Pub Date : 2025-03-27DOI: 10.1016/j.ijheatmasstransfer.2025.126982
Qian Jiang , Feng Ren , Chenglei Wang , Zhaokun Wang , Gholamreza Kefayati , Sasa Kenjeres , Kambiz Vafai , Xinguang Cui , Yang Liu , Hui Tang
Magnetic hyperthermia is a promising cancer treatment method that involves complex multiphysics phenomena, including interstitial tissue fluid flow, magnetic nanoparticle (MNP) transport, and temperature evolution. However, these intricate processes have rarely been studied simultaneously, primarily due to the lack of a comprehensive simulation tool. To address this issue, we develop a comprehensive numerical framework in this study. Using this framework, we simulate a circular-shaped tumor embedded in healthy tissue. The treatment process is examined under two scenarios: one considering gravity and the other neglecting it. Without gravity, the interstitial tissue flow remains stationary, and hence MNP transport and temperature evolution are determined solely by diffusion. The optimal treatment time, when the tumor cells are completely ablated, decreases with both the Lewis number and the heat source number, following a power law. When gravity is considered, treatment efficacy deteriorates due to buoyancy-induced MNP movement, significantly extending the time required to completely ablate the tumor cells. This required time increases with both the buoyancy ratio and the Darcy ratio, also following a power law. The results from this study could provide valuable guidelines for practical magnetic hyperthermia treatment.
{"title":"Multiphysics simulation of tumor ablation in magnetic hyperthermia treatment","authors":"Qian Jiang , Feng Ren , Chenglei Wang , Zhaokun Wang , Gholamreza Kefayati , Sasa Kenjeres , Kambiz Vafai , Xinguang Cui , Yang Liu , Hui Tang","doi":"10.1016/j.ijheatmasstransfer.2025.126982","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.126982","url":null,"abstract":"<div><div>Magnetic hyperthermia is a promising cancer treatment method that involves complex multiphysics phenomena, including interstitial tissue fluid flow, magnetic nanoparticle (MNP) transport, and temperature evolution. However, these intricate processes have rarely been studied simultaneously, primarily due to the lack of a comprehensive simulation tool. To address this issue, we develop a comprehensive numerical framework in this study. Using this framework, we simulate a circular-shaped tumor embedded in healthy tissue. The treatment process is examined under two scenarios: one considering gravity and the other neglecting it. Without gravity, the interstitial tissue flow remains stationary, and hence MNP transport and temperature evolution are determined solely by diffusion. The optimal treatment time, when the tumor cells are completely ablated, decreases with both the Lewis number and the heat source number, following a power law. When gravity is considered, treatment efficacy deteriorates due to buoyancy-induced MNP movement, significantly extending the time required to completely ablate the tumor cells. This required time increases with both the buoyancy ratio and the Darcy ratio, also following a power law. The results from this study could provide valuable guidelines for practical magnetic hyperthermia treatment.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"245 ","pages":"Article 126982"},"PeriodicalIF":5.0,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143705086","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}
Pub Date : 2025-03-27DOI: 10.1016/j.ijheatmasstransfer.2025.126997
Ying Liu , Yuhao Yan , Xilei Wu , Kangli Bao , Jialiang Yang , Maojin Zeng , Xiaohong Han
Pulsating Heat Pipes (PHPs) hold significant potential for efficient thermal management of electronic devices due to their superior heat transfer capabilities, flexible design, and cost-effective manufacturing. However, in view of the fact that there may be different heat transfer distances between heat sources and heat sinks, the widespread application of PHPs has been limited by the lack of accurate models and experimental data to predict and understand their flow and heat transfer performance at varying heat transfer distances. To address these limitations, a two-phase heat and mass transfer model incorporating liquid film dynamics was developed and partial visualization experiments were conducted to validate the reliability of the theoretical model. Based on these, the flow and heat transfer performance of R1336mzz(Z)-PHPs under various heat transfer distances were numerically simulated and experimentally investigated. The flow and heat transfer characteristics of R1336mzz(Z)-PHPs were compared with those of water-PHPs and ethanol-PHPs to investigate the influence of working fluids on the operating performance of PHPs through numerical simulation. The results revealed that the two-phase heat and mass transfer model could capture the local dry-out phenomenon and accurately simulate the heat and mass transfer process in PHPs through the comparison of experimental results with simulation results. According to simulation results, increasing heat input enhanced both flow and heat transfer performance for R1336mzz(Z)-PHPs, especially at shorter heat transfer distances. There was an optimal heat transfer distance at which the flow and heat transfer performance of the PHP were best. Compared to water and ethanol, R1336mzz(Z) generated a greater driving force while experiencing lower flow resistance, resulting in a higher average flow velocity of the working fluid. This enabled the transition from oscillatory flow to one-way circulation flow at various heat transfer distances and avoided the occurrence of local dry-out, leading to superior flow performance. Besides, the performance of the R1336mzz(Z)-PHP was relatively less affected by heat transfer distance. Even at a large heat transfer distance, R1336mzz(Z) maintained superior flow and heat transfer performance.
{"title":"A two-phase theoretical model incorporating liquid film dynamics for pulsating heat pipes","authors":"Ying Liu , Yuhao Yan , Xilei Wu , Kangli Bao , Jialiang Yang , Maojin Zeng , Xiaohong Han","doi":"10.1016/j.ijheatmasstransfer.2025.126997","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.126997","url":null,"abstract":"<div><div>Pulsating Heat Pipes (PHPs) hold significant potential for efficient thermal management of electronic devices due to their superior heat transfer capabilities, flexible design, and cost-effective manufacturing. However, in view of the fact that there may be different heat transfer distances between heat sources and heat sinks, the widespread application of PHPs has been limited by the lack of accurate models and experimental data to predict and understand their flow and heat transfer performance at varying heat transfer distances. To address these limitations, a two-phase heat and mass transfer model incorporating liquid film dynamics was developed and partial visualization experiments were conducted to validate the reliability of the theoretical model. Based on these, the flow and heat transfer performance of R1336mzz(Z)-PHPs under various heat transfer distances were numerically simulated and experimentally investigated. The flow and heat transfer characteristics of R1336mzz(Z)-PHPs were compared with those of water-PHPs and ethanol-PHPs to investigate the influence of working fluids on the operating performance of PHPs through numerical simulation. The results revealed that the two-phase heat and mass transfer model could capture the local dry-out phenomenon and accurately simulate the heat and mass transfer process in PHPs through the comparison of experimental results with simulation results. According to simulation results, increasing heat input enhanced both flow and heat transfer performance for R1336mzz(Z)-PHPs, especially at shorter heat transfer distances. There was an optimal heat transfer distance at which the flow and heat transfer performance of the PHP were best. Compared to water and ethanol, R1336mzz(Z) generated a greater driving force while experiencing lower flow resistance, resulting in a higher average flow velocity of the working fluid. This enabled the transition from oscillatory flow to one-way circulation flow at various heat transfer distances and avoided the occurrence of local dry-out, leading to superior flow performance. Besides, the performance of the R1336mzz(Z)-PHP was relatively less affected by heat transfer distance. Even at a large heat transfer distance, R1336mzz(Z) maintained superior flow and heat transfer performance.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"245 ","pages":"Article 126997"},"PeriodicalIF":5.0,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143705090","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}
Pub Date : 2025-03-27DOI: 10.1016/j.ijheatmasstransfer.2025.126955
J.E. Luna Valencia , A.V.S. Oliveira , T. Glantz , A. Labergue , M. Gradeck
Dispersed-flow film boiling (DFFB) is a flow regime found in several engineering applications, like cryogenic and energy industries or nuclear reactors in accidental conditions, comprising a continuous steam phase with dispersed droplets (with a high void fraction). This type of flow is rather complex because of its non-equilibrium nature, both thermal and dynamic, which makes it challenging to evaluate the many heat transfer paths involved. This study utilizes an in-house mechanistic code called NECTAR to simulate DFFB and compares the results with new experimental data for an internal steam-droplet flow in a vertical tube with high droplet volume fraction and elevated steam temperature. The experimental data were obtained for a variety of droplets’ mass flow rates, steam mass flow rates, and different tube diameters. While correlations of heat transfer for single-phase flow were validated, especially concerning wall-to-steam convection and radiation, there remain uncertainties in the wall-to-droplet heat transfer correlations. Therefore, we compared simulation results using different correlations specifically designed for droplet-impact heat transfer, recognizing the distinctions between these approaches. The validated simulation results provide insights into the intricate thermohydraulic factors involved in DFFB, especially regarding the contribution of each heat transfer path. For instance, the results show that droplet impact on heated walls, which has been neglected in several past models, can contribute up to 50% to the heat dissipation.
{"title":"Evaluation of heat dissipation phenomena in dispersed flow film boiling using a mechanistic model and different correlations for droplet impact heat transfer","authors":"J.E. Luna Valencia , A.V.S. Oliveira , T. Glantz , A. Labergue , M. Gradeck","doi":"10.1016/j.ijheatmasstransfer.2025.126955","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.126955","url":null,"abstract":"<div><div>Dispersed-flow film boiling (DFFB) is a flow regime found in several engineering applications, like cryogenic and energy industries or nuclear reactors in accidental conditions, comprising a continuous steam phase with dispersed droplets (with a high void fraction). This type of flow is rather complex because of its non-equilibrium nature, both thermal and dynamic, which makes it challenging to evaluate the many heat transfer paths involved. This study utilizes an in-house mechanistic code called NECTAR to simulate DFFB and compares the results with new experimental data for an internal steam-droplet flow in a vertical tube with high droplet volume fraction and elevated steam temperature. The experimental data were obtained for a variety of droplets’ mass flow rates, steam mass flow rates, and different tube diameters. While correlations of heat transfer for single-phase flow were validated, especially concerning wall-to-steam convection and radiation, there remain uncertainties in the wall-to-droplet heat transfer correlations. Therefore, we compared simulation results using different correlations specifically designed for droplet-impact heat transfer, recognizing the distinctions between these approaches. The validated simulation results provide insights into the intricate thermohydraulic factors involved in DFFB, especially regarding the contribution of each heat transfer path. For instance, the results show that droplet impact on heated walls, which has been neglected in several past models, can contribute up to 50% to the heat dissipation.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"245 ","pages":"Article 126955"},"PeriodicalIF":5.0,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143705008","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}
Pub Date : 2025-03-27DOI: 10.1016/j.ijheatmasstransfer.2025.127009
Mengqi Wu , Nan Gui , Zeliang Chen , Xingtuan Yang , Jiyuan Tu , Shengyao Jiang
Pool boiling, a fundamental heat transfer process, has been a subject of extensive research due to its significance in various industrial applications. Accurate heat flux quantification is essential for assessing heat transfer performance, but traditional methods face limitations such as complex modeling and intrusive measurement techniques. Recent advances in deep learning have enabled the use of visual data for heat flux quantification, yet challenges such as high dataset labeling costs, small sample sizes leading to overfitting, and the demand for high accuracy in fine-grained tasks persist. This paper proposes a two-stage neural network approach to address these challenges. In the first stage, a self-supervised learning model is pre-trained on public boiling image datasets to extract useful features without requiring labeled data. The second stage involves fine-tuning this model on a small, labeled in-house dataset for precise heat flux quantification. This approach significantly reduces the reliance on large labeled datasets while maintaining good predictive accuracy and effectiveness, even with limited data availability. The proposed method achieved an accuracy of 0.953 (ACC1) and 0.929 (ACC2) on the test set. Even when trained on smaller samples where traditional one-stage models experience a significant drop in accuracy, the two-stage training strategy ensures more effectively maintained prediction accuracy.
{"title":"A two-stage neural network approach for heat flux quantification from boiling images using vision transformers and transfer learning","authors":"Mengqi Wu , Nan Gui , Zeliang Chen , Xingtuan Yang , Jiyuan Tu , Shengyao Jiang","doi":"10.1016/j.ijheatmasstransfer.2025.127009","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.127009","url":null,"abstract":"<div><div>Pool boiling, a fundamental heat transfer process, has been a subject of extensive research due to its significance in various industrial applications. Accurate heat flux quantification is essential for assessing heat transfer performance, but traditional methods face limitations such as complex modeling and intrusive measurement techniques. Recent advances in deep learning have enabled the use of visual data for heat flux quantification, yet challenges such as high dataset labeling costs, small sample sizes leading to overfitting, and the demand for high accuracy in fine-grained tasks persist. This paper proposes a two-stage neural network approach to address these challenges. In the first stage, a self-supervised learning model is pre-trained on public boiling image datasets to extract useful features without requiring labeled data. The second stage involves fine-tuning this model on a small, labeled in-house dataset for precise heat flux quantification. This approach significantly reduces the reliance on large labeled datasets while maintaining good predictive accuracy and effectiveness, even with limited data availability. The proposed method achieved an accuracy of 0.953 (ACC1) and 0.929 (ACC2) on the test set. Even when trained on smaller samples where traditional one-stage models experience a significant drop in accuracy, the two-stage training strategy ensures more effectively maintained prediction accuracy.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"245 ","pages":"Article 127009"},"PeriodicalIF":5.0,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143705103","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}
In this study, we explore the connection between topography-optimized porous structures and theoretical frameworks like entropy generation minimization and equipartition of entropy production within a porous reaction-diffusion system. Using topography optimization (TO) with diverse objective functions—maximizing reaction rates, minimizing inlet concentration, reducing global total entropy generation, and enhancing uniformity in entropy generation—we analyze how optimized structures respond across Damköhler numbers ranging from 0.1 to 50. Our findings show that, despite the variation in objectives (except for enhancing uniformity in entropy generation), the optimized porous structures exhibit a root-like morphology that facilitates both mass transport and reaction, adapting to different conditions to balance reaction and diffusion processes. The results reveal that the entropy generation in these optimized structures becomes more uniform and approaches similar values across all objective functions, aligning with the principles of entropy generation minimization. In contrast, the optimized porous structure obtained for the case of enhancing uniformity in entropy generation exhibits a simple distribution, with higher porosity near the inlet and lower porosity at the farthest end. This uniformity in entropy generation indicates that structural evolution converges towards an efficient balance between reaction and transport requirements. These findings establish a foundational link between TO-derived porous structures and thermodynamic optimization principles, suggesting that design processes can leverage these principles directly to achieve high-efficiency structures.
{"title":"Design principle for topography-optimized porous reactors: entropy generation minimization and equipartition of entropy production","authors":"Mengly Long , Patcharawat Charoen-amornkitt , Mehrzad Alizadeh , Takahiro Suzuki , Shohji Tsushima","doi":"10.1016/j.ijheatmasstransfer.2025.127000","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.127000","url":null,"abstract":"<div><div>In this study, we explore the connection between topography-optimized porous structures and theoretical frameworks like entropy generation minimization and equipartition of entropy production within a porous reaction-diffusion system. Using topography optimization (TO) with diverse objective functions—maximizing reaction rates, minimizing inlet concentration, reducing global total entropy generation, and enhancing uniformity in entropy generation—we analyze how optimized structures respond across Damköhler numbers ranging from 0.1 to 50. Our findings show that, despite the variation in objectives (except for enhancing uniformity in entropy generation), the optimized porous structures exhibit a root-like morphology that facilitates both mass transport and reaction, adapting to different conditions to balance reaction and diffusion processes. The results reveal that the entropy generation in these optimized structures becomes more uniform and approaches similar values across all objective functions, aligning with the principles of entropy generation minimization. In contrast, the optimized porous structure obtained for the case of enhancing uniformity in entropy generation exhibits a simple distribution, with higher porosity near the inlet and lower porosity at the farthest end. This uniformity in entropy generation indicates that structural evolution converges towards an efficient balance between reaction and transport requirements. These findings establish a foundational link between TO-derived porous structures and thermodynamic optimization principles, suggesting that design processes can leverage these principles directly to achieve high-efficiency structures.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"245 ","pages":"Article 127000"},"PeriodicalIF":5.0,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143705083","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}
Pub Date : 2025-03-27DOI: 10.1016/j.ijheatmasstransfer.2025.127018
Sai Zhou , Guogeng He , Wei Sun , Mingjing Fan , Dechang Wang , Qinglu Song
Research on working fluids of refrigerant/absorbent mixture is important for the development of the absorption refrigeration technology. The ternary NH3/LiNO3+H2O working fluid has advantages including good cycle performance, simple system composition and superior heat-transfer performance compared with other binary ammonia-based solutions. In this paper, an experimental investigation is conducted on the flow boiling heat transfer coefficient of the NH3/LiNO3+H2O mixture in horizontal tubes. The effects of heat flux (from 4.6 to 78.5 kW/m2), vapor quality (from 0.044 to 0.133), mass flux (from 164.1 to 389.5 kg/(m2∙s)), and tube diameter (6, 8, 10 mm) are analyzed, and the experimental results are compared with semi-empirical correlations. Besides, this paper provides a comprehensive comparison of the flow boiling heat and mass transfer characteristics of ammonia-based working fluids: NH3/LiNO3, NH3/NaSCN, NH3/LiNO3+H2O with various H2O mass concentration of 5 %, 10 %, 15 % and 20 %. Experimental results show that heat flux has a positive impact on the intensity of flow boiling heat transfer at relatively low heat fluxes, but the positive correlation becomes less noticeable at the high heat flux range above 50 kW/m2 resulting from the concentration boundary layer in the boiling process of highly non-azeotropic mixtures. The flow boiling heat transfer coefficient shows a positive correlation with both the mean vapor quality and the mass flux, reduces with the decrease of tube diameters. The comparison results show that the mean flow boiling heat transfer coefficient of NH3/NaSCN working fluid is 157.3 % larger than that of NH3/LiNO3, and as the various H2O mass concentration increases, that of four NH3/LiNO3+H2O working fluids are 18.1 %, 67.0 %, 84.5 %, and 149.3 % larger than that of NH3/LiNO3, respectively. The present work provides references for the application of ammonia working fluids, and for the design and optimization of finned-tube or tube-in-tube generator in absorption refrigeration systems.
{"title":"Flow boiling heat transfer characteristic of NH3/LiNO3+H2O absorption refrigeration working fluid in horizontal tubes: A comprehensive experimental evaluation and comparison","authors":"Sai Zhou , Guogeng He , Wei Sun , Mingjing Fan , Dechang Wang , Qinglu Song","doi":"10.1016/j.ijheatmasstransfer.2025.127018","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.127018","url":null,"abstract":"<div><div>Research on working fluids of refrigerant/absorbent mixture is important for the development of the absorption refrigeration technology. The ternary NH<sub>3</sub>/LiNO<sub>3</sub>+H<sub>2</sub>O working fluid has advantages including good cycle performance, simple system composition and superior heat-transfer performance compared with other binary ammonia-based solutions. In this paper, an experimental investigation is conducted on the flow boiling heat transfer coefficient of the NH<sub>3</sub>/LiNO<sub>3</sub>+H<sub>2</sub>O mixture in horizontal tubes. The effects of heat flux (from 4.6 to 78.5 kW/m<sup>2</sup>), vapor quality (from 0.044 to 0.133), mass flux (from 164.1 to 389.5 kg/(m<sup>2</sup>∙s)), and tube diameter (6, 8, 10 mm) are analyzed, and the experimental results are compared with semi-empirical correlations. Besides, this paper provides a comprehensive comparison of the flow boiling heat and mass transfer characteristics of ammonia-based working fluids: NH<sub>3</sub>/LiNO<sub>3</sub>, NH<sub>3</sub>/NaSCN, NH<sub>3</sub>/LiNO<sub>3</sub>+H<sub>2</sub>O with various H<sub>2</sub>O mass concentration of 5 %, 10 %, 15 % and 20 %. Experimental results show that heat flux has a positive impact on the intensity of flow boiling heat transfer at relatively low heat fluxes, but the positive correlation becomes less noticeable at the high heat flux range above 50 kW/m<sup>2</sup> resulting from the concentration boundary layer in the boiling process of highly non-azeotropic mixtures. The flow boiling heat transfer coefficient shows a positive correlation with both the mean vapor quality and the mass flux, reduces with the decrease of tube diameters. The comparison results show that the mean flow boiling heat transfer coefficient of NH<sub>3</sub>/NaSCN working fluid is 157.3 % larger than that of NH<sub>3</sub>/LiNO<sub>3</sub>, and as the various H<sub>2</sub>O mass concentration increases, that of four NH<sub>3</sub>/LiNO<sub>3</sub>+H<sub>2</sub>O working fluids are 18.1 %, 67.0 %, 84.5 %, and 149.3 % larger than that of NH<sub>3</sub>/LiNO<sub>3</sub>, respectively. The present work provides references for the application of ammonia working fluids, and for the design and optimization of finned-tube or tube-in-tube generator in absorption refrigeration systems.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"245 ","pages":"Article 127018"},"PeriodicalIF":5.0,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143705089","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}
Pub Date : 2025-03-27DOI: 10.1016/j.ijheatmasstransfer.2025.126976
Pablo E. Pinto, Jorge Valdivia, Abhinandan Singh, Xiuqi Xi, Juan Cuevas, James L. Urban
This work seeks to better characterize the radiant heat transfer to a sample in the cone calorimeter, a widely used fire testing apparatus. Specifically, the spatial uniformity of the heat flux from the cone heater to a sample and to a heat flux sensor are investigated with analytical view factor models based on the idealized geometry of cone heater element (tapered helical coil) and experimental measurements. The view factors are calculated using the contours of the relevant geometries and applying Stokes’ theorem, with the contour integrals evaluated numerically. An uncertainty analysis is performed on the theoretical incident heat flux to evaluate the reliability of the model by comparing predicted and experimental values. The incident heat flux to the sample surface is measured using a water-cooled radiometer, while the temperature spatial variation of the cone heater surface is determined through color-ratio pyrometry thermograms with a digital camera. The measurements are used to showcase the proposed formulation. The findings contribute to a better understanding of the cone calorimeter heater view factor model, offering valuable insights for researchers and engineers seeking improved accuracy in fire safety assessments.
{"title":"Investigating radiation heat transfer from the cone calorimeter heater: A new view factor model and uncertainty quantification","authors":"Pablo E. Pinto, Jorge Valdivia, Abhinandan Singh, Xiuqi Xi, Juan Cuevas, James L. Urban","doi":"10.1016/j.ijheatmasstransfer.2025.126976","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.126976","url":null,"abstract":"<div><div>This work seeks to better characterize the radiant heat transfer to a sample in the cone calorimeter, a widely used fire testing apparatus. Specifically, the spatial uniformity of the heat flux from the cone heater to a sample and to a heat flux sensor are investigated with analytical view factor models based on the idealized geometry of cone heater element (tapered helical coil) and experimental measurements. The view factors are calculated using the contours of the relevant geometries and applying Stokes’ theorem, with the contour integrals evaluated numerically. An uncertainty analysis is performed on the theoretical incident heat flux to evaluate the reliability of the model by comparing predicted and experimental values. The incident heat flux to the sample surface is measured using a water-cooled radiometer, while the temperature spatial variation of the cone heater surface is determined through color-ratio pyrometry thermograms with a digital camera. The measurements are used to showcase the proposed formulation. The findings contribute to a better understanding of the cone calorimeter heater view factor model, offering valuable insights for researchers and engineers seeking improved accuracy in fire safety assessments.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"245 ","pages":"Article 126976"},"PeriodicalIF":5.0,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143705085","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}
Pub Date : 2025-03-26DOI: 10.1016/j.ijheatmasstransfer.2025.126924
Barak Kashi, Herman D. Haustein
A general analytical description for the heat transfer distribution (HTD) under an impinging submerged jet is derived, from the jet velocity profile arriving at the wall. First, the cause-and-effect chain is broken down: i) the streamline-bending projection of the arriving profile's dynamic pressure gives the wall pressure distribution; ii) the pressure gradient drives the radial acceleration; iii) the acceleration unlocks the entire flow field: boundary layer, wall-shear and vorticity distributions; iv) ultimately also the HTD is recovered from similarity; iv) this extends up to deceleration, approaching the known wall-jet solution.
This new theory is validated against simulations and experiments over a wide range of conditions: from uniform to fully developed issuing profiles, over a range of flights. Thus, confirming that the arriving profile contains everything needed for the subsequent wall-flow description, and demonstrating that the HTD diversity corresponds to that of the arrival profiles. This permits the prediction of the HTD in a universal way, from stagnation point to wall-jet. Specifically, relating the well-known off-center peak (boundary layer thinning) to an incoming profile shape with strong velocity gradients, as encountered in profiles with a potential core. Two different pathways for the generation of this off-center peak are studied and compared.
{"title":"Submerged jet's profile-specific heat transfer: Stagnation zone and beyond","authors":"Barak Kashi, Herman D. Haustein","doi":"10.1016/j.ijheatmasstransfer.2025.126924","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.126924","url":null,"abstract":"<div><div>A general analytical description for the heat transfer distribution (HTD) under an impinging submerged jet is derived, from the jet velocity profile arriving at the wall. First, the cause-and-effect chain is broken down: i) the streamline-bending projection of the arriving profile's dynamic pressure gives the wall pressure distribution; ii) the pressure gradient drives the radial acceleration; iii) the acceleration unlocks the entire flow field: boundary layer, wall-shear and vorticity distributions; iv) ultimately also the HTD is recovered from similarity; iv) this extends up to deceleration, approaching the known wall-jet solution.</div><div>This new theory is validated against simulations and experiments over a wide range of conditions: from uniform to fully developed issuing profiles, over a range of flights. Thus, confirming that the arriving profile contains everything needed for the subsequent wall-flow description, and demonstrating that the HTD diversity corresponds to that of the arrival profiles. This permits the prediction of the HTD in a universal way, from stagnation point to wall-jet. Specifically, relating the well-known off-center peak (boundary layer thinning) to an incoming profile shape with strong velocity gradients, as encountered in profiles with a potential core. Two different pathways for the generation of this off-center peak are studied and compared.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"245 ","pages":"Article 126924"},"PeriodicalIF":5.0,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143705084","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}
Pub Date : 2025-03-26DOI: 10.1016/j.ijheatmasstransfer.2025.126985
Hong Tang , Alexander Melnikov , MingRui Liu , Stefano Sfarra , Hai Zhang , Andreas Mandelis
As one of the essential parameters in thermophysical analysis, effective measurement of thermal diffusivity is necessary. This paper utilizes the Physics-Informed Neural Networks (PINN) framework to simulate the diffusion of thermal waves. The governing equations / boundary-value problem (BVP) for the thermal waves are expressed in a coupled partial differential form, derived using the method of separation of variables. The inverse problem associated with the coupled partial differential equations is solved using a dimensionless equation / BVP with a loss function that incorporates physical information. Even in the presence of experimental system errors, the neural network (NN) method introduced in this work (“new NN method”) was shown to be capable of robustly solving the thermal wave inverse problem without nonlinear DC components at different spatial locations, for determining the unknown thermal diffusivity of green (unsintered) metal powder compact materials. The results indicate that the coupled partial differential equations for the amplitude and phase of thermal waves within the PINN framework represent a promising strategy for determining thermophysical parameters.
{"title":"Physics informed neural networks for solving inverse thermal wave coupled boundary-value problems","authors":"Hong Tang , Alexander Melnikov , MingRui Liu , Stefano Sfarra , Hai Zhang , Andreas Mandelis","doi":"10.1016/j.ijheatmasstransfer.2025.126985","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.126985","url":null,"abstract":"<div><div>As one of the essential parameters in thermophysical analysis, effective measurement of thermal diffusivity is necessary. This paper utilizes the Physics-Informed Neural Networks (PINN) framework to simulate the diffusion of thermal waves. The governing equations / boundary-value problem (BVP) for the thermal waves are expressed in a coupled partial differential form, derived using the method of separation of variables. The inverse problem associated with the coupled partial differential equations is solved using a dimensionless equation / BVP with a loss function that incorporates physical information. Even in the presence of experimental system errors, the neural network (NN) method introduced in this work (“new NN method”) was shown to be capable of robustly solving the thermal wave inverse problem without nonlinear DC components at different spatial locations, for determining the unknown thermal diffusivity of green (unsintered) metal powder compact materials. The results indicate that the coupled partial differential equations for the amplitude and phase of thermal waves within the PINN framework represent a promising strategy for determining thermophysical parameters.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"245 ","pages":"Article 126985"},"PeriodicalIF":5.0,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143705087","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}
Pub Date : 2025-03-26DOI: 10.1016/j.ijheatmasstransfer.2025.126962
A.S. Purandare, G. Wennemars, S. Vanapalli
Investigating the sublimation characteristics of dry ice particles exposed to convective heating in an unsaturated gaseous medium holds significance for applications employing cooling through dry ice sprays. While the transport phenomena between dry ice and its surrounding gas medium are central to various applications, a comprehensive understanding of these processes during dry ice sublimation remains incomplete. As a model problem, this study experimentally and numerically examines the sublimation of an isolated dry ice sphere within a controlled gas flow environment. Schlieren imaging is utilized in experiments to visualize density gradients at the dry ice–vapor interface for different 2 concentrations in the surrounding gas. An additional set of experiments involving backlight imaging is conducted to observe dry ice morphology and track its boundary over time. Numerical simulations using COMSOL Multiphysics software are performed to simulate the shrinkage of the sublimating dry ice sphere, accounting for heat, mass, and momentum transport in the gas mixture surrounding the dry ice. The numerical predictions of the density gradient near the sublimating dry ice interface exhibit qualitative agreement with the variations in light intensity observed in Schlieren images, thus confirming the predictive capabilities of the numerical model in this context. Furthermore, the numerical prediction of the temporal variation in dry ice mass closely aligns with experimental observations up to a certain duration, until the onset of frost formation on the dry ice surface, causing distortion in its morphology as evident in the images obtained during the experiments.
{"title":"Vapor density gradients near the sublimating interface of a carbon dioxide sphere","authors":"A.S. Purandare, G. Wennemars, S. Vanapalli","doi":"10.1016/j.ijheatmasstransfer.2025.126962","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.126962","url":null,"abstract":"<div><div>Investigating the sublimation characteristics of dry ice particles exposed to convective heating in an unsaturated gaseous medium holds significance for applications employing cooling through dry ice sprays. While the transport phenomena between dry ice and its surrounding gas medium are central to various applications, a comprehensive understanding of these processes during dry ice sublimation remains incomplete. As a model problem, this study experimentally and numerically examines the sublimation of an isolated dry ice sphere within a controlled gas flow environment. Schlieren imaging is utilized in experiments to visualize density gradients at the dry ice–vapor interface for different <span><math><mi>CO</mi></math></span> <sub>2</sub> concentrations in the surrounding gas. An additional set of experiments involving backlight imaging is conducted to observe dry ice morphology and track its boundary over time. Numerical simulations using COMSOL Multiphysics software are performed to simulate the shrinkage of the sublimating dry ice sphere, accounting for heat, mass, and momentum transport in the gas mixture surrounding the dry ice. The numerical predictions of the density gradient near the sublimating dry ice interface exhibit qualitative agreement with the variations in light intensity observed in Schlieren images, thus confirming the predictive capabilities of the numerical model in this context. Furthermore, the numerical prediction of the temporal variation in dry ice mass closely aligns with experimental observations up to a certain duration, until the onset of frost formation on the dry ice surface, causing distortion in its morphology as evident in the images obtained during the experiments.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"245 ","pages":"Article 126962"},"PeriodicalIF":5.0,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143705088","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}
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