International Journal of Heat and Fluid Flow最新文献_第4页

Development and validation of two-phase flow & boiling module based on CorTAF framework

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2024-12-31 DOI: 10.1016/j.ijheatfluidflow.2024.109739

Xitong Liu , Kai Liu , Hanrui Qiu , Mingjun Wang , Chong Chen , Qi Lu , Jian Deng , Wenxi Tian , G.H. Su

Two-phase flow and heat transfer characteristics under boiling condition possesses vital significance for pressurized water reactor (PWR) core design. Traditional system code or subchannel analysis code had been widely applied for safety analysis of reactor core, but the more elaborate distribution of three-dimensional parameters is unable to obtained. In this paper, a two-phase flow & boiling module is developed and implemented based on the previously proposed nuclear reactor core thermal–hydraulic characteristics analysis code CorTAF. The two-phase flow and boiling heat transfer analysis method under drift-flux model is established, combining constitutive model such as bubble formation, grid effect, turbulent mixing, coupled boiling heat transfer and the prediction of critical heat flux under diverse boiling states. The benchmarks including CE5 × 5 and PSBT are selected to perform the comprehensive code validation. Crucial physical parameters are compared with the experiment data. The maximum error of wall temperature is under 4 K in CE5 × 5, maximum error of void fraction and CHF in PSBT is under 0.07 and 15 % respectively, indicating that the two-phase flow & boiling module implemented in CorTAF is capable for accurate prediction of two-phase thermal–hydraulic characteristics in reactor core. Additionally, to visually demonstrate the calculation result by CorTAF, a brief simulation of multiple assemblies under partial blockage is also carried out. This work provides valuable references for safety analysis under reactivity insertion accident and further studies on multi-physics coupling of reactor core.

{"title":"Development and validation of two-phase flow & boiling module based on CorTAF framework","authors":"Xitong Liu , Kai Liu , Hanrui Qiu , Mingjun Wang , Chong Chen , Qi Lu , Jian Deng , Wenxi Tian , G.H. Su","doi":"10.1016/j.ijheatfluidflow.2024.109739","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109739","url":null,"abstract":"<div><div>Two-phase flow and heat transfer characteristics under boiling condition possesses vital significance for pressurized water reactor (PWR) core design. Traditional system code or subchannel analysis code had been widely applied for safety analysis of reactor core, but the more elaborate distribution of three-dimensional parameters is unable to obtained. In this paper, a two-phase flow & boiling module is developed and implemented based on the previously proposed nuclear reactor core thermal–hydraulic characteristics analysis code CorTAF. The two-phase flow and boiling heat transfer analysis method under drift-flux model is established, combining constitutive model such as bubble formation, grid effect, turbulent mixing, coupled boiling heat transfer and the prediction of critical heat flux under diverse boiling states. The benchmarks including CE5 × 5 and PSBT are selected to perform the comprehensive code validation. Crucial physical parameters are compared with the experiment data. The maximum error of wall temperature is under 4 K in CE5 × 5, maximum error of void fraction and CHF in PSBT is under 0.07 and 15 % respectively, indicating that the two-phase flow & boiling module implemented in CorTAF is capable for accurate prediction of two-phase thermal–hydraulic characteristics in reactor core. Additionally, to visually demonstrate the calculation result by CorTAF, a brief simulation of multiple assemblies under partial blockage is also carried out. This work provides valuable references for safety analysis under reactivity insertion accident and further studies on multi-physics coupling of reactor core.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109739"},"PeriodicalIF":2.6,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140150","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Advances in the study of bubbles in boiling and their application to electrolytic hydrogen production

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2024-12-30 DOI: 10.1016/j.ijheatfluidflow.2024.109733

Huaqiang Chu , Chenhao Yang , Dong Wang , Weipeng Deng , Nian Xu

Boiling heat transfer is an efficient and green heat transfer method that is widely used in industrial production. Single bubble pool boiling is a specific case of pool boiling, which helps to observe the microscopic changes of bubbles and further study the heat transfer mechanism of bubbles in boiling heat transfer. This paper outlines a variety of approaches to single bubble generation. This review summarizes thermocouple, optical and acoustic techniques for quantitative or qualitative measurements of bubble parameters and their surrounding temperature fields during boiling. The geometrical structure and motion variations of microlayers, three phase lines and dry points in bubbles are described. This helps to further investigate the mechanism of heat and mass transfer in bubbles during boiling. To further improve the efficiency of boiling heat transfer, the effects of electric, magnetic and acoustic fields on bubble motion and heat transfer are presented. Because of the similar bubble phenomenon in boiling heat transfer and electrolytic hydrogen production, this paper outlines the application of single bubble enhancement technology in electrolytic hydrogen production. In addition, this paper reviews the advances in the study of single bubbles which are important for a deeper understanding and optimization of the boiling heat transfer process.

{"title":"Advances in the study of bubbles in boiling and their application to electrolytic hydrogen production","authors":"Huaqiang Chu , Chenhao Yang , Dong Wang , Weipeng Deng , Nian Xu","doi":"10.1016/j.ijheatfluidflow.2024.109733","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109733","url":null,"abstract":"<div><div>Boiling heat transfer is an efficient and green heat transfer method that is widely used in industrial production. Single bubble pool boiling is a specific case of pool boiling, which helps to observe the microscopic changes of bubbles and further study the heat transfer mechanism of bubbles in boiling heat transfer. This paper outlines a variety of approaches to single bubble generation. This review summarizes thermocouple, optical and acoustic techniques for quantitative or qualitative measurements of bubble parameters and their surrounding temperature fields during boiling. The geometrical structure and motion variations of microlayers, three phase lines and dry points in bubbles are described. This helps to further investigate the mechanism of heat and mass transfer in bubbles during boiling. To further improve the efficiency of boiling heat transfer, the effects of electric, magnetic and acoustic fields on bubble motion and heat transfer are presented. Because of the similar bubble phenomenon in boiling heat transfer and electrolytic hydrogen production, this paper outlines the application of single bubble enhancement technology in electrolytic hydrogen production. In addition, this paper reviews the advances in the study of single bubbles which are important for a deeper understanding and optimization of the boiling heat transfer process.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109733"},"PeriodicalIF":2.6,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Lubrication heating behavior of elliptical groove face seals under multi-point conditions

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2024-12-30 DOI: 10.1016/j.ijheatfluidflow.2024.109736

Jing Yang, Kui Deng, Shaoxian Bai

With the increasing requirement of multi-point working conditions, the problem of lubrication heat in liquid face seals attracts more attentions, which often results in a high risk of seal failure due to unstable opening force and leakage. The precise design considering heating effect of face grooves under complex working conditions is necessary. Here, based on the fluid lubrication theory, a thermo-dynamic model for liquid face seals with elliptical groove was established to analyze the lubrication heat behavior. The novelty of this model is to take the complex seal structure, cavitation effect and fluid thermo-viscous effect into consideration together, which was validated by experimental work. The temperature distribution and temperature rise were investigated for both smooth and elliptical groove face seals. The effects of rotational speed, film thickness and sealing pressure on temperature distribution and sealing performance of liquid film were further studied. When the film thickness increasing from 2 to 5 μm, the maximum temperature for face seals with elliptical groove and smooth surface decreases from 355.6 K to 350.45 K and from 354.9 K to 350.4 K, respectively. The values of maximum temperature present no obvious difference for both smooth and elliptical faces. However, it is found that elliptical groove presents an obvious influence on temperature distribution of liquid sealing film. The maximum temperature occurs near the inner diameter for the smooth face, but near the outer diameter for the elliptical groove face. The obtained results also suggest that the cavitation effect and hydrodynamic effect induced by shear effect make the sealing performance unstable, accompanying multi-peaks phenomena under multi-velocity and multi-pressure conditions. Face grooves could provide a potential way to control temperature distribution in precise sealing design.

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引用次数: 0

Modeling of wall heat flux in flame–wall interaction using machine learning

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2024-12-30 DOI: 10.1016/j.ijheatfluidflow.2024.109727

Takuki Kaminaga, Ye Wang, Mamoru Tanahashi

A machine-learning-based model is proposed for the wall heat flux in the flame–wall interaction (FWI). The model is trained by the neural network (NN), and the direct numerical simulation (DNS) database of FWI of head-on quenching and side-wall quenching are employed as the training data, considering the premixed methane–air combustion in a one-dimensional and two-dimensional constant volume vessel. In this NN model, the time-averaged wall heat flux, as the output quantity, is considered as a function of FWI characteristics, including combustion equivalence ratio, pressure, preheat temperature of unburned mixture, and wall temperature. The performance of the model is evaluated with

a p r i o r i

analysis. Results indicate that the NN model trained solely with one-dimensional DNS results demonstrates satisfactory performance in predicting wall heat flux in head-on quenching scenarios under various thermochemical conditions, achieving a Pearson’s correlation coefficient of 0.95 or higher. For the prediction of wall heat flux in a two-dimensional turbulent combustion scenario, the NN model trained with both one-dimensional and two-dimensional DNS results also produces a correlation coefficient over 0.9. The prediction accuracy slightly decreases in turbulent combustion conditions, which is probably due to the limited incorporation of near-wall flame-turbulence interaction effect in the model training. The current study serves as an initial exploration of wall heat flux modeling by incorporating FWI characteristics as significant factors. Also, it underlines the FWI dynamics and wall heat transfer within wall-bounded combustion.

{"title":"Modeling of wall heat flux in flame–wall interaction using machine learning","authors":"Takuki Kaminaga, Ye Wang, Mamoru Tanahashi","doi":"10.1016/j.ijheatfluidflow.2024.109727","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109727","url":null,"abstract":"<div><div>A machine-learning-based model is proposed for the wall heat flux in the flame–wall interaction (FWI). The model is trained by the neural network (NN), and the direct numerical simulation (DNS) database of FWI of head-on quenching and side-wall quenching are employed as the training data, considering the premixed methane–air combustion in a one-dimensional and two-dimensional constant volume vessel. In this NN model, the time-averaged wall heat flux, as the output quantity, is considered as a function of FWI characteristics, including combustion equivalence ratio, pressure, preheat temperature of unburned mixture, and wall temperature. The performance of the model is evaluated with <span><math><mrow><mi>a</mi><mspace></mspace><mi>p</mi><mi>r</mi><mi>i</mi><mi>o</mi><mi>r</mi><mi>i</mi></mrow></math></span> analysis. Results indicate that the NN model trained solely with one-dimensional DNS results demonstrates satisfactory performance in predicting wall heat flux in head-on quenching scenarios under various thermochemical conditions, achieving a Pearson’s correlation coefficient of 0.95 or higher. For the prediction of wall heat flux in a two-dimensional turbulent combustion scenario, the NN model trained with both one-dimensional and two-dimensional DNS results also produces a correlation coefficient over 0.9. The prediction accuracy slightly decreases in turbulent combustion conditions, which is probably due to the limited incorporation of near-wall flame-turbulence interaction effect in the model training. The current study serves as an initial exploration of wall heat flux modeling by incorporating FWI characteristics as significant factors. Also, it underlines the FWI dynamics and wall heat transfer within wall-bounded combustion.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109727"},"PeriodicalIF":2.6,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Spatio-temporal temperature distribution and heat transfer analysis during subcooled nucleate pool boiling on plates

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2024-12-28 DOI: 10.1016/j.ijheatfluidflow.2024.109737

Bikash Pattanayak , Hardik B. Kothadia

Nucleating bubbles contributes to improved heat transfer during the liquid–vapor phase transition and becomes beneficial in confined spaces where substantial energy transfer is necessary. The study is conducted to analyse the heat transfer mechanism and associated bubble behaviour during nucleate boiling at subcooled condition. The analysis is performed on horizontally oriented plates under ambient conditions. The temperature distribution over the plates at given heat flux is visualized using non-invasive IR thermal camera. The captured thermal images were initially analyzed to comprehend the impact of subcooling on different stages of the boiling process. It encompasses free convection from the surface, isolated heterogeneous nucleation, and the vertical agglomeration of detaching bubbles. The study gives an ideation to introspect the wall heat flux regime during subcooled pool boiling. Various phenomena associated with subcooled pool boiling, for instance, bubble ebullition, subcooling effect on heat transfer is discussed. The gradual shrinkage of bubble in the liquid pool is observed. The analysis of subcooled nucleate pool boiling on plates revealed intriguing insights into the spatio-temporal temperature variations, showcasing distinct patterns at different heat flux levels. Additionally, the study delved into the intricate wall heat flux partitioning among various boiling regimes, shedding light on the dynamics of bubble ebullition under subcooled conditions. An empirical correlation is suggested for predicting convective heat transfer coefficient for the subcooled pool boiling.

{"title":"Spatio-temporal temperature distribution and heat transfer analysis during subcooled nucleate pool boiling on plates","authors":"Bikash Pattanayak , Hardik B. Kothadia","doi":"10.1016/j.ijheatfluidflow.2024.109737","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109737","url":null,"abstract":"<div><div>Nucleating bubbles contributes to improved heat transfer during the liquid–vapor phase transition and becomes beneficial in confined spaces where substantial energy transfer is necessary. The study is conducted to analyse the heat transfer mechanism and associated bubble behaviour during nucleate boiling at subcooled condition. The analysis is performed on horizontally oriented plates under ambient conditions. The temperature distribution over the plates at given heat flux is visualized using non-invasive IR thermal camera. The captured thermal images were initially analyzed to comprehend the impact of subcooling on different stages of the boiling process. It encompasses free convection from the surface, isolated heterogeneous nucleation, and the vertical agglomeration of detaching bubbles. The study gives an ideation to introspect the wall heat flux regime during subcooled pool boiling. Various phenomena associated with subcooled pool boiling, for instance, bubble ebullition, subcooling effect on heat transfer is discussed. The gradual shrinkage of bubble in the liquid pool is observed. The analysis of subcooled nucleate pool boiling on plates revealed intriguing insights into the spatio-temporal temperature variations, showcasing distinct patterns at different heat flux levels. Additionally, the study delved into the intricate wall heat flux partitioning among various boiling regimes, shedding light on the dynamics of bubble ebullition under subcooled conditions. An empirical correlation is suggested for predicting convective heat transfer coefficient for the subcooled pool boiling.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109737"},"PeriodicalIF":2.6,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Novel artificial neural network approach for hybrid nanofluid flow over nonlinear permeable stretching sheets with Thomson and Troian boundary conditions

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2024-12-27 DOI: 10.1016/j.ijheatfluidflow.2024.109721

Shazia Habib , Zeeshan Khan , Esraa N. Thabet , A.M. Abd-Alla , S.H. Elhag

The study investigates the flow of a hybrid nanofluid over a non-linear, permeable stretched sheet under Thomson and Troian boundary conditions, while also considering the Darcy-Forchheimer relationship. We employ the Cattaneo-Christov heat flux model and novel artificial neural networks for the first time. This paper describes a new way to use artificial neural networks to add carbon nanotubes to hybrid nanofluids with Thomson and Troian boundary conditions. This creates induced MHD. The MSE ranges from

10^{- 08}

to

10^{- 09}

. The AE range for all the cases lies around

10^{- 03}

to

10^{- 07}

. The value of mu is around

10^{- 08}

, while gradient ranges from

10^{- 07}

to

10^{- 08}

. This shows the high accuracy and precision of the proposed scheme. This research highlights the variation of different parameters with velocity, temperature and concentration. As the solid volume fraction rises, fluid velocity diminishes and temperature rises. Nanofluids exhibit enhancement with elevated inertial coefficient and Eckert number values. Increased inertial coefficient and Eckert number values correspond to rising temperatures. Concentration diminishes with rising solid volume percentage; yet, elevated activation energy results in enhanced concentration dispersion. It proves superior thermal conductivity and heat transmission capabilities, with future studies investigating the additional factors. Potential areas for further investigation include the study of other nanoparticles and different hybrid nanofluids and the investigation of real engineering challenges associated to heat and mass transfer in porous media. A graphic comparison between simple and hybrid nanofluids is presented. It is shown that the solid volume fraction improves the temperature distribution while decreasing the velocity profile. Furthermore, hybrid nanofluids perform better in heat transfer and have higher thermal conductivity than simple nanofluids.

{"title":"Novel artificial neural network approach for hybrid nanofluid flow over nonlinear permeable stretching sheets with Thomson and Troian boundary conditions","authors":"Shazia Habib , Zeeshan Khan , Esraa N. Thabet , A.M. Abd-Alla , S.H. Elhag","doi":"10.1016/j.ijheatfluidflow.2024.109721","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109721","url":null,"abstract":"<div><div>The study investigates the flow of a hybrid nanofluid over a non-linear, permeable stretched sheet under Thomson and Troian boundary conditions, while also considering the Darcy-Forchheimer relationship. We employ the Cattaneo-Christov heat flux model and novel artificial neural networks for the first time. This paper describes a new way to use artificial neural networks to add carbon nanotubes to hybrid nanofluids with Thomson and Troian boundary conditions. This creates induced MHD. The MSE ranges from <span><math><mrow><msup><mn>10</mn><mrow><mo>-</mo><mn>08</mn></mrow></msup></mrow></math></span> to <span><math><mrow><msup><mn>10</mn><mrow><mo>-</mo><mn>09</mn></mrow></msup></mrow></math></span>. The AE range for all the cases lies around <span><math><mrow><msup><mn>10</mn><mrow><mo>-</mo><mn>03</mn></mrow></msup></mrow></math></span> to <span><math><mrow><msup><mn>10</mn><mrow><mo>-</mo><mn>07</mn></mrow></msup></mrow></math></span>. The value of mu is around <span><math><mrow><msup><mn>10</mn><mrow><mo>-</mo><mn>08</mn></mrow></msup></mrow></math></span>, while gradient ranges from <span><math><mrow><msup><mn>10</mn><mrow><mo>-</mo><mn>07</mn></mrow></msup></mrow></math></span> to <span><math><mrow><msup><mn>10</mn><mrow><mo>-</mo><mn>08</mn></mrow></msup></mrow></math></span>. This shows the high accuracy and precision of the proposed scheme. This research highlights the variation of different parameters with velocity, temperature and concentration. As the solid volume fraction rises, fluid velocity diminishes and temperature rises. Nanofluids exhibit enhancement with elevated inertial coefficient and Eckert number values. Increased inertial coefficient and Eckert number values correspond to rising temperatures. Concentration diminishes with rising solid volume percentage; yet, elevated activation energy results in enhanced concentration dispersion. It proves superior thermal conductivity and heat transmission capabilities, with future studies investigating the additional factors. Potential areas for further investigation include the study of other nanoparticles and different hybrid nanofluids and the investigation of real engineering challenges associated to heat and mass transfer in porous media. A graphic comparison between simple and hybrid nanofluids is presented. It is shown that the solid volume fraction improves the temperature distribution while decreasing the velocity profile. Furthermore, hybrid nanofluids perform better in heat transfer and have higher thermal conductivity than simple nanofluids.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109721"},"PeriodicalIF":2.6,"publicationDate":"2024-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Experimental investigation on the fabrication of electroplating masks for silicon heterojunction solar cell grid electrodes via inkjet printing

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2024-12-27 DOI: 10.1016/j.ijheatfluidflow.2024.109729

Shaoqi Wang , Wei Song , Yang Zhang , Lixin Wang , Zhuli Liu , Yahao Ren , Haobo Shen , Zunlong Jin , Changliang Wang

Replacing screen-printed silver grids with electroplated copper grid technology enables the large-scale production and application of silicon heterojunction solar cells. The grid electroplating mask is crucial for forming well-defined copper grids with high aspect ratios. This paper introduces a novel process for fabricating grid electroplating masks for silicon heterojunction solar cells using inkjet printing, which indirectly prepares the masks through two rounds of inkjet printing. Initially, hot-melt wax lines are printed to define the grid pattern, wherein the effects of piezoelectric nozzle waveform configurations on inkjet droplet morphology and size, the printing height on droplet stacking patterns, and the printing speed on hot-melt wax line widths are investigated. The results show that reducing the rise, fall, and retention time of the waveform will reduce the droplet volume, the inkjet printing height of 2.2 μm is conducive to the cooling of hot melted wax droplets and obtaining better droplet stacking morphology, and the inkjet printing speed of 50 mm/s is conducive to the obtaining of narrower hot-melt wax lines. Consequently, hot-melt wax lines with an average line width of 22.67 μm and a line height of 18 μm are successfully obtained on the seed layer silicon wafers. Subsequently, mask printing and hot-melt wax line removal are performed, yielding grid electroplating masks with trench widths of 20.254 μm, heights of 12.241 μm, and an aspect ratio reaching 0.6. This approach significantly simplifies the electroplating mask process and is of great significance for achieving copper grids with higher aspect ratios.

{"title":"Experimental investigation on the fabrication of electroplating masks for silicon heterojunction solar cell grid electrodes via inkjet printing","authors":"Shaoqi Wang , Wei Song , Yang Zhang , Lixin Wang , Zhuli Liu , Yahao Ren , Haobo Shen , Zunlong Jin , Changliang Wang","doi":"10.1016/j.ijheatfluidflow.2024.109729","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109729","url":null,"abstract":"<div><div>Replacing screen-printed silver grids with electroplated copper grid technology enables the large-scale production and application of silicon heterojunction solar cells. The grid electroplating mask is crucial for forming well-defined copper grids with high aspect ratios. This paper introduces a novel process for fabricating grid electroplating masks for silicon heterojunction solar cells using inkjet printing, which indirectly prepares the masks through two rounds of inkjet printing. Initially, hot-melt wax lines are printed to define the grid pattern, wherein the effects of piezoelectric nozzle waveform configurations on inkjet droplet morphology and size, the printing height on droplet stacking patterns, and the printing speed on hot-melt wax line widths are investigated. The results show that reducing the rise, fall, and retention time of the waveform will reduce the droplet volume, the inkjet printing height of 2.2 μm is conducive to the cooling of hot melted wax droplets and obtaining better droplet stacking morphology, and the inkjet printing speed of 50 mm/s is conducive to the obtaining of narrower hot-melt wax lines. Consequently, hot-melt wax lines with an average line width of 22.67 μm and a line height of 18 μm are successfully obtained on the seed layer silicon wafers. Subsequently, mask printing and hot-melt wax line removal are performed, yielding grid electroplating masks with trench widths of 20.254 μm, heights of 12.241 μm, and an aspect ratio reaching 0.6. This approach significantly simplifies the electroplating mask process and is of great significance for achieving copper grids with higher aspect ratios.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109729"},"PeriodicalIF":2.6,"publicationDate":"2024-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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

Unsteady Reynolds-Averaged Navier-Stokes simulation of turbulent flow fields around a line of trees and a steep hill using a new turbulent inflow generation method

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2024-12-27 DOI: 10.1016/j.ijheatfluidflow.2024.109705

Takeshi Ishihara, Xiangyan Chen

In this study, mean and turbulent flow fields around a line of trees and a steep hill are investigated by unsteady Reynolds-Averaged Navier-Stokes (URANS) simulation with a new turbulent inflow generation method. First, an inflow generation method is presented for the URANS model, utilizing a prespecified averaging time to divide the turbulent flow fields into resolved and modelled parts and ensure conservation of the total turbulence kinetic energy. The turbulent flow fields reproduced by the URANS model are then evaluated over flat terrain, a line of trees and a steep hill to demonstrate the performance of the URANS model. A large averaging time can be applied to the URANS model for flat terrain and a line of trees because the turbulent flow field can be simulated well by the turbulence model, but suitable averaging times are required for the URANS simulation to predict large separation vortices behind the steep hill as resolved coherent structures. Finally, an indicator is proposed to assess the performance of turbulence models considering the prediction accuracy and computational efficiency. The proposed method exhibits the best performance in predicting the mean velocity and turbulence kinetic energy, compared to Reynolds-Averaged Navier-Stokes model and Large Eddy Simulation.

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引用次数: 0

Effects of operating conditions on flame evolution and preheating performance of intake manifold burner aided by spray atomization

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2024-12-27 DOI: 10.1016/j.ijheatfluidflow.2024.109730

Tong Liang , Jianli Liu , Haoyang Mo , Chia-fon Lee , Ziman Wang , Zhishuang Li , Mingchen Cong

The intake manifold burner acts as a cold start auxiliary equipment for heavy diesel engines. The typical intake manifold burner, however, has some drawbacks, including unreliable fuel delivery, insufficient combustion, and poor windproof performance. In this study, a novel intake manifold burner with boosted fuel dispersion was designed, and tests were carried out to investigate the effects of injection pressure, injection frequency, injection duration, and airflow velocity on flame behavior. In addition, the fuel–air mixing process was simulated using a three-dimensional CFD (Computational Fluid Dynamics). To explore the impacts of operating conditions on the gas mixture, the variation tendency of gas/liquid fuel mass was analyzed, and the flame area was quantified. According to the findings, optimization of fuel supply parameters and intake parameters is conducive to flame development and intake air heating. Increasing the amount of fuel injection raises the local and global equivalency ratio, expands the fuel vapor distribution region behind the burner, boosting the flame growth. Airflow velocity and combustion heat release both have an impact on flame evolution. The effects of heat release on flame growth are nearly comparable at low airflow velocity (3–5 m/s), however at high airflow velocity, airflow becomes the dominant factor. High-velocity airflow (greater than 9 m/s) increases heat dissipation, limits flame growth, delays ignition and even blow-out phenomenon. When the air velocity is in the range of 6–7 m/s, the preheating effect is the best.

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引用次数: 0

Experimental studies on swirl injector with varying L/D ratio of hybrid rocket motor

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2024-12-26 DOI: 10.1016/j.ijheatfluidflow.2024.109734

Arpit Dubey, Rajiv Kumar, Shelly Biswas

In this paper, effect of swirl injector on varying the L/D (length to diameter) ratio of the hybrid rocket motor was experimentally investigated. The use of swirl injector was observed to improve regression rate and other performance parameters, but it is expected to change with the varying L/D ratio of the hybrid rocket motor. It was further compared with the conventional showerhead injector for the same L/D ratios. Gaseous oxygen was used as an oxidizer while paraffin wax was used as the fuel. Three different L/D ratio motors, specifically 9.5, 13.5 and 17 were used for the experiments. For the regression rate study, the three major factors responsible for the increment in regression rate are longer residence time due to larger motor length, diminishing effect of swirling flow with increasing motor length and the behaviour of mass flux exponent. The investigation revealed that the 13.5 L/D ratio motor can be said to have a better regression rate performance as it gives a balanced results for all three factors. Also, considering the other performance parameters such as chamber pressure, combustion efficiency and thrust generation for the showerhead as well as swirl injector, 13.5 L/D ratio motor showed superior results compared to other two L/D ratio motors. The increment observed for 13.5 L/D ratio motor were 27 %, 11 % and 25 % for chamber pressure, combustion efficiency and thrust generated values, respectively when compared with the base case of 9.5 L/D ratio motor for the swirl injector study. These experimental findings for pressure and thrust values are in corelation with the thrust equation where the thrust value is directly proportional to the chamber pressure value and the nozzle throat area.

{"title":"Experimental studies on swirl injector with varying L/D ratio of hybrid rocket motor","authors":"Arpit Dubey, Rajiv Kumar, Shelly Biswas","doi":"10.1016/j.ijheatfluidflow.2024.109734","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109734","url":null,"abstract":"<div><div>In this paper, effect of swirl injector on varying the L/D (length to diameter) ratio of the hybrid rocket motor was experimentally investigated. The use of swirl injector was observed to improve regression rate and other performance parameters, but it is expected to change with the varying L/D ratio of the hybrid rocket motor. It was further compared with the conventional showerhead injector for the same L/D ratios. Gaseous oxygen was used as an oxidizer while paraffin wax was used as the fuel. Three different L/D ratio motors, specifically 9.5, 13.5 and 17 were used for the experiments. For the regression rate study, the three major factors responsible for the increment in regression rate are longer residence time due to larger motor length, diminishing effect of swirling flow with increasing motor length and the behaviour of mass flux exponent. The investigation revealed that the 13.5 L/D ratio motor can be said to have a better regression rate performance as it gives a balanced results for all three factors. Also, considering the other performance parameters such as chamber pressure, combustion efficiency and thrust generation for the showerhead as well as swirl injector, 13.5 L/D ratio motor showed superior results compared to other two L/D ratio motors. The increment observed for 13.5 L/D ratio motor were 27 %, 11 % and 25 % for chamber pressure, combustion efficiency and thrust generated values, respectively when compared with the base case of 9.5 L/D ratio motor for the swirl injector study. These experimental findings for pressure and thrust values are in corelation with the thrust equation where the thrust value is directly proportional to the chamber pressure value and the nozzle throat area.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109734"},"PeriodicalIF":2.6,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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