International Journal of Thermal Sciences最新文献

{"title":"Experimental investigation on maximum ceiling temperature and longitudinal attenuation in a closed tunnel with an inclined shaft","authors":"Mingxuan Qiu ,&nbsp;Lin Xu ,&nbsp;Yinghao Zhao ,&nbsp;Chao Ding ,&nbsp;Shengzhong Zhao ,&nbsp;Wei Yu ,&nbsp;Longyue Li ,&nbsp;Xiaoxuan Zhou","doi":"10.1016/j.ijthermalsci.2024.109484","DOIUrl":"10.1016/j.ijthermalsci.2024.109484","url":null,"abstract":"<div><div>For tunnel fires with open and closed tunnel ends, the smoke flow pattern and air supply conditions vary considerably, resulting in different maximum excess ceiling temperature (<em>ΔT</em>_max) and its longitudinal distribution (<em>ΔT</em>_<em>x</em>). However, few studies have focused on the tunnel closed at both ends with an inclined shaft (typical tunnel structure during construction). Hence, tunnel model 1 (tunnel closed at both ends with an inclined shaft) and tunnel model 2 (tunnel open at both ends) are built for comparison and analysis. The results show that tunnel model 1 has higher ceiling temperatures and slower attenuation than tunnel model 2. Therefore, the <em>ΔT</em>_<em>x</em> in tunnel model 1 needs to be re-analyzed in detail. Different inclined shaft slopes, fire heat release rates, longitudinal and vertical fire positions are considered. In tunnel model 1, for <em>h</em> (lifting height of burner surface) = 0, the <em>ΔT</em>_max value tends to be constant for the same heat release rate, irrespective of the longitudinal fire position. For <em>h</em> = 5 cm, the <em>ΔT</em>_max value takes on a rising trend with the fire moving downstream. Moreover, the inclined shaft slope within this study has little influence on <em>ΔT</em>_<em>x</em>. As the fire moves downstream, the downstream <em>ΔT</em>_<em>x</em>/<em>ΔT</em>_max value decreases more rapidly. From <em>h</em> = 0 to <em>h</em> = 5 cm, the value of <em>ΔT</em>_<em>x</em>/<em>ΔT</em>_max drops slightly faster, but the gap is small and can be ignored. Finally, the experimental correlations are proposed to estimate the longitudinal ceiling temperature distribution in a closed tunnel with an inclined shaft.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109484"},"PeriodicalIF":4.9,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432741","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}

{"title":"Contact angle evolution during nanodroplet nucleation","authors":"Yuxuan Chen ,&nbsp;Jianye Yang ,&nbsp;Xiaokang Liu ,&nbsp;Xiuliang Liu","doi":"10.1016/j.ijthermalsci.2024.109469","DOIUrl":"10.1016/j.ijthermalsci.2024.109469","url":null,"abstract":"<div><div>Vapor condensation is widely adopted in thermal management technology and condenser of energy power plant, benefiting from its high heat transfer coefficient. Contact angle is the key factor to regulate vapor condensation rate, leading to the rapid development of surfaces with various wettability fabricated by micro/nanoengineering. However, the nucleated nanodroplets (1–100 nm) at the beginning of condensation exhibit different wetting dynamics from macroscopic droplets, the mechanisms of which are not well understood. In this work, we perform molecular dynamic (MD) simulations to study the evolution of contact angle during nanodroplet nucleation processes. The results show the nucleated contact angle of a nanodroplet is smaller than the contact angle predicted by the classical Young equation on a hydrophobic surface, while it is opposite for nanodroplet nucleating on hydrophilic surface. Moreover, we have calculated line tension for the nucleated nanodroplet on the surfaces with different wettability to explain this discovery, and found positive line tension on hydrophobic surface, while negative line tension for nucleated nanodroplet on hydrophilic surface. Furthermore, the calculated line tension, which is at the order magnitude of 10⁻¹¹ J/m, aligns well with the data documented in the literature.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":""},"PeriodicalIF":4.9,"publicationDate":"2024-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421695","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}

{"title":"Numerical study on heat and mass transfer of droplet collision on superheated bio-inspired surfaces","authors":"Bowen Yu ,&nbsp;Zhiguo Xu ,&nbsp;Zhaolin Li ,&nbsp;Jingxiang Wang","doi":"10.1016/j.ijthermalsci.2024.109476","DOIUrl":"10.1016/j.ijthermalsci.2024.109476","url":null,"abstract":"<div><div>The velocity and temperature fields of droplet evaporation on bio-inspired surfaces are investigated based on the single-component multiphase pseudopotential lattice Boltzmann method and liquid-vapor phase-change model. The morphology of the surface is inspired by the hierarchical cuticle of springtails which have the feature of doubly reentrant pillars. The dynamic mechanism of droplet collision and evaporation is revealed in the study. The effects of Jakob number, solid thermal conductivity, and pillar spacing on the behavior of the droplet collision on superheated bio-inspired surfaces are statistically analyzed. The study provides detailed snapshots depicting the evolution of droplet morphology. The trends of substrate heat flux, droplet lifetime, and droplet volume with time are presented. For the doubly re-entrant superheated surface, the droplet is easier to split and the droplet lifetime is shorter compared to that on smooth substrates. The reduction ratio of droplet lifetime is 66.2 % when Jakob number equals 0.12. When Jakob number increases, Leidenfrost vapor layer is generated on the surface and it deteriorates droplet evaporation. The lifetime of droplets does not consistently decrease with increasing solid-liquid thermal conductivity ratio across different Jakob numbers, primarily due to variations in droplet morphology under different conditions. Moreover, an increase in pillar spacing leads to an enhancement in the evaporation rate under the same superheating conditions. The droplet lifetime of 20 pillar spacing is 58.72 % of 8 pillar spacing.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109476"},"PeriodicalIF":4.9,"publicationDate":"2024-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432735","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}

{"title":"Multi-objective optimization of heat transfer performance and power consumption of Taylor-Couette flow with elliptical helical slits wall","authors":"Ya-Zhou Song ,&nbsp;Dong Liu ,&nbsp;Si-Liang Sun ,&nbsp;Hyoung-Bum Kim","doi":"10.1016/j.ijthermalsci.2024.109474","DOIUrl":"10.1016/j.ijthermalsci.2024.109474","url":null,"abstract":"<div><div>Heat transfer performance and power consumption of Taylor-Couette flow with helical slit wall are analyzed. Slit number, width, and spacing are selected for multi-objective optimization of heat transfer performance and power consumption. Energy loss within the coaxial cylinder is analyzed using the entropy generation principle. Different Machine learning methods are applied to predict the heat transfer and power consumption of Taylor-Couette flow. A comparison made between the predictive findings of the XGBoost model and other three different models. The XGBoost prediction model for heat transfer and power consumption not only exhibits the highest determination coefficient, but also achieves the lowest mean absolute percentage error, root mean squared error, mean absolute error, which has the best predictive performance. Finally, the NSGA-II algorithm is used to optimize the elliptical helical slit structure, and obtained the Pareto front of the optimized design of the helical slit structure. Comparing results with the original model, the maximum improvement in heat transfer performance is 18.68 % and maximum reduction in power consumption is 15.28 %. In practical design, reasonable slit structure parameters can be selected from the obtained set of optimal parameter solutions based on design requirements.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":""},"PeriodicalIF":4.9,"publicationDate":"2024-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421693","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}

{"title":"A fast quadrupole-based analytical model for solving transient heat transfer in ventilated double-skin walls and assessing their energy saving potential","authors":"Safaa Lahayrech ,&nbsp;Anas El Maakoul ,&nbsp;Alain Degiovanni ,&nbsp;Ismail Khay ,&nbsp;Monica Siroux","doi":"10.1016/j.ijthermalsci.2024.109463","DOIUrl":"10.1016/j.ijthermalsci.2024.109463","url":null,"abstract":"<div><div>This research proposes a fast and accurate method for modeling transient heat transfer in ventilated double-skin façades (VDFs) with forced ventilation to predict their energy-saving potential. Using the thermal quadrupole formalism, the method solves the VDF problem in the Laplace domain while considering the full transient nature of the heat transfer; the only approximation is in space. The solution involves obtaining a general transfer function that predicts heat transfer rates or air temperatures at ventilated cavity's exit. The quadrupole method is validated against computational fluid dynamic numerical simulations conducted under similar meteorological, design and boundary conditions. A very good agreement was found (less than 3 % average deviation) with a significant reduction in computation time (less than 3s against 6h for CFD calculations). The model is computationally efficient and can consider important factors such as the opacity of the walls, construction materials, and air cavity design parameters. Finally, the model allows the assessment of the energy-saving potential of VDFs under various scenarios compared to conventional systems, which helps contributing to more sustainable building design practices. The energy efficiency of a VDF configuration was compared against a conventional wall system. Energy savings of 8.4 and 5.2 % were obtained, in cold and hot climates respectively.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109463"},"PeriodicalIF":4.9,"publicationDate":"2024-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421692","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}

{"title":"Thermal-hydraulic analysis and geometric optimization on a microchannel with stacked combinations of ribs and cavities","authors":"Liang Du ,&nbsp;Ningkang Deng ,&nbsp;Jin Yuan ,&nbsp;Yongfeng Qu ,&nbsp;Zhaoyang Zhang ,&nbsp;Wenbo Hu ,&nbsp;Hongxing Wang","doi":"10.1016/j.ijthermalsci.2024.109456","DOIUrl":"10.1016/j.ijthermalsci.2024.109456","url":null,"abstract":"<div><div>In order to effectively reduce the operating temperature of electronic devices and improve their working stability and service life, this study has designed the microchannel with stacked combinations of ribs and cavities. The thermal-hydraulic characteristics of microchannel with stacked combinations of cuboid cavities and various rib shapes (1/4 ellipsoid, triangular prism, 1/4 cylinder, trapezoidal prism, and cuboid) were investigated using numerical simulation. Subsequently, their comprehensive performance and energy saving effect were assessed. It is shown that the microchannel with stacked combinations of ribs and cavities not only increases the solid-liquid contact area, but also enhance the mixing efficiency between cold water in the channel center and hot water along the side walls. This improvement helps to reduce temperature and thermal resistance, leading to enhanced heat transfer within the microchannel. As a result, it exhibits excellent comprehensive performance and energy saving effects. When the relative rib width and height ratio of rib to cavity of microchannel with stacked combinations of cuboid cavity and cuboid rib are 0.733 and 0.765, respectively, the figure of merit reaches 2.23, which has high comprehensive performance.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109456"},"PeriodicalIF":4.9,"publicationDate":"2024-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421696","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}

{"title":"Experimental studies on the influence of smoke acceleration effect feedback to the flame behavior in the U shaped shaft of a high-rise building","authors":"Man Li ,&nbsp;Yize Shen ,&nbsp;Zhongkun Cai ,&nbsp;Qishen Xiao ,&nbsp;Haowei Hu","doi":"10.1016/j.ijthermalsci.2024.109465","DOIUrl":"10.1016/j.ijthermalsci.2024.109465","url":null,"abstract":"<div><div>This paper presents an experimental investigation of the feedback effect with smoke acceleration on flame behaviors in the U shaped shaft of a high-rise building. Heat release rate of the fire, depths and widths of the U shaped shaft are changed. The flame height, vertical maximum temperature in the open shaft and the heat flux distribution on the façade are studied. Results show that the flame height is elongated by the smoke acceleration effect in the U shaped shaft and larger than that in the open space. Correlations for the flame height are established by taking into account the geometries of the U shaped shaft. The vertical maximum temperature in the U shaped shaft first decreases rapidly then keeps room temperature, which are compared with that under stack effect in the staircase. The exponential decay law between the vertical maximum temperature and height is modified. The total heat flux is mainly affected by the width and heat release rate. Radiation heat transfer fraction is larger than 80 % in the continuous and intermittent flame regions, of which the flame emissivity is about 0.53.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109465"},"PeriodicalIF":4.9,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421691","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}

{"title":"Multidisciplinary design optimization of axisymmetric exhaust systems: Integrating aerodynamic performance and infrared stealth capabilities","authors":"Lan Bo,&nbsp;Qiang Wang,&nbsp;Haiyang Hu","doi":"10.1016/j.ijthermalsci.2024.109462","DOIUrl":"10.1016/j.ijthermalsci.2024.109462","url":null,"abstract":"<div><div>An integration of collaborative optimization (CO) strategy was undertaken to improve aerodynamic performance and mitigate the infrared signature of the axisymmetric exhaust system. The Optimal Latin Hypercube method was utilized to construct a kriging surrogate model, considering influential factors such as nozzle geometric parameters, thermodynamic parameters, and material properties of nozzle components. The aerodynamic performance of the nozzle was computed using the Computational Fluid Dynamics (CFD) method, while the assessment of infrared characteristics of the exhaust system was conducted using the multiscale multigroup wide band k-distribution model (MSMGWB) and the Ray Tracing Method. Following a comprehensive evaluation and selection process of optimized results, improvements were observed: the discharge coefficient experienced an increase of up to 1.72 %, the thrust coefficient showed an increase of up to 1.19 %, and a notable reduction of up to 31.23 % in tail direction dimensionless infrared radiation intensity was achieved among all optimized outcomes. The CO method successfully decouples these two tightly coupled disciplines, enabling independent optimization while ensuring consistency between them. By transforming the multi-objective optimization problem into a single-objective optimization within the system and optimizer, this method allows for the rapid and accurate identification of the optimal design that balances aerodynamic performance and infrared stealth according to mission requirements.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109462"},"PeriodicalIF":4.9,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421690","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}

{"title":"Study on flow and heat transfer characteristics of two axial preswirl structures","authors":"Zeyu Wu ,&nbsp;Nan Cao ,&nbsp;Jiahua Liu ,&nbsp;Xiang Luo","doi":"10.1016/j.ijthermalsci.2024.109439","DOIUrl":"10.1016/j.ijthermalsci.2024.109439","url":null,"abstract":"<div><div>Turbine blade cooling air is facilitated in part by the pre-swirl system, a crucial part of the aero-engine secondary air system. This article primarily focuses on the pre-swirl angle and the turbine co-rotating cavity in order to improve the pre-swirl system's temperature drop. It also employs the thermochromic liquid crystal test method to investigate the pre-swirl system's temperature drop characteristics and the cavity's cooling effect. The experimental parameters are measured at different flow rates when the rotational Reynolds number is between 2.97 × 10⁶ and 4.23 × 10⁶. The results indicate that within the experimental operating range, for the axial pre-swirl structure, the fluid velocity is fast and the static temperature is significantly reduced after pre-rotation. The higher the rotational Reynolds number, the lower the static temperature of the fluid passing through the receiving hole, and the higher the outlet temperature rise. The tangential velocity of the 15-degree preswirl structure is low, the static temperature of the receiving hole is high, and the average outlet temperature increases. In terms of pressure loss, the higher the rotational Reynolds number, the lower the fluid static pressure. The larger the pre-swirl flow rate, the higher the static pressure inside the cavity. The outlet static pressure of the 15-degree structure is higher than that of the 10-degree structure. The swirl ratio increases with an increasing flow rate. The swirl ratio decreases as the rotational Reynolds number increases. The 15-degree structure's swirl ratio is significantly lower than that of the 10-degree structure. Entropy generation is mostly produced along the trailing edge of the blade and in the vicinity of the wall, and the entropy generation of the 15-degree preswirl structure is higher than that of the 10-degree structure. On the disc's surface, the convective heat transfer coefficient rises with a rising dimensionless flow rate and falls with an increasing rotational Reynolds number.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109439"},"PeriodicalIF":4.9,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421694","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}

{"title":"A liquid-cooled plate based on bionic flow channels evolved from the shape of leaf veins and tree roots","authors":"Hanxu Xia,&nbsp;Jun Wang,&nbsp;Yan Shen,&nbsp;Kai Fang","doi":"10.1016/j.ijthermalsci.2024.109468","DOIUrl":"10.1016/j.ijthermalsci.2024.109468","url":null,"abstract":"<div><div>With the rapid development of lithium-ion (Li-ion) batteries, battery thermal management (BTMS) is increasingly essential for the temperature control of Li-ion batteries. The energy required to control temperature is coming into focus. In order to consume less energy to control temperature and improve temperature uniformity, the liquid-cooled plate (LCP) based on bionic flow channels evolved from the shape of leaf veins and tree roots is proposed. In this BLCP, different from the others BLCPs, it is divided into a reinforced heat exchange area located in the middle and back part of the plate and a normal area located in the front part of the plate. Firstly, 16 sets of orthogonal tests are conducted based on four parameters: the distance of the hexagon from the outlet (a), the distance from the inlet (b), the distance between two adjacent hexagons (c) and the size of the hexagon (d). Secondly, Optimization was investigated based on NSGA-II for two objectives: temperature and pressure drop. The simulation results are analyzed based on the optimized structural parameters (a = 30 mm, b = 8 mm, c = 50 mm and d = 90 mm). After Comparing the optimization results with the simulation results, the temperature and pressure drop errors were 0.56 percent and 3.8 percent, respectively. The effects of flow rate and thickness of the fluid domain on temperature and pressure drop are next discussed separately. Finally, after comparing the optimized bionic liquid cooling plate (BLCP) with the conventional liquid cooling plate (CLCP) based on temperature pressure drop, velocity, and synergy angle, conclusions are made at the same inlet width, height, flow rate, and velocity (V = 0.2 m/s). This leads to the criterion of energy loss becoming only the pressure drop. The BLCP for pressure drop is 14.2 percent lower than the CLCP, which means less energy loss. The maximum temperature of the BLCP is 0.7 °C lower than that of the CLCP. Furthermore, the former has a better ability to suppress the rate of temperature rise and better temperature uniformity. In addition, this proposed new structure and research methods can be applied to the subsequent study of LCP.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109468"},"PeriodicalIF":4.9,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421689","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}