Pub Date : 2025-01-25DOI: 10.1016/j.ijheatmasstransfer.2025.126713
Fatmir Asllanaj , Sylvain Contassot-Vivier , Fabien Pascale , Roberta J.C. da Fonseca , Guilherme C. Fraga , Francis H.R. França
<div><div>A unified gas radiation model over the entire temperature range — the Unified model based on the Weighted-Sum-of-Gray-Gases (UWSGG) is proposed, which improves the accuracy of the standard WSGG model. The pressure absorption coefficient <span><math><msub><mrow><mi>κ</mi></mrow><mrow><mi>p</mi><mo>,</mo><mn>1</mn></mrow></msub></math></span> and the weighting factor <span><math><msub><mrow><mi>a</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> are approximated with quadratic polynomial functions of the temperature <span><math><mi>T</mi></math></span>. For <span><math><mi>K</mi></math></span> gray gases and <span><math><mrow><mn>2</mn><mo>≤</mo><mspace></mspace><mi>k</mi><mspace></mspace><mo>≤</mo><mi>K</mi></mrow></math></span>, <span><math><msub><mrow><mi>a</mi></mrow><mrow><mi>k</mi></mrow></msub></math></span> are determined by translation from <span><math><msub><mrow><mi>a</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> and <span><math><msub><mrow><mi>κ</mi></mrow><mrow><mi>p</mi><mo>,</mo><mi>k</mi></mrow></msub></math></span> by translation and multiplicative factors from <span><math><msub><mrow><mi>κ</mi></mrow><mrow><mi>p</mi><mo>,</mo><mn>1</mn></mrow></msub></math></span>. An efficient inverse method and a Genetic Algorithm are used to find all the model parameters from the total radiative heat source <span><math><msub><mrow><mi>S</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span> computed with the Line-by-Line (LBL) method based on HITEMP2010 data. It can be noted that <span><math><msub><mrow><mi>κ</mi></mrow><mrow><mi>p</mi><mo>,</mo><mi>k</mi></mrow></msub></math></span> depend highly on <span><math><mi>T</mi></math></span> and the <span><math><msub><mrow><mi>a</mi></mrow><mrow><mi>k</mi></mrow></msub></math></span> depend weakly on <span><math><mi>T</mi></math></span> whereas in the standard WSGG model, <span><math><msub><mrow><mi>κ</mi></mrow><mrow><mi>p</mi><mo>,</mo><mi>k</mi></mrow></msub></math></span> are usually constants and <span><math><msub><mrow><mi>a</mi></mrow><mrow><mi>k</mi></mrow></msub></math></span> depend highly on <span><math><mi>T</mi></math></span>. It is shown, on 92 selected 1D cases of CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>-H<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O mixtures (at atmospheric pressure with a mole fraction ratio of 2) within the temperature range [300 K; 3,000 K], that the maximum relative errors on <span><math><msub><mrow><mi>S</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span> for the UWSGG model with <span><math><mrow><mi>K</mi><mo>=</mo><mn>6</mn></mrow></math></span> do not exceed 7.5 %. Conversely, for the standard WSGG model by Dorigon et al. (2013) on the first 72 cases (<span><math><mrow><mi>T</mi><mo>></mo></mrow></math></span> 2500 K in the other cases and the model by Dorigon is limited to 2500 K), these errors vary up to 20.4 % (seven cases have errors higher than 15.0 %,
{"title":"Unified gas radiation model over the entire temperature range based on WSGG","authors":"Fatmir Asllanaj , Sylvain Contassot-Vivier , Fabien Pascale , Roberta J.C. da Fonseca , Guilherme C. Fraga , Francis H.R. França","doi":"10.1016/j.ijheatmasstransfer.2025.126713","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.126713","url":null,"abstract":"<div><div>A unified gas radiation model over the entire temperature range — the Unified model based on the Weighted-Sum-of-Gray-Gases (UWSGG) is proposed, which improves the accuracy of the standard WSGG model. The pressure absorption coefficient <span><math><msub><mrow><mi>κ</mi></mrow><mrow><mi>p</mi><mo>,</mo><mn>1</mn></mrow></msub></math></span> and the weighting factor <span><math><msub><mrow><mi>a</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> are approximated with quadratic polynomial functions of the temperature <span><math><mi>T</mi></math></span>. For <span><math><mi>K</mi></math></span> gray gases and <span><math><mrow><mn>2</mn><mo>≤</mo><mspace></mspace><mi>k</mi><mspace></mspace><mo>≤</mo><mi>K</mi></mrow></math></span>, <span><math><msub><mrow><mi>a</mi></mrow><mrow><mi>k</mi></mrow></msub></math></span> are determined by translation from <span><math><msub><mrow><mi>a</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> and <span><math><msub><mrow><mi>κ</mi></mrow><mrow><mi>p</mi><mo>,</mo><mi>k</mi></mrow></msub></math></span> by translation and multiplicative factors from <span><math><msub><mrow><mi>κ</mi></mrow><mrow><mi>p</mi><mo>,</mo><mn>1</mn></mrow></msub></math></span>. An efficient inverse method and a Genetic Algorithm are used to find all the model parameters from the total radiative heat source <span><math><msub><mrow><mi>S</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span> computed with the Line-by-Line (LBL) method based on HITEMP2010 data. It can be noted that <span><math><msub><mrow><mi>κ</mi></mrow><mrow><mi>p</mi><mo>,</mo><mi>k</mi></mrow></msub></math></span> depend highly on <span><math><mi>T</mi></math></span> and the <span><math><msub><mrow><mi>a</mi></mrow><mrow><mi>k</mi></mrow></msub></math></span> depend weakly on <span><math><mi>T</mi></math></span> whereas in the standard WSGG model, <span><math><msub><mrow><mi>κ</mi></mrow><mrow><mi>p</mi><mo>,</mo><mi>k</mi></mrow></msub></math></span> are usually constants and <span><math><msub><mrow><mi>a</mi></mrow><mrow><mi>k</mi></mrow></msub></math></span> depend highly on <span><math><mi>T</mi></math></span>. It is shown, on 92 selected 1D cases of CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>-H<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O mixtures (at atmospheric pressure with a mole fraction ratio of 2) within the temperature range [300 K; 3,000 K], that the maximum relative errors on <span><math><msub><mrow><mi>S</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span> for the UWSGG model with <span><math><mrow><mi>K</mi><mo>=</mo><mn>6</mn></mrow></math></span> do not exceed 7.5 %. Conversely, for the standard WSGG model by Dorigon et al. (2013) on the first 72 cases (<span><math><mrow><mi>T</mi><mo>></mo></mrow></math></span> 2500 K in the other cases and the model by Dorigon is limited to 2500 K), these errors vary up to 20.4 % (seven cases have errors higher than 15.0 %, ","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"241 ","pages":"Article 126713"},"PeriodicalIF":5.0,"publicationDate":"2025-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130840","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 : 2025-01-24DOI: 10.1016/j.ijheatmasstransfer.2025.126750
Po-Shen Cheng, Shwin-Chung Wong
Before this article, no visualization research has ever been conducted for a low-surface-tension fluid in a closed loop pulsating heat pipe (CLPHP) with large inner diameter. In this work, a transparent CLPHP is built by bending a glass capillary tube with the inner diameter of 6 mm. Under the vertical orientation, even all the ethanol sinks to the bottom as liquid pools before the test due to its high Bond number of 3.56, two types of pulsation motion can still be observed. Short liquid slugs are repeatedly propelled upward, but only within the original evaporator U bend, which is called local pulsation. Geyser pulsation normally occurs in an ultra-long liquid slug, which is so intense as to redistribute the working fluid over the CLPHP and facilitate the following pulsation motion. Under the horizontal orientation, part of the ethanol drains into sections of stratified film, with the remaining ethanol forming liquid slugs. The local pulsation still appears and acts as a primary drive to trigger a series of pulsation motion. Without the gravity effect, the liquid slug trains can move with ease. At 80 W, the dynamic pulsating behavior disappears and transforms into a static mode with leading thermal performance. The lower stratified liquid film facilitates film evaporation, and the upper vapor passage sends the generated vapor to the condenser without hindrance. This thermosyphon-like heat transfer mode under the horizontal orientation is first observed and is recommended for real applications for its leading thermal performance.
{"title":"Detailed visualization experiments on the low-surface-tension ethanol in a pulsating heat pipe with large internal diameter","authors":"Po-Shen Cheng, Shwin-Chung Wong","doi":"10.1016/j.ijheatmasstransfer.2025.126750","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.126750","url":null,"abstract":"<div><div>Before this article, no visualization research has ever been conducted for a low-surface-tension fluid in a closed loop pulsating heat pipe (CLPHP) with large inner diameter. In this work, a transparent CLPHP is built by bending a glass capillary tube with the inner diameter of 6 mm. Under the vertical orientation, even all the ethanol sinks to the bottom as liquid pools before the test due to its high Bond number of 3.56, two types of pulsation motion can still be observed. Short liquid slugs are repeatedly propelled upward, but only within the original evaporator U bend, which is called local pulsation. Geyser pulsation normally occurs in an ultra-long liquid slug, which is so intense as to redistribute the working fluid over the CLPHP and facilitate the following pulsation motion. Under the horizontal orientation, part of the ethanol drains into sections of stratified film, with the remaining ethanol forming liquid slugs. The local pulsation still appears and acts as a primary drive to trigger a series of pulsation motion. Without the gravity effect, the liquid slug trains can move with ease. At 80 W, the dynamic pulsating behavior disappears and transforms into a static mode with leading thermal performance. The lower stratified liquid film facilitates film evaporation, and the upper vapor passage sends the generated vapor to the condenser without hindrance. This thermosyphon-like heat transfer mode under the horizontal orientation is first observed and is recommended for real applications for its leading thermal performance.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"241 ","pages":"Article 126750"},"PeriodicalIF":5.0,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130767","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 : 2025-01-24DOI: 10.1016/j.ijheatmasstransfer.2025.126733
Mason Pratt, Tim Ameel, Sameer R. Rao
An omnimagnetic field generator, or Omnimagnet, is a novel electromagnet that can potentially be used to remotely detumble electrically conductive, nonmagnetic space debris objects via eddy currents. Omnimagnets use three concentric, orthogonal copper solenoids wound around aluminum frames to generate magnetic fields. Operating an Omnimagnet generates large amounts of Joule heating in the solenoids, which can lead to overheating and device failure. Radiative cooling at the outermost surfaces is the only mechanism for heat dissipation. Heat dissipation of the innermost components is limited by the concentric geometry, causing elevated temperatures. Omnimagnet systems cannot be designed without understanding the relationships between Joule heating, Omnimagnet size, and detumbling capability, which are not adequately captured by existing models. The goal of this work is to calculate the detumbling capability of Omnimagnets in space while ensuring overheating does not occur. This work develops a finite element analysis (FEA) model to simulate Omnimagnet thermal behavior in space. Model results show that the innermost Omnimagnet components reach higher temperatures than the outermost components due to limited heat transfer pathways. Applying a high-emissivity coating to aluminum surfaces leads to increased radiative cooling, allowing for a 14% increase in applied current density without overheating. Scaling relationships between nondimensional Omnimagnet length and radiative cooling, maximum current density and magnetic dipole moment are developed to predict the detumbling capability of any size Omnimagnet. These scaling relationships show that radiative cooling scales approximately with nondimensional length squared. This relationship allows the prediction of the upper limit of heat generation via Joule heating. The applied current density scales with nondimensional length to the -0.686 power. Larger Omnimagnets must reduce current density because radiative cooling and Joule heating scale differently with nondimensional length. Magnetic dipole moment scales with nondimensional length to the 3.538 power, indicating that large Omnimagnets produce substantially stronger magnetic fields. Larger Omnimagnets are more efficient per mass than smaller Omnimagnets, which is critical for space applications. This work establishes the critical dependence of Omnimagnet size and detumbling capability on thermal behavior, marking the first step in thermally guided Omnimagnet design. Additionally, it identifies the significant role that surface radiative properties, such as emissivity, can play in enhancing thermal performance, further advancing the potential for successful detumbling missions in space.
{"title":"Modeling of thermal enhancement and scaling analysis for omnidirectional magnetic field generator to actively detumble space debris","authors":"Mason Pratt, Tim Ameel, Sameer R. Rao","doi":"10.1016/j.ijheatmasstransfer.2025.126733","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.126733","url":null,"abstract":"<div><div>An omnimagnetic field generator, or Omnimagnet, is a novel electromagnet that can potentially be used to remotely detumble electrically conductive, nonmagnetic space debris objects via eddy currents. Omnimagnets use three concentric, orthogonal copper solenoids wound around aluminum frames to generate magnetic fields. Operating an Omnimagnet generates large amounts of Joule heating in the solenoids, which can lead to overheating and device failure. Radiative cooling at the outermost surfaces is the only mechanism for heat dissipation. Heat dissipation of the innermost components is limited by the concentric geometry, causing elevated temperatures. Omnimagnet systems cannot be designed without understanding the relationships between Joule heating, Omnimagnet size, and detumbling capability, which are not adequately captured by existing models. The goal of this work is to calculate the detumbling capability of Omnimagnets in space while ensuring overheating does not occur. This work develops a finite element analysis (FEA) model to simulate Omnimagnet thermal behavior in space. Model results show that the innermost Omnimagnet components reach higher temperatures than the outermost components due to limited heat transfer pathways. Applying a high-emissivity coating to aluminum surfaces leads to increased radiative cooling, allowing for a 14% increase in applied current density without overheating. Scaling relationships between nondimensional Omnimagnet length and radiative cooling, maximum current density and magnetic dipole moment are developed to predict the detumbling capability of any size Omnimagnet. These scaling relationships show that radiative cooling scales approximately with nondimensional length squared. This relationship allows the prediction of the upper limit of heat generation via Joule heating. The applied current density scales with nondimensional length to the -0.686 power. Larger Omnimagnets must reduce current density because radiative cooling and Joule heating scale differently with nondimensional length. Magnetic dipole moment scales with nondimensional length to the 3.538 power, indicating that large Omnimagnets produce substantially stronger magnetic fields. Larger Omnimagnets are more efficient per mass than smaller Omnimagnets, which is critical for space applications. This work establishes the critical dependence of Omnimagnet size and detumbling capability on thermal behavior, marking the first step in thermally guided Omnimagnet design. Additionally, it identifies the significant role that surface radiative properties, such as emissivity, can play in enhancing thermal performance, further advancing the potential for successful detumbling missions in space.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"241 ","pages":"Article 126733"},"PeriodicalIF":5.0,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130776","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 : 2025-01-24DOI: 10.1016/j.ijheatmasstransfer.2025.126698
Marten Lache , Tim Nissen , Jann Unkhoff , Mirko Engelpracht , André Bardow , Jan Seiler
Adsorption chillers often employ the refrigerant water despite its two challenges: (1) The temperature limitation due to its freezing point and (2) the need to evaporate at low pressure for typical cool temperatures in cooling applications. These challenges can be addressed individually: Anti-freezing agents help to overcome challenge (1), while capillary-assisted thin-film evaporation can mitigate the static pressure issue associated with challenge (2). However, the combination of both measures remains to be explored. Hence, this study investigates the heat transfer during evaporation of water as primary refrigerant, ethanol as anti-freezing agent, and their mixtures on finned tubes exploiting capillary action. The results show that capillary-assisted thin-film evaporation can also be exploited for ethanol and water–ethanol mixtures. Ethanol can achieve overall heat transfer coefficient comparable to water, while -values of water–ethanol mixtures decreased up to 51 %. The most likely reason for the heat transfer deterioration are mass transfer resistances due to increased viscosity of water–ethanol mixtures. These results provide insights into the heat transfer of alternative refrigerants to expand the cooling temperature of adsorption chillers.
{"title":"Capillary-assisted thin-film evaporation of water–ethanol mixtures","authors":"Marten Lache , Tim Nissen , Jann Unkhoff , Mirko Engelpracht , André Bardow , Jan Seiler","doi":"10.1016/j.ijheatmasstransfer.2025.126698","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.126698","url":null,"abstract":"<div><div>Adsorption chillers often employ the refrigerant water despite its two challenges: (1) The temperature limitation due to its freezing point and (2) the need to evaporate at low pressure for typical cool temperatures in cooling applications. These challenges can be addressed individually: Anti-freezing agents help to overcome challenge (1), while capillary-assisted thin-film evaporation can mitigate the static pressure issue associated with challenge (2). However, the combination of both measures remains to be explored. Hence, this study investigates the heat transfer during evaporation of water as primary refrigerant, ethanol as anti-freezing agent, and their mixtures on finned tubes exploiting capillary action. The results show that capillary-assisted thin-film evaporation can also be exploited for ethanol and water–ethanol mixtures. Ethanol can achieve overall heat transfer coefficient <span><math><mi>U</mi></math></span> comparable to water, while <span><math><mi>U</mi></math></span>-values of water–ethanol mixtures decreased up to 51<!--> <!-->%. The most likely reason for the heat transfer deterioration are mass transfer resistances due to increased viscosity of water–ethanol mixtures. These results provide insights into the heat transfer of alternative refrigerants to expand the cooling temperature of adsorption chillers.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"241 ","pages":"Article 126698"},"PeriodicalIF":5.0,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130699","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 : 2025-01-24DOI: 10.1016/j.ijheatmasstransfer.2025.126745
Wanze Wu , Uwe Hampel , Wei Ding , Baozhi Sun
To explore the heat transfer enhancement mechanism of swirling two-phase flow, we conducted a numerical simulation study for twisted tubes with 18 different cross-sectional sizes using the GENTOP modelling scheme. In this study, we analyzed the phase distribution and the influence of centrifugal force and wall shear on the boiling crisis. The results show that, under the given operating conditions, the performance comparison indices for all 18 helical tubes are greater than 1, with more than half falling within the range of 1.5 to 2.5, and swirling increases the heat transfer coefficient between 24.2% and 101%, which demonstrating significantly enhanced heat transfer performance. Furthermore, swirling flow modifies the boiling crisis nature and postpones its onset. Particularly, the centrifugal force affects the onset point of the boiling crisis, with the delay distance ranging between 0.05 and 0.2 m. The larger the centrifugal force is, the more delayed is the occurrence of dryout. Wall shear increases with increasing liquid velocity and its increase rate decreases due to the tearing of the continuous liquid film on the wall. We propose a correlation that relates the channel center area ratio and the volume fraction ratio of continuous gas, which yet needs further experimental validated.
{"title":"A numerical study on heat transfer and boiling crisis in twisted heat exchanger tubes","authors":"Wanze Wu , Uwe Hampel , Wei Ding , Baozhi Sun","doi":"10.1016/j.ijheatmasstransfer.2025.126745","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.126745","url":null,"abstract":"<div><div>To explore the heat transfer enhancement mechanism of swirling two-phase flow, we conducted a numerical simulation study for twisted tubes with 18 different cross-sectional sizes using the GENTOP modelling scheme. In this study, we analyzed the phase distribution and the influence of centrifugal force and wall shear on the boiling crisis. The results show that, under the given operating conditions, the performance comparison indices for all 18 helical tubes are greater than 1, with more than half falling within the range of 1.5 to 2.5, and swirling increases the heat transfer coefficient between 24.2% and 101%, which demonstrating significantly enhanced heat transfer performance. Furthermore, swirling flow modifies the boiling crisis nature and postpones its onset. Particularly, the centrifugal force affects the onset point of the boiling crisis, with the delay distance ranging between 0.05 and 0.2 m. The larger the centrifugal force is, the more delayed is the occurrence of dryout. Wall shear increases with increasing liquid velocity and its increase rate decreases due to the tearing of the continuous liquid film on the wall. We propose a correlation that relates the channel center area ratio and the volume fraction ratio of continuous gas, which yet needs further experimental validated.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"241 ","pages":"Article 126745"},"PeriodicalIF":5.0,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130765","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 : 2025-01-24DOI: 10.1016/j.ijheatmasstransfer.2025.126748
Xin Wang , Lingxiao Yang , Bo Xu , Zhenqian Chen
In the existing experimental research on flow and heat transfer of supercritical carbon dioxide (S-CO2) in horizontal heated tube, the distinction of inlet temperature states is often neglected. To fill this research gap, this paper conducted a series of extensive experiments and conducted comparative analyses of three different heat transfer coefficients. The results indicate that when inlet temperature is below critical temperature and outlet temperature is below pseudocritical temperature, local heat transfer coefficient increases with the increase of heat flux. For inlet temperature ranging from 282 K to 285 K, average heat transfer coefficient obtained through the method based on average local wall temperature and fluid temperature exhibits a peak as heat flux increases. Notably, there are significant differences in the growth rates of pressure drop in liquid region and supercritical region. Average absolute deviations of three heat transfer correlations are 4.79 %, 3.55 % and 4.44 %, respectively. In heat transfer region where inlet temperature is below 304 K, average absolute errors of flow correlations, without considering wall temperature and with wall temperature taken into account, are 14.61 % and 9.39 % respectively. The work presented in this paper can provide theoretical guidance for design of heat exchangers.
{"title":"Experimental study on heat transfer and flow characteristics of supercritical CO2: In-depth analysis of three heat transfer coefficients","authors":"Xin Wang , Lingxiao Yang , Bo Xu , Zhenqian Chen","doi":"10.1016/j.ijheatmasstransfer.2025.126748","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.126748","url":null,"abstract":"<div><div>In the existing experimental research on flow and heat transfer of supercritical carbon dioxide (S-CO<sub>2</sub>) in horizontal heated tube, the distinction of inlet temperature states is often neglected. To fill this research gap, this paper conducted a series of extensive experiments and conducted comparative analyses of three different heat transfer coefficients. The results indicate that when inlet temperature is below critical temperature and outlet temperature is below pseudocritical temperature, local heat transfer coefficient increases with the increase of heat flux. For inlet temperature ranging from 282 K to 285 K, average heat transfer coefficient obtained through the method based on average local wall temperature and fluid temperature exhibits a peak as heat flux increases. Notably, there are significant differences in the growth rates of pressure drop in liquid region and supercritical region. Average absolute deviations of three heat transfer correlations are 4.79 %, 3.55 % and 4.44 %, respectively. In heat transfer region where inlet temperature is below 304 K, average absolute errors of flow correlations, without considering wall temperature and with wall temperature taken into account, are 14.61 % and 9.39 % respectively. The work presented in this paper can provide theoretical guidance for design of heat exchangers.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"241 ","pages":"Article 126748"},"PeriodicalIF":5.0,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130774","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 : 2025-01-23DOI: 10.1016/j.ijheatmasstransfer.2025.126738
Xu Huang , Bo Wang , Jinyun Zhou , Jing Ye
Nonreciprocal thermal radiation represents an innovative approach to radiative heat transfer that overcomes the symmetric reciprocity constraints imposed by Kirchhoff's law. However, most existing nonreciprocal thermal radiation devices are limited to single polarization and typically necessitate large angles and significant magnetic fields. This paper presents a dual-band dual-polarization nonreciprocal thermal emitter made up of periodic arrays of silicon cylinders hollowed, a magneto-optical material layer, and a metallic plate. Rigorous coupled-wave analysis is employed to examine the structural parameters and the efficiency. Results demonstrate that the efficiencies of the two nonreciprocal bands for transverse electric (TE) and transverse magnetic (TM) polarizations exceed 90 % when subjected to a 1 T magnetic field and an incident angle of 5°. The underlying physical mechanism of strong nonreciprocity is elucidated through an investigation of coupled mode theory and the distributions of electromagnetic fields. Additionally, the validity of the computational results is corroborated using the finite element method. Furthermore, the impact of various parameters on nonreciprocity is analyzed. Compared to traditional nonreciprocal thermal emitters, the proposed emitter effectively reduces reliance on both magnetic field strength and incident angle, significantly enhancing its practical applicability in the field of energy harvesting.
{"title":"Silicon cylinders hollowed for nonreciprocal thermal radiation under a magnetic field of 1 T","authors":"Xu Huang , Bo Wang , Jinyun Zhou , Jing Ye","doi":"10.1016/j.ijheatmasstransfer.2025.126738","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.126738","url":null,"abstract":"<div><div>Nonreciprocal thermal radiation represents an innovative approach to radiative heat transfer that overcomes the symmetric reciprocity constraints imposed by Kirchhoff's law. However, most existing nonreciprocal thermal radiation devices are limited to single polarization and typically necessitate large angles and significant magnetic fields. This paper presents a dual-band dual-polarization nonreciprocal thermal emitter made up of periodic arrays of silicon cylinders hollowed, a magneto-optical material layer, and a metallic plate. Rigorous coupled-wave analysis is employed to examine the structural parameters and the efficiency. Results demonstrate that the efficiencies of the two nonreciprocal bands for transverse electric (TE) and transverse magnetic (TM) polarizations exceed 90 % when subjected to a 1 T magnetic field and an incident angle of 5°. The underlying physical mechanism of strong nonreciprocity is elucidated through an investigation of coupled mode theory and the distributions of electromagnetic fields. Additionally, the validity of the computational results is corroborated using the finite element method. Furthermore, the impact of various parameters on nonreciprocity is analyzed. Compared to traditional nonreciprocal thermal emitters, the proposed emitter effectively reduces reliance on both magnetic field strength and incident angle, significantly enhancing its practical applicability in the field of energy harvesting.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"241 ","pages":"Article 126738"},"PeriodicalIF":5.0,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130575","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 : 2025-01-23DOI: 10.1016/j.ijheatmasstransfer.2025.126671
Abhijeet Banthiya, Bruno Navaresse, Liang Pan, Justin A. Weibel
Cold plate topology optimization is a focus area of research in thermal management, often approached with simplified two-dimensional models to maintain the low computational costs needed for iterative design. However, embracing higher dimensionality in optimization can yield significant performance enhancements, as exemplified by cold plate architectures like manifolded microchannels. In this study, we present a novel 2.5D topology optimization framework tailored to two-flow-layer manifold cold plates, leveraging the homogenization approach to topology optimization. Under this framework, multiple stacked flow layers are simultaneously optimized within a 2D stack while considering local mass and energy exchange between them, enabling the design of intricate 3D flow geometries with the computational efficiency of 2D simulations. The mass and energy exchange between the layers is governed by the optimizable inter-layer flow resistance. This approach is demonstrated for a test case with two coupled flow layers between enclosing solid substrates heated from their external surfaces. The homogenization approach is used to define the local design variables in these layers based on the physical porosity of microstructures (viz., square pin-fins) and the inter-layer coupling within computational cells. A multi-objective cost function, encompassing total pressure drop and thermal resistance, guides the optimization of the microstructure distribution in each layer, resulting in a Pareto front of designs illustrating the balance between these two competing objectives. Full-scale, high-fidelity 3D flow simulations were performed on the topology-optimized two-flow-layer cold plate to validate results from the homogenized 2D simulations. The calculated flow fields showed good agreement between low-cost 2D simulations and high-fidelity 3D simulations, demonstrating the accuracy of the approach. The study provides valuable insights into the topology optimization of multi-layer cold plates, highlighting the potential for enhanced performance via higher dimensionality, as well as manufacturability through the homogenization approach.
{"title":"Simultaneous topology optimization of two hydraulically interconnected porous flow layers in cold plates","authors":"Abhijeet Banthiya, Bruno Navaresse, Liang Pan, Justin A. Weibel","doi":"10.1016/j.ijheatmasstransfer.2025.126671","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.126671","url":null,"abstract":"<div><div>Cold plate topology optimization is a focus area of research in thermal management, often approached with simplified two-dimensional models to maintain the low computational costs needed for iterative design. However, embracing higher dimensionality in optimization can yield significant performance enhancements, as exemplified by cold plate architectures like manifolded microchannels. In this study, we present a novel 2.5D topology optimization framework tailored to two-flow-layer manifold cold plates, leveraging the homogenization approach to topology optimization. Under this framework, multiple stacked flow layers are simultaneously optimized within a 2D stack while considering local mass and energy exchange between them, enabling the design of intricate 3D flow geometries with the computational efficiency of 2D simulations. The mass and energy exchange between the layers is governed by the optimizable inter-layer flow resistance. This approach is demonstrated for a test case with two coupled flow layers between enclosing solid substrates heated from their external surfaces. The homogenization approach is used to define the local design variables in these layers based on the physical porosity of microstructures (viz., square pin-fins) and the inter-layer coupling within computational cells. A multi-objective cost function, encompassing total pressure drop and thermal resistance, guides the optimization of the microstructure distribution in each layer, resulting in a Pareto front of designs illustrating the balance between these two competing objectives. Full-scale, high-fidelity 3D flow simulations were performed on the topology-optimized two-flow-layer cold plate to validate results from the homogenized 2D simulations. The calculated flow fields showed good agreement between low-cost 2D simulations and high-fidelity 3D simulations, demonstrating the accuracy of the approach. The study provides valuable insights into the topology optimization of multi-layer cold plates, highlighting the potential for enhanced performance via higher dimensionality, as well as manufacturability through the homogenization approach.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"241 ","pages":"Article 126671"},"PeriodicalIF":5.0,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130577","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 : 2025-01-23DOI: 10.1016/j.ijheatmasstransfer.2025.126663
Juan Yang , Jiacheng Tong , Yu Yang , Qingsong Zhang , Jianghao Niu
Lithium-ion batteries (LIBs) are usually used in a narrow space, which can cause serious fire accidents if thermal runaway (TR) occurs. However, few studies have investigated the effect of top-confined space on LIB's jet fire as well as thermal runaway propagation (TRP). In this work, the top-confined space was constructed using top baffle, and a battery module for heat transfer analysis was constructed using aluminum columns with refractory ceramic fibre (RCF). Collected the data of the whole thermal runaway process of the battery module in the top-confined space. The behaviours of TR ceiling jet fire under different heights of baffle have been divided into three stages. Confirmed the effect of early-produced gas being ignited on TRP. Innovating a kind of calculate method of heat release ratio (HRR) under top-confined space. Calculated the amount of battery being heated during ceiling jet fire process. Summarised the effect of baffle height on thermal runaway propagation. The results show that 3cm or less between the baffle and batteries can lead to a violent combustion stage which does not present at other heights of baffle. The HRR of this stage is at least 5 times higher than the stable combustion stage. When the distance between the baffle and batteries is increased from 1 to 3cm, the percentage of heat transfer from the ceiling jet fire decreases from 60.3 % to 24.3 %, and the percentage of heat transfer between batteries increased from 14.2 % to 61.6 %. When the distance between the baffle and batteries is 2cm or less, TRP time is at least 1.7 times higher than other heights of baffle, as well as reduce the intensity level of TR for the propagated battery.
{"title":"Characteristics of thermal runaway and propagation for 18650 lithium batteries in top-confined space","authors":"Juan Yang , Jiacheng Tong , Yu Yang , Qingsong Zhang , Jianghao Niu","doi":"10.1016/j.ijheatmasstransfer.2025.126663","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.126663","url":null,"abstract":"<div><div>Lithium-ion batteries (LIBs) are usually used in a narrow space, which can cause serious fire accidents if thermal runaway (TR) occurs. However, few studies have investigated the effect of top-confined space on LIB's jet fire as well as thermal runaway propagation (TRP). In this work, the top-confined space was constructed using top baffle, and a battery module for heat transfer analysis was constructed using aluminum columns with refractory ceramic fibre (RCF). Collected the data of the whole thermal runaway process of the battery module in the top-confined space. The behaviours of TR ceiling jet fire under different heights of baffle have been divided into three stages. Confirmed the effect of early-produced gas being ignited on TRP. Innovating a kind of calculate method of heat release ratio (HRR) under top-confined space. Calculated the amount of battery being heated during ceiling jet fire process. Summarised the effect of baffle height on thermal runaway propagation. The results show that 3cm or less between the baffle and batteries can lead to a violent combustion stage which does not present at other heights of baffle. The HRR of this stage is at least 5 times higher than the stable combustion stage. When the distance between the baffle and batteries is increased from 1 to 3cm, the percentage of heat transfer from the ceiling jet fire decreases from 60.3 % to 24.3 %, and the percentage of heat transfer between batteries increased from 14.2 % to 61.6 %. When the distance between the baffle and batteries is 2cm or less, TRP time is at least 1.7 times higher than other heights of baffle, as well as reduce the intensity level of TR for the propagated battery.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"241 ","pages":"Article 126663"},"PeriodicalIF":5.0,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130576","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 : 2025-01-23DOI: 10.1016/j.ijheatmasstransfer.2025.126729
Yanhong Sun , Zan Zhang , Guotao Zhang , Yuyan Jiang , Jun Zheng
Despite extensive studies and modeling of bubble dynamics manipulation in macroscale boiling, the effect of surface wettability on the bubble dynamics of microchannel flow boiling has seldom been investigated. The confinement of the microchannel and fluctuations in the dominant forces lead to unique confined bubble growth and distinctive bubble detachment. Surface wettability can significantly affect the bubble dynamics parameters, thereby influencing the heat transfer performance of microchannel flow boiling. In this study, we conducted subcooled flow boiling experiments and flow visualizations to quantitatively investigate the influence of surface wettability on sliding bubble dynamics, confined bubble growth, and heat transfer characteristics in a microchannel using HFE-7100 as the working fluid. Numerous nucleation sites were activated owing to the lower energy barrier for bubble nucleation on the hydrophobic surface. The elongated bubble shape was flatter, and the bubble size was larger, which could be attributed to the strong bubble adhesion force on the hydrophobic surface. The bubble sliding and growth velocities were much higher on the hydrophilic surface, and bubble acceleration increased the shear stress and pressure gradient surrounding the bubble, producing a more non-axisymmetric oblique triangle profile of the elongated bubble. The bubble growth rate on the hydrophilic surface was approximately three times higher than that on the hydrophobic surface. The heat transfer coefficients (HTCs) on the hydrophobic surface increased by up to 82 % and 25 % during microchannel flow boiling at mass fluxes of 112 and 230 kg·m−2·s−1, respectively, because of the activation of numerous bubble nucleation sites. Furthermore, the HTCs increased by up to 56 % for higher mass fluxes owing to the strengthening of microconvection and suppression of annular flow. The nucleate boiling mechanism dominated the microchannel flow boiling heat transfer.
{"title":"Effect of surface wettability on bubble dynamics and heat transfer in microchannel flow boiling","authors":"Yanhong Sun , Zan Zhang , Guotao Zhang , Yuyan Jiang , Jun Zheng","doi":"10.1016/j.ijheatmasstransfer.2025.126729","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.126729","url":null,"abstract":"<div><div>Despite extensive studies and modeling of bubble dynamics manipulation in macroscale boiling, the effect of surface wettability on the bubble dynamics of microchannel flow boiling has seldom been investigated. The confinement of the microchannel and fluctuations in the dominant forces lead to unique confined bubble growth and distinctive bubble detachment. Surface wettability can significantly affect the bubble dynamics parameters, thereby influencing the heat transfer performance of microchannel flow boiling. In this study, we conducted subcooled flow boiling experiments and flow visualizations to quantitatively investigate the influence of surface wettability on sliding bubble dynamics, confined bubble growth, and heat transfer characteristics in a microchannel using HFE-7100 as the working fluid. Numerous nucleation sites were activated owing to the lower energy barrier for bubble nucleation on the hydrophobic surface. The elongated bubble shape was flatter, and the bubble size was larger, which could be attributed to the strong bubble adhesion force on the hydrophobic surface. The bubble sliding and growth velocities were much higher on the hydrophilic surface, and bubble acceleration increased the shear stress and pressure gradient surrounding the bubble, producing a more non-axisymmetric oblique triangle profile of the elongated bubble. The bubble growth rate on the hydrophilic surface was approximately three times higher than that on the hydrophobic surface. The heat transfer coefficients (HTCs) on the hydrophobic surface increased by up to 82 % and 25 % during microchannel flow boiling at mass fluxes of 112 and 230 kg·m<sup>−2</sup>·s<sup>−1</sup>, respectively, because of the activation of numerous bubble nucleation sites. Furthermore, the HTCs increased by up to 56 % for higher mass fluxes owing to the strengthening of microconvection and suppression of annular flow. The nucleate boiling mechanism dominated the microchannel flow boiling heat transfer.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"241 ","pages":"Article 126729"},"PeriodicalIF":5.0,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130579","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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