Pub Date : 2024-11-21DOI: 10.1016/j.icheatmasstransfer.2024.108362
Junfeng Li , Yanxu Huang , Yunyu Qiu , Shixian Wang , Qunhui Yang , Kai Wang , Yunzhong Zhu
Nucleate boiling effectively dissipates heat through phase change, where heat is absorbed during the transition from liquid to vapor. However, this heat dissipation is strongly limited by Critical Heat Flux (CHF). When CHF is reached, a small increase in heat flux can lead to a sudden temperature surge, potentially causing the heated surface to burn out. CHF has been extensively studied for almost 100 years, and numerous methods have been proposed to predict CHF under various working conditions. In this paper, we aim to comprehensively review the methods for predicting CHF, from initial models derived from experimental correlations to advanced numerical simulations and state-of-the-art machine learning approaches. We begin by introducing CHF models based on experimental data and discuss prediction methods that utilize CHF databases. Next, we examine wall boiling models developed through numerical simulations at different scales. Furthermore, we explore the potential of machine learning in CHF prediction, highlighting the advantages of this approach. By summarizing these studies, we aim to provide researchers with a comprehensive understanding of CHF prediction methods and offer effective strategies for accurate CHF prediction in the future.
{"title":"Prediction of critical heat flux using different methods: A review from empirical correlations to the cutting-edge machine learning","authors":"Junfeng Li , Yanxu Huang , Yunyu Qiu , Shixian Wang , Qunhui Yang , Kai Wang , Yunzhong Zhu","doi":"10.1016/j.icheatmasstransfer.2024.108362","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108362","url":null,"abstract":"<div><div>Nucleate boiling effectively dissipates heat through phase change, where heat is absorbed during the transition from liquid to vapor. However, this heat dissipation is strongly limited by Critical Heat Flux (CHF). When CHF is reached, a small increase in heat flux can lead to a sudden temperature surge, potentially causing the heated surface to burn out. CHF has been extensively studied for almost 100 years, and numerous methods have been proposed to predict CHF under various working conditions. In this paper, we aim to comprehensively review the methods for predicting CHF, from initial models derived from experimental correlations to advanced numerical simulations and state-of-the-art machine learning approaches. We begin by introducing CHF models based on experimental data and discuss prediction methods that utilize CHF databases. Next, we examine wall boiling models developed through numerical simulations at different scales. Furthermore, we explore the potential of machine learning in CHF prediction, highlighting the advantages of this approach. By summarizing these studies, we aim to provide researchers with a comprehensive understanding of CHF prediction methods and offer effective strategies for accurate CHF prediction in the future.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"160 ","pages":"Article 108362"},"PeriodicalIF":6.4,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142699645","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 paper, a multiscale nonreciprocal multilayer structure based on the Weyl semimetal is investigated. This multilayer structure enables the realization of nonreciprocal thermal radiation, as well as angle and refractive index (RI) detection at both θ and -θ angles of the forward and backward scenarios. Scenarios are used to describe the electromagnetic waves (EWs) incident from forward or backward with θ or -θ direction. When the EWs incident from the four scenarios, the localized electric field energy caused by the defect mode triggers a sharp emission peak (EP) within the terahertz range. Moreover, the frequency points of EP will shift regularly with changes in physical quantities. Hence, by precisely locating the frequency points of EP, the angle and RI across four scenarios can be detected. The broadest detection range for angle and RI is 30 degrees∼70 degrees and 1.4–1.9. Furthermore, the best performance of quality factor, the figure of merit, and the detection limit are 508.9, 1.3 degree−1, 4.2 × 10−2 degrees, and 671.7, 63.6 RIU−1, 7.9 × 10−4 RIU, respectively. The concepts and conclusions obtained from this article can offer new possibilities for the construction of novel sensing devices, energy harvesting devices, energy conversion devices, nonreciprocal thermal emitters, etc.
{"title":"A multiscale nonreciprocal thermal radiation multilayer structure based on Weyl semimetal with angle and refractive index detection","authors":"Wen-Xiao Zhang, Jun-Yang Sui, Jia-Hao Zou, Hai-Feng Zhang","doi":"10.1016/j.icheatmasstransfer.2024.108365","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108365","url":null,"abstract":"<div><div>In this paper, a multiscale nonreciprocal multilayer structure based on the Weyl semimetal is investigated. This multilayer structure enables the realization of nonreciprocal thermal radiation, as well as angle and refractive index (RI) detection at both <strong><em>θ</em></strong> and -<strong><em>θ</em></strong> angles of the forward and backward scenarios. Scenarios are used to describe the electromagnetic waves (EWs) incident from forward or backward with <strong><em>θ</em></strong> or -<strong><em>θ</em></strong> direction. When the EWs incident from the four scenarios, the localized electric field energy caused by the defect mode triggers a sharp emission peak (EP) within the terahertz range. Moreover, the frequency points of EP will shift regularly with changes in physical quantities. Hence, by precisely locating the frequency points of EP, the angle and RI across four scenarios can be detected. The broadest detection range for angle and RI is 30 degrees∼70 degrees and 1.4–1.9. Furthermore, the best performance of quality factor, the figure of merit, and the detection limit are 508.9, 1.3 degree<sup>−1</sup>, 4.2 × 10<sup>−2</sup> degrees, and 671.7, 63.6 RIU<sup>−1</sup>, 7.9 × 10<sup>−4</sup> RIU, respectively. The concepts and conclusions obtained from this article can offer new possibilities for the construction of novel sensing devices, energy harvesting devices, energy conversion devices, nonreciprocal thermal emitters, etc.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"160 ","pages":"Article 108365"},"PeriodicalIF":6.4,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142699009","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 : 2024-11-21DOI: 10.1016/j.icheatmasstransfer.2024.108293
Hamid Shakibi , Sepideh Rezayani , Ali Salari , Mohammad Sardarabadi
The thermal efficiency of an electronic chipset is investigated in this study, utilizing a novel heat sink design. A thermal energy storage system is implemented, consisting of a Phase Change Material, Heat Sink, and Metal Foam (HS-FPCM) for efficient chipset temperature control. Analyzing the metal foam's composition, PCM type, and height is part of the system's performance assessment. The HS-FPCM system is designed in three dimensions for precise evaluation, and its outputs are verified against experimental data collected under comparable operating conditions. Several Machine Learning (ML) models are built in this study to predict the HS-FPCM system outputs. The Slime Mould Algorithm (SMA) is used to optimize the ML model's hyperparameters. Based on the results, the designed ML models exhibit varying performance, with the optimized CatBoost model ranking as the best performer and the Generalized Linear Model (GLM) model as the least effective. The Time Period of a Complete Operational Cycle (TPCOC) of the electronic chipset using the aluminum and copper foam obtained to be 149 min and 154 min, respectively. Furthermore, the TPCOC values for the systems utilizing RT-35, RT-47, and RT-65 are around 149 min, 120 min, and 104 min, respectively.
{"title":"Enhancing the thermal performance of an electronic chipset using an innovative cooling system: Insights from machine learning models","authors":"Hamid Shakibi , Sepideh Rezayani , Ali Salari , Mohammad Sardarabadi","doi":"10.1016/j.icheatmasstransfer.2024.108293","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108293","url":null,"abstract":"<div><div>The thermal efficiency of an electronic chipset is investigated in this study, utilizing a novel heat sink design. A thermal energy storage system is implemented, consisting of a Phase Change Material, Heat Sink, and Metal Foam (HS-FPCM) for efficient chipset temperature control. Analyzing the metal foam's composition, PCM type, and height is part of the system's performance assessment. The HS-FPCM system is designed in three dimensions for precise evaluation, and its outputs are verified against experimental data collected under comparable operating conditions. Several Machine Learning (ML) models are built in this study to predict the HS-FPCM system outputs. The Slime Mould Algorithm (SMA) is used to optimize the ML model's hyperparameters. Based on the results, the designed ML models exhibit varying performance, with the optimized CatBoost model ranking as the best performer and the Generalized Linear Model (GLM) model as the least effective. The Time Period of a Complete Operational Cycle (TPCOC) of the electronic chipset using the aluminum and copper foam obtained to be 149 min and 154 min, respectively. Furthermore, the TPCOC values for the systems utilizing RT-35, RT-47, and RT-65 are around 149 min, 120 min, and 104 min, respectively.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"160 ","pages":"Article 108293"},"PeriodicalIF":6.4,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698943","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 : 2024-11-20DOI: 10.1016/j.icheatmasstransfer.2024.108327
Hui Song , Lin Ye , Xinyu Wang , Cunliang Liu , Xiyuan Liang , Xuyang Ji
Strong swirling flow is an important characteristic that must be considered in the integrated design of combustors and turbines. The cooling pattern of turbine vanes obtained under the assumption of a uniform cascade inflow may not be able to guide the design of high-efficiency film cooling structures under swirling intake conditions. Therefore, it is necessary to carry out further research on the influence of inlet swirl on pressure surface film cooling and the mixing mechanism of jet and swirling flow. In this study, by considering varying swirl intensities and coolant flow rates, a steady-state pressure-sensitive paint (PSP) technology experiment was conducted to investigate the overall surface distribution of film cooling effectiveness (η) on a vane pressure surface. Comparative analyses of η differences between cylindrical and laidback fan-shaped holes were carried out. The results showed that swirling inflow leads to a radial pressure gradient at the pressure surface and radial deflection of streamlines at the wall surface. With the acceleration of airflow and the action of viscosity, the swirling core intensity weakens, and the influence of swirl inflow on the trailing edge region is gradually reduced. For the case of a weak swirl intensity, the sensitivity of the film trajectory distribution and η to the change in the freestream condition is minor, similar to that under the uniform inlet condition. On the other hand, strong swirl inflow can significantly enhance the radial deflection of the film trajectory; the uniformity of the η distribution decreases, and the relative standard deviation (RSD) increases by a maximum of 12.5 %. Increasing the coolant flow rate can relieve this phenomenon. The strong swirling flow characteristics also affect the laidback fan-shaped holes, and the radial deflection of the film is significant. The beneficial effect is that the dilation of the film-hole exit increases the extension ability of the film in the span and flow directions; the effective film coverage area is significantly increased. Compared with cylindrical holes, laidback fan-shaped holes increase the area-averaged η by 79.1 % and reduce the RSD by 20.5 %.
强漩涡流是燃烧器和涡轮机综合设计中必须考虑的一个重要特征。在均匀级联流入假设下获得的涡轮叶片冷却模式可能无法指导漩涡进气条件下高效薄膜冷却结构的设计。因此，有必要进一步研究进气漩涡对压力表面薄膜冷却的影响以及射流和漩涡流的混合机制。在本研究中，通过考虑不同的漩涡强度和冷却剂流速，进行了稳态压敏涂料（PSP）技术实验，以研究叶片压力表面膜冷却效果（η）的整体表面分布。对圆柱形孔和后置扇形孔之间的 η 差异进行了比较分析。结果表明，漩涡流入会导致压力表面的径向压力梯度和壁面流线的径向偏转。随着气流的加速和粘度的作用，漩涡核心强度减弱，漩涡流入对后缘区域的影响逐渐减小。在漩涡强度较弱的情况下，薄膜轨迹分布和 η 对自由流条件变化的敏感性很小，与均匀进气条件下的情况类似。另一方面，强漩涡流入会显著增强薄膜轨迹的径向偏移；η 分布的均匀性降低，相对标准偏差 (RSD) 最大增加 12.5%。提高冷却剂流速可以缓解这一现象。强烈的漩涡流动特性也会影响扇形孔的回铺，膜的径向偏转也很明显。这样做的好处是，薄膜孔出口的扩张增加了薄膜在跨度和流动方向上的延伸能力；薄膜的有效覆盖面积显著增加。与圆柱形孔相比，后铺扇形孔的面积平均 η 增加了 79.1%，RSD 降低了 20.5%。
{"title":"Assessing the effect of swirl flow on the film cooling effectiveness of a vane pressure surface","authors":"Hui Song , Lin Ye , Xinyu Wang , Cunliang Liu , Xiyuan Liang , Xuyang Ji","doi":"10.1016/j.icheatmasstransfer.2024.108327","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108327","url":null,"abstract":"<div><div>Strong swirling flow is an important characteristic that must be considered in the integrated design of combustors and turbines. The cooling pattern of turbine vanes obtained under the assumption of a uniform cascade inflow may not be able to guide the design of high-efficiency film cooling structures under swirling intake conditions. Therefore, it is necessary to carry out further research on the influence of inlet swirl on pressure surface film cooling and the mixing mechanism of jet and swirling flow. In this study, by considering varying swirl intensities and coolant flow rates, a steady-state pressure-sensitive paint (PSP) technology experiment was conducted to investigate the overall surface distribution of film cooling effectiveness (<em>η</em>) on a vane pressure surface. Comparative analyses of <em>η</em> differences between cylindrical and laidback fan-shaped holes were carried out. The results showed that swirling inflow leads to a radial pressure gradient at the pressure surface and radial deflection of streamlines at the wall surface. With the acceleration of airflow and the action of viscosity, the swirling core intensity weakens, and the influence of swirl inflow on the trailing edge region is gradually reduced. For the case of a weak swirl intensity, the sensitivity of the film trajectory distribution and <em>η</em> to the change in the freestream condition is minor, similar to that under the uniform inlet condition. On the other hand, strong swirl inflow can significantly enhance the radial deflection of the film trajectory; the uniformity of the <em>η</em> distribution decreases, and the relative standard deviation (<em>RSD</em>) increases by a maximum of 12.5 %. Increasing the coolant flow rate can relieve this phenomenon. The strong swirling flow characteristics also affect the laidback fan-shaped holes, and the radial deflection of the film is significant. The beneficial effect is that the dilation of the film-hole exit increases the extension ability of the film in the span and flow directions; the effective film coverage area is significantly increased. Compared with cylindrical holes, laidback fan-shaped holes increase the area-averaged <em>η</em> by 79.1 % and reduce the <em>RSD</em> by 20.5 %.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"160 ","pages":"Article 108327"},"PeriodicalIF":6.4,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698786","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 : 2024-11-20DOI: 10.1016/j.icheatmasstransfer.2024.108376
Quanying Yan, Bai Mu
The abundance of industrial waste heat resources offers valuable opportunities for the utilization of phase change heat exchangers in clean energy applications. This study focuses on the innovative development of binary phase change material (PCM) composed of paraffin and stearic acid (SA) in various ratios, aimed at optimizing waste heat recovery. Comprehensive analyses of the phase change temperature, latent heat, and thermal conductivity of these mixtures were conducted. The research identified a mixture with a 20 % paraffin and 80 % stearic acid ratio, which exhibits a phase change temperature of 62.73 °C and a latent heat of 205.53 J/g. This mixture stands out due to its minimal subcooling and consistent thermal properties, making it highly effective for low-temperature waste heat recovery. Additionally, a novel process design and simulation system for using these materials in heat exchangers to convert intermittent industrial waste heat into continuous thermal energy for heating were developed.
{"title":"Energy storage materials for phase change heat devices recovering industrial waste heat for heating purposes","authors":"Quanying Yan, Bai Mu","doi":"10.1016/j.icheatmasstransfer.2024.108376","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108376","url":null,"abstract":"<div><div>The abundance of industrial waste heat resources offers valuable opportunities for the utilization of phase change heat exchangers in clean energy applications. This study focuses on the innovative development of binary phase change material (PCM) composed of paraffin and stearic acid (SA) in various ratios, aimed at optimizing waste heat recovery. Comprehensive analyses of the phase change temperature, latent heat, and thermal conductivity of these mixtures were conducted. The research identified a mixture with a 20 % paraffin and 80 % stearic acid ratio, which exhibits a phase change temperature of 62.73 °C and a latent heat of 205.53 J/g. This mixture stands out due to its minimal subcooling and consistent thermal properties, making it highly effective for low-temperature waste heat recovery. Additionally, a novel process design and simulation system for using these materials in heat exchangers to convert intermittent industrial waste heat into continuous thermal energy for heating were developed.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"160 ","pages":"Article 108376"},"PeriodicalIF":6.4,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142699006","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 : 2024-11-20DOI: 10.1016/j.icheatmasstransfer.2024.108338
Shan Ali Khan , Houssam Eddine Abdellatif , Ahmed Belaadi , Adeel Arshad , Haihu Liu
The coupling of Organic Rankine Cycle (ORC) and Latent Heat Thermal Energy Storage (LHTES) is a novel strategy for efficiently using solar energy. The objective of this study is to explore the solidification performance of phase change material (PCM) with single-walled carbon nanotubes (SWCNTs) for thermal management in solar energy system. The evolution of temperature and liquid fraction during the solidification process is investigated across four cases: Case 01 without SWCNTs, and Cases 02, 03, and 04 with 2 %, 3 %, and 4 % SWCNTs dispersion, respectively. By analyzing the temperature and liquid fraction contours over time, the impact of SWCNTs concentration on thermal performance is assessed. Case 01 has a total solidification time of 14,400 s. In comparison, Case 02 achieves solidification in 13,600 s, Case 03 in 13,040 s, and Case 04 in 12,500 s, reflecting time savings of 5.55 %, 9.44 %, and 13.2 %, respectively. Additionally, Case 04 exhibits the highest sensible heat release of 527.9 kJ and a total heat energy release of 2851.09 kJ. The dimensionless TES rate P′ for Case 04 is 1.26, indicating a 26 % improvement in thermal energy storage performance over the baseline. These findings underscore the effectiveness of SWCNTs-enhanced PCM in optimizing solar energy systems through enhanced heat transfer and accelerated solidification.
{"title":"Numerical study of shell and tube thermal energy storage system: Enhancing solidification performance with single-walled carbon nanotubes in phase change material","authors":"Shan Ali Khan , Houssam Eddine Abdellatif , Ahmed Belaadi , Adeel Arshad , Haihu Liu","doi":"10.1016/j.icheatmasstransfer.2024.108338","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108338","url":null,"abstract":"<div><div>The coupling of Organic Rankine Cycle (ORC) and Latent Heat Thermal Energy Storage (LHTES) is a novel strategy for efficiently using solar energy. The objective of this study is to explore the solidification performance of phase change material (PCM) with single-walled carbon nanotubes (SWCNTs) for thermal management in solar energy system. The evolution of temperature and liquid fraction during the solidification process is investigated across four cases: Case 01 without SWCNTs, and Cases 02, 03, and 04 with 2 %, 3 %, and 4 % SWCNTs dispersion, respectively. By analyzing the temperature and liquid fraction contours over time, the impact of SWCNTs concentration on thermal performance is assessed. Case 01 has a total solidification time of 14,400 s. In comparison, Case 02 achieves solidification in 13,600 s, Case 03 in 13,040 s, and Case 04 in 12,500 s, reflecting time savings of 5.55 %, 9.44 %, and 13.2 %, respectively. Additionally, Case 04 exhibits the highest sensible heat release of 527.9 kJ and a total heat energy release of 2851.09 kJ. The dimensionless TES rate <em>P′</em> for Case 04 is 1.26, indicating a 26 % improvement in thermal energy storage performance over the baseline. These findings underscore the effectiveness of SWCNTs-enhanced PCM in optimizing solar energy systems through enhanced heat transfer and accelerated solidification.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"160 ","pages":"Article 108338"},"PeriodicalIF":6.4,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698784","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 : 2024-11-20DOI: 10.1016/j.icheatmasstransfer.2024.108298
Andrew D. Sommers , Hieu Phan , Giancarlo Corti
In this work, pendant water droplet behavior on a plain surface was simulated using the Surface Evolver (SE) finite element program to study the three-dimensional shape of the droplet on the surface. The critical droplet volume (CDV) before detachment from the surface was measured and compared against experimental data for different plain surfaces. These computational predictions were shown to agree well with experimental data. Next, patterned surfaces were studied which consisted of a central wetting region 2 mm to 5 mm wide sandwiched between two outer non-wetting superhydrophobic stripes. These superhydrophobic stripes served as “bumpers” to confine the droplet to the wetting region during its simulated growth. For these simulations, the primary inputs to the program were the droplet volume V, stripe width w, and surface static contact angle θ which was varied from 30° to 150°. Water droplet contact angle measurements on the plain surfaces used for initial benchmarking were also reported which included polished aluminum, mill finish aluminum, glass, plastic (acrylic), stainless steel, and copper. The idea of this study was to see if the superhydrophobic borders could be used to effectively “pinch off” a droplet in the wetting region, thereby reducing the critical droplet volume needed for detachment and drainage. The motivation for this work was condensation heat transfer which is common to many HVAC&R applications. In these systems, increasing the droplet shedding frequency is often associated with increased heat transfer and improved system efficiency.
Therefore, the baseline surface adopted in this study was aluminum with and without the use of superhydrophobic stripes. For these simulations, properties of water at 20 °C were used, and the droplet volume was gradually increased until the critical condition was reached and detachment was detected. Typically, more than 1000 iterations were performed before the droplet geometry converged and was ready for measurement. Grid refinement was also performed to make sure that the results were grid independent. According to Surface Evolver, the lowest predicted critical droplet volume on the plain surfaces was <5 μL for θ1 = 150°, whereas the highest CDV was >295 μL for θ1 = 30°. For θ1 = 90° which is typical of aluminum, the CDV on the plain surface was 74 μL for the fine mesh and 83 μL for the rough mesh. When a 3-mm wide θ1 = 90° wetting region was used, however, bordered by two superhydrophobic stripes with θ2 = 150°, this CDV was reduced to 71 μL for the rough mesh, and when a 2-mm wide wetting region was used, the CDV was reduced even further to 55 μL. This shows both the promise of the idea and the possibility of using a striped / patterned tube to reduce the critical droplet volume needed for droplet shedding in a condensation environment.
{"title":"Numerical simulation of pendant droplet behavior on plain and patterned surfaces using Surface Evolver: Applications to condensation heat transfer","authors":"Andrew D. Sommers , Hieu Phan , Giancarlo Corti","doi":"10.1016/j.icheatmasstransfer.2024.108298","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108298","url":null,"abstract":"<div><div>In this work, pendant water droplet behavior on a plain surface was simulated using the Surface Evolver (SE) finite element program to study the three-dimensional shape of the droplet on the surface. The critical droplet volume (CDV) before detachment from the surface was measured and compared against experimental data for different plain surfaces. These computational predictions were shown to agree well with experimental data. Next, patterned surfaces were studied which consisted of a central wetting region 2 mm to 5 mm wide sandwiched between two outer non-wetting superhydrophobic stripes. These superhydrophobic stripes served as “bumpers” to confine the droplet to the wetting region during its simulated growth. For these simulations, the primary inputs to the program were the droplet volume <em>V</em>, stripe width <em>w</em>, and surface static contact angle θ which was varied from 30° to 150°. Water droplet contact angle measurements on the plain surfaces used for initial benchmarking were also reported which included polished aluminum, mill finish aluminum, glass, plastic (acrylic), stainless steel, and copper. The idea of this study was to see if the superhydrophobic borders could be used to effectively “pinch off” a droplet in the wetting region, thereby reducing the critical droplet volume needed for detachment and drainage. The motivation for this work was condensation heat transfer which is common to many HVAC&R applications. In these systems, increasing the droplet shedding frequency is often associated with increased heat transfer and improved system efficiency.</div><div>Therefore, the baseline surface adopted in this study was aluminum with and without the use of superhydrophobic stripes. For these simulations, properties of water at 20 °C were used, and the droplet volume was gradually increased until the critical condition was reached and detachment was detected. Typically, more than 1000 iterations were performed before the droplet geometry converged and was ready for measurement. Grid refinement was also performed to make sure that the results were grid independent. According to Surface Evolver, the lowest predicted critical droplet volume on the plain surfaces was <5 μL for θ<sub>1</sub> = 150°, whereas the highest CDV was >295 μL for θ<sub>1</sub> = 30°. For θ<sub>1</sub> = 90° which is typical of aluminum, the CDV on the plain surface was 74 μL for the fine mesh and 83 μL for the rough mesh. When a 3-mm wide θ<sub>1</sub> = 90° wetting region was used, however, bordered by two superhydrophobic stripes with θ<sub>2</sub> = 150°, this CDV was reduced to 71 μL for the rough mesh, and when a 2-mm wide wetting region was used, the CDV was reduced even further to 55 μL. This shows both the promise of the idea and the possibility of using a striped / patterned tube to reduce the critical droplet volume needed for droplet shedding in a condensation environment.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"160 ","pages":"Article 108298"},"PeriodicalIF":6.4,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142699571","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}
Electronics cooling and thermal management presents an immense challenge to the electrification of society. From mobile devices to stationary systems, power densification of electronics platforms is putting pressureon thermal systems. This research uniquely combines superhydrophobic surfaces with pin-fin structures to investigate their combined effects on thermal performance and fluid dynamics. We examine the impact of superhydrophobic surfaces on different internal walls for both finned and non-finned microchannels. Three-dimensional finite volume method simulations are used to analyze fluid flow and heat transfer, with surface wettability modeled using a custom user-defined function. The results of the simulations were first validated against experimental data. Thermal-hydraulic performance for finned and non-finned microchannels was studied for both conventional and superhydrophobic surfaces. Superhydrophobic properties on different internal surfaces of the microchannel yielded different outcomes for finned versus non-finned designs. We show that superhydrophobic surfaces are effective in enhancing the performance of finned channels at high Reynolds number (Re). At Re = 500, finned microchannels with superhydrophobic side walls have the same performance factor () as a conventional microchannel without fins with a 9.4 °C lower average base surface temperature. Additionally, superhydrophobic side walls increase the pressure drop and Nusselt number by 8.9 % and 6.6 %, respectively, compared to conventional non-superhydrophobic finned surfaces. Conversely, superhydrophobic top and bottom surfaces reduce the pressure drop and Nusselt number by 13 % and 18.5 %, respectively. Our findings reveal that the location and intensity of vortices, influenced by fins, vary with different superhydrophobic surface configurations.
{"title":"Combining pin-fins and superhydrophobic surfaces to enhance the performance of microchannel heat sinks","authors":"Sajjad Sarvar , Pouya Kabirzadeh , Nenad Miljkovic","doi":"10.1016/j.icheatmasstransfer.2024.108351","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108351","url":null,"abstract":"<div><div>Electronics cooling and thermal management presents an immense challenge to the electrification of society. From mobile devices to stationary systems, power densification of electronics platforms is putting pressureon thermal systems. This research uniquely combines superhydrophobic surfaces with pin-fin structures to investigate their combined effects on thermal performance and fluid dynamics. We examine the impact of superhydrophobic surfaces on different internal walls for both finned and non-finned microchannels. Three-dimensional finite volume method simulations are used to analyze fluid flow and heat transfer, with surface wettability modeled using a custom user-defined function. The results of the simulations were first validated against experimental data. Thermal-hydraulic performance for finned and non-finned microchannels was studied for both conventional and superhydrophobic surfaces. Superhydrophobic properties on different internal surfaces of the microchannel yielded different outcomes for finned versus non-finned designs. We show that superhydrophobic surfaces are effective in enhancing the performance of finned channels at high Reynolds number (<em>Re</em>). At Re = 500, finned microchannels with superhydrophobic side walls have the same performance factor (<span><math><mi>η</mi></math></span>) as a conventional microchannel without fins with a 9.4 °C lower average base surface temperature. Additionally, superhydrophobic side walls increase the pressure drop and Nusselt number by 8.9 % and 6.6 %, respectively, compared to conventional non-superhydrophobic finned surfaces. Conversely, superhydrophobic top and bottom surfaces reduce the pressure drop and Nusselt number by 13 % and 18.5 %, respectively. Our findings reveal that the location and intensity of vortices, influenced by fins, vary with different superhydrophobic surface configurations.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"160 ","pages":"Article 108351"},"PeriodicalIF":6.4,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698787","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}
Electronic components often encounter issues such as performance degradation and thermal damage due to inherent heat generation during operation. Hence, ensuring their quality relies on scientific thermal design. In this study, we proposed a novel temperature analysis approach that integrates power loss assessment and thermal network modeling, with the consideration of thermal diffusion effects for power module components. Reliable heat flux is obtained by analyzing the power loss of circuit units based on the component operation mechanism. Additionally, we established a thermal network model for temperature analysis of the component, which consumes less than 0.04 % of the time compared with CFD simulation. Moreover, the model incorporates thermal diffusion effects within the package structure, enhancing temperature calculation accuracy. The findings demonstrate that combining power loss assessment and thermal network modeling yields more reliable temperature calculations, substantially reduces computation time, and lowers thermal design costs, providing valuable insights for electronic component thermal design processes.
{"title":"Component temperature analysis in power modules: Coupling with power loss evaluation and thermal network models considering thermal diffusion effects","authors":"Guangsheng Wu , Yinmo Xie , Bing Liu , Yingze Meng , Peihui Jiang , Xiaoyue Zhang , Jianyu Tan , Junming Zhao","doi":"10.1016/j.icheatmasstransfer.2024.108355","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108355","url":null,"abstract":"<div><div>Electronic components often encounter issues such as performance degradation and thermal damage due to inherent heat generation during operation. Hence, ensuring their quality relies on scientific thermal design. In this study, we proposed a novel temperature analysis approach that integrates power loss assessment and thermal network modeling, with the consideration of thermal diffusion effects for power module components. Reliable heat flux is obtained by analyzing the power loss of circuit units based on the component operation mechanism. Additionally, we established a thermal network model for temperature analysis of the component, which consumes less than 0.04 % of the time compared with CFD simulation. Moreover, the model incorporates thermal diffusion effects within the package structure, enhancing temperature calculation accuracy. The findings demonstrate that combining power loss assessment and thermal network modeling yields more reliable temperature calculations, substantially reduces computation time, and lowers thermal design costs, providing valuable insights for electronic component thermal design processes.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"160 ","pages":"Article 108355"},"PeriodicalIF":6.4,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698872","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 : 2024-11-20DOI: 10.1016/j.icheatmasstransfer.2024.108356
Chi Ma , Jiarui Hu , Mingming Li , Xiaogang Deng , Jun Yang , Jialong He , Chunlei Hua , Liang Wang , Jialan Liu , Kuo Liu , Yuansheng Zhou , Mengyuan Li , Jianqiang Zhou , Xiaolei Deng , Shengbin Weng
The machining accuracy of the gear grinding machine tool is significantly reduced by the thermal error, and then an effective control of thermal error is imperative. To control the thermal error, an innovative idea for directly cooling a moving heat source for the gear grinding machine tool is proposed to replace the substitute hollow screw cooling method, and a multi-objective topology optimization approach is proposed to design the cooling element for precision gear grinding machine tool. The results show that the heat transfer capability of the topology optimization-shaped channel is much more outstanding than that of the traditional serpentine-shaped cooling channel, and the pressure drop is reduced by 2–3 times compared with that of the traditional serpentine-shaped cooling channel. The cooling element is embedded into the precision gear grinding machine tool, leading that the temperature rise of the moving nut is reduced by more than 3 K in and that the thermal elongation of the screw shaft is reduced by 10 %. The improvement rate for the repetitive positioning accuracy is in the range of [29.03 %, 92.59 %] and the grinding accuracy is improved by approximately 65 % by using the designed cooling element with topology optimization-shaped channel.
{"title":"Multi-objective topology optimization for cooling element of precision gear grinding machine tool","authors":"Chi Ma , Jiarui Hu , Mingming Li , Xiaogang Deng , Jun Yang , Jialong He , Chunlei Hua , Liang Wang , Jialan Liu , Kuo Liu , Yuansheng Zhou , Mengyuan Li , Jianqiang Zhou , Xiaolei Deng , Shengbin Weng","doi":"10.1016/j.icheatmasstransfer.2024.108356","DOIUrl":"10.1016/j.icheatmasstransfer.2024.108356","url":null,"abstract":"<div><div>The machining accuracy of the gear grinding machine tool is significantly reduced by the thermal error, and then an effective control of thermal error is imperative. To control the thermal error, an innovative idea for directly cooling a moving heat source for the gear grinding machine tool is proposed to replace the substitute hollow screw cooling method, and a multi-objective topology optimization approach is proposed to design the cooling element for precision gear grinding machine tool. The results show that the heat transfer capability of the topology optimization-shaped channel is much more outstanding than that of the traditional serpentine-shaped cooling channel, and the pressure drop is reduced by 2–3 times compared with that of the traditional serpentine-shaped cooling channel. The cooling element is embedded into the precision gear grinding machine tool, leading that the temperature rise of the moving nut is reduced by more than 3 K in and that the thermal elongation of the screw shaft is reduced by 10 %. The improvement rate for the repetitive positioning accuracy is in the range of [29.03 %, 92.59 %] and the grinding accuracy is improved by approximately 65 % by using the designed cooling element with topology optimization-shaped channel.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"160 ","pages":"Article 108356"},"PeriodicalIF":6.4,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698785","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}
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