Applied Thermal Engineering最新文献

{"title":"Influence of piston bowl geometry and swirl ratio on spray dynamics and fuel–air mixing in compression ignition diesel engines","authors":"Hamidreza Sefatjoo,&nbsp;Hassan Khaleghi","doi":"10.1016/j.applthermaleng.2026.129908","DOIUrl":"10.1016/j.applthermaleng.2026.129908","url":null,"abstract":"<div><div>Improving fuel–air mixing remains a critical pathway for reducing emissions and enhancing efficiency in compression-ignition (CI) diesel engines, particularly under increasingly stringent environmental regulations. In-cylinder flow organization, governed primarily by piston bowl geometry and swirl ratio (SR), plays a decisive role in spray development, turbulence generation, and mixture preparation prior to ignition. Despite extensive prior research, the combined influence of multiple piston bowl geometries and swirl intensities under identical, non-reacting conditions has not been systematically quantified. In this study, a comprehensive numerical investigation is conducted to examine the coupled effects of piston bowl geometry and initial swirl ratio on in-cylinder flow evolution, spray dynamics, and fuel–air mixing under motored conditions. Four representative piston bowl geometries of ω-shaped, re-entrant, semi-ellipsoid, and double-swirl are analyzed using a validated Eulerian–Lagrangian CFD framework with the RNG k–ε turbulence model. All configurations are evaluated under equal bowl volume, compression ratio, and injection conditions, with initial SR varied from 0 to 3 to isolate aerodynamic effects from combustion chemistry.</div><div>The results reveal strong geometry-dependent swirl amplification and turbulence evolution near top dead center. The semi-ellipsoid bowl achieves the highest swirl amplification (up to ∼78%) and evaporation fraction (∼18%), owing to reduced shear losses and enhanced rotational preservation. The double-swirl geometry promotes distributed turbulence and minimizes wall impingement through flow partitioning, while the re-entrant bowl prioritizes turbulence generation at the expense of swirl amplification. Across all geometries, increasing SR reduces axial spray penetration (up to ∼8%) while enhancing lateral dispersion. To quantitatively assess mixture formation, a new effective penetration metric (combining axial penetration and lateral spread) is introduced. This metric demonstrates that moderate swirl levels (SR ≈ 2) maximize usable mixing volume (32–36 mm) for all geometries. Excessive swirl leads to jet distortion, plume interaction, and reduced chamber utilization. Overall, this work provides a unified, quantitative framework for evaluating bowl–swirl interactions and delivers practical design guidelines for advanced diesel combustion chambers, supporting cleaner and more efficient engine operation in next-generation applications.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"289 ","pages":"Article 129908"},"PeriodicalIF":6.9,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Film cooling performance of turbine blade leading edge with internal return-flow impingement cooling scheme","authors":"Nan Xu ,&nbsp;Han Yan ,&nbsp;Lei Luo ,&nbsp;Wei Du ,&nbsp;Licheng Guo","doi":"10.1016/j.applthermaleng.2026.129930","DOIUrl":"10.1016/j.applthermaleng.2026.129930","url":null,"abstract":"<div><div>Accompanied by annually rising gas temperature, the single internal cooling is not sufficient for the demand of thermal protection on the leading edge. In this study, a novel anti-crossflow return-flow impingement structure on the film cooling performance are studied by using CFD methods. The effects of angle parameters, blowing ratio (<em>M</em>) and target surface heating on the thermal protection capability are highlighted. From the results, the average film cooling effectiveness (<em>η</em>) is observed to improve with decreasing values of both the spanwise angle and circumferential angle. A trend of initial increase followed by subsequent decrease in the <em>η</em> is observed with respect to the <em>M</em>. When the <em>M</em> is set at 1.5, the highest <em>η</em>, reaching 0.26131, is achieved. The coolant is heated by the target surface, which consequently diminishes the <em>η</em>. This reduction is especially significant in the region downstream of the Row2 holes. This paper establishes the theoretical foundation for application in the blade of film cooling and return-flow impingement cooling.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"289 ","pages":"Article 129930"},"PeriodicalIF":6.9,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pyrolysis mechanism and radical evolution in C6F12O–N2 gas mixtures: A combined ReaxFF MD and DFT study","authors":"Kai Wang ,&nbsp;Dezheng Wang ,&nbsp;Bin Zheng ,&nbsp;Wei Wang ,&nbsp;Biao Zhou","doi":"10.1016/j.applthermaleng.2026.129899","DOIUrl":"10.1016/j.applthermaleng.2026.129899","url":null,"abstract":"<div><div>Perfluorohexanone (C₆F₁₂O) is a clean fire suppressant and is often used together with nitrogen (N₂), but the thermal pyrolysis behavior and radical evolution in C₆F₁₂O–N₂ mixtures are still not well understood. Previous studies mainly considered discharge conditions or other buffer gases and rarely combined experiments with multi-scale simulations. This study integrates tubular-furnace experiments, density functional theory (DFT) and ReaxFF molecular dynamics (MD) to clarify the dominant pyrolysis pathways of C₆F₁₂O–N₂ and the effects of operating conditions. Experiments at 450–750 °C show that significant C₆F₁₂O pyrolysis starts near 550 °C, with products evolving from higher perfluoroalkanes (C₅F₁₂, C₄F₁₀, C₃F₈) to smaller fluorocarbons (C₃F₆, CF₄) as temperature increases. DFT indicates that C<img>C bonds adjacent to the carbonyl group are the weakest, leading to primary radicals C₃F₇·, C₂F₅· and CF₃·, which explain the observed product spectrum. ReaxFF-MD reproduces these trends and resolves the time-dependent evolution of radicals under different temperature, mixing-ratio and pressure conditions. A moderate N₂ fraction promotes initial activation of C₆F₁₂O, whereas excessive N₂ or high pressure suppresses radical chain propagation and lowers the pyrolysis extent. The identified endothermic bond scission and fluorinated radicals that scavenge H·/OH· radicals provide mechanistic support for the combined cooling and chemical-inhibition effects responsible for fire suppression by C₆F₁₂O–N₂ mixtures.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"289 ","pages":"Article 129899"},"PeriodicalIF":6.9,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CFD-based optimization of oxygen-enriched combustion in copper anode refining furnace","authors":"Yuyang Chen ,&nbsp;Shiliang Yang ,&nbsp;Jiajun Lu ,&nbsp;Hua Wang","doi":"10.1016/j.applthermaleng.2026.129933","DOIUrl":"10.1016/j.applthermaleng.2026.129933","url":null,"abstract":"<div><div>The anode refining furnace is primarily utilized to purify blister copper derived from copper matte converting, typically relying on methane combustion for thermal energy. This study establishes a numerical framework to investigate turbulent diffusion combustion and oxygen-enhancement mechanisms within a rotary refining furnace. The model fidelity was rigorously validated against the Sandia Flame D benchmark. Subsequently, the effects of oxygen concentration were systematically evaluated, focusing on jet dynamics, thermal topology, turbulence characteristics, and pollutant formation. Results demonstrate that oxygen enrichment significantly modulates species evolution and thermal field distribution. Specifically, increasing oxygen concentration from 80% to 95% intensified CO generation and expanded the high-temperature flame core, yielding superior thermal homogeneity. However, this thermal enhancement incurred a substantial penalty where NO emissions surged to 385 ppm at 95% oxygen. This represents a nearly four fold increase relative to the 80% baseline.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"289 ","pages":"Article 129933"},"PeriodicalIF":6.9,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimization of thermal efficiency and heating uniformity for insulator production in tunnel ovens using CFD simulations and experimental studies","authors":"Kailin Ren,&nbsp;Xin Luo,&nbsp;Zhigao Huang,&nbsp;Xuyang Cai,&nbsp;Riqing Chen,&nbsp;Donglei Liu,&nbsp;Shaojian Zhang","doi":"10.1016/j.applthermaleng.2026.129895","DOIUrl":"10.1016/j.applthermaleng.2026.129895","url":null,"abstract":"<div><div>Optimizing the heating process is crucial for the efficient and high-performance application of insulators, yet this aspect has been largely overlooked in the current research. For the first time, this paper presents a comprehensive investigation into the thermal characteristics of insulators during heating, utilizing both experimental and numerical approaches. The heating uniformity and thermal efficiency of the oven system are chosen as the main two reference indicators of thermal performance. Furthermore, various oven heating structures were evaluated to identify an optimal design. The study also examined different operating conditions to determine the best heating strategy. A strong agreement was observed between experimental and numerical results, with a maximum relative discrepancy of 4.23%, validating the accuracy of the numerical methods. Significantly, under optimal conditions (inlet air velocity of 5 m/s and heating temperature of 140 °C), plan 3 (featuring panels on both sides of the oven) achieved a thermal efficiency of 15.64% and a coefficient of unevenness of 0.28. This represents a substantial improvement of 12.03% in thermal efficiency and a remarkable 94.83% reduction in the coefficient of unevenness compared to the original design. Therefore, plan 3 operated at 5 m/s and 140 °C is recommended as the most practical solution for heating insulators in the tunnel oven. Overall, this research provides a promising and effective methodology for optimizing insulator heating processes.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"289 ","pages":"Article 129895"},"PeriodicalIF":6.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Towards reliable model validation of evaporative coolers: Unified terminology and benchmark datasets","authors":"Alanis Zeoli ,&nbsp;Samuel Gendebien ,&nbsp;Titouan Janod ,&nbsp;Tala Moussa ,&nbsp;Chadi Maalouf ,&nbsp;Anna Pacak ,&nbsp;Vincent Lemort","doi":"10.1016/j.applthermaleng.2026.129928","DOIUrl":"10.1016/j.applthermaleng.2026.129928","url":null,"abstract":"<div><div>Evaporative cooling technologies are getting more attention in the scientific community due to the urgent need to satisfy the growing demand for cooling buildings while decreasing <span><math><msub><mrow><mtext>CO</mtext></mrow><mrow><mn>2</mn></mrow></msub></math></span> emissions. Evaporative coolers offer a promising alternative to standard vapour-compression cycles, and many evaporative cooler variants have emerged in recent years to improve their performance. Similarly, the number of models developed to assess the performance of evaporative cooler configurations and simulate their behaviour under various operating conditions is constantly increasing. To obtain relevant results using simulation, it is necessary to perform a proper model validation, which is often handled using experimental data from the literature. However, model validation based on data from the literature can be time-consuming because the terminology of evaporative cooler configurations is not unified throughout the literature, and it requires gathering data from existing papers, which is rarely accessible in tables. This paper provides a framework for model validation using a two-step approach. First, the authors propose a comprehensive classification of evaporative coolers to unify the denominations of evaporative cooler configurations and understand the advantages and drawbacks of existing configurations. Second, standardised datasets are provided for each identified type of evaporative cooler. 18 datasets have been generated using existing experimental and numerical data from the literature, covering various operating conditions. Full datasets are available in an online open-source database to help the reader with model validation of various evaporative cooler configurations.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"289 ","pages":"Article 129928"},"PeriodicalIF":6.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Forming and mechanism investigation of heat pipe wick with micro-nano pore using additive-subtractive composite processing","authors":"Weisong Ling ,&nbsp;Zhanpeng Hu ,&nbsp;Jiarong Cui ,&nbsp;Wenjun Xu ,&nbsp;Yi Zhu ,&nbsp;Chaofan Wang ,&nbsp;Baocai Zhang ,&nbsp;Wei Zhou","doi":"10.1016/j.applthermaleng.2026.129886","DOIUrl":"10.1016/j.applthermaleng.2026.129886","url":null,"abstract":"<div><div>This study proposes an additive-subtractive composite manufacturing method to fabricate micro-nano composite porous wicks by combining selective laser sintering (SLS) and anodizing techniques. Initially, 316 L stainless steel substrates with microporous structures were fabricated using SLS. Subsequently, anodizing was applied to produce nanopores on the microporous substrate, forming a hybrid micro-nano porous structure. The effects of key parameters such as anodizing time, electrolyte concentration, and substrate wall thickness on porosity, pore size, and pore distribution were systematically analyzed. A three-stage evolution mechanism of nanopore formation: initial rapid pore formation, intermediate rapid growth, and final stabilization was revealed. Results show that anodizing significantly enhanced the wettability and capillary pumping performance of wick. The absorption time of deionized water was reduced by 38.46%, and the maximum capillary pumping mass was increased by 22.04%. The application of the micro-nano composite wick in a loop heat pipe (LHP) further demonstrated its superior heat transfer performance. Under a high heat load of 300 W, the anodized wick exhibited a lower evaporator outlet temperature and higher cooling water outlet temperature. The heat transfer efficiency was improved by 5.84% while thermal runaway was avoided. These findings provide theoretical and technological insights for the design and optimization of high-performance thermal management materials.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"289 ","pages":"Article 129886"},"PeriodicalIF":6.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Calibration and inversion using a data-model fusion-driven method with application to lead‑bismuth cooled reactors","authors":"Shuo Liu ,&nbsp;Wenshu Li ,&nbsp;Chenglong Wang ,&nbsp;Dalin Zhang ,&nbsp;Pengrui Qiao ,&nbsp;Suizheng Qiu","doi":"10.1016/j.applthermaleng.2026.129924","DOIUrl":"10.1016/j.applthermaleng.2026.129924","url":null,"abstract":"<div><div>With the deepening understanding of turbulent heat transfer phenomena in liquid metals, neither purely experimental measurements or purely numerical simulations alone can meet the demands of current research. In recent years, the development and application of data assimilation technology can contribute to solve this problem. In this work, a data-model fusion-driven method was created based on the Ensemble Kalman filter (EnKF). Then it was applied to the calibration of turbulent Prandtl number (<em>Pr</em>_<em>t</em>) and the prediction of average Nusselt number (<em>Nu</em>) for the flow and heat transfer phenomena of lead‑bismuth eutectic (LBE). Using the calibrated <em>Pr</em>_<em>t</em> model, the prediction of the average <em>Nu</em> not only achieved high agreement with Johnson's experimental data, with a relative error within 5%, but also significantly outperformed existing correlation formulas. Although its prediction accuracy decreases when extrapolating at low Peclet number (<em>Pe</em>), the error remains within ±15%. Under the higher <em>Pe</em> number condition, a single measurement point suffices for the calibration requirement while under the lower <em>Pe</em> condition, at least two measurement points are required to ensure reliable correction.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"289 ","pages":"Article 129924"},"PeriodicalIF":6.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation on a novel air-cooled PEMFC stack with enhanced heat dissipation and self-driven heat replenishment via heat recovery","authors":"Mingguang Yang ,&nbsp;Zhenhua Quan ,&nbsp;Zejian Chang ,&nbsp;Yaohua Zhao ,&nbsp;Lei Xing ,&nbsp;Lincheng Wang","doi":"10.1016/j.applthermaleng.2026.129929","DOIUrl":"10.1016/j.applthermaleng.2026.129929","url":null,"abstract":"<div><div>A novel air-cooled proton exchange membrane fuel cell (PEMFC) stack with a dual-mode thermal management strategy is proposed to address challenges with both high-load heat dissipation and low-temperature operational challenges. The design integrates micro heat pipe arrays (MHPAs) to enhance heat transfer and enable self-driven heat recovery for inlet air preheating. A dynamic isothermal model is developed and validated against experimental results, providing guidance for structural optimization and operating strategies. Under the heat dissipation mode, coordinated fan control and MHPA configuration increased load capacity by 27.3% and boosted maximum power output by 12.6%. Under self-driven heat recovery mode, elevated the inlet air temperature from 0 °C to 12.8 °C, leading to a 9.0% improvement in low-temperature performance. These results demonstrate that the proposed PEMFC stack effectively combines a compact structure with energy-efficient operation, offering strong potential for reliable portable power applications under variable environmental conditions.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"289 ","pages":"Article 129929"},"PeriodicalIF":6.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental study on a multi-stage separated gravity heat pipe cooling system for liquid-cooled data center server racks","authors":"Yuxi Tao ,&nbsp;Peisheng Li ,&nbsp;Huiwu Liu ,&nbsp;Lingxiao Weng ,&nbsp;Xiaoliang Deng ,&nbsp;Ying Zhang ,&nbsp;Yuan Tian ,&nbsp;Fanghua Ye","doi":"10.1016/j.applthermaleng.2026.129887","DOIUrl":"10.1016/j.applthermaleng.2026.129887","url":null,"abstract":"<div><div>To address the heat dissipation challenges arising from the continuously increasing thermal load density in liquid-cooled data centers, a multi-stage separated gravity heat pipe cooling system is proposed in this work. The cooling system includes three plate heat exchangers connected in series forming the evaporator section and three microchannel heat exchangers arranged in parallel forming the condenser section. Each evaporator and its corresponding condenser are connected through gas riser and liquid downcomer pipes, which form three independent thermal circulation loops. This configuration enables staged heat transfer coupling, ensures reliable operation, and utilizes natural air as the cooling source to enhance system-level efficiency. To verify its thermal performance and operating characteristics, a comprehensive experimental platform was established. Experimental investigations on the effects of filling ratio, superheating, and subcooling on the system's heat transfer behavior were carried out. Experimental results showed that the overall heat transfer capacity first increased and then decreased with the filling ratio. The optimal performance was achieved when the filling ratios of the three stages was 30%–30%–30%. Under an ambient temperature of 30 °C, the system achieved a maximum heat transfer capacity of 17.82 kW and a corresponding Coefficient of Performance (COP) of 18.18, demonstrating excellent heat transfer capability under high heat flux conditions. Additionally, an appropriate degree of superheating enhanced the phase-change rate and the driving potential at the evaporator, while the effect of subcooling on the condenser exhibited nonlinear behavior. The heat transfer distribution among the stages revealed that the low-temperature stage consistently accounted for the highest proportion of total heat transfer. These findings demonstrate the effectiveness and efficiency of the proposed system and provide practical insights for the design and optimization of liquid-cooled server backplane systems.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"290 ","pages":"Article 129887"},"PeriodicalIF":6.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146096149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}