Case Studies in Thermal Engineering最新文献

{"title":"Three-dimensional analysis of thermohydraulic performance in corrugated channels with embedded baffles: Optimization of heat transfer and energy efficiency","authors":"Jamal-Eddine Salhi ,&nbsp;Tarik Zarrouk ,&nbsp;Tabish Alam ,&nbsp;Md Irfanul Haque Siddiqui ,&nbsp;Dan Dobrotă ,&nbsp;Mohd Aamir Mumtaz","doi":"10.1016/j.csite.2025.106019","DOIUrl":"10.1016/j.csite.2025.106019","url":null,"abstract":"<div><div>This study conducts a three-dimensional thermohydraulic analysis of wavy channels equipped with embedded baffles on the upper wall, aiming to optimize heat transfer while minimizing pressure losses. The efficiency of heat exchangers is crucial in many industrial applications, and research efforts have focused on improving their performance through geometric modifications. In this context, baffles play a significant role in increasing turbulence and enhancing heat transfer. Three channel configurations were examined: smooth walls, wavy walls, and wavy walls with rectangular baffles. Numerical simulations validated the model's reliability, with discrepancies below 6.49 % for configurations without baffles and 1.82 % for those with baffles. The results indicate that a baffle height of 5 mm achieves optimal thermal performance, yielding a thermal performance factor of 6.70394 at a Reynolds number of 6000. The introduction of perforated baffles allowed for the exploration of alternative geometries, although increasing the number of perforations reduced the Nusselt number due to decreased recirculation and fluid mixing. For the studied Reynolds number range (1000–6000), the thermal performance factor varies between 6.6022 and 6.7908, depending on the configuration. Models (2) and (4) stand out for their ability to offer an excellent trade-off between thermal performance and energy cost, outperforming the performance of smooth channels. These findings highlight the potential of wavy channels with optimized baffles to enhance the efficiency of thermal systems. Future studies could explore more complex variants of perforated baffles or integrate high-thermal-conductivity materials to further improve performance.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"69 ","pages":"Article 106019"},"PeriodicalIF":6.4,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143636235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on the evolutions of temperature and oxygen in the goaf of nearly vertical coal seam after low-temperature nitrogen injection","authors":"Gang Wang ,&nbsp;Shuliang Xie ,&nbsp;Enmao Wang ,&nbsp;Ruida Hao","doi":"10.1016/j.csite.2025.106021","DOIUrl":"10.1016/j.csite.2025.106021","url":null,"abstract":"<div><div>The near vertical coal seam adopts a segmented mining method to form a layered composite goaf, and its spontaneous combustion law is more complex. In order to understand the evolution law of temperature and oxygen after injecting low-temperature nitrogen into the goaf, the changes in oxygen and temperature before and after injecting low-temperature nitrogen into the goaf were analyzed through on-site observation and CFD numerical simulation. The results showed that after injecting low-temperature nitrogen into the goaf, the oxidation zone decreased by 10.7 m, and the return air corner temperature of this layer and the upper layer decreased by 16.6 K and 12 K, respectively, CO decreased to 0 mg/L; As the injection time of low-temperature nitrogen gas increases, the influence range of low-temperature nitrogen gas gradually increases, and the temperature and oxygen concentration in the goaf continue to decrease to below 283 K. The highest oxygen concentration in this layer's goaf is about 6 %, while the upper layer's goaf is less affected by low-temperature nitrogen gas than this layer's goaf, and the oxygen concentration decreases to 6.8 %. This study provides theoretical support for the prevention and control of coal spontaneous combustion in goaf areas near vertical coal seams.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"69 ","pages":"Article 106021"},"PeriodicalIF":6.4,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143628431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CFD-based optimization of solar water heating systems: Integrating evacuated tube and flat plate collectors for enhanced efficiency","authors":"Mukilarasan Nedunchezhiyan ,&nbsp;Sathiyamoorthi Ramalingam ,&nbsp;Poyyamozhi Natesan ,&nbsp;Senthil Sampath","doi":"10.1016/j.csite.2025.106017","DOIUrl":"10.1016/j.csite.2025.106017","url":null,"abstract":"<div><div>The current research aims to explore the dynamic movement of fluid and heat involved in a hybrid solar water heating system using CFD. It introduces evacuated tube collectors, integrating these into solar flat plate collectors. This experiment aims to explore and understand how velocity, pressure, temperature, and streamline flows in turbulent kinetic energy are affected under varying fluid flow rates ranging from 1 lpm to 10 lpm. The results show that the lower flow rates, specifically 1 lpm and 4 lpm, promote better fluid flow in the collector array, thus leading to optimal convective heat transfer. Pressure distribution is found to be a predominant factor in influencing the heat transfer efficiency, as it increases linearly from inlet to outlet due to an increased flow rate. For example, although the pressure fluctuation ranges may differ by 39.3 % from inlet to outlet, the flow rate is at 1 lpm, temperature distribution varies with a different flow rate where the inlet temperature peaks at an efficiency of 68.5 % at a flow rate of 1 lpm. The investigation considered the turbulent effects induced by the water and utilized the usual k-ε turbulent model. Turbulent kinetic energy (TKE) also escalates with higher flow rates, ranging from 97.5 % at 1 lpm to 98.9 % at 10 lpm. To obtain convergence of the governing equations, the investigation was carried out under conditions that were considered to be quasi-static. A total of one thousand (1000) iterations were utilized. A high-resolution advection methodology was applied in the research, and first-order turbulence was added to the analysis. A residual of 0.0001 was established as the necessary condition for convergence for each and every one of the governing equations. The study emphasizes the significance of optimizing flow rates for enhanced efficiency and productivity in solar water heating systems.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"69 ","pages":"Article 106017"},"PeriodicalIF":6.4,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143628427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on the characteristics of secondary oxidation and the key reactive groups of fire area coal by different cooling rates","authors":"Xun Zhang ,&nbsp;Ronghai Sun ,&nbsp;Bing Lu ,&nbsp;Ge Huang ,&nbsp;Ling Qiao ,&nbsp;Huimin Liang","doi":"10.1016/j.csite.2025.106014","DOIUrl":"10.1016/j.csite.2025.106014","url":null,"abstract":"<div><div>In order to reveal the effects of different cooling rates (slow and rapid) on the secondary oxidation characteristics of coal in coalfield fire area (primary heating to 180 °C). Simultaneous thermal analysis (TG-DSC), programmed heating and in situ Fourier transform infrared (FTIR) experiments were used. Thermodynamic analysis as well as Pearson and grey correlation analyses were used to analyze the low-temperature oxidation processes in raw coal and in coal from the fire area that underwent different cooling rates. The results showed that there was a significant difference of coal. The maximum cumulative heat release of raw coal was 35.942 J. The slow cooling (SC) and rapid cooling (RC) coals were only 17.188 and 23.761 J. At 200 °C, the CO production of the raw coal was 8432 ppm, and the SC and RC coals were 521 and 1166 ppm higher than it, respectively. In the correlation analysis, it was found that the key reactive groups in SC coal were -CH₂ and -COOH, whereas in RC coal it was -CH₂. There are two fundamental reasons for the difference: (1) SC coal accumulated more -COOH groups. (2) The -CH₂ groups of RC coal are more easily oxidized than those of SC coal.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"69 ","pages":"Article 106014"},"PeriodicalIF":6.4,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143609746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical investigation of oscillating jet film cooling on a flat plate for enhanced thermal management in high-temperature turbine applications","authors":"Abdalazeem Adam ,&nbsp;Weifeng He ,&nbsp;Pengfei Su ,&nbsp;Dong Han ,&nbsp;Chen Wang ,&nbsp;Shuo Dai ,&nbsp;Omer Musa","doi":"10.1016/j.csite.2025.105972","DOIUrl":"10.1016/j.csite.2025.105972","url":null,"abstract":"<div><div>Jet film cooling is essential for ensuring the thermal integrity of turbine blades in high-temperature environments. Previous research highlights the need for optimized cooling methods to enhance turbine component performance and longevity. This study examines the use of a fluidic oscillator in the cooling process, addressing the increasing demand for efficient and durable turbine designs. The focus is on evaluating the effectiveness of jet film cooling on high-temperature hydrogen turbine blades and understanding how factors such as cooling air velocities, hot gas compositions, and wet air cooling influence temperature distribution and flow behavior. Utilizing the Eulerian-Lagrangian method, the study presents quantitative findings based on varying cooling inlet velocities. At a cooling inlet velocity of 30 m/s, maximum blade temperatures near the cooling entrance reach 1217 K, while temperatures decrease to 866 K at the outlet. Increasing the inlet velocity to 40 m/s results in a maximum temperature rise to 1222 K, accompanied by increased turbulence. At 50 m/s, temperatures reach their peak at 1250 K due to vortex formation, with vortex areas showing a decrease in temperature to 820 K. Notably, the research indicates that variations in hot gas composition have minimal impact on the cooling process, while wet air cooling effectively lowers temperatures in the mixing area, leading to a more uniform film on the hot surface. Overall, the findings confirm that oscillating jet film cooling serves as an efficient approach for enhancing thermal management in turbine blade applications, paving the way for practical implementations in cooling systems.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"69 ","pages":"Article 105972"},"PeriodicalIF":6.4,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143632098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancement in heat generation through ternary hybrid nanofluid in a periodic channel","authors":"Anum Tanveer ,&nbsp;Iram ,&nbsp;M.Z. Alqarni ,&nbsp;S. Saleem ,&nbsp;A. Al-Zubaidi","doi":"10.1016/j.csite.2025.106011","DOIUrl":"10.1016/j.csite.2025.106011","url":null,"abstract":"<div><div>This study presents a novel analysis of peristaltic flow involving a couple stress fluid embedded with a ternary hybrid nanofluid consisting of titanium dioxide (<span><math><mrow><mi>T</mi><mi>i</mi><msub><mi>O</mi><mn>2</mn></msub></mrow></math></span>), alumina (<span><math><mrow><mi>A</mi><msub><mi>l</mi><mn>2</mn></msub><msub><mi>O</mi><mn>3</mn></msub></mrow></math></span>), and copper (<span><math><mrow><mi>C</mi><mi>u</mi></mrow></math></span>) nanoparticles, with blood as the base fluid, in the presence of a magnetohydrodynamics. The investigation focuses on the combined influence of entropy generation, homogeneous-heterogeneous chemical reactions, thermal radiation, viscous dissipation, thermophoresis, Brownian motion and Joule heating. The governing equations of the system are transformed into dimensionless form and solved numerically using the NDSolve in Mathematica, based a fourth-order Runge-Kutta method for accurate and efficient results. Key findings reveal that entropy generation is significantly reduced—by up to <strong>12 %</strong> with an increase in the Hartmann number (M) and dimensionless temperature difference (<span><math><mrow><mi>Ω</mi></mrow></math></span>). Additionally, the inclusion of thermophoresis (Nt) and Brownian motion (Nb) enhances heat transfer, leading to a <strong>15 %</strong> increase in temperature profile compared to traditional nanofluid models. The concentration profile demonstrates a unique dependency, showing a <strong>10 %</strong> improvement with higher heterogeneous reaction rates (H) and Schmidt number (Sc), while the velocity profile decreases by <strong>15 %</strong> with elevated M, indicating precise control of flow behavior in MHD environments. Furthermore, the size of the trapped bolus decreases with increasing M, offering potential for enhanced biomedical applications, such as targeted drug delivery and controlled blood flow. This study is the first to explore the combined effects of ternary hybrid nanoparticles, couple stress fluids and MHD field on peristaltic motion with entropy generation. The findings provide new insights into optimizing thermal and fluid transport processes for advanced biomedical devices and industrial heat transfer systems. Specifically, the research supports the development of advanced peristaltic pump systems for drug delivery, waste removal and fluid transport in biophysiological environments.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"69 ","pages":"Article 106011"},"PeriodicalIF":6.4,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143632097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Energy storage hydrothermal and entropy analysis of micro-polar Nano-encapsulated phase change materials under the effect of exothermic reaction and external magnetic field","authors":"Ahmed M. Hassan ,&nbsp;Mohammed Azeez Alomari ,&nbsp;Abdalrahman Alajmi ,&nbsp;Abdellatif M. Sadeq ,&nbsp;Faris Alqurashi ,&nbsp;Mujtaba A. Flayyih","doi":"10.1016/j.csite.2025.106010","DOIUrl":"10.1016/j.csite.2025.106010","url":null,"abstract":"<div><div>In recent years, the growing demand for electricity has underscored the need for efficient energy storage solutions. This study investigates the energy storage, hydrothermal performance, and entropy analysis of micro-polar nano-encapsulated phase change materials (NEPCMs) under the influence of an exothermic reaction and an external magnetic field. The novelty of this work, which focuses on energy storage applications, lies in the use of a novel geometry and a range of highly effective parameters. The numerical study explores the physical interactions between heat and mass transfer, considering a wide range of parameters, including the Rayleigh number (10³ ≤Ra≤ 10⁵), Lewis number (0.1 ≤ <em>Le</em> ≤ 10), buoyancy ratio (1 ≤ Nz ≤ 5), Hartmann number (0 ≤ <em>Ha</em> ≤50), magnetic field inclination angle (0^o ≤ γ ≤ 90^o), Frank-Kamenetskii number (0 ≤ FK ≤ 2.5), NEPCM concentration (0.01 ≤ ϕ ≤ 0.035), fusion temperature (0.01 ≤ θ_f ≤ 0.035), Stefan number (0.1 ≤ Ste ≤0.9), and aspect ratio (0.5≤AR≤1.5). The results demonstrate that increasing Ra enhances the average Nusselt number (Nu_av) by up to 429.9 % and the average Sherwood number (Sh_av) by up to 206 %, while increasing the total entropy generation (S_total) by up to 13,014 %. Increasing FK reduces Nu_av by up to 27.8 % but increases Sh_av by up to 42.7 %. The <em>Le</em>, Nz, and ϕ significantly impact the hydrothermal performance and entropy generation, with Nu_av increasing by up to 36.3 % and Sh_av decreasing by up to 5.6 % as ϕ increases. The <em>Ha</em> substantially reduces Nu_av and Sh_av by up to 62.3 % and 31.2 %, respectively, while the γ exhibits a non-monotonic behavior with an optimal angle around 60°. The most prominent conclusions highlight the complex interplay between various parameters, with Ra, <em>Le</em>, Nz, and <em>Ha</em> having substantial effects on the hydrothermal performance and entropy generation. The findings provide valuable insights for optimizing the design and operation of energy storage systems based on micro-polar NEPCMs.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"69 ","pages":"Article 106010"},"PeriodicalIF":6.4,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143618337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Computational investigation of heat transfer and fluid flow in a NEPCM-filled cavity with sinusoidal porous layer: Influence of magnetic field and exothermic reactions","authors":"Mohammed Azeez Alomari ,&nbsp;Ahmed M. Hassan ,&nbsp;Hawkar Qsim Birdawod ,&nbsp;Faris Alqurashi ,&nbsp;Mujtaba A. Flayyih ,&nbsp;Abdellatif M. Sadeq","doi":"10.1016/j.csite.2025.106013","DOIUrl":"10.1016/j.csite.2025.106013","url":null,"abstract":"&lt;div&gt;&lt;div&gt;This pioneering study presents a novel investigation of the complex interplay of magnetohydrodynamic (MHD) free convection, double-diffusion, and exothermic reactions in a square cavity with a unique configuration. A corrugated porous layer with a thickness of 0.2L adheres to the left wall. The cavity is partially filled with a nano-enhanced phase change material (NEPCM) suspended porous medium. This innovative design combines the benefits of corrugated surfaces, NEPCMs, and magnetic field control for enhanced thermal management. Using the Galerkin finite element method and PARDISO solver, a comprehensive numerical analysis investigates the effects of various parameters on heat transfer, mass transfer, and entropy generation. These parameters include Frank-Kameneteskii number (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;mi&gt;K&lt;/mi&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mn&gt;2.5&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), Darcy number (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;msup&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), Rayleigh number (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/msup&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;msup&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), buoyancy ratio (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mi&gt;N&lt;/mi&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), Lewis number (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;0.1&lt;/mn&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), fusion temperature (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;0.1&lt;/mn&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;msub&gt;&lt;mi&gt;θ&lt;/mi&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;/msub&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mn&gt;0.9&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), Stefan number (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;0.1&lt;/mn&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mn&gt;0.9&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), magnetic field inclination (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;°&lt;/mo&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mn&gt;90&lt;/mn&gt;&lt;mo&gt;°&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), Hartmann number (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mn&gt;50&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), and NEPCM concentration (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;0.01&lt;/mn&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mi&gt;ϕ&lt;/mi&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mn&gt;0.035&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;). Results demonstrate that increasing Ra from &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; to &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; enhances the average Nusselt number by 324 % at &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;mi&gt;K&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. Nanoparticle volume fraction significantly improves heat transfer, with a 67.6 % increase in Nusselt number as &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;ϕ&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; rises from 0.01 to 0.035. The magnetic field suppresses convection, reducing Nusselt and Sherwood numbers by 57.8 % and 27.4 %, respectively, as &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; increases from 0 to 50. Entropy generation decreases by 84 % under the same conditions. These findings are particularly relevant for design","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"69 ","pages":"Article 106013"},"PeriodicalIF":6.4,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143618336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental study on the optimization of thermal environment and airflow organization in a ventilated underground refuge chamber using deflectors","authors":"Hang Jin ,&nbsp;Zujing Zhang ,&nbsp;Ruiyong Mao ,&nbsp;Jiri Zhou ,&nbsp;Hongwei Wu ,&nbsp;Xing Liang","doi":"10.1016/j.csite.2025.106023","DOIUrl":"10.1016/j.csite.2025.106023","url":null,"abstract":"<div><div>Acceptable temperature is crucial for underground refuge chamber (URC) to ensure the safety and comfort of occupants. A novel temperature control scheme combining mechanical ventilation with deflectors was proposed for URCs. In this study, the effects of ventilation rate (VR), deflector height and deflector angle on ambient temperature control performance and airflow organization of URC were investigated through orthogonal experiments. Results show that: (Ⅰ) The ambient temperature gradient of URC decreases with the increase of VR and deflector height. (Ⅱ) With VR of 350 m³/h, deflector height of 1.40 m, and deflector angle of 0°, compared to the situation without deflectors, the temperature unevenness coefficient can be effectively reduced, the head-to-foot temperature difference can meet the design standard requirements, the waste heat emissions efficiency is increased by 46.1 %, and an average decrease in ambient temperature of 2 °C (Ⅲ) The influence of various factors on the ambient temperature control performance in the URC is as follows: deflector height &gt; VR &gt; deflector angle.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"69 ","pages":"Article 106023"},"PeriodicalIF":6.4,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143632045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of using BN/water nanofluid on the thermal performance, energy saving, and power consumption of a panel radiator heating system","authors":"Ahmet Çağlar","doi":"10.1016/j.csite.2025.106024","DOIUrl":"10.1016/j.csite.2025.106024","url":null,"abstract":"<div><div>Heating systems account for a significant portion of global energy consumption, yet conventional fluids like water limit the thermal efficiency of panel radiators. Improving radiator performance while reducing energy use is critical for achieving sustainability goals. This study addresses this challenge by investigating boron nitride (BN)-doped water nanofluid as an advanced heat transfer fluid, which promises enhanced thermal performance and energy savings compared to water. A Type 11 Panel-Convector (PC) radiator was tested experimentally under transient regime conditions with both water and nanofluid. The amount of heat emitted from the radiator to the room and the air-side heat transfer coefficient were determined for both fluids at a radiator inlet temperature of 75 °C. Additionally, energy consumptions during the experiments for both fluids are compared. The results indicate that the desired room temperature was reached in 17 min using nanofluid, while it took 27 min with water. The air-side heat transfer coefficient increased by an average of 71 %, while the heat emission rate improved by up to 45 % compared to water. The use of BN-water nanofluid results in an 8.1 % overall energy savings in the heating system. The BN-water nanofluid significiantly improves radiator performance and overall system energy efficiency.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"69 ","pages":"Article 106024"},"PeriodicalIF":6.4,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143628429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}