Applied Thermal Engineering最新文献

{"title":"Thermal performance and visualization of dual-diameter channel pulsating heat pipes additively manufactured through stereolithography","authors":"Md. Jubayer Hossain,&nbsp;Max Pawlick,&nbsp;Bhavin Yardi,&nbsp;Satish Kumar","doi":"10.1016/j.applthermaleng.2025.127318","DOIUrl":"10.1016/j.applthermaleng.2025.127318","url":null,"abstract":"<div><div>As two-phase passive heat transfer devices, pulsating heat pipes (PHPs) have attracted widespread research interest for their potential to enhance heat dissipation and contribute to energy-efficient thermal management. This study experimentally assesses the thermal behavior and flow-characteristics of PHPs fabricated using Stereolithography (SLA) additive manufacturing technology. The investigation focuses on PHPs with dual-diameter channels, also called non-uniform channels, in three configurations: 2-turn center-heated, 10-turn center-heated, and 10-turn end-heated. Experiments were performed in vertical and horizontal orientations using acetone, except in one test with deionized (DI) water for performance comparison. For baseline comparison, tests were also conducted on uncharged PHPs. Results reveal that 2-turn PHP failed to initiate startup in the horizontal orientation, while all 10-turn PHPs started successfully, emphasizing the importance of increasing turns, even with a capillary-enhanced dual-diameter channel. The 10-turn center-heated PHP demonstrated orientation-independent operation with the lowest thermal resistance of ∼4.7 K/W, slightly outperforming end-heated cases. With DI water, the 10-turn PHP reached 121 °C evaporator temperature at 38.5  W. Flow visualization was conducted to capture fluid movement throughout the PHP channels for 10-turn PHPs in both orientations, revealing differences in flow stability, oscillation amplitude, and liquid distribution, particularly emphasizing the influence of initial fluid distribution on startup in vertical orientations. Evaluation of effective thermal conductivity indicates conventional methods overestimate it for polymer-PHPs by disregarding axial-conduction through heat sources and sinks. A refined methodology is proposed for improved accuracy. These insights pave the path for optimizing polymer-based PHPs for thermal management applications requiring low-mass, low-cost, or electrically insulating solutions.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"278 ","pages":"Article 127318"},"PeriodicalIF":6.1,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144534270","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 and machine learning-based investigation of additively manufactured PCM encapsulation geometries for enhanced thermal and electrical performance in battery thermal management system","authors":"Abid Ustaoglu ,&nbsp;Bilal Kursuncu ,&nbsp;Ferhat Yıldız ,&nbsp;Junnosuke Okajima","doi":"10.1016/j.applthermaleng.2025.127309","DOIUrl":"10.1016/j.applthermaleng.2025.127309","url":null,"abstract":"<div><div>In this study, the thermal and electrical performances of phase change material (PCM) based battery thermal management systems (BTMS) with different macro-encapsulation geometries (hexagonal – Hx, square – Sq, circle – Cr) and produced by additive manufacturing method were experimentally evaluated. The developed BTMS structures provided a safe and stable structure by preventing PCM leakage and direct contact with the battery. Hexagonal (Hx) geometry showed superior thermal performance compared to other geometries by providing the lowest battery temperatures at all C rates. Hx BTMS limited the increase in internal resistance by increasing the heat transfer from the battery to the PCM, thus maintaining voltage stability and increasing the energy density by up to 6.90 %. At high discharge rates, the latent heat storage feature of PCM was activated only in the Hx structure, and this made active heat management possible. It was shown in the analyses performed with an artificial neural network (ANN) that the experimental data could be predicted with high accuracy, and it was determined by SHAP analysis that Hx geometry had the highest positive effect on the voltage. These results demonstrate the critical importance of macro-encapsulation geometry in BTMS design and demonstrate that Hx geometry offers a superior solution in terms of thermal safety, voltage stability, and long cycle life.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"278 ","pages":"Article 127309"},"PeriodicalIF":6.1,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144500873","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":"Feasibility and thermodynamic analysis on rural building envelope energy storage-photovoltaic electric heating system on the Qinghai-Tibet Plateau","authors":"Yuhao Yi ,&nbsp;Chuan Xiong ,&nbsp;Jinwei Li ,&nbsp;Mengsi Deng ,&nbsp;Zongyan Li ,&nbsp;Yitong Luo ,&nbsp;Ke Zhang ,&nbsp;Rongjiang Ma","doi":"10.1016/j.applthermaleng.2025.127323","DOIUrl":"10.1016/j.applthermaleng.2025.127323","url":null,"abstract":"<div><div>Utilizing the building envelope energy storage-photovoltaic electric heating system to fully realize the rural residential space heating requirements is an effective approach to achieve clean energy utilization on the Qinghai-Tibet Plateau. However, there is currently no research confirming the feasibility of this system throughout the heating season and no performance analysis and optimization research, which leads to a lack of effective system design principles. The task of this paper is to address the above issues. To this end, the feasibility and thermodynamic analysis are completed by numerical simulation methods with a typical rural house on the Qinghai-Tibet Plateau as the object. Firstly, the numerical model of the system is established in the MATLAB software based on the photovoltaic cell engineering model and the finite difference method. Then, the feasibility analysis is carried out based on the two-level feasibility analysis method proposed in this paper, and the effective conclusions of the building insulation renovation ideas, photovoltaic capacity configuration principles, and system operation strategies are summarized. Moreover, the thermodynamic analysis of the system is carried out based on energy and exergy parameters, and the process optimization principle is proposed. The thermal efficiency and exergy efficiency of the system under the typical condition are 85.13% and 14.35% respectively. This paper recommends selecting the inner wall as the thermal storage building envelope and increasing its area as much as possible. Meanwhile, it is recommended to set the electric heating film in the middle of the building envelope. Based on this principle, the process is optimized, and the photovoltaic self-sufficiency ratio for heating of the optimized system improves to 97.69 %. The relevant conclusions provide effective theoretical guidance and process design principles for rural building envelope energy storage-photovoltaic electric heating system on the Qinghai-Tibet Plateau.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"278 ","pages":"Article 127323"},"PeriodicalIF":6.1,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144513902","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":"Optimizing geometry of linear thermoelectric generators for enhanced performance","authors":"Boyang Liang,&nbsp;Xiangning Meng,&nbsp;Zhuang Miao,&nbsp;Xi Li","doi":"10.1016/j.applthermaleng.2025.127313","DOIUrl":"10.1016/j.applthermaleng.2025.127313","url":null,"abstract":"<div><div>Thermoelectric conversion technology enables the direct transformation of thermal energy into electrical energy. Thermoelectric generator (TEG) based on this technology offer numerous advantages and have been widely utilized. Conventional TEGs tend to develop significant thermal stress concentration on the hot side during operation, thereby shortening TEG lifespan. Recent studies have proposed linear TEG structures that partially relieve stress concentrations but have very limited heat transfer efficiency. Moreover, the impact of thermoelectric leg geometry on the performance of linear TEGs has not been fully investigated. In this study, a novel linear TEG structure is proposed, based on the existing linear design. Numerical simulations indicate that the proposed structure reduces thermal stress and deformation by 54.3 % and 18.6 %, respectively, and increases the maximum output power to 119.17 mW, representing a 6.59 % improvement. The results also reveal that stress and deformation are primarily concentrated along the edges of the thermoelectric legs. Based on this observation, eight leg geometries were designed and analyzed to further optimize performance. The thermal stress and distortion of the optimized configuration are further reduced to 62.96 % and 19.11 % respectively. Among these, the cylindrical leg design demonstrated the highest conversion efficiency. Finally, cross-validation confirmed the effectiveness and robustness of the geometric optimization strategy for linear TEG structure.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"278 ","pages":"Article 127313"},"PeriodicalIF":6.1,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144500861","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":"Performance of the PEMEC for hydrogen production and two-phase flow under gradient flow field conditions","authors":"Hengkai Li ,&nbsp;Cong Sun ,&nbsp;Huangang Shi ,&nbsp;Jifa Qu ,&nbsp;Wenyi Tan","doi":"10.1016/j.applthermaleng.2025.127315","DOIUrl":"10.1016/j.applthermaleng.2025.127315","url":null,"abstract":"<div><div>The gradient flow field of a proton exchange membrane electrolysis cell (PEMEC) is favorable for improving electrical performance. The effects of the gradient flow field structure and operating parameters on the electrical performance of a PEMEC were revealed via optical visualization techniques according to bubble–water two-phase flow. The results show that the gradient type II flow field proposed in this paper has a smaller pressure drop, smaller bubble size and uniform distribution than the traditional parallel flow field and serpentine flow field do, which is conducive to the discharge of oxygen bubbles and is more suitable for PEMEC. An increase in the inlet flow rate favors the removal of bubbles in the flow channel. Moreover, additional water plays a cooling role in the PEMEC. The temperature effect overwhelms the turbulent effect of the flow field; therefore, the performance is slightly reduced under the overall influence.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"278 ","pages":"Article 127315"},"PeriodicalIF":6.1,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144518902","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":"Energy and exergy evaluation of R404A and R290 in a shelf-cooled commercial vertical deep freezer","authors":"Egemen Biçen,&nbsp;Seda Kırmacı Arabacı","doi":"10.1016/j.applthermaleng.2025.127287","DOIUrl":"10.1016/j.applthermaleng.2025.127287","url":null,"abstract":"<div><div>The European Union F-Gas regulation has accelerated the transition from high-GWP refrigerants to environmentally friendly alternatives in commercial vertical refrigeration systems. This study experimentally investigates the use of R290-propane as a replacement for R404A-hydrofluorocarbon in a shelf-cooled commercial vertical deep freezer without modifying external components. While previous studies primarily focused on energy analyses, this research uniquely integrates both energy and exergy evaluations. Experimental results show that the R290 system demonstrated a 7 % higher coefficient of performance and a 17 % increase in exergy efficiency compared to the R404A system, confirming its superior thermodynamic behavior. The total exergy losses in the R290 system were approximately 0.043 kW lower, primarily influenced by enhanced compressor performance, which contributed the most to system irreversibilities. Additionally, the system’s equivalent carbon emissions were reduced by 99.92 %, highlighting its significant environmental advantages. These findings demonstrate that R290 is a highly efficient and sustainable alternative to R404A for commercial vertical refrigeration, offering improved thermodynamic performance, lower energy consumption, and a substantially reduced carbon footprint.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"278 ","pages":"Article 127287"},"PeriodicalIF":6.1,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144549326","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":"Solar still performance enhancement with reflectors and various shapes of absorber plates","authors":"Ali Maghsoudian ,&nbsp;Saman Rashidi ,&nbsp;Roohollah Rafee","doi":"10.1016/j.applthermaleng.2025.127261","DOIUrl":"10.1016/j.applthermaleng.2025.127261","url":null,"abstract":"<div><div>Considering the importance of desalination and the freshwater crisis in the world, as well as the low efficacy of solar still distillation systems, it is important to enhance the productivity of solar desalination systems using proper techniques. In this experimental study, two devices were built and two methods were applied to improve the productivity of solar still systems. The first method is to corrugate the absorber plate to have higher surfaces for evaporation and solar radiation absorption, and the second method is to use reflective mirrors. So far, various methods have been used to enhance the performance of the solar stills, but in this study, for the first time, the simultaneous effect of using upper and lower reflective mirrors and different geometries of the absorber plate on the efficiency enhancement of solar still systems have been investigated. The purpose of this study is to conduct several tests on the solar desalination devices with reflectors and different absorber plates, including a simple absorber plate, a triangular absorber plate. The reflectors are used to increase the solar radiation absorption by the evaporation unit of the solar desalination device. It was found that the production of freshwater is higher by using the triangular absorber plate as compared with square and simple absorber plates. The use of reflectors significantly increases freshwater production during the afternoon hours. The lowest cost of 0.036 $/L/m2 for producing freshwater belongs to the solar still with an external reflector and a triangular absorber plate. The highest daily efficiency of 32.1% was reported for the solar still with a reflector and a triangular absorber plate. Using a reflector in the solar still system enhances the efficiency of freshwater production by 26% compared to a desalination system without a reflector. Using a triangular absorber plate and a square absorber plate in a solar still increases the efficacy of freshwater production by 25.7% and 20%, respectively, compared to a desalination system with a simple absorber plate.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"278 ","pages":"Article 127261"},"PeriodicalIF":6.1,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144500875","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 phase change material-based thermoelectric generation system for near-earth satellites: Enabling continuous power supply and thermal regulation","authors":"Jiameng Song,&nbsp;Zhibin Li,&nbsp;Youwei Yang,&nbsp;Yong Shuai","doi":"10.1016/j.applthermaleng.2025.127187","DOIUrl":"10.1016/j.applthermaleng.2025.127187","url":null,"abstract":"<div><div>Low Earth Orbit (LEO) satellites experience extreme temperature fluctuations due to the alternating day–night cycles, making it challenging for traditional power supply systems to ensure continuous power generation. This work presents a novel thermoelectric generation (TEG) system incorporating phase change materials (PCM) and a decoupled equivalent filling model. Unlike conventional 3D FEM approaches that often suffer from convergence issues and high computational cost, the proposed model simplifies thermal–electric coupling while achieving a temperature error of less than 1.05% and a power error of less than 1.4% under high heat flux conditions. The system also analyzes the balance between solar radiation absorption and thermal dissipation in circular LEO. By incorporating PCM, the system achieves temperature stabilization (fluctuation <span><math><mo>&lt;</mo></math></span> ±5 °C) and efficient waste heat utilization. Using a transient finite element model, the optimal operating performance of the TEG module was investigated at different orbital altitudes. Unlike conventional 3D FEM approaches that often suffer from convergence issues and high computational cost, the proposed model simplifies thermal–electric coupling while achieving a temperature error of less than 1.05% and a power error of less than 1.4% under high heat flux conditions. Although the current energy density of the system is relatively low (approximately 0.1 Wh/kg), future improvements in TEG efficiency and thermal management optimization could make this system a promising solution for providing reliable continuous power to LEO satellites.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"278 ","pages":"Article 127187"},"PeriodicalIF":6.1,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144490100","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":"Modelling the effects of particle migration and viscous dissipation on a nanofluid-cooled microchannel heat sink using porous medium approach","authors":"A.K.W. Loh,&nbsp;G.M. Chen,&nbsp;B.K. Lim","doi":"10.1016/j.applthermaleng.2025.127299","DOIUrl":"10.1016/j.applthermaleng.2025.127299","url":null,"abstract":"<div><div>This study investigates the combined effect of particle migration, specifically Brownian diffusion and thermophoresis, and viscous dissipation on fluid flow and heat transfer of titania-oxide nanofluids in an asymmetrically heated microchannel heat sink as the transport of nanofluids alters its momentum diffusion and the heat advection. The heat sink is modelled using the porous medium approach and the solid and fluid temperatures are solved numerically using MATLAB’s BVP4C solver. The presence of solid fins causes a more uniform fluid velocity and temperature profile, with heat transfer dominated by solid conduction due to the solid fins’ high thermal conductivity. Particle migration enhances heat advection near the heated wall and improves heat diffusion in the core, resulting in an increase of up to 5.11 % in Nusselt number (<em>Nu</em>) when the porosity of the porous medium is 0.9. However, viscous dissipation dilutes the <em>Nu</em> enhancement due to particle migration, leading to a deterioration of up to 4.76 % as the Brinkman number (<em>Br</em>) increases from 0 to 5. Titania-oxide water nanofluid lowers the thermal resistance for fluid conduction near the heated wall and increases the heat transfer coefficient by up to 12.78 %. The more dominant effect of the increased viscosity over the increased thermal conductivity in the nanofluid, however, leads to a Performance Evaluation Criteria (<em>PEC</em>) <span><math><mrow><mo>&lt;</mo><mn>1</mn></mrow></math></span> trend for Brownian Diffusivity to Thermophoretic Diffusivity Ratio (<em>N_BT</em>) in the range of 1 and 5 and <em>Br</em> in the range of 0 and 5. This numerical study incorporates particle migration in the porous medium approach to model a microchannel heat sink, offering insights on the local heat transfer effects due to the use of nanofluids.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"278 ","pages":"Article 127299"},"PeriodicalIF":6.1,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144519165","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":"Characterization of CO2 fluid crossing critical region flow and heat transfer in a vertical loop. Part ΙI: mode analysis","authors":"Dong Yang ,&nbsp;Yongchang Feng ,&nbsp;Rufan Song ,&nbsp;Igor Pioro ,&nbsp;Lin Chen","doi":"10.1016/j.applthermaleng.2025.127305","DOIUrl":"10.1016/j.applthermaleng.2025.127305","url":null,"abstract":"<div><div>Supercritical circulation loop flow and heat transfer is crucial for the application design of nuclear power and also for solar thermal conversion systems. In this study, the transcritical flow and heat transfer behavior of CO₂ flowing upward in a vertical circular loop has been numerically and experimentally investigated. In Part I of this study, basic experimental system verification and trend analysis have been reported. In Part II, five heat transfer modes have been categorized and the effects the transcritical interface, radial physical properties, and heat transfer mechanisms have been explained. The analysis of the interface evolution along with heat transfer behaviors in this study revealed that the thinner gas-like layer (<em>d</em>/<em>R</em> &lt; 0.1) undergoes radial expansion and competes with the liquid-like layer, intensifying heat transfer along the flow direction. When the subcritical-to-supercritical transition area reaches the core of the circular tube, the distance between the interface and the wall continuously increases, leading to a thicker gas-like layer (<em>d</em>/<em>R</em> &gt; 0.1) and consequently decrease the heat transfer capacity. From Mode I to Mode IV, and to Mode V, with the increase of inlet temperature or the increase of boundary heat input intensity, the “cross pseudo-critical interface” will move and interacts with core flow, then heat transfer can be categorized, to be several different modes and contribute to normal heat transfer, enhanced heat transfer and/or deteriorated heat transfer.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"278 ","pages":"Article 127305"},"PeriodicalIF":6.1,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144549235","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}