Heat Transfer最新文献

{"title":"Effects of Heat Transport Characteristics and Chemical Reaction in Unsteady Flow of Williamson Fluid and Entropy Generation: The Keller-Box Numerical Scheme","authors":"Amala Olkha,&nbsp;Mukesh Kumar,&nbsp;Sunil Kumar Meena","doi":"10.1002/htj.23287","DOIUrl":"https://doi.org/10.1002/htj.23287","url":null,"abstract":"<div>\u0000 \u0000 <p>The study of heat and mass transport in non-Newtonian fluid flow over a stretching surface accompanying relevant characteristics is important in several engineering and industrial processes like annealing and thinning of copper wires, aerodynamic extrusion of plastic and rubber sheet, glass fiber, and so forth. Based on significant practical applications, the objective of this investigation is to assess the time-dependent flow of Williamson fluid influenced by porous sheet stretching in exponential manner accompanied by thermal and mass transport and entropy generation. Various factors affecting fluid flow, thermal and mass transport (viscous dissipation, non-linear radiation, porous media, chemical reaction, and heat source) are considered. The regulating PDEs are turned into ODEs in nondimensional form utilizing adequate similarity transformation relations. The problem is solved numerically on MATLAB adopting the Keller-Box scheme. On fluid flow, temperature, and concentration distribution the effects of relevant parameters are depicted by drawing sketches and discussed. Besides, second law analysis is also evoked in the study in terms of entropy generation accompanying the Bejan number. Moreover, quantities of physical significance such as skin friction coefficient, Sherwood number, and Nusselt number are computed, compared with prior research and found in excellent agreement. It is concluded that temperature profile magnifies due to radiation and heat generation effects. The reaction coefficient and order of the reaction exhibited opposite effects on concentration profile. It is also concluded that entropy production reduces with increasing slips and temperature difference parameter, while opposite effect is observed due to Brinkman number. Furthermore, it is observed that skin-friction coefficient at the surface decreases with velocity slip and non-Newtonian parameter however, trend is reversed due to unsteadiness parameter. The results of the study may find applications of practical importance in engineering fields such as designing heat exchangers, cooling processes, improving energy storage systems, and so forth.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"54 3","pages":"2218-2234"},"PeriodicalIF":2.8,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143801606","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":"Improving Thermal Performance in Building Heating, Ventilation, and Air Conditioning Systems: A Study of Natural Convection and Entropy in Plus-Shaped Cavity","authors":"Alaa R. Al-Badri,&nbsp;Ahmed A. Y. Al-Waaly,&nbsp;Goutam Saha,&nbsp;Tinni Saha,&nbsp;Suvash C. Saha","doi":"10.1002/htj.23288","DOIUrl":"https://doi.org/10.1002/htj.23288","url":null,"abstract":"<div>\u0000 \u0000 <p>The impact of building design on energy efficiency has been widely studied, with cavity cooling emerging as an effective solution for indoor thermal comfort, where obstacles within the cavity can enhance fluid flow and improve natural convection heat transfer (HT). This research builds on the principles of cavity cooling for indoor thermal comfort, investigating entropy generation and HT behavior in a unique plus-shaped cavity containing a cold cylindrical element, analyzed through Computational Fluid Dynamics simulations. The Rayleigh number (<i>Ra</i>) ranges from 10³ to 10⁶, with a fixed Prandtl number (<i>Pr</i>) of 0.71, representing air as the working fluid, radius (<i>r</i>) of the cylinder ranges from 0 to 0.1, where <i>r</i> = 0 indicates no cylinder. The results indicate significant shifts in flow structure and temperature distribution across the cavity at varying <i>Ra</i> values, impacting the local and global entropy generation. High Rayleigh numbers lead to enhanced convective flows, intensifying entropy production near the cylinder surface due to steeper thermal gradients and vigorous recirculation zones. The increase in <i>Ra</i> from 10³ to 10⁶ leads to an increase in <i>Nu</i>_avg from 24.27 to 56.40 for the model without a cold object while from 39.62 to 123.83 for the model with a cold object. Moreover, the maximum enhancement in <i>Nu</i>_avg was 137.48% for <i>Ra</i> = 10⁵. Whereas, for the same value of <i>Ra</i> = 10⁵, the maximum increase in <i>E</i>_gen and <i>Be</i> was 474.92% and 33.16%, respectively. Also, a new correlation is proposed to calculate <i>Nu</i>_avg using response surface methodology. This study offers a comprehensive examination of heat flow characteristics and entropy generation rates in confined geometries, contributing valuable knowledge to thermal management and optimization in systems with internal obstacles.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"54 3","pages":"2235-2250"},"PeriodicalIF":2.8,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143801609","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 Double Diffusion of nth Order Chemically Reactive Stagnated Flow of Walters' B Fluid With Elastic Distortion in a Porous Medium","authors":"Debozani Borgohain,&nbsp;D. Dey,&nbsp;Robin Pegu,&nbsp;Debosmita Choudhury","doi":"10.1002/htj.23279","DOIUrl":"https://doi.org/10.1002/htj.23279","url":null,"abstract":"<div>\u0000 \u0000 <p>The present study explores the steady two-dimensional flow of an incompressible viscous fluid past a vertically stretching surface in the presence of a transverse magnetic field. The fluid flow is guided by Walters' B fluid constitutive model. The plate is given a linear stretching and maintained with thermal and concentration slips. Further, the effects of <i>n</i>th-order chemical reactions are also considered. Applying practical assumptions and compatible similarity transformations, a system of nonlinear partial differential equations has been converted into a relevant nonlinear ordinary differential equations system. The governing equations are computed numerically by applying MATLAB built-in bvp4c solver tool. The obtained results are presented graphically and in tabular form, encompassing different values of flow parameters included in the solution. The change in the pivotal values of the thermal slip parameter (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <msub>\u0000 <mi>λ</mi>\u0000 \u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 </mrow>\u0000 </semantics></math>) from 1.1 to 1.3, 1.3 to 1.5, and 1.5 to 1.8 correspond to a reduction in temperature by 15.38%, 26.67%, and 38.89%, respectively. This illustrates the significant role that thermal slip plays in viscoelastic fluid flow by improving heat transfer and reducing the boundary friction. Moreover, higher order chemical reaction lightens the fluid particles' concentration with decelerated rates of thermal and solutal movements, indicating that minute variations in concentration implies larger changes in the rate of reaction. The findings of this work will be relevant in engineering and industrial fields, dealing with heat and mass transfer problems in the polymer industries, nuclear power plants, and so on.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"54 3","pages":"2194-2204"},"PeriodicalIF":2.8,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143801607","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":"Thermal Distribution in Fins of Different Geometries With Temperature and Wavelength Dependent Properties","authors":"Kanwalpreet Kaur,&nbsp;Surjan Singh","doi":"10.1002/htj.23280","DOIUrl":"https://doi.org/10.1002/htj.23280","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 &lt;p&gt;In this research work, we developed a mathematical model of heat transfer for different profiles of fins. This paper investigates heat transfer dynamics in continuously moving fins (rectangular, trapezoidal and concave parabolic), focusing on temperature-dependent thermal conductivity, heat transfer coefficients, internal heat generation and emissivity that varies with temperature and wavelength. The different values of the heat transfer coefficient capture various types of convection, nucleate boiling, condensation, and radiation effects, while treating thermal conductivity as a linear function of temperature. This problem is converted into a dimensionless form, and we adopted the Legendre wavelet collocation method (LWCM) to get the solution of the fin problem for various profiles. An exact solution in specific cases shows congruence up to seven to eight decimal places with LWCM results. Moreover, our analysis explores the effect of numerous non-dimensional parameters such as thermal conductivity 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;mi&gt;A&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, 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;, surface emissivity parameter &lt;i&gt;B&lt;/i&gt;, convention-conduction 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;N&lt;/mi&gt;\u0000 \u0000 &lt;mi&gt;cc&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, radiation-conduction 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;N&lt;/mi&gt;\u0000 \u0000 &lt;mi&gt;rc&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, internal heat generation &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;Q&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, &lt;i&gt;D&lt;/i&gt; fin taper ratio on the temperature profile and fin efficiency were studied in detail. As &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;N&lt;/mi&gt;\u0000 \u0000 &lt;mi&gt;cc&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, &lt;","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"54 3","pages":"2205-2217"},"PeriodicalIF":2.8,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143801608","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":"Horizontal Magnetic Field Influence on Fluid Flow Across a Variable Thickness Rotating Disk With Stretching and Melting Phenomenon","authors":"Amar Rauf,&nbsp;Gosikere Kenchappa Ramesh,&nbsp;Syeda Fatima,&nbsp;Sabir Ali Shehzad,&nbsp;Javali Kotresh Madhukesh,&nbsp;Muhammad Kamran Siddiq","doi":"10.1002/htj.23285","DOIUrl":"https://doi.org/10.1002/htj.23285","url":null,"abstract":"<div>\u0000 \u0000 <p>An incompressible steady-state flow of viscous fluid subjected to a variable thickness rotating surface is examined. The laminar flow stream is also affected by the disk stretching. A horizontal magnetic field is applied along the disk to stabilize the flow dynamics depending on its orientation and strength. The implication of a horizontal magnetic field is also effective in regulating the thermal energy in high-temperature environments such as turbines and nuclear reactors. The thermal features are also characterized by thermal radiation and melting heating. The melting phenomenon is useful in phase-change materials for efficient thermal storage and release like polymer molding or metal casting. Similarity transformations that account for the variable thickness of the disk surface are utilized to dimensionalize the flow equations and to obtain a self-similar solution. The numerical scheme Runge-Kutta-Fehlberg (RKF-45) built-in package is used for the solution of the normalized flow model. The salient nature of the physical parameters is illustrated in the momentum and thermal fields. The numerical data on skin-friction coefficient and local Nusselt number at the stretchable surface is also calculated. The graphical results indicate that the flow and temperature profiles are strongly influenced by the physical parameters under consideration. It can be deduced that melting decreases the fluid resistance close to the surface, reducing drag, and in turn increasing flow velocity. The latent energy absorbed during the melting process reduces the effective thermal energy into the fluid that reduces the temperature gradients in the thermal boundary layer flow. The stabilizing effect of the horizontal magnetic field on the flow phenomenon along the radial direction is observed for the angle <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <msub>\u0000 <mi>α</mi>\u0000 \u0000 <mn>1</mn>\u0000 </msub>\u0000 </mrow>\u0000 </mrow>\u0000 </semantics></math> varying from 0 to 30 degrees. It is seen that the dimensionless radius facilitates the thermal transport phenomenon from the disk surface to the fluid, thus resulting in reduction of the thermal field.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"54 3","pages":"2184-2193"},"PeriodicalIF":2.8,"publicationDate":"2025-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143801353","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":"Growth of Two-Phase Bubble-Drop in a Three-Phase Direct-Contact Heat Transfer System: Experimental Study","authors":"Ahmed R. Kareem,&nbsp;Hameed B. Mahood,&nbsp;Ali Sh. Baqir","doi":"10.1002/htj.23282","DOIUrl":"https://doi.org/10.1002/htj.23282","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 &lt;p&gt;Optimizing the continuous phase hydrostatic pressure and the temperature differential between working phases is essential in designing direct contact heat exchangers. This study presents an experimental investigation into the influences of the continuous phase active height, corresponding to hydrostatic pressure, and the temperature differential between the working liquids on the evaporation dynamics of a single volatile drop in an immiscible fluid. The experiments were carried out within a Perspex rectangular column with 100 × 100 × 600 mm dimensions. N-pentane (C&lt;sub&gt;5&lt;/sub&gt;H&lt;sub&gt;12&lt;/sub&gt;) at its saturation temperature was utilized as the dispersed phase, while the continuous phase comprised warm water at three distinct temperatures, resulting in three distinct Jacobian numbers (&lt;i&gt;Ja&lt;/i&gt; = 18, 30, and 45). Three active water heights (300, 400, and 500 mm) were investigated to assess the impact of hydrostatic pressure on droplet evaporation. A high-speed camera was employed to capture the droplet's evaporation along the continuous phase's active height, and the images were analyzed using FASTCAM (PFV-4) and AutoCAD (3D) software. The key parameters measured included droplet volume (or diameter), open angle (&lt;i&gt;β&lt;/i&gt;), vaporization ratio (&lt;i&gt;x&lt;/i&gt;), and the total time required for complete droplet evaporation. The experimental findings indicate that the droplet's diameter, open-angle (&lt;i&gt;β&lt;/i&gt;), and vaporization ratio (&lt;i&gt;x&lt;/i&gt;) increased over time and were notably influenced by the continuous phase hydrostatic pressure. Additionally, the growth rate of the two-phase drop-bubble accelerated, and the total time for complete evaporation decreased as the active height of the continuous phase was reduced. An empirical correlation for the two-phase drop-bubble size &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 \u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;(&lt;/mo&gt;\u0000 \u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;D&lt;/mi&gt;\u0000 \u0000 &lt;mo&gt;/&lt;/mo&gt;\u0000 \u0000 &lt;msub&gt;\u0000 &lt;mi&gt;D&lt;/mi&gt;\u0000 \u0000 &lt;mi&gt;o&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 \u0000 &lt;mo&gt;)&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; in terms of &lt;i&gt;Ja&lt;/i&gt;, &lt;i&gt;H&lt;/i&gt;, &lt;i&gt;H&lt;/i&gt;&lt;sub&gt;&lt;i&gt;o&lt;/i&gt;&lt;/sub&gt;, and &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;τ&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; was developed and compared successfully with the experimental data with a maximum error of about &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 \u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;∓&lt;/mo&gt;\u0000 ","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"54 3","pages":"2152-2164"},"PeriodicalIF":2.8,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143801588","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":"Comparative Investigation of Novel Thermo-Hydraulic Flow Characteristics and Augmentation of Heat Efficiency in 3D Pipes Based on Parametrical Corrugated Shape Configurations","authors":"Ahmed Ramadhan Al-Obaidi","doi":"10.1002/htj.23286","DOIUrl":"https://doi.org/10.1002/htj.23286","url":null,"abstract":"<div>\u0000 \u0000 <p>This study investigates the effects of various corrugation shapes on heat performance and pressure drop characteristics in 3D pipe surfaces. Evaluating corrugation pipes' thermo-hydrodynamic performance with respect to different corrugation configurations and Re is the main goal. The smooth flow is broken up in the double-dimpled corrugated shape, causing tiny swirl zones to form and creating turbulence that increases heat exchanger performance and keeps particles from falling out of suspension. A heat exchanger is made possible by the corrugation's distinctive design, which improves heat transfer. Corrugated heat exchangers have the ability to alter the dimensions of smooth ones based on the application, whenever companies want a compact size for operation. Numerical simulations at Re ranging from 4000 to 12,000 are carried out under the assumption of a steady and consistent heat flux of 10,000 W/m². Utilizing various models, the computational fluid dynamics solver is utilized to examine the effective characteristics of corrugation. The outcomes of temperature distributions, pressure drop, heat transfer coefficient, Nu, and f factors under various circumstances are discussed. For the conventional pipe, it was shown that different corrugation forms had a 22%–30% higher heat transfer coefficient. Because of the intricate corrugations, which enhance heat transfer and pressure drop, a greater Nu is achieved. Because corrugated geometries have a performance assessment criterion PEF greater than unity, they can outperform smooth pipes.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"54 3","pages":"2165-2183"},"PeriodicalIF":2.8,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143801589","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":"Performance and Emission Characteristics of Bombyx mori Biodiesel Blends With SiO2 Nanoadditive in DI-CI Engines","authors":"Bharathwaaj Ramani,&nbsp;Yazan Taamneh,&nbsp;Nadanakumar Vinagayam,&nbsp;Ravishankar Sathyamurthy","doi":"10.1002/htj.23277","DOIUrl":"https://doi.org/10.1002/htj.23277","url":null,"abstract":"<div>\u0000 \u0000 <p>A major global concern is climate change and its effects on the environment. The combustion of mineral diesel plays a major role in creating pollution. This creates an interest for the researchers to identify an alternate source for the same. In this work, the biodiesel obtained from silkworm oil is blended with 70%. The biodiesel obtained from silkworm oil was blended with 70% by volume of diesel and SiO₂ nanoparticles at three different proportions, 25, 50, and 75 ppm. The biodiesel blends containing 75 ppm SiO₂ nanoparticles showed better combustion performance than diesel and other blends considered. From the results obtained from the single cylinder 4 stroke Compression Ignition engine, it can be evidently seen that the brake thermal efficiency of the biodiesel blends has been increased by 12.46% at full load operation of the engine. The experimental results also show a decrease in Brake-specific fuel consumption by 13.44% for biodiesel blends compared to that of diesel. The emission for the better-performance blend witnessed a decrease in CO by 38.33%, an increase in NO<i>x</i> by 27.41%, and a reduction in UBHC by 43.63%. The overall results of the experiment show that the fuel blend with 30% by volume biodiesel and 75 ppm nanoparticles performed better than diesel in all aspects and can be a potential alternative for diesel.</p></div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"54 3","pages":"2140-2151"},"PeriodicalIF":2.8,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143801337","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":"Experimental Study on the Performance of Gradient Pores Density Metal Foam in a Rectangular Channel","authors":"Mohammed H. Hasan,&nbsp;Raed G. Saihood","doi":"10.1002/htj.23248","DOIUrl":"https://doi.org/10.1002/htj.23248","url":null,"abstract":"<div>\u0000 \u0000 <p>Various approaches are employed to enhance the heat transfer coefficient and Nusselt number inside the channels. One of the techniques employed for these enhancements is the utilization of porous media. In the current article, a practical investigation of forced convection heat transfer in a rectangular cross-section channel (0.05 × 0.1 m²) with 0.25 m length is conducted. A heater with a heat flux range (450–6000 W/m²) is imposed under a copper plate, and the other sides are covered by insulation layers. The air is considered as a working fluid with <i>Re</i> (600–2100). The test section is fully filled with gradient pores per inch (PPI) metal foam by taking three different pores densities PPI (10, 20, and 40 PPI) and studying its effects on the temperature of copper plate, the local heat transfer coefficient, average Nusselt number, pressure drop, friction factor, and the performance factor. Three cases were studied inside the channel: one empty case and two with gradient pore density case A (40–20–10) PPI and case B (10–20–40) PPI. The results showed that inserting the metal foam inside the channel improves <i>h</i> and <i>Nu</i>. Case B appeared the best of this improvement in <i>h</i> and <i>Nu</i> by 12% and 25%, respectively, compared with that in case A. While the friction factor was the same for two cases A and B. So, the performance factor in case B showed an improvement of around 25% and 50% in comparison to case A and the empty case, respectively.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"54 3","pages":"2127-2139"},"PeriodicalIF":2.8,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143801380","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":"Numerical Enhancement of Forced Convection Heat Transfer Characteristics for Skewed Wavy Channel Partially Inserted With Copper Metal Foam","authors":"Nooralhuda A. Mohammed,&nbsp;Dhamyaa S. Khudhur","doi":"10.1002/htj.23276","DOIUrl":"https://doi.org/10.1002/htj.23276","url":null,"abstract":"<div>\u0000 \u0000 <p>In this paper, the convective heat transfer (HT) and airflow characteristics are numerically examined for skewed wavy rectangular channels inserted partially with copper metal foam. Calculations were performed using ANSYS Fluent 19.2 at the airflow with a laminar range of Reynolds number from 700 to 1700. The thermohydraulic performance (THP), friction factor (<i>f</i>), and average Nusselt number (<i>Nu</i>_avg) variation with <i>Re</i> for foam heights of <i>h</i>_mf = 0.2–0.3<i>H</i> and foam pore densities of 10, 20, 30 and 40 pores per inch (PPI) have been examined for the tested channels. The results indicated that partial metal foam inserts enhance temperature distribution and increase the HT rate inside the channel due to the large HT surface area, high-thermal conductivity of copper, and increased flow resistance, which increases the velocity of the fluid passing through the heat exchange system. Also, increasing <i>h</i>_mf, PPI, and <i>Re</i> improves the HT rate in the channel, leading to an increase in both <i>Nu</i>_avg and <i>f</i> due to decreased permeability. In addition, under constant <i>h</i>_mf conditions, the THP exhibited a rise when the PPI and <i>Re</i> increased. Furthermore, at constant PPI and <i>Re</i>, the THP value lowers when the <i>h</i>_mf grows due high increase in flow restriction. At <i>h</i>_mf = 0.2<i>H</i>, 40 PPI, and <i>Re</i> = 1700, the THP reaches a maximum value of 1.51.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"54 3","pages":"2110-2126"},"PeriodicalIF":2.8,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143801633","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}