International Journal of Thermal Sciences最新文献

{"title":"Development and experimental validation of a 3D numerical model to investigate performance of phase change based cooling vest in hot environments","authors":"Kedumese u Mekrisuh ,&nbsp;Dushyant Singh ,&nbsp;Udayraj","doi":"10.1016/j.ijthermalsci.2024.109487","DOIUrl":"10.1016/j.ijthermalsci.2024.109487","url":null,"abstract":"<div><div>To ensure health and safety of outdoor workers exposed to harsh environment, particularly during summer, they must be protected against heat-related injuries. Personal cooling device like cooling vest are viable solution in such situations considering their cooling capabilities and ergonomic aspects. In the present study, a 3D numerical model is developed for analyzing performance of PCM vest and it is validated with experimental results obtained from a torso thermal manikin facility fabricated in-house. Thermal performance of the PCM vest is analyzed in terms of temperature, liquid fraction and energy storage of PCM and skin temperature for different thermophysical properties of PCM, ambient conditions and mode of operations. Based on the study, PCM with higher latent heat and melting temperature is recommended for the longer working duration of the vest. Increasing ambient temperature from 40 °C to 45 °C reduces the effectiveness time by 20 % while decreasing ambient temperature from 40 °C to 35 °C increases effectiveness time of the PCM vest by 32 %. Fraction of energy stored by the PCM from the body and environment remains unaffected by the change in the latent heat of PCM. Further, it is noticed that increasing the air flow rate or using the PCM vest in hybrid mode of operation is not recommended from the point of view of its effective useable duration. Overall, the study presents a comprehensive approach to estimate performance of the PCM vest realistically and provides guidelines for the design of effective cooling vest for various practical applications.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109487"},"PeriodicalIF":4.9,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446563","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":"Circular perforations on vertically sinusoidal wave form plate fin heat sinks for laminar natural convection heat dissipation","authors":"Mohammed Salam Taha ,&nbsp;Ali Ates ,&nbsp;Eyüb Canli ,&nbsp;Aziz Hakan Altun","doi":"10.1016/j.ijthermalsci.2024.109470","DOIUrl":"10.1016/j.ijthermalsci.2024.109470","url":null,"abstract":"<div><div>Aluminum straight plate fin heat sink geometry was modified with vertical sinusoidal wave profile on the fins for different amplitudes. The heat sink fins were further modified by means of circular perforations with increasing diameters. Fully experimental examination was adopted for conducting the work. The heat sinks were assessed on a heat source to see the effect of the modifications on the heat sink fins in terms of heat sink base plate temperature. Heat source was controlled so that the natural convection heat transfer remained in the laminar regime. The experimental methodology elaborately described to share practical experiences on implicit nature and critical points of the commonly used approaches. Up to 40 W heat dissipation is realized with the heat sinks while 2.5 × 10⁶ Rayleigh number value bases a limit for the natural convection potential. The perforations on the fins reduce the performance difference between different wave form amplitudes towards the favorable direction. The 3 mm and 6 mm perforations on the sinusoidally wavy fin profile with 1 mm amplitude value result the least base plate surface temperatures. Therefore, when the cost is justified by the performance improvement, perforations on plate fin heat sinks are recommended in terms of passive cooling applications. In terms of thermal application, present results indicate thermal performance increase of plate fin heat sinks by perforations on the fin surfaces. The experiences throughout the experimental process in the present work reveal unintuitive, implicit, and covert phenomena about the insulation box design and heating power measurement, which are elucidated in the present content. Insulation box can function as an additional heat dissipation surface at the proximity of the heat sink based on the box design. The voltage measurement approach, which is shallowly mentioned in the literature most of the time, can have an effect on the absolute values of the heat dissipation value.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109470"},"PeriodicalIF":4.9,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441003","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":"Investigating the effects of near-wall active vortex generators on heat transfer inside a channel","authors":"O. Damanafshan,&nbsp;Y. Amini,&nbsp;S.E. Habibi","doi":"10.1016/j.ijthermalsci.2024.109479","DOIUrl":"10.1016/j.ijthermalsci.2024.109479","url":null,"abstract":"<div><div>Most of previous researches on enhancing the heat transfer rate in pipes and channels have focused on passive methods. This article introduces near wall active vortex generators (NWAVG) as a strong way to enhance the heat transfer rate from rectangular channels and simultaneously keep friction losses as low as possible. This article considers three different motion patterns for NWAVG at a constant Reynolds number of 1000. Also, the impact of different numbers of vortex generators and different parameters of each motion pattern on the Darcy friction factor, the Nusselt number and the overall hydrothermal efficiency are examined. The results show that the effect of vortex generators on the heat transfer rate increases significantly when they approach the channel wall. Moreover, the results show that the NWAVG can achieve an 185 % increase in the Nusselt number with an overall hydrothermal efficiency of 1.26.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109479"},"PeriodicalIF":4.9,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441004","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":"Thermo-hydraulic characteristics of offset strip fin heat exchanger with vortex generators","authors":"Taipeng Guo ,&nbsp;Qifan Wang ,&nbsp;Yu Zhang ,&nbsp;Zhentao Liu","doi":"10.1016/j.ijthermalsci.2024.109459","DOIUrl":"10.1016/j.ijthermalsci.2024.109459","url":null,"abstract":"<div><div>The finned structure of the Offset Strip Fin (OSF) and the vortex generators (VG) both offer significant potential for enhanced heat transfer. This paper investigates the thermal-hydraulic characteristics of the OSF heat exchanger (HEX) with VG installed on the rib base surface. The study examines the geometrical configuration of the VG, including their shape, spatial positioning, longitudinal extent, and angle of attack, to determine their respective impacts on system performance. VG shapes perform differently across various Reynolds numbers (Re), defining the transition point as the Thermal Exchange Efficacy Transition Re (Re_TEET). Findings suggest that increasing the distance of VG from the fin's leading edge, along with extending their length and increasing their angle of attack, collectively improves heat transfer efficiency and reduces the Re_TEET. However, achieving the Re_TEET becomes unfeasible when the angle of attack surpasses a certain threshold. At lower Reynolds numbers, the optimum performance occurs at a 45° angle of attack. As the Reynolds number increases, the optimum performance decreases with an increased angle of attack.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109459"},"PeriodicalIF":4.9,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142440891","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":"Effect of crossflow orientations in the impinging jet flow channel on flow and heat transfer enhancement under rotations","authors":"Natthaporn Kaewchoothong ,&nbsp;Thantup Nontula ,&nbsp;Chayut Nuntadusit","doi":"10.1016/j.ijthermalsci.2024.109478","DOIUrl":"10.1016/j.ijthermalsci.2024.109478","url":null,"abstract":"<div><div>An experimental and numerical investigation was conducted to elucidate the flow and heat transfer characteristics of a row of impinging jets within a confined, rotating channel. The study focused on a jet Reynolds number (Re_<em>j</em>) of 9,000, examining three distinct crossflow orientations: radially outward (ROCF), radially inward (RICF), and a combined radially outward and inward (ROICF) scheme. Jet-to-impingement surface distances (<em>h/d</em>_<em>j</em>) of 2, 4, and 6 (where dj represents the jet orifice diameter) were considered, along with channel rotation speeds corresponding to Rotation numbers (<em>Ro</em>) from 0 to 0.0046. Heat transfer on the leading and trailing sides of the impinging jets was measured using a steady thermochromic liquid crystal (TLC) technique under constant heat flux conditions. Additionally, RANS simulations were employed to investigate the flow fields associated with the impinging jets. The results reveal that in both the ROCF and RICF schemes, heat transfer, characterized by the Nusselt number, decreases from upstream to downstream for each impinging jet. Increasing the rotation number (Ro) leads to enhanced heat transfer, with the trailing side exhibiting marginally higher values than the leading side. In the ROICF scheme, at <em>h/d</em>_<em>j</em> = 2, a more uniform Nusselt number distribution is observed across all jet holes compared to the ROCF and RICF schemes, and this uniformity increases with higher <em>Ro</em>. However, for <em>h/d</em>_<em>j</em> = 4 or 6, the heat transfer becomes non-uniform and can even deteriorate below the stationary case at high <em>Ro</em> numbers, attributed to the combined effects of Coriolis and centrifugal forces.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109478"},"PeriodicalIF":4.9,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142438021","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-mechanical influence aspects and evaluation of helical cruciform single rod in fluoride-salt-cooled high-temperature advanced reactor","authors":"Yiwen Chen ,&nbsp;Dalin Zhang ,&nbsp;Dianqiang Jiang ,&nbsp;Wei Li ,&nbsp;Qi Lu ,&nbsp;Wenxi Tian ,&nbsp;Suizheng Qiu ,&nbsp;Guanghui Su","doi":"10.1016/j.ijthermalsci.2024.109483","DOIUrl":"10.1016/j.ijthermalsci.2024.109483","url":null,"abstract":"<div><div>Helical cruciform fuels are novel in nuclear reactors, potential to increase reactor's power density. However, the geometry is complicated so influence of it on the fuel performance is not identified yet. To evaluate flow and heat transfer performance of the fuel, thermal and mechanical characteristics of fuel used in Fluoride-Salt-cooled high-Temperature Advanced Reactor are analyzed. Impact of power density, cross-section parameters, and twist pitch on the fuel is discussed separately based on fluid-thermal-mechanical coupling. In general, twist pitch is vital to helical cruciform fuel while others have few effects considering thermal-mechanical features. For thermal features, increase in twist pitch leads to temperature rise owing to weaker mixing effects. Fuel center temperature at middle plane of 300 mm-pitch rod is 829.58 °C, 54.66 °C higher than that of 100 mm-pitch rod. Besides, axial temperature of cladding outer surface increases wavelike due to complex geometry. For mechanical features, not geometry sizes but temperature affects stress distribution. Maximum Von-Mises stress appears at the elbow, where maximum temperature exists, 116.8 MPa under normal conditions, lower than tensile strength of the material. After identifying the influence of these factors, five dimensionless parameters are proposed to evaluate and rate fuel performance based on Technique for Order Preference by Similarity to an Ideal Solution. As a result, an optimization comes up, scoring 0.310, twice more than the original design, owing to the thermal uniformity and mechanical safety. This study provides a reference for identifying the performance of helical structure and a new fuel design in Fluoride-Salt-cooled high-Temperature Reactor.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109483"},"PeriodicalIF":4.9,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432736","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 characterisation and visualisation of a novel two-phase flexible heat transfer device","authors":"Kannan Pandi ,&nbsp;V.M. Jaganathan ,&nbsp;S. Suresh ,&nbsp;Kasturi Vikas","doi":"10.1016/j.ijthermalsci.2024.109472","DOIUrl":"10.1016/j.ijthermalsci.2024.109472","url":null,"abstract":"<div><div>The importance of passive Flexible Heat Transfer Device (FHTD) in electronic cooling or space applications lies in their ability to provide efficient, reliable, and adaptable thermal management solutions. Heat transfer enhancement studies pertaining to FHTD developed to meet the thermal management demands of futuristic flexible electronic devices are presented in the current work. The possibility of extending the heat transport limit of FHTD beyond 24 W by limiting the maximum operating temperature to 60 °C is discussed. The superior performance of FHTD at varying heat loads from 5 W to 40 W at 45°and 90°bending angles is brought out compared with existing heat transfer devices like Flexible Heat Pipe (FHP) and copper thermal straps. The performance is reported in thermal resistance and equivalent thermal conductivity. A commercial dielectric liquid is used as a working fluid in FHTD to enhance the heat transfer limit employing phase change. The evaporator and condenser sections of the flexible section are made transparent to visualise the boiling and condensation phenomenon. Under steady-state operation at a 45°bending angle, The FHTD demonstrates a minimum thermal resistance of 0.73 K/W and a peak effective thermal conductivity of 8172 W/m K. The heat transfer coefficient ranges from 200 to 700 W/m<span><math><msup><mrow></mrow><mrow><mn>2</mn></mrow></msup></math></span> K, consistent with values reported for heat pipes in the literature. Additionally, the study explores the impact of modifying the external surface texture to create more nucleation sites, thereby enhancing the performance of the FHTD. The results show that the laser-textured surface on the heat pipe condenser effectively reduces the onset of nucleate boiling for dielectric fluid by 3.5 °C and decreases the maximum temperature of the evaporator by 4.5 °C. The present work dictates the fundamental baseline for possible design choices of futuristic passive flexible heat transfer devices.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109472"},"PeriodicalIF":4.9,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432738","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":"Simulation study of heat transfer in the space under the clothing of mining ventilation suits in typical human labour positions","authors":"Bo You ,&nbsp;Siqi Wang ,&nbsp;Ming Yang ,&nbsp;Ke Gao ,&nbsp;Qiaoyun Han ,&nbsp;Meifeng Xu","doi":"10.1016/j.ijthermalsci.2024.109423","DOIUrl":"10.1016/j.ijthermalsci.2024.109423","url":null,"abstract":"<div><div>The objective of this study is to examine the distribution of space under a ventilated suit when the human body is wearing a ventilated suit with different piping structures in labor postures, such as lifting the arms and bending the waist. Additionally, the study aims to investigate the impact of the space under the ventilated suit on heat transfer through numerical simulation, with the goal of identifying the optimal piping design. The study demonstrates that in an inhomogeneous space, the airflow is susceptible to turbulence, which results in the accumulation of heat. Furthermore, the implementation of distinct air flow patterns within the transverse and longitudinal piping structures of the ventilated suit can result in notable alterations to the heat transfer process and the overall cooling effect. The transverse piping structure offers superior support and a more uniform air flow distribution, thereby significantly enhancing the cooling effect of the ventilated suit. In contrast, the longitudinal piping structure is designed to concentrate the air flow on the back side, resulting in a comparatively weaker ventilation effect on the front side. A comparison of the weights of the two piping structures using the entropy value method revealed that the transverse piping structure had a weight that was approximately 4.5 % higher than that of the longitudinal piping structure. This finding suggests that the cooling effect of the transverse piping structure is more pronounced.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109423"},"PeriodicalIF":4.9,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432740","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 novel hybrid-composite microchannel heat sink for extreme hotspot mitigation","authors":"Danish Ansari ,&nbsp;Wasim Raza ,&nbsp;Ji Hwan Jeong ,&nbsp;Kwang-Yong Kim","doi":"10.1016/j.ijthermalsci.2024.109473","DOIUrl":"10.1016/j.ijthermalsci.2024.109473","url":null,"abstract":"<div><div>Most of the heat generated by a microprocessor comes from its cores, resulting in hotspots with exceptionally high heat flux. In contrast, the remaining processor area experiences significantly lower heat flux, leading to substantial temperature nonuniformity across the chip. An efficient heat sink must be capable of applying distinct cooling capacities specific to each zone. This study presents an energy-efficient heat sink design aimed at mitigating severe temperature variations in microprocessors. The design concept involves dividing the processor's hot surface into zones based on heat flux intensity and integrating different microstructures and materials into each respective zone for optimized thermal management. The proposed hybrid-composite design was developed by incorporating silicon microchannels for the low-heat-flux zone and diamond microfins for the high-heat-flux zone. Integrating microfins (hybrid design) substantially enhances the solid-fluid interface area over the hotspot zone, while using diamond (composite design) dramatically improves heat conduction from the hotspot. Full heat sinks were modeled for conjugate heat transfer investigation. The thermo-hydraulic performance of hybrid-composite design was compared against that of simple, simple-composite, and hybrid designs. The hybrid-composite design demonstrated substantial enhancement in thermal performance compared to all the other designs, with a moderate rise in pumping power. In comparison to the simple microchannel design, the hybrid-composite design demonstrated a 66.0 % reduction in thermal resistance and a 74.3 % decrease in temperature nonuniformity. Additionally, the hybrid-composite design could effectively mitigate a hotspot heat flux of up to 2400 W/cm² with only 8.6 % higher pumping power, while the simple microchannel design reached the maximum permissible temperature limit at 700 W/cm².</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109473"},"PeriodicalIF":4.9,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432739","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":"Solidification behavior of WC particles reinforced nickel alloy cladding layers by plasma surfacing: Simulation and experiment","authors":"Chunlin Zhang ,&nbsp;Li Zhang ,&nbsp;Yonghong Wang ,&nbsp;Shengli Li ,&nbsp;Jing Li ,&nbsp;Zhiwen Xie","doi":"10.1016/j.ijthermalsci.2024.109482","DOIUrl":"10.1016/j.ijthermalsci.2024.109482","url":null,"abstract":"<div><div>In this work, a numerical simulation model was developed to investigate the complex heat and mass transfer process inside the molten pool during plasma surfacing. The temperature distribution and fluid flow were employed to depict the evolution of the molten pool. The findings revealed that the maximum temperature is located on the surface of the cladding layer corresponding to the position of heat source, and the temperature distribution follows a Gaussian distribution along the scanning direction. Thermal accumulation is obvious due to the continuous energy input in the initial stage, as a result, the maximum temperature and fluid flow velocity gradually increase with the deposition process. The maximum temperature and fluid flow velocity at 4.0 s are 1893 K and 0.281 m/s in case 110 A, respectively. The predicted shapes and dimensions are consistent with the results of the deposition experiments, with a maximum error of no more than 15 %. In order to investigate the impact of WC particles on the solidification microstructure of nickel composite layers, corresponding plasma surfacing experiment was implemented. The solidification characteristics of the microstructure follow planar-cellular-columnar-equiaxed crystals in the bonding layer and WC particles-columnar-equiaxed dendritic crystals in hard layer, respectively. Furthermore, the Ni dendritic near the retained WC particles transformed into columnar crystals due to temperature gradient in the local area.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"208 ","pages":"Article 109482"},"PeriodicalIF":4.9,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432737","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}