Shaoqi Wang , Wei Song , Yang Zhang , Lixin Wang , Zhuli Liu , Yahao Ren , Haobo Shen , Zunlong Jin , Changliang Wang
{"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}
{"title":"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","authors":"Takeshi Ishihara, Xiangyan Chen","doi":"10.1016/j.ijheatfluidflow.2024.109705","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109705","url":null,"abstract":"<div><div>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.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109705"},"PeriodicalIF":2.6,"publicationDate":"2024-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140184","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}
Tong Liang , Jianli Liu , Haoyang Mo , Chia-fon Lee , Ziman Wang , Zhishuang Li , Mingchen Cong
{"title":"Effects of operating conditions on flame evolution and preheating performance of intake manifold burner aided by spray atomization","authors":"Tong Liang , Jianli Liu , Haoyang Mo , Chia-fon Lee , Ziman Wang , Zhishuang Li , Mingchen Cong","doi":"10.1016/j.ijheatfluidflow.2024.109730","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109730","url":null,"abstract":"<div><div>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.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109730"},"PeriodicalIF":2.6,"publicationDate":"2024-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140157","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}
{"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}
Viacheslav Papkov , Boyan Zhang , Han Su , Haojie Chen , Dmitry Pashchenko
{"title":"Numerical modeling of laminar flow over a porous cylinder under endothermic steam methane reforming reaction","authors":"Viacheslav Papkov , Boyan Zhang , Han Su , Haojie Chen , Dmitry Pashchenko","doi":"10.1016/j.ijheatfluidflow.2024.109725","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109725","url":null,"abstract":"<div><div>This paper deals with the numerical simulation of laminar flow over a porous cylinder under endothermic steam methane reforming reactions. The two-dimensional RANS approach is used to understand the effect of endothermic chemical reactions on the Kármán vortex street and heat transfer coefficient for a wide range of governing temperatures relevant to industrial applications of steam methane reforming. To achieve this goal, a set of calculations is performed for both transient and steady-state regimes, as well as for reactive and non-reactive flows. It was observed that steam methane reforming reactions have an effect on the Kármán vortex parameters. An increase in the catalytic cylinder temperature leads to an increase in the size of the single vortex and the length of the period. Under the analyzed conditions, for a cylinder temperature of 1200 K, the effect of chemical reactions on the Kármán vortex is maximal because the reaction rates strongly depend on temperature. Visualizations of the Kármán vortex formation for reactive and non-reactive flows are provided. Particular attention is paid to the analysis of the heat transfer coefficients on the cylinder surface. It was shown that endothermic chemical reactions significantly increase the heat supplied from the surface to the reacting flow.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109725"},"PeriodicalIF":2.6,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140867","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}
Vinh Nguyen Duy , Tan Nguyen Tien , Dien Vu Minh , Quang Khong Vu
{"title":"An experimental and Comparative performance of a thermal electric generator system using different heat exchanger fluids","authors":"Vinh Nguyen Duy , Tan Nguyen Tien , Dien Vu Minh , Quang Khong Vu","doi":"10.1016/j.ijheatfluidflow.2024.109732","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109732","url":null,"abstract":"<div><div>This study investigates the effects of the heat transfer performance of the fluids and their supplied pressure on TEGs’ performance. Consequently, experiments are conducted to evaluate the fluids as mentioned and the impact of various pressures on the bars from 2 to 6. In addition, the TEG’s working temperature is adjusted to adapt each fluid’s characteristics to find the maximum power point tracker. In general, the study’s results reveal that the power of the TEG significantly depends on the features of the fluids. Indeed, freshwater shows superior heat exchange efficiency compared to other liquids. When fixing the temperature of the cold side about 30 °C, the maximum power for the fluids corresponding to the different hot side temperature is 9.8, 30, 35, and 44 W, and for the fluids of water, ethylene glycol, lubricant, and glycerin, respectively. In addition, when the flow rate changes from 1 to 5 L/min, the voltage and output capacity of the thermoelectric device tend to increase gradually. In conclusion, working fluids’ boundary conditions and characteristics dramatically affect the TEG performance.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109732"},"PeriodicalIF":2.6,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140158","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}
Tao Li , Zhengquan Chen , Wenxuan Zhao , Jianing Yuan , Chunxiang Wang , Yuchun Zhang
{"title":"Study on the smoke sealing efficiency of air curtain and maximum ceiling temperature rise under longitudinal ventilation in bifurcated tunnel","authors":"Tao Li , Zhengquan Chen , Wenxuan Zhao , Jianing Yuan , Chunxiang Wang , Yuchun Zhang","doi":"10.1016/j.ijheatfluidflow.2024.109711","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109711","url":null,"abstract":"<div><div>Due to the ever-growing development and construction of municipalities, the underground tunnel structures raises the probability of traffic accidents and the fire risks. The effects of different longitudinal ventilation velocities and air curtain spouting angles (ASA) on the temperature distribution and maximum ceiling temperature rise in a scaled bifurcated tunnel were investigated experimentally and numerically with different heat release rates. Induced by synergistic effect of longitudinal ventilation and air curtain, the maximum ceiling temperature in the fire zone was shifted. The high temperature ranges of ceiling expanded as ASA increased. The smoke sealing effect (SSE) of different ASA ranged from 0.6 to 0.82, and the 15 ° showed a more stable SSE. Besides, based on the Li model, the factor <span><math><mi>θ</mi></math></span> of ASA was introduced for predicting the maximum ceiling temperature rise, which is consistent with the experimental data. Comparison between the experiments and the simulations showed good agreement.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109711"},"PeriodicalIF":2.6,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140154","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}
{"title":"Experimental study on thermal performance of a single-phase immersion cooling unit for high-density computing power data center","authors":"Xinshan Sun, Zhan Liu, Shenrui Ji, Kaifeng Yuan","doi":"10.1016/j.ijheatfluidflow.2024.109735","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109735","url":null,"abstract":"<div><div>Traditional air-cooling systems cannot meet special requirements of high-density computing power data centers (DCs). The single-phase immersion cooling (SPIC) is considered as one of the best ways to effectively cool high-density computing power DC cabinets. In this study, a SPIC unit was experimentally investigated with dielectric fluid Noah 3000D under a designed heat load of 20 kW. The impact of the cooling water flow rate <em>q<sub>v</sub></em><sub>2</sub> on the thermal characteristics, flow resistance and power consumption of the SPIC unit were investigated. The results show that the temperatures of both the coolant and cooling water decrease with the increase of <em>q<sub>v</sub></em><sub>2</sub>, but the temperature difference of coolant increases with the increase of <em>q<sub>v</sub></em><sub>2</sub>. An increase in coolant temperature difference means an increase in temperature non-uniformity. The increase in <em>q<sub>v</sub></em><sub>2</sub> also leads to an increase in system flow resistance. In this experiment, the pressure loss of the heat exchanger and pipelines on the coolant side, account for about 56 % and 44 %, respectively. The power usage effectiveness of the cooling system in DC (cPUE) and coefficient of performance (COP) of the SPIC unit vary in the range of 1.08–1.09 and 5.69–7.21, respectively. Moreover, it is found that simply increasing <em>q<sub>v</sub></em><sub>2</sub> cannot significantly improve the heat exchange of SPIC units, but will increase system’s energy consumption to a certain extent. The present study mainly focuses on the laboratory experimental test on the SPIC unit, and the related conclusions are significant to the design and operation of SPIC units in high-density computing power DCs.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109735"},"PeriodicalIF":2.6,"publicationDate":"2024-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140868","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}
{"title":"Comprehensive review of heat transfer and fluid flow characteristics of elliptical/oval twisted tubes","authors":"Aliakbar Sheikhi Azizi , S. Morteza Mousavi , Kambiz Vafai , A.Ali Rabienataj Darzi","doi":"10.1016/j.ijheatfluidflow.2024.109639","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109639","url":null,"abstract":"<div><div>Heat exchangers have long been widely used tools in various industries. The close association of heat exchangers with energy consumption motivates engineers to strive for high thermal efficiency through modifications in size and cost minimization in the design process. Active, passive, and compound techniques are employed to enhance heat transfer. Twisted tubes and inserts fall within the category of passive swirl flow devices. These devices enhance heat transfer by generating secondary flows and disrupting the thermal boundary layer. Twisted tubes have the potential to further augment heat transfer and improve the efficiency of heat exchangers by enlarging the surface area, mixing fluid flow, and amplifying turbulence. This review specifically focuses on twisted tubes with elliptical/oval cross-sections. Geometrical parameters such as twist pitch (number of twists) and cross-section characteristics significantly influence heat transfer enhancement in twisted tubes. In this review, studies that involve the combination of twisted elliptical/oval tubes with other passive techniques, such as inserts (wire coils, twisted tapes), and nanofluids, as well as active techniques, are also discussed. This work aims to contribute to enhancing heat exchanger performance through the application of the twisted tube technique.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109639"},"PeriodicalIF":2.6,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140603","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}
Xingwen Peng , Wen Yao , Xingchen Li , Xiaoqian Chen
{"title":"A divide-and-conquer deep learning approach to reconstruct flow and temperature fields","authors":"Xingwen Peng , Wen Yao , Xingchen Li , Xiaoqian Chen","doi":"10.1016/j.ijheatfluidflow.2024.109707","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109707","url":null,"abstract":"<div><div>Reconstructing flow and temperature fields from limited sensor measurements is a critical capability for state evaluation, optimization, and control of flow and heat transfer processes. While deep learning has been harnessed for physical field reconstruction and has demonstrated impressive performance, it faces the challenge of achieving enhanced precision and computational efficiency, particularly when dealing with intricate, nonlinear problems. Inspired by the observation that numerous physical phenomena exhibit distinct behaviors within isolated regions of the spatial domain, such as boundary layers and separated flows, we introduce a novel deep learning approach that employs a “divide-and-conquer” strategy. In this methodology, the entire spatial domain is partitioned into various subdomains, each of which is entrusted to a dedicated neural network for precise reconstruction of the flow and temperature fields. Initially, the physical domain is segmented into discrete subdomains using K-means clustering based on cosine distance. Subsequently, individual deep neural networks are constructed to map from limited sensor measurements to the physical field within each subdomain. Finally, the separately reconstructed fields are amalgamated to constitute the ultimate physical field representation. To validate the efficacy of our approach, numerical experiments were conducted across four diverse cases: flow around a cylinder, turbulent channel flow, transonic flow, and conduction involving multiple heat sources. The results demonstrate the superior accuracy and efficiency of the proposed method. In comparison to the non-partitioned approach, our method achieves a minimum reduction of 44.6% in mean absolute error, simultaneously enhancing training efficiency by approximately 30.0% under the premise that the model can utilize multi-GPUs parallel training, all while maintaining a manageable model complexity.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109707"},"PeriodicalIF":2.6,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140870","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}