</mo><mi>F</mi><mo>/</mo><mi>F</mi><mo>)</mo></mrow></math></span> for the stationary case, while oscillatory instabilities are analyzed for the F/F case. Graphical representations are used to illustrate how the main controlling parameters affect the stationary and oscillatory onset. It is reported that the system is more stable with increasing values of <span><math><mi>H</mi></math></span> (inter-phase heat transfer coefficient) and <span><math><mtext>Da</mtext></math></span> (Darcy number), while it is less stable with increasing values of <span><math><mi>χ</mi></math></span> (Damköhler number), <span><math><msub><mrow><mi>M</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> (linear viscosity variation parameters), <span><math><msub><mrow><mi>M</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> (nonlinear viscosity variation parameters), and <span><math><msub><mrow><mi>Q</mi></mrow><mrow><mi>f</mi></mrow></msub></math></span> (the fluid heat generation parameter). It is also established that the system is more stable for <span><math><mrow><mi>R</mi><mo>/</mo><mi>R</mi></mrow></math></span> boundary combinations and least stable for <span><math><mrow><mi>F</mi><mo>/</mo><mi>F</mi></mrow></math></span> boundaries.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"30 ","pages":"Article 101412"},"PeriodicalIF":0.0,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145098015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Experimental and numerical investigation of developing correlations for convective heat transfer coefficient for internal room surfaces considering ceiling diffusers effects 考虑天花板扩散器效应的室内表面对流换热系数发展相关性的实验和数值研究
International Journal of Thermofluids Pub Date : 2025-09-18 DOI: 10.1016/j.ijft.2025.101421
Sajad Abasnezhad, Abdolsalam Ebrahimpour, Jafar Ghafouri
{"title":"Experimental and numerical investigation of developing correlations for convective heat transfer coefficient for internal room surfaces considering ceiling diffusers effects","authors":"Sajad Abasnezhad,&nbsp;Abdolsalam Ebrahimpour,&nbsp;Jafar Ghafouri","doi":"10.1016/j.ijft.2025.101421","DOIUrl":"10.1016/j.ijft.2025.101421","url":null,"abstract":"<div><div>An experimental and numerical study analyzed convective heat transfer in a room. The experiments involved measuring temperatures in a room with a window and a diffuser placed in different positions. Numerical simulations modeled a room with windows of varying sizes on the south wall, slot diffusers, and radiators. This research aims to address gaps in calculating convective heat transfer coefficients for innovative window designs by proposing new correlations to improve the accuracy of cooling and heating load predictions. Solar radiation data from Tabriz City was incorporated. Key parameters included volumetric inlet flow rate, diffuser inlet angle, and window-to-wall ratio. CFD simulations employed the SIMPLE algorithm with second-order discretization and the standard K-epsilon turbulence model. The findings indicate that the reference temperature strongly influences the results. Supply temperature consistently showed a higher convective heat transfer coefficient compared to the reference temperature, usually defined as the average room temperature. Moreover, the window-to-wall ratio emerged as the most critical factor, with larger windows leading to a notable increase in the convective heat transfer coefficient.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"30 ","pages":"Article 101421"},"PeriodicalIF":0.0,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145119554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Nano enhanced phase change materials for thermal energy storage system applications: A comprehensive review of recent advancements and future challenges 热能储存系统应用的纳米增强相变材料:近期进展和未来挑战的全面回顾
International Journal of Thermofluids Pub Date : 2025-09-16 DOI: 10.1016/j.ijft.2025.101418
Bayew Adera , Venkata Ramayya Ancha , Tassew Tadiwose , Eshetu Getahun
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