Applied Thermal Engineering最新文献

{"title":"Enhancing the thermal energy storage performance of multiphase PCM using triply periodic minimal surface structures","authors":"Haonan Yang,&nbsp;Zhaohui Wang,&nbsp;Rongqing Bao,&nbsp;Zhengding Zheng,&nbsp;Shousheng Hong","doi":"10.1016/j.applthermaleng.2026.133459","DOIUrl":"10.1016/j.applthermaleng.2026.133459","url":null,"abstract":"<div><div>Phase change materials (PCMs) are hindered by low thermal conductivity and the limitation of a single melting point in coping with complex thermal conditions, which significantly constrains the thermal regulation capability and thermal response rate of latent heat thermal energy storage systems. To overcome this bottleneck, this study exploits the triply periodic minimal surface (TPMS) structures, which offer both high specific surface area and spatially independent compartmentalization, to systematically investigate the thermal storage performance of single-phase and multi-phase PCMs under different spatially segregated configurations. The results reveal that, in single-phase systems, elevating the PCM melting point nonlinearly extends the complete melting time; when the melting point is set at 313 K, the latent heat contribution reaches its maximum proportion and the system achieves the highest thermal storage rate. By utilizing TPMS to divide the enclosed space into two independent regions, this study constructs a multi-phase PCM system. The advantage of this system lies in its synergistic functionality: the low-melting-point component enables rapid heat absorption, while the high-melting-point component sustains long-term thermal storage, thereby allowing the system to maintain continuous heat absorption across the entire temperature range. The results indicate that when a single-phase system with a melting point of 324 K is replaced by a multi-phase combination, the heat absorption rates of the P type and G type structures are enhanced by 17.0% and 22.2%, respectively. During the discharge stage, the solidification sequence of the multi-phase system is opposite to that of the melting process, and the total solidification time is primarily governed by the low-melting-point component. Without altering the total heat release, the multi-phase system can effectively modulate the discharge rate by flexibly combining PCMs with different melting points. This study provides important theoretical support for the selection of multi-phase materials and the design of TPMS structures in latent heat thermal energy storage systems.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"307 ","pages":"Article 133459"},"PeriodicalIF":7.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149156572","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 cooling performance of a radiative sky water-cooling module with serpentine channels: experiments and CFD simulation","authors":"Yifei Li,&nbsp;Dongyang Ren,&nbsp;Tao Wu,&nbsp;Jiqin Li,&nbsp;Yiqiang Jiang","doi":"10.1016/j.applthermaleng.2026.133420","DOIUrl":"10.1016/j.applthermaleng.2026.133420","url":null,"abstract":"<div><div>The radiative sky water-cooling module (RSWCM) utilizes a radiative cooling surface to reject heat to the cold sky, thereby cooling circulating water. This technology has potential applications in building energy savings, auxiliary cooling in air-conditioning systems, and condenser cooling in power plants. While previous research to enhance cooling performance has focused primarily on optimizing the optical properties of radiative cooling materials, the influence of internal flow-channel structures on water-side heat transfer in RSWCMs remains inadequately investigated. To address this gap and enhance water-side heat transfer through optimized internal flow routing, this study proposes a serpentine-channel RSWCM and comprehensively evaluates its dynamic cooling performance through outdoor experiments and numerical simulations. The results reveal that the serpentine channel re-routes the internal flow, leading to a moderate increase in the average cooling power from 65.18 to 66.72 W/m². Increasing the channel number enhances water-side heat transfer, albeit with diminishing marginal returns in cooling gain. Furthermore, as the channel height increases from 5 to 15 mm, the average cooling power decreases from 65.59 to 49.44 W/m², indicating that a smaller channel height is more advantageous for water-side cooling performance. Increasing the flow rate from 30 to 480 mL/min raises the average cooling power from 58.50 to 71.94 W/m², but simultaneously reduces the average temperature drop from 2.46 to 0.21 °C. Additionally, as the tilt angle increases from 0° to 90°, the average cooling power decreases from 66.59 to 33.61 W/m², indicating that a horizontal orientation is preferable under the investigated nighttime conditions.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"307 ","pages":"Article 133420"},"PeriodicalIF":7.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149156575","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":"Gas-particle flow, low-load combustion and anti-slagging characteristics of prototype and improved burners for Zhundong coal boiler: From laboratory to industrial scale","authors":"Zheng Liu,&nbsp;Chujun Chen,&nbsp;Zhengqi Li","doi":"10.1016/j.applthermaleng.2026.133433","DOIUrl":"10.1016/j.applthermaleng.2026.133433","url":null,"abstract":"<div><div>Against the background of deep peak shaving requirements and severe slagging and burnout issues of swirl burners in Zhundong coal-fired boilers, an improved Inner-Pulverized-Coal-Concentration (IIPCC) burner is proposed in this study. The flow and combustion characteristics of the original Outer-Pulverized-Coal-Concentration (OPCC) burner and the IIPCC burner are systematically investigated via a 1:6 cold-state gas-solid two-phase test and 600 MW industrial experiments. The results show that central air significantly suppresses the recirculation zone and delays ignition of the OPCC burner; reducing central air opening advances ignition only slightly, and the minimum stable combustion load remains as high as 60% rated load. Compared with the OPCC burner, the IIPCC burner removes central air, adds swirling slit air and three-stage concentration rings, and optimizes the secondary air nozzle. It forms a larger recirculation zone (max height from 0.22d to 0.33d), weakens the near-nozzle recirculation intensity (recirculation ratio from 24.10% to 18.36%), and achieves obvious internal-rich and external-lean pulverized coal distribution. Based on these cold model gas/particle experiments and flow field analysis, the IIPCC burner is projected to achieve stable combustion at a 20% rated load, and reduce the risk of burner slagging and burnout. This new technology exhibits a high engineering value, with simple modification and low cost, providing a feasible technical solution for deep peak shaving and anti-slagging retrofit of Zhundong coal-fired boilers.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"307 ","pages":"Article 133433"},"PeriodicalIF":7.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149156652","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":"Cascading pit thermal energy storage: enabling simultaneous heating and cooling in centralized district energy systems","authors":"Michael Bayer,&nbsp;Artem Sotnikov,&nbsp;Abdulrahman Dahash,&nbsp;Heimo Walter,&nbsp;Willy Villasmil","doi":"10.1016/j.applthermaleng.2026.133365","DOIUrl":"10.1016/j.applthermaleng.2026.133365","url":null,"abstract":"<div><div>Fifth generation district heating and cooling (5GDHC) networks enable simultaneous heating and cooling and the integration of renewable heat at low temperatures, but rely on distributed, hydraulically complex architectures. Centralized district heating and cooling (DHC) systems are operationally simpler, yet conventional centralized storage in a single large volume spanning a wide temperature range limits thermal stratification and cannot serve heating and cooling simultaneously, which precludes renewable integration in systems without chillers. This study introduces a cascading storage concept in which the total seasonal storage volume is distributed across three units: a high temperature unit, a low temperature unit, and a buffer unit between them. Because the storage is split into narrower temperature ranges, the cascade preserves stratification through its architecture rather than within a single wide volume, enabling simultaneous heating and cooling and the integration of external heat at suitable temperatures from a centralized design. The cascade is evaluated with dynamic system simulations and benchmarked against a centralized single storage base case and against bidirectional and reservoir network configurations under identical boundary conditions. The uninsulated cascade reaches a stratification deviation index of 0.13 after 90 days, outperforming the insulated single storage case (0.23), cuts electricity consumption by 46% versus the base case, and reaches a seasonal performance factor of 5.8 that matches the 5GDHC benchmarks at comparable cost. Beyond new installations, the concept offers a route to decarbonize existing centralized DHC networks by adding cooling and integrating renewable heat at lower supply temperatures, without converting to a distributed architecture.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"307 ","pages":"Article 133365"},"PeriodicalIF":7.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149156927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Leakage control and cooling mechanisms in LO2 lubricated mechanical seals with backflow channels under high-speed conditions","authors":"Xuezhong Ma,&nbsp;Hao Chen","doi":"10.1016/j.applthermaleng.2026.133393","DOIUrl":"10.1016/j.applthermaleng.2026.133393","url":null,"abstract":"<div><div>To address the problem that low-viscosity media are prone to causing excessive leakage of mechanical seals under high-speed conditions, this paper proposes a leakage suppression scheme based on the channel backflow control. A continuous boiling numerical model for mechanical seals is established, considering the fluid film, channel fluid, sealing chamber fluid, and sealing rings. The leakage control and cooling mechanisms of mechanical seals under high-speed conditions are systematically investigated. The results show that when the rotor rotates at high speed, fluid enters the sealing clearance from the sealing chamber. Due to the hydrodynamic effect, a local high-pressure region forms at the downstream pumping groove root, where the pressure exceeds the sealing chamber pressure. A portion of the fluid is pumped into the channel, flows back to the sealing chamber, and subsequently re-enters the sealing clearance. Thus, a complete circulation is formed between the sealing clearance and the sealing chamber. Continuous fluid exchange realizes leakage suppression and active dissipation of frictional heat on the sealing end faces. At 20000 r/min, the backflow channels reduce the leakage rate by 54.16% compared with the double-row spiral groove seal due to the backflow pumping effect. Meanwhile, the backflow pumping effect enables effective heat migration, reducing the end face temperature rise by 9.53% and the vapor area ratio by 5.14% correspondingly. The backflow pumping effect weakens with increasing inlet temperature, film thickness, and downstream pumping groove depth, but strengthens with increasing rotational speed and channel inlet angle. When high-pressure fluid flows back into the sealing chamber, radial impingement generates two vortices. An increase in medium pressure enlarges the vortex area, thereby significantly enhancing heat transfer on the outer sidewalls of sealing rings. The results show that the proposed scheme effectively controls seal leakage and sealing face temperature rise.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"307 ","pages":"Article 133393"},"PeriodicalIF":7.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149156876","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":"Hybrid parabolic dish-fresnel lens solar system with transparent dual-aperture baffle-guided receiver: Comprehensive energy and exergy analysis","authors":"Vahid Madadi Avargani,&nbsp;Syed Imtiaz,&nbsp;Salim Ahmed,&nbsp;Sohrab Zendehboudi","doi":"10.1016/j.applthermaleng.2026.133408","DOIUrl":"10.1016/j.applthermaleng.2026.133408","url":null,"abstract":"<div><div>This study proposes a transparent dual-aperture receiver with baffle-guided spiral flow for hybrid solar parabolic dish concentrator (PDC) and Fresnel lens (FRL) systems. Transparent walls on both faces admit the reflected and transmitted beams into the receiver's internal surfaces, while radial baffles guide the fluid across both irradiated surfaces in series. A transient framework coupling Monte Carlo ray tracing (MCRT), computational fluid dynamics (CFD), conjugate heat transfer, and exergy analysis is validated against experimental data with mean absolute percentage errors below 1.2%, within the ±1.41 °C measurement uncertainty. The flow stays laminar at pressure drops of 4.90–19.16 Pa. At 25 °C inlet temperature, a water mass flow rate of 100 kg/h, and a peak direct solar irradiance of 1050 W/m², the receiver delivers 64.6% thermal efficiency, 2.08% exergy efficiency, and 4890 W peak useful heat. Reducing water flow rate from 150 to 75 kg/h improves exergy efficiency by 136%, and raising inlet temperature from 20 to 30 °C raises exergy gain by 137%, through the higher exergy of a hotter outlet. The off-focal position <em>R</em>_<em>PDC</em> = 0.9 gives 72.5% thermal efficiency, 2.67% exergy efficiency, and 5424 W peak useful heat. Against a bare-type receiver of equal fluid volume, the design increases daily thermal efficiency from 45.0% to 59.3% and exergy efficiency from 2.15% to 3.98%; against a single dish, it delivers 13.3% higher thermal efficiency, 39.6% higher exergy efficiency, and 60% higher exergy gain. Although the receiver achieves high thermal efficiency, its low exergy efficiency reflects the inherent second-law penalty associated with converting concentrated solar radiation into low-temperature heat. Thus, the proposed system is better suited to higher-temperature thermal applications than to conventional low-temperature water heating.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"307 ","pages":"Article 133408"},"PeriodicalIF":7.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149156563","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":"Optimization of thermoelectric generators with a finned phase change material heat sink for energy harvesting","authors":"Daniel Jalontzki,&nbsp;Moshe Bukai,&nbsp;Yoram Kozak","doi":"10.1016/j.applthermaleng.2026.133396","DOIUrl":"10.1016/j.applthermaleng.2026.133396","url":null,"abstract":"<div><div>In this study, we investigate thermoelectric generators (TEGs) coupled with a phase change material (PCM) heat sink for enhanced energy harvesting. An integrated experimental and numerical approach is employed, in which a TEG array is connected to an aluminum plate-fin heat sink filled with <span><math><mi>n</mi></math></span>-Eicosane and subjected to a constant heat flux. The numerical model is carefully validated against the experimental measurements. The results reveal the existence of an optimal PCM-to-fin thickness ratio and heat flux that maximize the total electrical energy output during the melting cycle. At these optimal conditions, the PCM melting time coincides with the time at which the TEG hot side reaches its maximum allowable temperature. Motivated by these findings, a semi-analytical model is developed to predict the optimal design parameters. The model shows good agreement with the numerical results, with discrepancies below 10% for the optimal fin spacing, thermal power, and the corresponding maximum harvested energy. Furthermore, the theoretical analysis suggests that, for a PCM with high latent heat and highly conductive fins with a sufficiently large TEG-to-heat-sink thermal resistance ratio, the optimal design parameters – PCM-to-fin thickness ratio and thermal power – are only weakly sensitive to the PCM latent heat, melting temperature, and maximum allowable TEG temperature. These results provide a practical framework for the rapid design and optimization of TEG–PCM systems with conduction-dominant plate-fin heat sinks attached to the cold side of the TEG and a constant heat flux.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"307 ","pages":"Article 133396"},"PeriodicalIF":7.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149156565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Coupled operations and decoupled performance: Field testing and operational assessment of a ground source heat pump integrating energy piles and boreholes","authors":"Zhiwen Sun,&nbsp;Gangqiang Kong,&nbsp;Liang Chen,&nbsp;Ting Bao,&nbsp;Hanlong Liu","doi":"10.1016/j.applthermaleng.2026.133362","DOIUrl":"10.1016/j.applthermaleng.2026.133362","url":null,"abstract":"<div><div>Ground source heat pump (GSHP) systems with energy piles (EPs) and borehole heat exchangers (BHEs) provide a potential pathway for building decarbonization. However, how these components share thermal loads and how factors affect the system energy efficiency remain unclear. This study evaluated a full-scale GSHP system consisting of 20 EPs and 6 BHEs installed in cohesive soil during winter and summer operation. The seasonal thermal responses, load-sharing behaviors, system energy efficiency, and parameter sensitivities were quantified. An operational evaluation was conducted. The seasonal load-sharing patterns differed between winter and summer. During the initial winter heating stage, EPs dominated heat extraction (load-sharing index&gt;0.6) because of their structural thermal mass. Deep BHEs dominated early summer heat rejection because they were less affected by surface temperature variations. Furthermore, the pile and ground temperature changes indicated a thermal hysteresis effect caused by the thermal inertia of cohesive soil. Statistical analysis revealed that the ground-side pump frequency showed the highest contribution to energy efficiency variations, and indoor parameters determined thermal comfort. The proposed operational strategy achieved a coefficient of performance (COP) of 3.68 and an energy efficiency ratio (EER) of 3.91 while maintaining a small indoor temperature deviation of ≤0.34 °C.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"307 ","pages":"Article 133362"},"PeriodicalIF":7.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149156566","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":"Corrigendum to “Experimental investigation of the correlation between LBO performance and near-LBO combustion characteristics in a centrally staged combustor” [Appl. Therm. Eng. 290 (2026) 129962]","authors":"Jie Li,&nbsp;Wenyan Song,&nbsp;Bolun Sun,&nbsp;Zhibo Cao,&nbsp;Tao Xia,&nbsp;Ziwan Li,&nbsp;Yuanhua Li","doi":"10.1016/j.applthermaleng.2026.133261","DOIUrl":"10.1016/j.applthermaleng.2026.133261","url":null,"abstract":"","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"307 ","pages":"Article 133261"},"PeriodicalIF":7.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149212266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence mechanism of a single microbubble on frost crystal growth characteristics on a sessile frozen water droplet","authors":"Siyuan Liu,&nbsp;Mengjie Song,&nbsp;Fan Gao,&nbsp;Xuan Zhang,&nbsp;Qun Dang,&nbsp;Keke Shao","doi":"10.1016/j.applthermaleng.2026.133402","DOIUrl":"10.1016/j.applthermaleng.2026.133402","url":null,"abstract":"<div><div>Frosting is a prevalent phenomenon in nature and industry, but often brings negative effects. As common impurities inside water droplets, air bubbles can change the freezing morphology and affect frost crystal growth. To reveal the underlying mechanism, freezing and frosting experiments of a sessile water droplet containing an air bubble on horizontal and inclined cold plates were carried out. On a horizontal cold plate, the bubble shows a negligible effect on the freezing front migration, with the relative deviation of freezing rates among different positions within 8%. Meanwhile, the freezing tip deflection generally increases with bubble size and offset ratio. On an inclined cold plate, the freezing tip naturally inclines downward under gravity but turns counterclockwise upwards after injecting an air bubble on the upper side. Based on the above freezing characteristics, the frosting behavior is further analyzed. On a horizontal cold plate, as bubble size increases from 0.1<!--> <!-->μL to 0.3<!--> <!-->μL, the maximum frost crystal heights are 2.037, 2.004, 1.811, 1.813, and 1.801 mm, respectively. The growth rate of the maximum frost crystal decreases monotonically with increasing air bubble size. Besides, the bubble also leads to asymmetric frost growth between the bubble-containing side and the bubble-free side. This study reveals the regulatory mechanism of air bubbles on frosting, providing theoretical guidance for improving anti-frosting/defrosting surfaces and designing ice-suppressing surfaces.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"307 ","pages":"Article 133402"},"PeriodicalIF":7.5,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149156570","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}