International Journal of Thermal Sciences最新文献

{"title":"Research on parameter optimization algorithms for acoustic collaborative measurement of multiple physical fields","authors":"Qian Kong ,&nbsp;Yihao Zhao ,&nbsp;Zhe Wang ,&nbsp;Yuechao Liu ,&nbsp;Gen-shan Jiang","doi":"10.1016/j.ijthermalsci.2025.110294","DOIUrl":"10.1016/j.ijthermalsci.2025.110294","url":null,"abstract":"<div><div>In the combustion process of large boilers, in order to ensure sufficient and stable combustion of combustion materials, it is necessary to monitor the physical fields such as temperature and flue gas flow fields during coal powder combustion in real time. Considering the refraction of sound waves, acoustic collaborative reconstruction model for multiple physical fields based on radial basis function in the furnace is established. The improved Tikhonov regularization algorithm is used to obtain a new regularization matrix and solve the ill posed problem. Optimization research was conducted on various parameters that affect the quality of physical field reconstruction in collaborative measurement processes. The shape parameters of the radial basis function were optimized using the equilibrium optimization algorithm, and the regularization parameters in the Tikhonov algorithm were determined using the robust generalized cross validation method. The reconstruction steps for the acoustic temperature field and velocity field collaborative measurement were provided by simultaneously optimizing the two parameters. To verify the feasibility of the proposed parameter optimization algorithm, numerical simulations were conducted to reconstruct the typical temperature field and tangential velocity field in the furnace using multiple physical fields. In addition, the combustion process of high-temperature swirling flow is simulated and non-uniform temperature and complex flow fields are simultaneously reconstructed in a furnace. In end, an experimental acoustic measurement system is developed to measure the temperature and velocity fields and evaluate our proposed method. All the results confirm the feasibility, effectiveness and noise immunity of our proposed method to simultaneously reconstruct multi-physics fields under different complicated environment.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"220 ","pages":"Article 110294"},"PeriodicalIF":5.0,"publicationDate":"2025-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145046283","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 the comprehensive heat transfer performance of double-pipe heat exchangers with twisted elliptical tubes and with corrugated tubes","authors":"Yin Ying-de ,&nbsp;Nong Ya-shan ,&nbsp;Li Yuan-yu ,&nbsp;Hu Rong ,&nbsp;Liu Shi-jie ,&nbsp;Zheng Wen-heng","doi":"10.1016/j.ijthermalsci.2025.110280","DOIUrl":"10.1016/j.ijthermalsci.2025.110280","url":null,"abstract":"<div><div>Twisted elliptical tubes (TETs) and corrugated tubes (CTs) are both key elements for enhancing heat transfer in double-pipe heat exchangers (DPHEs). In order to investigate the comprehensive heat transfer performance of these DPHEs, an experimental study was conducted. The Nusselt number (<span><math><mrow><mi>N</mi><mi>u</mi></mrow></math></span>) and friction factor (<span><math><mrow><mi>f</mi></mrow></math></span>) criterion correlation formulas for the tube side and shell side of the two DPHEs were fitted, and a factor (<span><math><mrow><mi>η</mi></mrow></math></span>) was used to evaluate the comprehensive heat transfer performance. Experimental results indicated that both the overall heat transfer coefficients (<span><math><mrow><mi>U</mi></mrow></math></span>) of the twisted elliptical tube double-pipe heat exchanger (TETDPHE) and the corrugated tube double-pipe heat exchanger (CTDPHE) increased as the flow velocity ranged from 0.1 to 1.5 m/s, and the latter had an average increase of 13 % compared to the former. Under the same Reynolds number (<span><math><mrow><mi>R</mi><mi>e</mi></mrow></math></span>), the <span><math><mrow><mi>U</mi></mrow></math></span> and pressure drop (<span><math><mrow><mo>Δ</mo><mi>P</mi></mrow></math></span>) of these two DPHEs were basically not affected by the temperature difference (<span><math><mrow><mo>Δ</mo><mi>T</mi></mrow></math></span>) between the hot and cool side at the inlet. The maximum <span><math><mrow><mi>η</mi></mrow></math></span> values of TETDPHE and CTDPHE were 1.43 times and 1.24 times of the smooth circular tube double-pipe heat exchanger (SCTDPHE), respectively. In the range of <span><math><mrow><mi>N</mi><mi>u</mi></mrow></math></span> from 2000 to 31000, the <span><math><mrow><mi>η</mi></mrow></math></span> value of TETDPHE was better than that of CTDPHE and SCTDPHE. In the range of <span><math><mrow><mi>N</mi><mi>u</mi></mrow></math></span> from 2000 to 8300, the <span><math><mrow><mi>η</mi></mrow></math></span> value of CTDPHE was better than that of SCTDPHE. Thus, the CTDPHE is suitable for the scenario with lower Reynolds numbers, while the TETDPHE can be widely applied.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"220 ","pages":"Article 110280"},"PeriodicalIF":5.0,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145020127","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":"Novel cooling approach in microchannel with fixed and variable fins configuration","authors":"Nahum Y. Godi","doi":"10.1016/j.ijthermalsci.2025.110276","DOIUrl":"10.1016/j.ijthermalsci.2025.110276","url":null,"abstract":"<div><div>This paper explores a 3-D numerical simulation of a microchannel with a rectangular configuration. The objective of the study is to enhance performance by minimising thermal resistance within a fixed volume, considering two cases: fixed and variable fin configurations. A heat load of 438 W is applied to the bottom wall surface. Heat dissipation is achieved using forced convection under steady-state laminar conditions, with the fluid Reynolds number ranging from 100 to 150 and the convective air stream Reynolds number between 10 and 12. The fluid and heat fields are predicted using the finite volume (FVM) technique and a computational fluid dynamic (CFD) methodology. The results of the study indicate that minimised resistance decreased in both parallel and counterflow configurations, even with modifications to the fin characteristic profiles. Based on the numerical findings, at a maximum water pumping power of 0.23 W and an average air pressure drop of 0.706 kPa, the counterflow configuration with variable fin designs achieved the best performance, reducing minimised resistance by up to 33.3 %. This is followed closely by the parallel flow design, which achieved a 32.02 % reduction. In the heat sink with a fixed fin design, the fin height-to-length ratio is 1.75. In contrast, for the variable fin design, the fin length ratio ranges from 1.13 to 1.17 in parallel flow, with a height-to-length ratio between 1.29 and 2.23. In the counterflow configuration, the fin length ratio varies from 0.85 to 0.89. The numerical scheme is validated using both experimental and numerical data in open literature.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"220 ","pages":"Article 110276"},"PeriodicalIF":5.0,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145020114","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":"Influence of fluctuating heat sources and the subzone rotation strategy on the solid-liquid phase transition process: experimental and numerical studies","authors":"Xinyu Huang ,&nbsp;Jiantao Xia ,&nbsp;Bin Xiao ,&nbsp;Xiaohu Yang ,&nbsp;Bengt Sundén","doi":"10.1016/j.ijthermalsci.2025.110274","DOIUrl":"10.1016/j.ijthermalsci.2025.110274","url":null,"abstract":"<div><div>The application of the rotation mechanism promotes heat exchange in the phase-change energy storage (PCES) process and improves the temperature non-uniformity at the end. This research proposes a novel type of subzone rotation condition, where different rotational speeds and rotation directions are applied to distinct phase transition regions, and it is implemented in the triple-tube heat storage process. An experimental system is constructed to monitor the temperature of PCM inside the PCES unit connected to the motor for rotation. Cross-comparisons are made with numerical process of PCES under the application of rotation conditions to verify its accuracy. The effect of constant and fluctuating heat sources on this PCES under different subzone rotation conditions is also considered. The comparison results indicate that the fluctuating heat source on overall melting behavior can be ignored, while the subzone rotation condition can improve the negative effect of the difficult-to-melt area. After applying a subzone rotational speed of 0.2 rpm, compared with static energy storage process, the mean PCES rate increased by 299.43 %, while the required time for heat storage completion is reduced by 74.73 %. The novel active enhanced heat exchange method proposed in the research is conducive to the further development of PCES technology.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"220 ","pages":"Article 110274"},"PeriodicalIF":5.0,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145011158","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":"Hydrothermal and entropy generation analysis of mixed convection heat transfer in Couette–Poiseuille flow of a trihybrid nanofluid over a backward-facing step","authors":"Mehran Sharifi ,&nbsp;Amirhosein Mohammadi ,&nbsp;Ali J. Chamkha ,&nbsp;Abdelraheem M. Aly","doi":"10.1016/j.ijthermalsci.2025.110283","DOIUrl":"10.1016/j.ijthermalsci.2025.110283","url":null,"abstract":"&lt;div&gt;&lt;div&gt;This study introduces and systematically investigates a novel Couette–Poiseuille backward-facing step configuration, in which the conventional stationary upper wall is replaced by a uniformly moving belt. The flow domain is filled with a trihybrid nanofluid composed of (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mtext&gt;Al&lt;/mtext&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;msub&gt;&lt;mi&gt;O&lt;/mi&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/msub&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mtext&gt;Cu&lt;/mtext&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mtext&gt;MWCNT&lt;/mtext&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;) nanoparticles, enabling the interplay of pressure-driven and shear-driven forces within a sudden-expansion geometry with &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mtext&gt;ER&lt;/mtext&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. Numerical analysis explores the effects of varying Reynolds numbers (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;100&lt;/mn&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;msub&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/msub&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mn&gt;500&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), Rayleigh numbers (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;6.99&lt;/mn&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;mo&gt;≤&lt;/mo&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;msub&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/msub&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mn&gt;1.75&lt;/mn&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;msup&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mn&gt;7&lt;/mn&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), Grashof numbers (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;1.0&lt;/mn&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;msup&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;/msup&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;msub&gt;&lt;mtext&gt;Gr&lt;/mtext&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/msub&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mn&gt;2.5&lt;/mn&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;), and top wall terminal velocity ratios (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;msub&gt;&lt;mi&gt;U&lt;/mi&gt;&lt;mrow&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;mi&gt;l&lt;/mi&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;) on flow behavior, heat transfer, and entropy generation, with the constant Prandtl number (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;Pr&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;) of &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;69.93&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. At low &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;msub&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, aiding wall motion stabilizes the flow and minimizes entropy generation, while opposing wall motion induces strong recirculation, vortex shedding, and Kelvin–Helmholtz instabilities at higher &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;msub&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. Thermal field analysis reveals that counter-flow enhances convective mixing and thermal dispersion, whereas co-flow confines heated fluid near the lower wall. The moving wall improves heat transfer performance by up to &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;14&lt;/mn&gt;&lt;mo&gt;%&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; in optimal opposing-flow conditions and reduces the Irreversibility-to-Heat Transfer Index (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mtext&gt;IHTI&lt;/mtext&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;) by over &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;90&lt;/mn&gt;&lt;mo&gt;%&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; at low &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;msub&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, where values remain below &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;5&lt;/mn&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;7&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, indicating high thermodynamic efficiency. However, at high &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;msub&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;500&lt;/mn&gt;&lt;","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"220 ","pages":"Article 110283"},"PeriodicalIF":5.0,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145005132","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":"Deep learning-based model for predicting physical fields during frozen startup of high-temperature heat pipes","authors":"Xin Yu ,&nbsp;Zeqin Zhang ,&nbsp;Xiaoyan Wang ,&nbsp;Tianyuan Liu ,&nbsp;Kailun Guo ,&nbsp;Haocheng Zhao ,&nbsp;Chunping Tian ,&nbsp;Mingjun Wang ,&nbsp;Suizheng Qiu ,&nbsp;Guanghui Su ,&nbsp;Wenxi Tian","doi":"10.1016/j.ijthermalsci.2025.110263","DOIUrl":"10.1016/j.ijthermalsci.2025.110263","url":null,"abstract":"<div><div>High-Temperature Heat Pipes (HTHPs) are widely used due to their excellent thermal performance and passive characteristics. However, their complex frozen startup process presents significant challenges for numerical simulations, particularly regarding efficiency and accuracy. This study introduces a Convolutional Neural Network (CNN) framework to develop an end-to-end model that predicts and analyzes the physical fields of HTHPs based on operating parameters, enabling rapid and accurate predictions of the frozen startup process. A large-scale dataset encompassing various operating conditions was generated through numerical simulations to train the CNN model. Convergence analysis results indicated that a training size of 1.0 and a network depth of 4 layers are the optimal parameters for the model. The CNN model accurately predicted the physical fields, achieving mean absolute errors of 0.41 K for temperature, 5.12 × 10⁻⁵ m/s for axial velocity, 3.24 × 10⁻⁶ m/s for radial velocity, and 23.53 Pa for pressure. Additionally, the model demonstrated a prediction speed nearly four orders of magnitude faster than traditional Computational Fluid Dynamics (CFD) methods. It also accurately predicted the wall temperature of HTHPs, with a mean absolute error of only 0.47 K. This study highlights the potential of deep learning for advancing HTHP analysis.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"220 ","pages":"Article 110263"},"PeriodicalIF":5.0,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145005020","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":"Study on the magnetic-thermal evolution and air cooling synergy of bevel gears: based on asynchronous multi-frequency electromagnetic heating","authors":"Zhuge Shao ,&nbsp;Yingde Zhang ,&nbsp;Yi Han ,&nbsp;Yao Xiao ,&nbsp;Lijian Xuan","doi":"10.1016/j.ijthermalsci.2025.110291","DOIUrl":"10.1016/j.ijthermalsci.2025.110291","url":null,"abstract":"<div><div>This study proposes an asynchronous multi-frequency heating (TFH) method combined with air-cooling control, revealing the magneto-thermal evolution law in spiral bevel gear heating. Research demonstrates that TFH achieves pulsed thermal excitation on gear surfaces through time-domain modulation of electromagnetic parameters, while the heat flux penetration depth (<em>d</em>) exhibits asymmetric characteristics on bilateral tooth surfaces. A Gaussian eddy-current model incorporating an attenuation term demonstrates that this asymmetry arises from localized eddy-current concentration difference dictated by sharp corner effect driven by tangential edge angle (<em>α</em>). Discrepancies of <em>α</em> at the gear's large end cause 76.3 % greater <em>d</em> on the concave side (smaller <em>α</em>) versus the convex side. Conversely, gradual tooth-profile variations at the small end invert this trend, yielding 85.1 % deeper heating on the convex side. Investigations reveal gradient-distributed air-cooling rates at tooth tip, middle, and bottom sections during frequency switching, with this dynamic thermal dissipation behavior effectively compensating temperature differentials induced by gradual tooth-profile variations. The bi-directional dispersion degree of the tooth surface temperature (<em>S</em>), as a temperature uniformity metric, demonstrates a 60 % reduction when using TFH compared to single-frequency methods, indicating the significant advantage of this strategy in achieving uniform heating for complex workpieces.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"220 ","pages":"Article 110291"},"PeriodicalIF":5.0,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145007781","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":"Numerical simulation of heat transfer and flow behavior of molten pool under figure-8 oscillating laser cladding","authors":"Xinshun Wang ,&nbsp;Yinghua Lin ,&nbsp;Jinhai Lin ,&nbsp;Longsheng Peng ,&nbsp;Xinlin Wang","doi":"10.1016/j.ijthermalsci.2025.110279","DOIUrl":"10.1016/j.ijthermalsci.2025.110279","url":null,"abstract":"<div><div>The figure-8 oscillating laser can improve the quality of cladding and has great value for industrial applications, but its molten pool heat transfer and flow behavior are poorly known and seldom reported. For this reason, an in-depth understanding of the heat flow characteristics of the molten pool in this special laser mode is of great significance to the molding law of microstructure as well as the regulation work. In this work, a finite element model of laser cladding with multi-physical fields is established to investigate the effects and laws of different oscillation frequencies and amplitudes on the size of the cladding layer, heat transfer, and the fluid flow. The reliability of the numerical model is verified through experiments. The results show that the introduction of the figure-8 oscillation mode expands the range of the effective heat source, and the depth-to-width ratio of the molten pool is decreased. The temperature distribution is more uniform, and the nodal temperature values show periodic fluctuations consistent with the frequency. The complex laser overlap path periodically generates vortices that interfere with the Marangoni effect, and the flow of the molten pool becomes more complex. The microstructure of the cladding layer is refined due to sufficient mixing of the molten material, and the hardness is more uniform along the depth direction. This work provides insights and guidance for understanding the characteristics of the figure-8 oscillating laser cladding process and controlling metallurgical defects.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"220 ","pages":"Article 110279"},"PeriodicalIF":5.0,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145005019","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":"Study on supersonic film cooling using gaseous hydrocarbon fuel as coolant with segmented injection regulation method","authors":"Jingying Zuo ,&nbsp;Jingjia Xue ,&nbsp;Silong Zhang ,&nbsp;Jianfei Wei ,&nbsp;Xin Li ,&nbsp;Wen Bao ,&nbsp;Naigang Cui","doi":"10.1016/j.ijthermalsci.2025.110281","DOIUrl":"10.1016/j.ijthermalsci.2025.110281","url":null,"abstract":"<div><div>Hydrocarbon fueled supersonic film cooling is considered to be one of the most promising thermal protection methods for scramjet combustors, while regulating its flow and combustion characteristics and improving its cooling performance are of great significance for engine performance. In this paper, the effects of segmented injection regulation method on hydrocarbon fueled supersonic film cooling performance are numerically investigated. The results indicate that, with single film injection, film combustion first brings beneficial effect and then brings negative effect on the supersonic film cooling. Whereas, segmented injection reorganizes near-wall chemical reaction and flow characteristics, resulting in endothermic-exothermic- endothermic reaction characteristics near the wall, leading to the combustion high-temperature region distributed in the film potential-core flow characteristic region and suppressing the mixing process. Therefore, segmented injection regulation method can significantly shorten the negative effect region brought by the film combustion, and further improve the supersonic film cooling performance based on that with single film injection. It is worth mentioning that, the overall film cooling performance with segmented injection is not sensitive to the flow distribution ratio in the variation range from 5:5 to 7:3. Furthermore, the second film injection arranges at the separation point of the first film, where the combustion begins to have negative effect on the film cooling, can eliminate the negative effect. Within the 500 mm length range without increasing the mass flow rate of film coolant, segmented injection by dual films with flow equalization principle and evenly distributed position can increase the average supersonic film cooling effectiveness by 19 %, and decrease the average wall skin friction by 20.1 %. The forward movement of the second film layout position to the separation point can further increase the average supersonic film cooling effectiveness by 2.85 %.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"220 ","pages":"Article 110281"},"PeriodicalIF":5.0,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145005022","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":"Effect of Fe3O4/ZnO hybridization ratios on heat transfer and transition behavior in the transition flow regime","authors":"Victor O. Adogbeji,&nbsp;Tartibu Lagouge","doi":"10.1016/j.ijthermalsci.2025.110238","DOIUrl":"10.1016/j.ijthermalsci.2025.110238","url":null,"abstract":"<div><div>Optimizing thermal management in heat transfer systems has sparked increased interest in hybrid nanofluids, particularly due to their tunable properties from nanoparticle blending. This study experimentally investigates the thermal behavior, efficiency, and entropy generation of <span><math><mrow><msub><mrow><mspace></mspace><mtext>Fe</mtext></mrow><mn>3</mn></msub><msub><mi>O</mi><mn>4</mn></msub></mrow></math></span>/ZnO hybrid nanofluids in circular pipes at various hybridization ratios (80:20, 60:40, 50:50, 40:60, and 20:80) with a constant volume concentration of 0.0125 %. The 80:20 blend exhibited the greatest heat transfer enhancement, demonstrating a 36 % improvement in the transition regime and 9 % in turbulent flow. In contrast, the 20:80 ratio achieved a 37 % enhancement in the transition regime but only a 3 % improvement in turbulence, indicating lower thermal effectiveness at higher Reynolds numbers. The Total Efficiency Index (TEI) peaked at 1.53 for the 80:20 mixture, followed by 1.47 for the 60:40 blend. A higher ZnO fraction delayed the onset of flow transition, thus enhancing thermal regulation. Regarding pressure drop, the 20:80 blend consistently showed the highest resistance, while the 60:40 ratio demonstrated the lowest, indicating superior hydraulic performance. However, this ratio did not yield the best heat transfer results, suggesting a tradeoff between thermal and flow efficiency. The 50:50 ratio provided balanced performance in both heat transfer and pressure loss, making it a promising choice for practical applications. These findings highlight the influence of <span><math><mrow><msub><mrow><mspace></mspace><mtext>Fe</mtext></mrow><mn>3</mn></msub><msub><mi>O</mi><mn>4</mn></msub></mrow></math></span>’s magnetic properties in enhancing heat transport and the critical role of hybridization ratio in optimizing thermofluid performance. Future research should investigate the effects of surfactants, alternative base fluids, and external magnetic fields on long-term nanofluid stability and performance.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"220 ","pages":"Article 110238"},"PeriodicalIF":5.0,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145005021","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}