Heat Transfer最新文献

{"title":"Energy and Exergy (2E) Analysis of Organic Flash Cycle With Waste Heat Recovery","authors":"Uddarraju Dhana Satya Prathap Varma,&nbsp;Balakrishna Gogulamudi,&nbsp;Tarun Kumar Kotteda,&nbsp;Vajeer Baba Shaik,&nbsp;K. V. Murali Krishnam Raju","doi":"10.1002/htj.70233","DOIUrl":"https://doi.org/10.1002/htj.70233","url":null,"abstract":"<div>\u0000 \u0000 <p>The world is experiencing an increased power demand, hence the need for sustainable sources of power at the expense of conventional sources. This paper explores the minimization of energy waste using the organic flash cycle in combination with a regenerator to recover the waste heat with 1,1,1,3,3-pentafluoropropane as a working fluid. A thermodynamic model was designed to optimize the operating conditions primarily in the heat recovery vapor generator (HRVG) pressure. When HRVG pressure is raised, both cycle efficiency and power will go up, but turbine inlet temperature has a greater influence on the overall performance of the system. The results indicate that boiler pressure reaches a minimum level during waste heat recovery operations compared with traditional fuel-fired facilities, and increasing source temperatures leads to increased pressure in both cases. The optimal operation pressure for the boiler reaches 12.79 bar when the source temperature stands at 150°C. Operating under those conditions allows the system to achieve 13.20% energy efficiency and 19.53% exergy efficiency.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"55 5","pages":"2908-2925"},"PeriodicalIF":2.6,"publicationDate":"2026-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148208900","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}

{"title":"Efficiency Optimization of Moving Pin Fins of Different Profiles by Keller-Box Method","authors":"S. Lalith Kumar,&nbsp;H. G. Nagaraja","doi":"10.1002/htj.70238","DOIUrl":"https://doi.org/10.1002/htj.70238","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 &lt;p&gt;We consider heat transfer with convection and radiation effects on continuously moving fully wet spines of different profiles, namely cylindrical, convex parabolic, conical, and concave parabolic spines with varying degrees of curvature (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 \u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;b&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;). The Keller-box method efficiently solves the highly nonlinear equation imposed with the adiabatic tip condition, and further validation of the result obtained is carried out with the help of the spectral quasilinearization method. The thermal profile is enhanced with the increase in the curvature parameter until a threshold value is reached (at &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 \u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;b&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; = 0.66127), beyond which it starts decreasing. The volume-adjusted base heat transfer rate drop with an increase in the Peclet number (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 \u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;Pe&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;) is more significant in convex profiled fins than in concave profiled fins. We have identified the critical values of the curvature parameter (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 \u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;b&lt;/mi&gt;\u0000 \u0000 &lt;mi&gt;c&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;) where maximum efficiency is attained, and its dependence on the relative velocity of the ambient fluid with the fin is reported (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 \u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;b&lt;/mi&gt;\u0000 \u0000 &lt;mi&gt;c&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; = 2.15 at &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 \u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;Pe&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; = 0, &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 \u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;b&lt;/mi&gt;\u0000 \u0000 &lt;mi&gt;c&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; = 0.9216 at &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 ","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"55 5","pages":"2995-3008"},"PeriodicalIF":2.6,"publicationDate":"2026-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148209055","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}

{"title":"Enhancing the Performance of an Indirect Solar Dryer Based on Baffle Geometry Optimization: An Experimental Study on Mint Drying Under Saharan Climate","authors":"Noureddine Meneceur,&nbsp;Khalil Deghoum,&nbsp;Salah S. Abed AlKareem,&nbsp;Ahmed Qasim Mohammed,&nbsp;Oday Ibraheem Abdullah,&nbsp;Khadra Aliouat,&nbsp;Yacine Aoun,&nbsp;Munaf S. Majeed","doi":"10.1002/htj.70240","DOIUrl":"https://doi.org/10.1002/htj.70240","url":null,"abstract":"<div>\u0000 \u0000 <p>Solar drying provides an eco-friendly and energy-efficient alternative to traditional drying ‎methods, making it a practical choice for agriculture and food preservation in regions with high ‎solar availability. This paper describes research on an indirect solar drying (ISD) system that ‎uses a flat-plate collector with three baffle geometries: simple, triangular, and serpentine. The ‎performance of the ISD was evaluated by the drying of mint plants, a significant agricultural ‎product in the arid climate of El-Oued, Algeria. Experimental measurements were conducted ‎over several days in May under actual weather conditions, with data from the most stable day ‎chosen for analysis. Measurements were taken from 8:00 a.m. to 5:00 p.m. A thorough ‎evaluation of the system's thermal performance was performed, focusing on key factors such as ‎collector temperature, drying chamber temperature, moisture content, mass loss, shrinkage rate, ‎and thermal efficiency. The results indicate that the serpentine baffle design significantly ‎improved solar dryer ‎performance, ‎reaching a maximum outlet temperature of 67°C (vs. 62°C ‎for triangular and ‎‎56°C for simple ‎designs) and a drying chamber temperature of 52°C (4°C–6°C ‎higher than ‎others). The thermal ‎efficiency attained 36%–48%, above the triangular (29%–38%) and ‎simple (15%–‎‎32%) configurations. ‎Drying was fastest with the serpentine baffle, reducing mint ‎moisture ‎from 78% to 0% in 7.5 h ‎‎(by 3:30 p.m.)، finishing 1 h earlier than the triangular ‎and 1.5 ‎hours earlier than the simple design. A ‎logarithmic model best fit the data (<i>R</i>² = 0.9964, ‎RMSE ‎‎ = 0.0178), confirming a strong correlation ‎between baffle design and the efficiency of ‎the ‎drying process.‎</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"55 5","pages":"3029-3046"},"PeriodicalIF":2.6,"publicationDate":"2026-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148208804","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}

{"title":"Nanofluid Convection in Horizontal Annuli With Decoupled Thermal and Concentration Boundaries","authors":"Naseem Uddin,&nbsp;Muhammad Abid","doi":"10.1002/htj.70242","DOIUrl":"https://doi.org/10.1002/htj.70242","url":null,"abstract":"<div>\u0000 \u0000 <p>This study examines fully developed laminar nanofluid convection in a horizontal concentric annulus using the Buongiorno two-component model, accounting for Brownian diffusion and thermophoresis. A new boundary configuration is introduced in which nanoparticle concentration is prescribed at the isothermal outer wall, while the inner wall is adiabatic, thereby decoupling concentration from the heat source. The nonlinear governing equations are solved as a boundary-value problem with concentration-dependent thermophysical properties and a reciprocal iteration scheme to enforce the target bulk concentration. Validation against the benchmark studies demonstrates good agreement for velocity, temperature, and concentration fields. Results show that, under the decoupled boundary condition, the average Nusselt number decreases monotonically with increasing Brownian-to-thermophoretic diffusivity ratio (<i>N</i>_BT). Alumina nanofluids exhibit higher heat-transfer performance than titania, while ternary nanofluids display nearly <i>N</i>_BT-independent behavior. The pressure-drop parameter depends strongly on nanoparticle concentration and axial forcing, approaching saturation at high <i>N</i>_BT due to Brownian homogenization. These findings highlight the critical role of boundary placement in governing nanoparticle migration and thermal performance in annular nanofluid systems.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"55 5","pages":"3062-3075"},"PeriodicalIF":2.6,"publicationDate":"2026-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148208890","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}

{"title":"Optimization of Thermal Energy Storage in Solar Systems Using Phase Change Materials: Design, Simulation, and Applications","authors":"Rajesh Kumar,&nbsp;Abhay Kumar Singh,&nbsp;Manish Kumar","doi":"10.1002/htj.70226","DOIUrl":"https://doi.org/10.1002/htj.70226","url":null,"abstract":"<div>\u0000 \u0000 <p>Phase change material (PCM)-based thermal energy storage systems offer a promising solution to bridge the mismatch between intermittent solar energy availability and continuous energy demand. However, their practical use is often constrained by the inherently low thermal conductivity of PCMs, which leads to sluggish melting and incomplete heat transfer. This study aims to enhance the thermal performance of a horizontal shell-and-tube latent heat storage unit employing paraffin-based PCM RT42 through a hybrid computational optimization framework combining “computational fluid dynamics” (CFD) and a “genetic algorithm” (GA). A two-dimensional axisymmetric CFD model developed in ANSYS Fluent simulates the melting behavior of RT42 under natural convection and conduction. The GA, implemented in Python, optimizes fin geometry specifically fin length and inclination angle—to minimize total melting time and maximize energy efficiency. The optimized configuration achieved a 30% reduction in melting (charging) time and a 15%–20% improvement in thermal efficiency compared with the baseline system. Sensitivity analysis revealed that excessive PCM thickness and fin spacing hinder heat transfer, while fluid velocities above 0.03 m/s offer minimal benefit. The results demonstrate that the CFD–GA integrated approach provides a robust and scalable method for optimizing PCM-based storage units in solar thermal systems. This research establishes a reproducible framework for designing high-performance TES units, promoting efficient and sustainable solar energy utilization.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"55 5","pages":"2808-2819"},"PeriodicalIF":2.6,"publicationDate":"2026-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148209019","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}

{"title":"Cooling Enhancement of Li-Ion Battery With MXene-Based Phase Change Materials Using Battery Model: A Numerical Approach","authors":"Nilesh Krishnadhari Singh,&nbsp;Nitisha Sharma,&nbsp;Rashmi Rekha Sahoo","doi":"10.1002/htj.70241","DOIUrl":"https://doi.org/10.1002/htj.70241","url":null,"abstract":"<div>\u0000 \u0000 <p>This numerical study investigates the enhancement of lithium-ion battery thermal management using MXene-based nano-enhanced phase change materials (PCMs), namely capric acid, n-octadecane, and RT-33. The thermal performance is evaluated over discharge rates of 1C–4C by analyzing cell temperature, PCM temperature, heat flux, voltage drop, discharge duration, and melting fraction distribution of both pure and MXene-enhanced PCMs. The results indicate that for MXene-enhanced n-octadecane, the temperature rise is limited to 1.7 K while the thermally safe operating duration decreases as the discharge rate increases from 1C to 4C. At 4C for 838 s, MXene-based n-octadecane exhibits the highest melting fraction (61.63%), followed by n-octadecane, MXene-based RT-33, RT-33, capric acid, and MXene-based capric acid. At the same C-rate, capric acid and MXene-enhanced capric acid show peak heat flux values of 12.04 and 16.69 W/m² at 250 and 450 s, respectively. Compared to MXene-based capric acid, MXene-based n-octadecane extends the thermally permissible operation by approximately 5 s at 4C, while the maximum cell temperature recorded is 310.52 K for MXene-based capric acid. Overall, among the studied materials, MXene-enhanced n-octadecane provides superior cooling performance, particularly at lower discharge rates, effectively maintaining lower cell temperatures and improved temperature uniformity, making it a promising candidate for enhanced battery thermal stability and safety.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"55 5","pages":"3047-3061"},"PeriodicalIF":2.6,"publicationDate":"2026-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148209028","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}

{"title":"Parametric Study on the Irreversibility of Fully Wet Porous Exponential Fin: A Comparative Analysis of Geometric Variations and Diverse Tip Conditions","authors":"N. V. Manvitha,&nbsp;B. J. Gireesha","doi":"10.1002/htj.70225","DOIUrl":"https://doi.org/10.1002/htj.70225","url":null,"abstract":"<div>\u0000 \u0000 <p>Examining fins under various operational conditions aids in understanding heat transfer, which directly influences their thermal performance. Also, by comprehending the imposed boundary conditions, such as insulated, convective or others, engineers can design fins that optimize thermal performance by effectively managing thermal gradients. In view of this, the current study focuses on a fully wet porous exponential fin under convective-radiative conditions, with surface emissivity modeled as a linear function of temperature. Further, the effects of insulated and convective boundary conditions are examined for inverted, rectangular, and tapered exponential fins. Heat distribution is characterized by a nonlinear differential equation, which is then reformulated into a non-dimensional version using appropriate dimensionless parameters. To solve the resulting model, the Runge–Kutta–Fehlberg method is employed. Visual representations show the effects of various factors on the energy field and average entropy generation. Under an insulated tip condition, an increase in the surface emissivity parameter leads to a rise in average entropy generation by <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mn>3.98</mn>\u0000 \u0000 <mo>%</mo>\u0000 \u0000 <mo>,</mo>\u0000 \u0000 <mo> </mo>\u0000 \u0000 <mn>2.9</mn>\u0000 \u0000 <mo>%</mo>\u0000 </mrow>\u0000 </mrow>\u0000 </semantics></math>, and <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mn>2.03</mn>\u0000 \u0000 <mo>%</mo>\u0000 </mrow>\u0000 </mrow>\u0000 </semantics></math> for inverted, rectangular and tapered fin structures, respectively. Additionally, fins with an insulated tip exhibit higher levels of entropy and thermal dispersion compared to those with a convective tip condition.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"55 5","pages":"2793-2807"},"PeriodicalIF":2.6,"publicationDate":"2026-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148208986","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}

{"title":"Heat Transfer and Entropy Generation on Natural Convection of Air Flow Within a “⊥”-Shaped Cavity Inserting an RVW Obstacle: A Comprehensive Study of CFD, RSM, and ANN-Based Prediction","authors":"Md. Mostakim,&nbsp;Bijan Krishna Saha,&nbsp;Abdullah Ahmed Foisal,&nbsp;Sajal Saha,&nbsp;Suvash C. Saha","doi":"10.1002/htj.70231","DOIUrl":"https://doi.org/10.1002/htj.70231","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 &lt;p&gt;Natural convection (NC) and heat transfer (HT) are significant in engineering, particularly in thermal management systems. This study analyzes the thermal behavior and entropy generation (&lt;i&gt;E&lt;/i&gt;&lt;sub&gt;gen&lt;/sub&gt;) within a “⊥”-shaped cavity with a rectangular vertical wall (RVW). The inclusion of RVW in a “⊥”-shaped cavity with a square wall below, demonstrating complexity and improvements. This study explores the interaction between thermal gradients, buoyancy-driven flow, and the impact of the RVW. This study aims to analyze the influence of the Rayleigh number (&lt;i&gt;Ra&lt;/i&gt;) on HT performance, flow characteristics, &lt;i&gt;E&lt;/i&gt;&lt;sub&gt;gen&lt;/sub&gt;, and also the impact of the RVW. It further assesses environmental efficiency using the Ecological Coefficient Performance (ECOP) that identifies thermally optimal configurations by demonstrating a balance between enhanced HT and thermodynamic irreversibility. Additionally, this study investigates Response Surface Methodology (RSM) to evaluate the sensitivity analysis for finding which parameter mostly affects the average Nusselt number (&lt;i&gt;Nu&lt;/i&gt;&lt;sub&gt;avg&lt;/sub&gt;) and demonstrates the predictions of the &lt;i&gt;Nu&lt;/i&gt;&lt;sub&gt;avg&lt;/sub&gt; with RSM and Artificial Neural Network (ANN). The current analysis employs the finite element method to explore the NC and HT in a “⊥”-shaped cavity with a square heated wall below using COMSOL Multiphysics software 6.3. The flow is considered to be two-dimensional, laminar, incompressible, and steady state in nature. A grid independence test confirms numerical reliability. For numerical validation, the calculated results are compared with the findings from earlier published studies to verify accuracy and reliability. Key parameters, Rayleigh numbers (10&lt;sup&gt;3&lt;/sup&gt; ≤ &lt;i&gt;Ra&lt;/i&gt; ≤ 10&lt;sup&gt;6&lt;/sup&gt;) and Prandtl number (&lt;i&gt;Pr&lt;/i&gt;), are fixed at 0.71 (air). Dimensionless parameters, including &lt;i&gt;Nu&lt;/i&gt;&lt;sub&gt;avg&lt;/sub&gt;, &lt;i&gt;E&lt;/i&gt;&lt;sub&gt;gen&lt;/sub&gt;, and &lt;i&gt;Be&lt;/i&gt;&lt;sub&gt;avg&lt;/sub&gt;, are calculated to assess HT and quantify optimal configuration. &lt;i&gt;Nu&lt;/i&gt;&lt;sub&gt;avg&lt;/sub&gt; and &lt;i&gt;E&lt;/i&gt;&lt;sub&gt;gen&lt;/sub&gt; increase with increasing &lt;i&gt;Ra&lt;/i&gt;, but &lt;i&gt;Be&lt;/i&gt;&lt;sub&gt;avg&lt;/sub&gt; decreases in both cases. The shape and position of the RVW significantly enhanced the HT. The inclusion of RVW gives 78.60% higher &lt;i&gt;Nu&lt;/i&gt;&lt;sub&gt;avg&lt;/sub&gt; and 61.61% higher &lt;i&gt;E&lt;/i&gt;&lt;sub&gt;gen&lt;/sub&gt; than without RVW at &lt;i&gt;Ra&lt;/i&gt; = 10&lt;sup&gt;6&lt;/sup&gt;. According to the ECOP, for a lower &lt;i&gt;Ra&lt;/i&gt;, case-1 (without RVW) is more efficient than case-2 (with RVW), but when the &lt;i&gt;Ra&lt;/i&gt; increases, case-2 (with RVW) becomes more efficient. Sensitivity analysis demonstrates that &lt;i&gt;Nu&lt;/i&gt;&lt;sub&gt;avg&lt;/sub&gt; is mostly influenced by &lt;i&gt;Ra&lt;/i&gt;, then by the height of the RVW, and slightly by the width of the RVW. With a limited data set, the RSM model with lower mean squared error demonstrates superior predictive accuracy and reliability compared with the ANN model. This study provides useful insights for designing better thermal systems, which shows how th","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"55 5","pages":"2876-2892"},"PeriodicalIF":2.6,"publicationDate":"2026-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148209069","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}

{"title":"Nonlinear Buoyancy and Radiation Effects on Viscoelastic Double-Diffusive Boundary Layer Flow With Inclined Magnetic Field: A Neural Network Prediction With Composite Index","authors":"Anjali Rawal,&nbsp;Chinta Mani Tiwari","doi":"10.1002/htj.70235","DOIUrl":"https://doi.org/10.1002/htj.70235","url":null,"abstract":"<div>\u0000 \u0000 <p>This study investigates the influence of nonlinear thermal and solutal buoyancy forces, together with inclined magnetic fields, on mixed convection boundary-layer flow of a viscoelastic fluid over a vertically stretching permeable plate, while also assessing the predictive capability of artificial neural networks (ANNs) for heat transfer and flow characteristics under nonlinear effects. A collocation-based solver (MATLAB bvp5c) is employed to numerically analyze the governing boundary layer equations under both linear and quadratic Boussinesq approximations, with three radiation models (linear, quadratic, and nonlinear). Parametric studies are conducted to evaluate the roles of the magnetic field inclination angle, viscoelasticity and radiation parameter on velocity, temperature, concentration, Nusselt number, and skin friction, while an ANN model is trained on <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <msup>\u0000 <mn>5</mn>\u0000 \u0000 <mn>5</mn>\u0000 </msup>\u0000 </mrow>\u0000 </mrow>\u0000 </semantics></math> simulation datasets using different training algorithms and evaluated through a newly proposed composite index combining <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <msup>\u0000 <mi>R</mi>\u0000 \u0000 <mn>2</mn>\u0000 </msup>\u0000 </mrow>\u0000 </mrow>\u0000 </semantics></math>, RMSE, and sMAPE. The results reveal that nonlinear thermal and solutal buoyancy effects substantially modify the velocity, temperature, and concentration fields. The ANN model demonstrates excellent predictive performance along with sensitivity analysis, with Bayesian regularization emerging as the most reliable training algorithm according to the composite evaluation metric. Overall, sensitivity analysis of the Nusselt number indicates that the radiation parameter has the strongest influence on heat transfer, whereas the viscoelastic parameter exhibits the least effect.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"55 5","pages":"2944-2960"},"PeriodicalIF":2.6,"publicationDate":"2026-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148208902","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}

{"title":"Investigation of Hydrothermal Characteristics in Heat-Exchanger Tubes Featuring a Novel Perforated Ramp-Shaped Turbulator","authors":"Mustafa Abdullah,&nbsp;B. Venkatesh,&nbsp;Kiran D. Parmar,&nbsp;Akanksha Mishra,&nbsp;D. T. Arunkumar,&nbsp;Jasgurpreet Singh Chohan,&nbsp;Ripendeep Singh,&nbsp;Abinash Mahapatro,&nbsp;V. K. Bupesh Raja","doi":"10.1002/htj.70237","DOIUrl":"https://doi.org/10.1002/htj.70237","url":null,"abstract":"<div>\u0000 \u0000 <p>Enhancing heat transfer remains a major challenge in heat-exchanger systems. To address this limitation, this study numerically investigates a novel ramp-shaped turbulator, introduced and analyzed here for the first time. The turbulator is designed to simultaneously generate strong radial and swirling flows within the tube, thereby substantially improving heat transfer and overall hydrothermal performance. Both solid and perforated configurations are examined over Reynolds numbers of 2500–9000, and the effects of key geometric parameters—including bending distance (2–12 mm), perforation diameter (0–4 mm), and hole height (3–8 mm)—on heat transfer, pressure loss, and the thermal enhancement factor (TEF) are systematically evaluated. Thermally, the solid turbulator exhibits superior performance, with an 8-mm bending distance yielding a 2.54-fold increase in the Nusselt number and a 5.3-fold rise in the friction factor compared with a plain tube. However, from a hydrothermal perspective based on TEF, the perforated configuration becomes more favorable. The perforated ramp achieves a maximum TEF of 1.4 at an 8-mm bending distance, 2 mm perforation diameter, and 3 mm hole height. In addition, generalized correlations are developed to predict the influence of the geometric parameters, offering a practical framework for designing and optimizing next-generation high-performance heat exchangers.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"55 5","pages":"2983-2994"},"PeriodicalIF":2.6,"publicationDate":"2026-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148209029","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}