Applied Thermal Engineering最新文献

{"title":"Highly thermally conductive and electrically insulated ceramic heat pipes based on powder-sintered glass capillary wick","authors":"Xuepeng Yuan ,&nbsp;Yifu Liang ,&nbsp;Fuye Liang ,&nbsp;Shiwei Zhang ,&nbsp;Yong Tang ,&nbsp;Caiman Yan","doi":"10.1016/j.applthermaleng.2025.126716","DOIUrl":"10.1016/j.applthermaleng.2025.126716","url":null,"abstract":"<div><div>Electronic devices with high heat flux are increasingly demanding on both highly thermally conductive and electrically insulated technology. However, electrical insulation and thermal conduction are contradictory properties, making the development of technology that satisfies both an ongoing research challenge. In this study, a novel highly thermally conductive and electrically insulated ceramic heat pipe (CHP) is developed to solve this dilemma. The insulating wick of CHP consists of sintered irregular glass powders. The microscopic morphology and wettability of the insulating wicks on the capillarity were investigated in detail. Meanwhile, the effects of filling rate (FR) and different working conditions on the performance of CHP were investigated. It is found that the 75 % FR CHP is recommended for low power (≤ 30 W) with thermal resistance down to 0.85 °C/W, while the 100 % and 125 % FR CHPs have more advantages in heat dissipation at high power. The 100 % FR CHP combines the advantages of thermal conductivity and thermal power, with a high thermal conductivity of 4021.18 W/(mK) at 65 W and a maximum thermal power of 70 W. Moreover, CHP has an ultra-high withstand voltage value (27.45 kV). The reliability of the CHP also passes helium leak detection and aging tests under extreme conditions of high-low temperatures. The novel CHP with excellent thermal conductivity, electrical insulation and reliability, is the optimal component for high-voltage electrical insulating devices cooling.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"274 ","pages":"Article 126716"},"PeriodicalIF":6.1,"publicationDate":"2025-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143936994","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":"Investigation of the localized discomfort due to vertical radiant asymmetry in a test room with radiant and mechanical ventilation systems","authors":"Beatrice Riccardi ,&nbsp;Marco Marigo ,&nbsp;Giacomo Tognon ,&nbsp;Michele De Carli ,&nbsp;Angelo Zarrella","doi":"10.1016/j.applthermaleng.2025.126787","DOIUrl":"10.1016/j.applthermaleng.2025.126787","url":null,"abstract":"<div><div>The indoor environmental conditions play a crucial role in the general well-being and performance of building occupants. As people nowadays spend an increasing amount of time indoors, the investigation of thermo-hygrometric comfort has become extremely relevant. Numerous studies have explored this issue, examining both on a general and localized level. The aim of this work is to specifically investigate localized discomfort while ensuring that general comfort is maintained. To achieve this condition a series of experiments was conducted in a test room, where the variation every 90 min of ceiling water supply temperatures (30 °C, 35 °C, 40 °C) created a vertical radiant asymmetry with the floor, whose temperature was maintained at a constant temperature (18 °C). The novelty of this work consists of the realistic room and HVAC settings, that represents a typical everyday environment, where thermal conditions change dynamically. A balance between air and radiant temperatures was necessary to achieve a neutral PMV, ensuring global thermal comfort while isolating localized discomfort. The 39 involved participants provided feedback on warm and cold sensations in specific body regions through structured questionnaires. Results reveal a clear progression of discomfort: warm sensations predominated in the upper body during initial phases, while cold sensations intensified in the lower extremities as air supply temperatures decreased.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"274 ","pages":"Article 126787"},"PeriodicalIF":6.1,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144071511","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":"Modeling and simulation of a novel thermal management strategy and temperature distribution in PEMFC","authors":"Yang Luo ,&nbsp;Mohammed A.H. Ali ,&nbsp;Nik Nazri Nik Ghazali ,&nbsp;Retna Apsari ,&nbsp;Wen Tong Chong ,&nbsp;Zhenzhong Yang ,&nbsp;Haichao Liu","doi":"10.1016/j.applthermaleng.2025.126772","DOIUrl":"10.1016/j.applthermaleng.2025.126772","url":null,"abstract":"<div><div>The thermal management control scheme is essential for ensuring an optimal performance of Proton Exchange Membrane Fuel Cells (PEMFC). An in-depth analysis of the temperature distribution within the fuel cell can provide insights for enhancing thermal management control scheme. This paper initially introduced a novel control technique, called the Integral laser simulator logic controller (ILSL), to control the stack and coolant inlet temperatures in PEMFC. The proposed ILSL controller has been compared with Integral fuzzy control strategy (IFL), PID control strategy (PID) and reinforcement learning based controllers for controlling the PEMFC stack and coolant temperature. The temperature distribution law inside the fuel cell is investigated using a joint simulation of MATLAB/Simulink and Fluent under the three temperature management schemes. The study findings indicate that the temperature control strategy employing the ILSL has several advantages in the temperature control process which include low overshoot, short regulation time, no static error and strong robustness. Based on the temperature distribution analysis, the ILSL controller can effectively prevent the risk of overheating in the high temperature zone and reduce the duration of high temperature.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"274 ","pages":"Article 126772"},"PeriodicalIF":6.1,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143941773","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":"Critical heat flux enhancement by breathing phenomenon induced by lotus/groove heat transfer surface","authors":"Kazuhisa Yuki ,&nbsp;Takuya Ide ,&nbsp;Kohei Yuki ,&nbsp;Tetsuro Ogushi ,&nbsp;Masaaki Murakami","doi":"10.1016/j.applthermaleng.2025.126776","DOIUrl":"10.1016/j.applthermaleng.2025.126776","url":null,"abstract":"<div><div>This study aims to dramatically enhance critical heat flux of a two-phase immersion cooling based on the breathing phenomenon induced by jointing a lotus type of a porous copper plate onto a grooved heat transfer surface, as a cooling technology for next-generation SiC-based automotive on-board inverters. First, the cooling mechanism is investigated by CFD simulation in order to obtain hints on how to further enhance the critical heat flux. The simulation demonstrates that when a large vapor bubble is discharged from the one-side groove end, the cooling liquid penetrates from the opposite end of the groove as well as from the lotus copper plate side. In that sense, not impeding the liquid supply by the liquid penetration from the groove end is one way to enhance the critical heat flux as well as reducing flow resistance of both the vapor and liquid flows in the groove. Based on the findings by the CFD simulation, we deepen the groove depth to improve the liquid supply, which leads to tremendous increase in the critical heat flux up to 735 W/cm² at the maximum (Cooling performance of 700 W/cm² at the wall superheat of 100 K) in saturated pool boiling experiments using water.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"274 ","pages":"Article 126776"},"PeriodicalIF":6.1,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144068179","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 coal purification-combustion system: Effects of activation atmosphere on product characteristics and system efficiency","authors":"Ruifang Cui ,&nbsp;Qiangqiang Ren ,&nbsp;Shaobo Yang ,&nbsp;Shaobo Han ,&nbsp;Yujie Hu","doi":"10.1016/j.applthermaleng.2025.126768","DOIUrl":"10.1016/j.applthermaleng.2025.126768","url":null,"abstract":"<div><div>To support the goal of carbon neutrality, a novel coal purification-combustion technology has been developed to enhance the clean and efficient utilization of coal. In this study, experiments were conducted on a 200 kW coal purification-combustion platform to systematically investigate the impact of activation atmospheres on fuel performance and process irreversibility. Thermodynamic analyses and physicochemical characterizations were employed to correlate microstructural evolution with macroscopic performance. Under a 29 % O₂/CO₂ activation atmosphere, the semi-coke produced with the most active sites and the lowest gasification activation energy. Moreover, during the high-temperature reduction (HTR) stage, enhanced gasification rates and increased yields of CO and H₂ effectively reduced irreversible losses. The highest exergy efficiency of 74.47 % was achieved during the purification process under 25 % O₂/CO₂ activation. By optimizing the exergy distribution of purified fuel and improving the combustion characteristics of purified fly ash, the irreversibility in the mild combustion unit was significantly reduced. Overall, under 25 % O₂/CO₂ condition, the purification-combustion system achieved a peak exergy efficiency of 54.5 %. In summary, this study provides valuable insights into enhancing coal utilization efficiency, advancing clean coal technology and promoting sustainable energy conversion.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"274 ","pages":"Article 126768"},"PeriodicalIF":6.1,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143947531","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 improving phase transition uniformity in elastocaloric regenerators","authors":"Yutong Wang ,&nbsp;Zetong Gan ,&nbsp;Chenqi Li ,&nbsp;Jungang Shi ,&nbsp;Yibingxin Fan ,&nbsp;Suxin Qian","doi":"10.1016/j.applthermaleng.2025.126756","DOIUrl":"10.1016/j.applthermaleng.2025.126756","url":null,"abstract":"<div><div>Elastocaloric cooling is an emerging novel solid-state cooling technology with the potential to reduce carbon emissions in the refrigeration sector. In elastocaloric cooling systems, the core component is the active elastocaloric regenerator that exchanges heat between elastocaloric materials and heat transfer fluid. However, the temperature gradient within the active regenerator leads to inhomogeneous phase transitions along the flow direction, which could result in degradation of cooling performance or even fatigue of the material. To mitigate such a problem, in this study, four improvement strategies are proposed, namely segmented constrained strain, segmented variable strain profile, variable cross-sectional area, and variable transition temperature of the material. A one-dimensional simulation model based on energy equations is constructed to evaluate their improvement potential. In addition, considering practical constraints, the feasibility and generalization of each enhancement scheme are discussed. It was found that altering the cross-sectional area of the elastocaloric material can achieve a uniform phase transition with a 76.0% improvement in specific cooling power (<em>SCP</em>) and a 92.4% improvement in elastocaloric effect (<em>eCE</em>) within achievable processing precision.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"274 ","pages":"Article 126756"},"PeriodicalIF":6.1,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143937075","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":"Channel geometry and throttling regulation effects on printed circuit Joule-Thomson cryocooler performance","authors":"Hailong She ,&nbsp;Guangzhong Hu ,&nbsp;Xiaoyu Cui ,&nbsp;Zhongbin Liu ,&nbsp;Hang Li ,&nbsp;Di Peng ,&nbsp;Zhe Zhao ,&nbsp;Peng Yin","doi":"10.1016/j.applthermaleng.2025.126785","DOIUrl":"10.1016/j.applthermaleng.2025.126785","url":null,"abstract":"<div><div>To solve the shortcomings of the current microchannel Joule-Thomson (J-T) cryocooler, such as monotonous channel configurations and limited parallelization, this study integrates printed circuit heat exchanger fabrication technology with distributed throttling refrigeration theory. A distributed J-T effect cryocooler featuring a multi-rectangular microchannel parallel structure was successfully developed. Performance investigations were conducted with the cryocooler as the prototype. By analyzing the thermodynamic parameter evolution of Ar at critical nodes, the weak link of the prototype was identified: the low J-T coefficient <span><math><msub><mi>μ</mi><mrow><mi>jt</mi></mrow></msub></math></span> at the throttling inlet limits overall efficiency. To resolve this, a dual optimization strategy was proposed. First, topology optimization of the channel form of the counterflow heat exchanger was implemented to enhance precooling. The results show that the airfoil fin channels exhibit superior performance compared to other configurations. When the inlet parameters are 6.0 MPa and 285.0 K, compared with the prototype, the cold-end temperature decreases from 194.9 K to 167.8 K, the J-T efficiency is increased from 49.1 % to 56.1 %. the airfoil geometry intensifies heat transfer, thereby promoting more significant distributed J-T effect and heat transfer coupling in the throttling section, which is the key to improving refrigeration performance. In addition, length ratio optimization between counterflow heat exchanger and throttle was explored. The results show that increasing the length ratio of the throttling channel can effectively suppress the limit velocity of the fluid, thus delaying the occurrence of choked flow. Conversely, reducing this proportion lowers the cold-end temperature. constrained by choked flow limits, the minimum throttling length under the conditions described in this study is 12 mm, achieving a further temperature drop to 136.4 K, with peak J-T efficiency (74.1 %) and heat flux (2.77 W/mm). The established dual optimization framework, structural refinement and zonal proportioning, provides theoretical and technical guidance for for designing high-performance microchannel J-T cryocoolers.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"274 ","pages":"Article 126785"},"PeriodicalIF":6.1,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143947328","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":"Visual experimental study on subcooled boiling characteristics in a manifold jet microchannel heat sink","authors":"Wenhao Fan ,&nbsp;Jing Wang ,&nbsp;Wei Liu ,&nbsp;Zhichun Liu ,&nbsp;Haichuan Cui","doi":"10.1016/j.applthermaleng.2025.126788","DOIUrl":"10.1016/j.applthermaleng.2025.126788","url":null,"abstract":"<div><div>Jet microchannel cooling technology, integrating the compactness of microchannel architectures with the high efficiency of jet impingement, presents a promising approach for extreme heat flux thermal management. Current research remains predominantly confined to single-phase heat transfer owing to limited understanding of gas–liquid interfacial dynamics and phase-change mechanisms within these systems. To bridge this gap, a two-phase flow visualization platform was developed to systematically investigate the thermal performance and flow resistance of a manifold jet microchannel heat sink operating under subcooled boiling. Analysis of bubble dynamics and surface temperature revealed a wall temperature reduction of 0.3∼2.1 °C (termed “temperature overshoot”) upon reaching the onset of nucleate boiling (ONB), with the overshoot magnitude increasing proportionally with higher flow rates and lower inlet liquid temperatures. The impacts of operational parameters (inlet flow rate, temperature, and heat flux) and flow pattern transitions on boiling heat transfer and flow resistance were rigorously characterized. Notably, periodic boiling cycles (100∼180 ms duration) near the ONB threshold were identified, exhibiting progressive temporal compression under elevated flux or reduced inlet temperatures. Furthermore, distinct bubble behaviors linked to two-phase flow patterns were correlated with significant alterations in thermal resistance and pressure drop. These findings provide fundamental insights into phase-change mechanisms in microconfined spaces, advancing the rational design of high-flux thermal management systems.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"274 ","pages":"Article 126788"},"PeriodicalIF":6.1,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143942009","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 lobe-type rear variable area bypass injector on flow field characteristics in a variable cycle engine model afterburner under different modes","authors":"Zhijie He,&nbsp;Guanghai Liu,&nbsp;Yuying Liu","doi":"10.1016/j.applthermaleng.2025.126791","DOIUrl":"10.1016/j.applthermaleng.2025.126791","url":null,"abstract":"<div><div>The influence of the rear variable area bypass injector (RVABI) on the flow field characteristics of the afterburner is crucial, particularly for combustion stability in a variable cycle engine (VCE), as both the bypass ratio and the flow pattern vary significantly under different modes. Herein, the evolution of vortex structure and the characteristics of the recirculation zone (RZ) are numerically investigated in a VCE afterburner configured with lobe-type RVABI, core-region stabilizer (CRS), and mixing-region stabilizer (MRS). The results show that in the three-bypass mode, the large-scale streamwise vortices induced by lobe-type RVABI split into pairs when interacting with MRS, and then the orthogonal vortices are formed, which leads to significant asymmetry in spanwise vortex structures and a shortened RZ shape. Compared with the CRS, the length and width of RZ behind MRS are reduced by up to 29.94% and 28.21%, accompanied by migration of the asymmetric spanwise vortex core. This phenomenon is attributed to the mass transport within RZ under the entrainment effect of streamwise vortices behind MRS. Moreover, in the two-bypass mode, the disturbances caused by RVABI to MRS and CRS are both weak, and the symmetric RZ shapes and stable spanwise vortices for both stabilizers are maintained, which is different from those in the three-bypass mode.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"274 ","pages":"Article 126791"},"PeriodicalIF":6.1,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144071512","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":"Design and optimization of falling film absorbers by air flow modification for cold store dehumidification using a newly developed open-source OpenFOAM-based CFD solver","authors":"Felix Hochwallner ,&nbsp;Clarissa Stracke ,&nbsp;Johann Emhofer ,&nbsp;Christoph Reichl","doi":"10.1016/j.applthermaleng.2025.126478","DOIUrl":"10.1016/j.applthermaleng.2025.126478","url":null,"abstract":"<div><div>This study investigates the design and optimization of falling film absorbers with vertical plates by air flow modification for dehumidification in cold store applications. Two novel absorber designs – the wire geometry and the stacked arrangement – were developed and analyzed using a newly created open-source computational fluid dynamics (CFD) solver based on OpenFOAM. The study addresses the limited vapor diffusion from the humid air core to the desiccant film surface, a critical constraint in falling film absorbers.</div><div>The wire geometry, incorporating wires into the air channel, significantly enhances mixing of the air flow through induced vortex shedding. A single 1.5 mm wire increased the absorbed mass flow rate by up to 28%, allowing for a 35% shorter absorber but raising the pressure drop by 60%. The stacked arrangement, featuring offset absorber steps to ensure contact between the humid air core and the desiccant surface, demonstrated superior performance. With three absorber steps, the design reduced the absorber length by 25% while limiting the increase in pressure drop to 25%. Thus, the stacked arrangement achieved similar absorption improvements as the wire geometry with significantly lower pressure drop, making it the more suitable for practical use.</div><div>The open-source solver developed in this study facilitates reproducibility and provides a platform for further research in open absorption systems. These findings highlight the potential of falling film absorbers to enhance energy efficiency in cold store by preventing frost formation and utilizing low-grade waste heat for desiccant regeneration. The results pave the way for industrial implementation of these optimized designs, with the stacked arrangement offering the most compelling balance of performance and efficiency.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"274 ","pages":"Article 126478"},"PeriodicalIF":6.1,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143941771","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}