International Journal of Thermal Sciences最新文献_第8页

Numerical investigation of transient flow characteristics and heat transfer in a fluidized bed particle solar receiver

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2025-03-12 DOI: 10.1016/j.ijthermalsci.2025.109859

Xiaoyu Li , Yongkang Hao , Ziang Zhu , Anjun Li , Zhuangjun Wu , Xiaogang Xu , Fuyao Wang

The heat absorption efficiency of particles in a solar receiver is significantly affected by internal flow characteristics. A detailed investigation of the transient behavior of bubbles is essential for optimizing receiver design and improving its control. The present work investigates the transient flow characteristics and heat transfer in a fluidized bed particle solar receiver through numerical simulations with a Eulerian-Eulerian framework. The results reveal that the gas volume fraction showed significant temporal fluctuations, with increased gas flow rates and higher axial positions promoting the formation of larger gas core structures. The transient distribution of bubble diameters was obtained and analyzed. As the axial position and inlet flow rate increased, the growth rate of the cumulative curve declined, leading to a reduced cumulative probability of smaller bubbles. The power spectral energy was predominantly concentrated in the 0–1 Hz frequency range. With higher inlet flow rates, the spectral energy peak shifted leftward, indicating an extended period of bubble diameter variation. Finally, wall-to-bed heat transfer was analyzed. Higher flow rates led to improved temperature distribution and wall-to-bed heat transfer coefficient, but beyond a critical threshold, further increases would hinder effective heat transfer.

{"title":"Numerical investigation of transient flow characteristics and heat transfer in a fluidized bed particle solar receiver","authors":"Xiaoyu Li , Yongkang Hao , Ziang Zhu , Anjun Li , Zhuangjun Wu , Xiaogang Xu , Fuyao Wang","doi":"10.1016/j.ijthermalsci.2025.109859","DOIUrl":"10.1016/j.ijthermalsci.2025.109859","url":null,"abstract":"<div><div>The heat absorption efficiency of particles in a solar receiver is significantly affected by internal flow characteristics. A detailed investigation of the transient behavior of bubbles is essential for optimizing receiver design and improving its control. The present work investigates the transient flow characteristics and heat transfer in a fluidized bed particle solar receiver through numerical simulations with a Eulerian-Eulerian framework. The results reveal that the gas volume fraction showed significant temporal fluctuations, with increased gas flow rates and higher axial positions promoting the formation of larger gas core structures. The transient distribution of bubble diameters was obtained and analyzed. As the axial position and inlet flow rate increased, the growth rate of the cumulative curve declined, leading to a reduced cumulative probability of smaller bubbles. The power spectral energy was predominantly concentrated in the 0–1 Hz frequency range. With higher inlet flow rates, the spectral energy peak shifted leftward, indicating an extended period of bubble diameter variation. Finally, wall-to-bed heat transfer was analyzed. Higher flow rates led to improved temperature distribution and wall-to-bed heat transfer coefficient, but beyond a critical threshold, further increases would hinder effective heat transfer.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"214 ","pages":"Article 109859"},"PeriodicalIF":4.9,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143601403","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}

引用次数: 0

QUASI-3D modelling of heat generation in rotor-stator systems: Explicit roles of bolt geometry and operating parameters 转子-定子系统发热的 QUASI-3D 建模：螺栓几何形状和运行参数的明确作用

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2025-03-11 DOI: 10.1016/j.ijthermalsci.2025.109840

Bo Ren , Shihao Yang , Lixin Yang , Xiang Luo , Zeyu Wu

In the rotor-stator system, the windage effect due to rotating bolts has become a significant limitation on the cooling performance of the secondary air system (SAS). To address this issue, this paper develops a quasi-3D modeling method for the rotor-stator system with superimposed flow, capable of effectively analyzing the power consumption and temperature rise under different bolt geometries (shape and number) and operating parameters (throughflow Reynolds number and rotating Reynolds number). The results using quasi-3D modeling method can not only preserve the effect of non-uniform flow on power consumption and temperature rise but also align well with the experimental values. The windage losses due to bolts account for over 81 % of the total power consumption and changing bolt shape leads to significant differences in form drag. Using cylindrical bolts can apparently reduce the windage losses and heating compared to polygonal bolts. The bolt shape has minimal influence on the windage in cavity region. The adiabatic wall temperature is sensitive to the bolt number as the turbulent parameter is below 0.219. Both the power consumption and temperature rise decrease due to lower form drag losses once the pitch ratio exceeds 0.69. Using a bolt cover to create a continuous band distribution can effectively alleviate the windage effect from bolts. The quasi-3D modeling method enhances efficiency in applying CFD to SAS design and the findings hold significant implications for improving the cooling properties of SAS and controlling the power consumption of windage losses in the rotor-stator system.

{"title":"QUASI-3D modelling of heat generation in rotor-stator systems: Explicit roles of bolt geometry and operating parameters","authors":"Bo Ren , Shihao Yang , Lixin Yang , Xiang Luo , Zeyu Wu","doi":"10.1016/j.ijthermalsci.2025.109840","DOIUrl":"10.1016/j.ijthermalsci.2025.109840","url":null,"abstract":"<div><div>In the rotor-stator system, the windage effect due to rotating bolts has become a significant limitation on the cooling performance of the secondary air system (SAS). To address this issue, this paper develops a quasi-3D modeling method for the rotor-stator system with superimposed flow, capable of effectively analyzing the power consumption and temperature rise under different bolt geometries (shape and number) and operating parameters (throughflow Reynolds number and rotating Reynolds number). The results using quasi-3D modeling method can not only preserve the effect of non-uniform flow on power consumption and temperature rise but also align well with the experimental values. The windage losses due to bolts account for over 81 % of the total power consumption and changing bolt shape leads to significant differences in form drag. Using cylindrical bolts can apparently reduce the windage losses and heating compared to polygonal bolts. The bolt shape has minimal influence on the windage in cavity region. The adiabatic wall temperature is sensitive to the bolt number as the turbulent parameter is below 0.219. Both the power consumption and temperature rise decrease due to lower form drag losses once the pitch ratio exceeds 0.69. Using a bolt cover to create a continuous band distribution can effectively alleviate the windage effect from bolts. The quasi-3D modeling method enhances efficiency in applying CFD to SAS design and the findings hold significant implications for improving the cooling properties of SAS and controlling the power consumption of windage losses in the rotor-stator system.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"214 ","pages":"Article 109840"},"PeriodicalIF":4.9,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143592527","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}

引用次数: 0

IR-thermography studies of high-speed gas-dynamic flows

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2025-03-10 DOI: 10.1016/j.ijthermalsci.2025.109827

Irina Znamenskaya, Murat Muratov, Daria Dolbnya

This study investigates the application of a specific infrared thermography technique to visualize high-speed flows by analyzing the emerging thermal distribution on quartz windows of a shock tube channel’s sidewalls (

24 \times 48 m m

). The interaction between non-stationary flow (

M = 1.8 - 4.0

) and the streamlined channel walls results in energy exchange at the interface, forming a corresponding thermal load distribution due to the heat tangential conduction. These integral heat flux traces were captured using an infrared camera and quantitatively investigated. Panoramic infrared imaging conducted by a thermal camera with operating range

1.5 - 5.1 μ m

and an exposure time of up to

500 μ s

was combined and compared with a frame-by-frame shadowgraphy. The resulting radiation intensity integral maps were analyzed as a function of the incident shock wave Mach number, local flow-quartz interaction duration and heat flux magnitude, influenced by non-stationary boundary layer behavior. It is shown that the acquired inhomogeneous integral thermal patterns on the channel inner surfaces accurately correspond to the gas-dynamic structures of the flow according to their duration and intensity. The analysis underscores key local flow characteristics, including regions of deceleration and compression, stagnation zones, and rarefaction areas. Thermal maps captured from different observation angles (

Θ \approx 0 °, 25 °, 36 °

) revealed sidewall-specific heating patterns and composite images of overall radiation intensity. Experimental findings underline the feasibility of using this approach to investigate spatial–temporal characteristics of non-stationary flows via evolving thermal distributions on streamlined surfaces under conditions of non-stationary heat and mass transfer.

{"title":"IR-thermography studies of high-speed gas-dynamic flows","authors":"Irina Znamenskaya, Murat Muratov, Daria Dolbnya","doi":"10.1016/j.ijthermalsci.2025.109827","DOIUrl":"10.1016/j.ijthermalsci.2025.109827","url":null,"abstract":"<div><div>This study investigates the application of a specific infrared thermography technique to visualize high-speed flows by analyzing the emerging thermal distribution on quartz windows of a shock tube channel’s sidewalls (<span><math><mrow><mn>24</mn><mo>×</mo><mn>48</mn><mspace></mspace><mi>m</mi><mi>m</mi></mrow></math></span>). The interaction between non-stationary flow (<span><math><mrow><mi>M</mi><mo>=</mo><mn>1</mn><mo>.</mo><mn>8</mn><mo>−</mo><mn>4</mn><mo>.</mo><mn>0</mn></mrow></math></span>) and the streamlined channel walls results in energy exchange at the interface, forming a corresponding thermal load distribution due to the heat tangential conduction. These integral heat flux traces were captured using an infrared camera and quantitatively investigated. Panoramic infrared imaging conducted by a thermal camera with operating range <span><math><mrow><mn>1</mn><mo>.</mo><mn>5</mn><mo>−</mo><mn>5</mn><mo>.</mo><mn>1</mn><mspace></mspace><mi>μ</mi><mi>m</mi></mrow></math></span> and an exposure time of up to <span><math><mrow><mn>500</mn><mspace></mspace><mi>μ</mi><mi>s</mi></mrow></math></span> was combined and compared with a frame-by-frame shadowgraphy. The resulting radiation intensity integral maps were analyzed as a function of the incident shock wave Mach number, local flow-quartz interaction duration and heat flux magnitude, influenced by non-stationary boundary layer behavior. It is shown that the acquired inhomogeneous integral thermal patterns on the channel inner surfaces accurately correspond to the gas-dynamic structures of the flow according to their duration and intensity. The analysis underscores key local flow characteristics, including regions of deceleration and compression, stagnation zones, and rarefaction areas. Thermal maps captured from different observation angles (<span><math><mrow><mi>Θ</mi><mo>≈</mo><mn>0</mn><mo>°</mo><mo>,</mo><mn>25</mn><mo>°</mo><mo>,</mo><mn>36</mn><mo>°</mo></mrow></math></span>) revealed sidewall-specific heating patterns and composite images of overall radiation intensity. Experimental findings underline the feasibility of using this approach to investigate spatial–temporal characteristics of non-stationary flows via evolving thermal distributions on streamlined surfaces under conditions of non-stationary heat and mass transfer.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"214 ","pages":"Article 109827"},"PeriodicalIF":4.9,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143579328","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}

引用次数: 0

Combined Eulerian–Eulerian Multiphase Frost model and solidification and melting model to predict the cooling performance of subcooled eutectic plates

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2025-03-10 DOI: 10.1016/j.ijthermalsci.2025.109837

Jihyuk Jeong , Sébastien Poncet , Benoit Michel , Jocelyn Bonjour

To limit the environmental footprint of refrigeration, transport of frozen goods based on natural fluids and phase change materials (PCMs) may be a promising solution. However, frost formation on the surface of the PCM encasing might limit the heat exchange and overall efficiency of the frozen food transport. The present work reports the numerical modeling of the heat and mass transfer for a flat plate cooled by a melting PCM located inside an air channel on which frost develops. Eulerian–Eulerian multiphase model is employed in conjunction with the

k - ω

Shear Stress Transport (SST) model to simulate the frost formation on the surface of the PCM encasing. It is first favorably validated against a number of published experimental and numerical data. Then the melting model based on the so-called enthalpy-porosity approach is applied as a User-Defined Function (UDF). The solidification and melting model as an applied UDF has been also validated against experimental and numerical works for lauric acid as PCM. The combined Eulerian–Eulerian Multiphase frost model and the solidification and melting model show that the flow must be below the PCM rather than above, in order to promote the formation of the Rayleigh–Bénard convection cells within the PCM when the melting process begins. Otherwise, the heat released from the frost formation on the surface of the PCM encasing and the heat transferred from the high temperature humid air are not effectively diffused within the PCM and results in localized high-temperature zones within the PCM.

{"title":"Combined Eulerian–Eulerian Multiphase Frost model and solidification and melting model to predict the cooling performance of subcooled eutectic plates","authors":"Jihyuk Jeong , Sébastien Poncet , Benoit Michel , Jocelyn Bonjour","doi":"10.1016/j.ijthermalsci.2025.109837","DOIUrl":"10.1016/j.ijthermalsci.2025.109837","url":null,"abstract":"<div><div>To limit the environmental footprint of refrigeration, transport of frozen goods based on natural fluids and phase change materials (PCMs) may be a promising solution. However, frost formation on the surface of the PCM encasing might limit the heat exchange and overall efficiency of the frozen food transport. The present work reports the numerical modeling of the heat and mass transfer for a flat plate cooled by a melting PCM located inside an air channel on which frost develops. Eulerian–Eulerian multiphase model is employed in conjunction with the <span><math><mrow><mi>k</mi><mo>−</mo><mi>ω</mi></mrow></math></span> Shear Stress Transport (SST) model to simulate the frost formation on the surface of the PCM encasing. It is first favorably validated against a number of published experimental and numerical data. Then the melting model based on the so-called enthalpy-porosity approach is applied as a User-Defined Function (UDF). The solidification and melting model as an applied UDF has been also validated against experimental and numerical works for lauric acid as PCM. The combined Eulerian–Eulerian Multiphase frost model and the solidification and melting model show that the flow must be below the PCM rather than above, in order to promote the formation of the Rayleigh–Bénard convection cells within the PCM when the melting process begins. Otherwise, the heat released from the frost formation on the surface of the PCM encasing and the heat transferred from the high temperature humid air are not effectively diffused within the PCM and results in localized high-temperature zones within the PCM.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"214 ","pages":"Article 109837"},"PeriodicalIF":4.9,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143579327","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}

引用次数: 0

Enhanced printed-circuit heat exchanger for supercritical CO2 Brayton cycle pre-coolers with innovative convergent-divergent mini-channel design

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2025-03-10 DOI: 10.1016/j.ijthermalsci.2025.109857

Joffin Jose Ponnore , Fayez Aldawi

Supercritical CO₂ (sCO₂) operates under extreme pressure and temperature conditions, with its thermophysical properties changing rapidly near the critical point. These conditions exceed the capabilities of common welded heat exchangers to handle the substance in sCO₂ Brayton Cycle power plants. Among the most suitable heat exchangers for this application is the Printed Circuit Heat Exchanger (PCHE), which has been extensively adopted in sCO₂ power systems. This unique heat exchanger offers the thermal effectiveness of a plate-type heat exchanger combined with the temperature/pressure capability of a shell-and-tube heat exchanger. Additionally, PCHEs are 75 %–85 % smaller and lighter than the shell-and-tube heat exchangers required in the mentioned cycle. The only drawback of PCHEs is the complexity and cost of the manufacturing process. That is why any proposed thermal improvement techniques for PCHEs are expected not to increase the cost or complexity of the manufacturing or tooling process. As shown in the graphical abstract, precise parallel mini channels are created on thin metal sheets using the photochemical etching process and then joined together with the diffusion bonding technique, making it a single solid-state bond (free from joints, gaskets, brazing, and welding). This research proposes an innovative modification for the mentioned mini-channels in which the diameter of the semi-cylindrical channels is gradually increased or decreased along the sheets, creating convergent-divergent fluid flow behavior to boost its thermal performance without affecting the production cost or complexity of the process. Various convergent/divergent arrangement scenarios are possible, all of which are examined under various area ratios (A_r), inlet temperatures, mass flux (G), and operating pressures from thermal, frictional, and exergetic viewpoints. According to the validated 3D numerical simulation results, this modification is found to be so promising that, in some cases, the improved heat transfer coefficient is over two times higher than that in the base model due to enhanced turbulence and fluid mixing from the convergent-divergent scenario. All other detailed results are presented and discussed in this paper.

{"title":"Enhanced printed-circuit heat exchanger for supercritical CO2 Brayton cycle pre-coolers with innovative convergent-divergent mini-channel design","authors":"Joffin Jose Ponnore , Fayez Aldawi","doi":"10.1016/j.ijthermalsci.2025.109857","DOIUrl":"10.1016/j.ijthermalsci.2025.109857","url":null,"abstract":"<div><div>Supercritical CO<sub>2</sub> (sCO<sub>2</sub>) operates under extreme pressure and temperature conditions, with its thermophysical properties changing rapidly near the critical point. These conditions exceed the capabilities of common welded heat exchangers to handle the substance in sCO<sub>2</sub> Brayton Cycle power plants. Among the most suitable heat exchangers for this application is the Printed Circuit Heat Exchanger (PCHE), which has been extensively adopted in sCO<sub>2</sub> power systems. This unique heat exchanger offers the thermal effectiveness of a plate-type heat exchanger combined with the temperature/pressure capability of a shell-and-tube heat exchanger. Additionally, PCHEs are 75 %–85 % smaller and lighter than the shell-and-tube heat exchangers required in the mentioned cycle. The only drawback of PCHEs is the complexity and cost of the manufacturing process. That is why any proposed thermal improvement techniques for PCHEs are expected not to increase the cost or complexity of the manufacturing or tooling process. As shown in the graphical abstract, precise parallel mini channels are created on thin metal sheets using the photochemical etching process and then joined together with the diffusion bonding technique, making it a single solid-state bond (free from joints, gaskets, brazing, and welding). This research proposes an innovative modification for the mentioned mini-channels in which the diameter of the semi-cylindrical channels is gradually increased or decreased along the sheets, creating convergent-divergent fluid flow behavior to boost its thermal performance without affecting the production cost or complexity of the process. Various convergent/divergent arrangement scenarios are possible, all of which are examined under various area ratios (A<sub>r</sub>), inlet temperatures, mass flux (G), and operating pressures from thermal, frictional, and exergetic viewpoints. According to the validated 3D numerical simulation results, this modification is found to be so promising that, in some cases, the improved heat transfer coefficient is over two times higher than that in the base model due to enhanced turbulence and fluid mixing from the convergent-divergent scenario. All other detailed results are presented and discussed in this paper.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"214 ","pages":"Article 109857"},"PeriodicalIF":4.9,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143579325","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}

引用次数: 0

Numerical modeling of natural convection heat transfer from a horizontally positioned tube layer immersed in a tank

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2025-03-10 DOI: 10.1016/j.ijthermalsci.2025.109853

Koray Sahin

This study addresses the problem of heating heavy fuel oil (HFO) in ship storage tanks. The 3D natural convection heat transfer from a horizontally positioned tube layer immersed in a tank for heating the HFO was investigated in the Rayleigh (Ra) number ranges of 10⁵≤Ra_H≤10⁷, 170≤ Ra_D≤16990. The effect of the ratio of computational domain height (H) to width (W), (A = H/W), on heat transfer by natural convection was also examined. Analyses were performed for 3 different H/W (1.66, 2.5 and 3.33). The governing equations of heat transfer by natural convection in the tank were solved using the finite volume method. The function related to the variation in the HFO viscosity with temperature was compiled into a finite volume solver. The flow and thermal fields inside the tank were obtained by the isosurface technique. The average Nusselt numbers (

\overline{Nu}

) on the tube and horizontal walls were calculated. The findings of the study are that the Ra number increased, the

\overline{Nu}

in the tube and the top horizontal walls increased, but there was no significant change in the

\overline{Nu}

numbers for the bottom wall. Additionally, the

\overline{Nu}

values for the tube increased in the 10⁵≤Ra_H≤10⁶ range as the H/W ratio increased. At Ra_H = 10⁷, the increase in the H/W ratio from 2.5 to 3.33 had no effect on the heat transfer rate in the tube. As a result, the effect of the H/W ratio on the heat transfer rate in the tube gradually decreased with the increase of Ra number. Correlations between Ra number, aspect ratio and

\overline{Nu}

were developed.

{"title":"Numerical modeling of natural convection heat transfer from a horizontally positioned tube layer immersed in a tank","authors":"Koray Sahin","doi":"10.1016/j.ijthermalsci.2025.109853","DOIUrl":"10.1016/j.ijthermalsci.2025.109853","url":null,"abstract":"<div><div>This study addresses the problem of heating heavy fuel oil (HFO) in ship storage tanks. The 3D natural convection heat transfer from a horizontally positioned tube layer immersed in a tank for heating the HFO was investigated in the Rayleigh (Ra) number ranges of 10<sup>5</sup>≤Ra<sub>H</sub>≤10<sup>7</sup>, 170≤ Ra<sub>D</sub>≤16990. The effect of the ratio of computational domain height (H) to width (W), (A = H/W), on heat transfer by natural convection was also examined. Analyses were performed for 3 different H/W (1.66, 2.5 and 3.33). The governing equations of heat transfer by natural convection in the tank were solved using the finite volume method. The function related to the variation in the HFO viscosity with temperature was compiled into a finite volume solver. The flow and thermal fields inside the tank were obtained by the isosurface technique. The average Nusselt numbers (<span><math><mrow><mover><mrow><mtext>Nu</mtext><mspace></mspace></mrow><mo>‾</mo></mover></mrow></math></span>) on the tube and horizontal walls were calculated. The findings of the study are that the Ra number increased, the <span><math><mrow><mover><mrow><mtext>Nu</mtext><mspace></mspace></mrow><mo>‾</mo></mover></mrow></math></span> in the tube and the top horizontal walls increased, but there was no significant change in the <span><math><mrow><mover><mrow><mtext>Nu</mtext><mspace></mspace></mrow><mo>‾</mo></mover></mrow></math></span> numbers for the bottom wall. Additionally, the <span><math><mrow><mover><mrow><mtext>Nu</mtext><mspace></mspace></mrow><mo>‾</mo></mover></mrow></math></span> values for the tube increased in the 10<sup>5</sup>≤Ra<sub>H</sub>≤10<sup>6</sup> range as the H/W ratio increased. At Ra<sub>H</sub> = 10<sup>7</sup>, the increase in the H/W ratio from 2.5 to 3.33 had no effect on the heat transfer rate in the tube. As a result, the effect of the H/W ratio on the heat transfer rate in the tube gradually decreased with the increase of Ra number. Correlations between Ra number, aspect ratio and <span><math><mrow><mover><mrow><mtext>Nu</mtext><mspace></mspace></mrow><mo>‾</mo></mover></mrow></math></span> were developed.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"214 ","pages":"Article 109853"},"PeriodicalIF":4.9,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143592526","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}

引用次数: 0

Enhancing the efficiency of latent heat thermal energy storage units with twisted fin induced natural convection

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2025-03-10 DOI: 10.1016/j.ijthermalsci.2025.109842

Peng Ding, Qiangqiang Ji, Yuxiang Zou

This study presents the design of a novel twisted fin structure aimed at enhancing natural convection to examine its effects on phase change material (PCM) melting in a shell-and-tube thermal storage system. Numerical simulations are employed to assess the performance of the latent thermal energy storage system with twisted fins, utilizing the enthalpy-porosity method. Two key factors are analyzed: the twist angle of the fins and the orientation of the thermal storage unit (vertical and horizontal). Thermal performance is evaluated by comparing the liquid fraction, average temperature, and velocity distribution. This paper attempts to demonstrate the advantages of the novel structure through a more visual representation of spatial streamlines. The results indicate that in the vertical orientation, twisted fins significantly improve the melting rate of the PCM compared to annular fins by alleviating the suppression of natural convection. In the horizontal orientation, twisted fins generate strong upward convection and weaker lateral convection. A fin twist angle of 35°is found to yield the highest melting enhancement, with average heat storage rates increasing by 10.7 % in the vertical and 14.8 % in the horizontal configurations, compared to annular fins.

{"title":"Enhancing the efficiency of latent heat thermal energy storage units with twisted fin induced natural convection","authors":"Peng Ding, Qiangqiang Ji, Yuxiang Zou","doi":"10.1016/j.ijthermalsci.2025.109842","DOIUrl":"10.1016/j.ijthermalsci.2025.109842","url":null,"abstract":"<div><div>This study presents the design of a novel twisted fin structure aimed at enhancing natural convection to examine its effects on phase change material (PCM) melting in a shell-and-tube thermal storage system. Numerical simulations are employed to assess the performance of the latent thermal energy storage system with twisted fins, utilizing the enthalpy-porosity method. Two key factors are analyzed: the twist angle of the fins and the orientation of the thermal storage unit (vertical and horizontal). Thermal performance is evaluated by comparing the liquid fraction, average temperature, and velocity distribution. This paper attempts to demonstrate the advantages of the novel structure through a more visual representation of spatial streamlines. The results indicate that in the vertical orientation, twisted fins significantly improve the melting rate of the PCM compared to annular fins by alleviating the suppression of natural convection. In the horizontal orientation, twisted fins generate strong upward convection and weaker lateral convection. A fin twist angle of 35°is found to yield the highest melting enhancement, with average heat storage rates increasing by 10.7 % in the vertical and 14.8 % in the horizontal configurations, compared to annular fins.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"214 ","pages":"Article 109842"},"PeriodicalIF":4.9,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143579326","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}

引用次数: 0

Teardrop-like micro pin fin coated nanotube arrays chip for enhancement of flow boiling electronics cooling

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2025-03-08 DOI: 10.1016/j.ijthermalsci.2025.109854

Hongqiang Chen , Quan Gao , Xiang Ma , Kai Li , Wangfang Du , Caifeng Li , Yonghai Zhang , Jinjia Wei

Phase change flow boiling heat transfer in microchannel is a very efficient thermal management mode for high-power electronics/devices cooling. However, achieving comprehensive enhancement of flow boiling heat transfer performance at low power consumption is still challenging. Herein, we devised and manufactured a teardrop-like micro-pin-fin coated stable copper hydroxide nanotubes array chip surfaces (S-Nanotube), demonstrating their exceptional enhancement in flow boiling heat transfer efficiency. A series of experiments were conducted using HFE-7100 as a working fluid within a semi-open microchannel. Compared to the smooth surface, the critical heat flux (CHF) and the maximum boiling heat transfer coefficient (HTC) of the S-Nanotube is increased by 82.1 % (from 45.1 to 72.9 and then to 82.1 W/cm²) and 140.5 % (from 5955 to 11,325 and then to 14,316 W/m²·K) at extremely low-pressure drop (≤4 kPa), showing a high coefficient of performance (COP). The temperature of the onset of nucleate boiling on the S-Nanotube surface is reduced by 26.4 %, and the heat flux is greatly increased in a small wall temperature variations (ΔT ≤ 10 °C). In situ observation and analysis of the surface properties and the bubble dynamics, the S-Nanotube chip promotes the phase change heat transfer process by providing massive nucleation sites, reducing bubbles size and residence time, and enhancing the wicking wetting capacity. These findings provide guidance for the rational design of boiling heat transfer-enhanced surfaces and heat sinks and point the way to achieving efficient thermal management of power devices.

{"title":"Teardrop-like micro pin fin coated nanotube arrays chip for enhancement of flow boiling electronics cooling","authors":"Hongqiang Chen , Quan Gao , Xiang Ma , Kai Li , Wangfang Du , Caifeng Li , Yonghai Zhang , Jinjia Wei","doi":"10.1016/j.ijthermalsci.2025.109854","DOIUrl":"10.1016/j.ijthermalsci.2025.109854","url":null,"abstract":"<div><div>Phase change flow boiling heat transfer in microchannel is a very efficient thermal management mode for high-power electronics/devices cooling. However, achieving comprehensive enhancement of flow boiling heat transfer performance at low power consumption is still challenging. Herein, we devised and manufactured a teardrop-like micro-pin-fin coated stable copper hydroxide nanotubes array chip surfaces (S-Nanotube), demonstrating their exceptional enhancement in flow boiling heat transfer efficiency. A series of experiments were conducted using HFE-7100 as a working fluid within a semi-open microchannel. Compared to the smooth surface, the critical heat flux (CHF) and the maximum boiling heat transfer coefficient (HTC) of the S-Nanotube is increased by 82.1 % (from 45.1 to 72.9 and then to 82.1 W/cm<sup>2</sup>) and 140.5 % (from 5955 to 11,325 and then to 14,316 W/m<sup>2</sup>·K) at extremely low-pressure drop (≤4 kPa), showing a high coefficient of performance (COP). The temperature of the onset of nucleate boiling on the S-Nanotube surface is reduced by 26.4 %, and the heat flux is greatly increased in a small wall temperature variations (Δ<em>T</em> ≤ 10 °C). In situ observation and analysis of the surface properties and the bubble dynamics, the S-Nanotube chip promotes the phase change heat transfer process by providing massive nucleation sites, reducing bubbles size and residence time, and enhancing the wicking wetting capacity. These findings provide guidance for the rational design of boiling heat transfer-enhanced surfaces and heat sinks and point the way to achieving efficient thermal management of power devices.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"214 ","pages":"Article 109854"},"PeriodicalIF":4.9,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143579323","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}

引用次数: 0

Thermal performance of thermal management system combining bionic fern-vein liquid channel with phase change materials for prismatic Lithium-ion battery 棱柱形锂离子电池仿生蕨脉液体通道与相变材料相结合的热管理系统的热性能

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2025-03-08 DOI: 10.1016/j.ijthermalsci.2025.109844

Lingyue Kong , Jinquan Zheng , Qiang Li , Yunhao Li , Guiyue Kou , Xiang Wen , Jiang Sun , Mingfei Mu

Thermal management is crucial for prolonging the life and ensuring the safety of Lithium-ion battery. Two hybrid battery thermal management system (BTMS) are proposed, that paraffin-based phase change materials containing alkanes (PCM) are wrapped around bionic fern leaf vein channels or bionic fern leaf vein fins in cold plate. Then the thermal characteristic of cold plate, like non-bionic (NON-B), bionic fern-vein channel (BFC), and bionic fern-vein fin (BFF) were numerically investigated to evaluate the thermal performance of three distinct cold plates at different mass flow rates, fluid inlet temperatures, and ambient temperatures. The results indicated that the BFC (40.71 °C) cold plate reduced the maximum temperature more effectively than the BFF (41.26 °C) and NON-B (44.12 °C) plates, with maximum reductions of 7.7 % and 21.3 %, respectively. Additionally, compared to the BFF (21.6 Pa) and NON-B (33.1 Pa) plates, the BFC (14.2 Pa) cold plate achieved maximum reductions in pressure drop and pumping power by 57.1 % and 20.8 %, respectively. The heat transfer and flow resistance performance of the cold plates were evaluated using a dimensionless comprehensive thermal performance evaluation factor j/f. The j/f of BFC (5.82) increased by 390 % and 396 % compared to BFF (1.19) and NON-B (1.17), indicating that the BFC cold plate has the best comprehensive performance. The proposed BTMS can increase the contact area between PCM and cold plate through the integration of bionic fins, which improves the thermal performance.

{"title":"Thermal performance of thermal management system combining bionic fern-vein liquid channel with phase change materials for prismatic Lithium-ion battery","authors":"Lingyue Kong , Jinquan Zheng , Qiang Li , Yunhao Li , Guiyue Kou , Xiang Wen , Jiang Sun , Mingfei Mu","doi":"10.1016/j.ijthermalsci.2025.109844","DOIUrl":"10.1016/j.ijthermalsci.2025.109844","url":null,"abstract":"<div><div>Thermal management is crucial for prolonging the life and ensuring the safety of Lithium-ion battery. Two hybrid battery thermal management system (BTMS) are proposed, that paraffin-based phase change materials containing alkanes (PCM) are wrapped around bionic fern leaf vein channels or bionic fern leaf vein fins in cold plate. Then the thermal characteristic of cold plate, like non-bionic (NON-B), bionic fern-vein channel (BFC), and bionic fern-vein fin (BFF) were numerically investigated to evaluate the thermal performance of three distinct cold plates at different mass flow rates, fluid inlet temperatures, and ambient temperatures. The results indicated that the BFC (40.71 °C) cold plate reduced the maximum temperature more effectively than the BFF (41.26 °C) and NON-B (44.12 °C) plates, with maximum reductions of 7.7 % and 21.3 %, respectively. Additionally, compared to the BFF (21.6 Pa) and NON-B (33.1 Pa) plates, the BFC (14.2 Pa) cold plate achieved maximum reductions in pressure drop and pumping power by 57.1 % and 20.8 %, respectively. The heat transfer and flow resistance performance of the cold plates were evaluated using a dimensionless comprehensive thermal performance evaluation factor <em>j/f</em>. The <em>j/f</em> of BFC (5.82) increased by 390 % and 396 % compared to BFF (1.19) and NON-B (1.17), indicating that the BFC cold plate has the best comprehensive performance. The proposed BTMS can increase the contact area between PCM and cold plate through the integration of bionic fins, which improves the thermal performance.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"214 ","pages":"Article 109844"},"PeriodicalIF":4.9,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143579324","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}

引用次数: 0

Enhancing electrospray cooling via electrode ring: An experimental and numerical study

IF 4.9 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Thermal Sciences

Pub Date : 2025-03-07 DOI: 10.1016/j.ijthermalsci.2025.109839

H. Wan , P.J. Liu , F. Qin , X.G. Wei , G.Q. He , W.Q. Li

Electrospray cooling is a promising technique for its high heat transfer efficiency and extreme low coolant and energy consumption. However, few articles focused on the enhancement of electrospray cooling using auxiliary electrodes. Moreover, there is no article referring to the numerical model for electrospray cooling with auxiliary electrode. Herein, we develop a numerical model and set up an experimental system to explore the influence of electrode ring on electrospray cooling. Results demonstrate that the potential difference between the electrode ring voltage and the capillary voltage determines the electrospray mode, and the electrode ring can enlarge the atomization angle and increase the velocity of the atomized droplets, thereby intensifying electrospray heat transfer coefficient. When the electrode ring is grounded, the capillary-ring electric potential rises, causing both increases in charge density and average velocity of cone jet. When the total voltage is the same in the cone-jet mode, the grounding electrode ring can reduce the wall temperature by 7.5 %. In the cone-jet and multi-jet modes, the larger the total voltage of capillary tube and electrode ring, the better the cooling effect. Increasing the inner diameter of the electrode ring from 2 mm to 4 mm and 6 mm can respectively improve heat transfer coefficient by 49.3 % and 116.7 %.

{"title":"Enhancing electrospray cooling via electrode ring: An experimental and numerical study","authors":"H. Wan , P.J. Liu , F. Qin , X.G. Wei , G.Q. He , W.Q. Li","doi":"10.1016/j.ijthermalsci.2025.109839","DOIUrl":"10.1016/j.ijthermalsci.2025.109839","url":null,"abstract":"<div><div>Electrospray cooling is a promising technique for its high heat transfer efficiency and extreme low coolant and energy consumption. However, few articles focused on the enhancement of electrospray cooling using auxiliary electrodes. Moreover, there is no article referring to the numerical model for electrospray cooling with auxiliary electrode. Herein, we develop a numerical model and set up an experimental system to explore the influence of electrode ring on electrospray cooling. Results demonstrate that the potential difference between the electrode ring voltage and the capillary voltage determines the electrospray mode, and the electrode ring can enlarge the atomization angle and increase the velocity of the atomized droplets, thereby intensifying electrospray heat transfer coefficient. When the electrode ring is grounded, the capillary-ring electric potential rises, causing both increases in charge density and average velocity of cone jet. When the total voltage is the same in the cone-jet mode, the grounding electrode ring can reduce the wall temperature by 7.5 %. In the cone-jet and multi-jet modes, the larger the total voltage of capillary tube and electrode ring, the better the cooling effect. Increasing the inner diameter of the electrode ring from 2 mm to 4 mm and 6 mm can respectively improve heat transfer coefficient by 49.3 % and 116.7 %.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"214 ","pages":"Article 109839"},"PeriodicalIF":4.9,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143562735","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}

引用次数: 0