As electronic devices become smaller and more powerful, effective heat dissipation has become a critical challenge, particularly at solid-solid interfaces where thermal contact resistance impedes heat flow. Graphene films, known for their high thermal conductivity and mechanical flexibility, are promising candidates for thermal interface materials. However, their low surface energy leads to poor wetting and liquid metal leakage, limiting their effectiveness. In this study, we use magnetron sputtering to deposit tungsten films of controlled thickness onto graphene, aiming to enhance the liquid metal-graphene interface. Our results show that the tungsten coating increases the surface energy of graphene, reducing the liquid metal contact angle by 25.9° and improving adhesion. The optimized coating, achieved after 40 min of sputtering, lowers the total thermal contact resistance to 5.49 ± 0.18 mm2K/W. Additionally, leakage tests under applied pressure demonstrate that the modified graphene films prevent liquid metal escape while maintaining stable solid-liquid contact. This work presents a novel strategy for engineering surface energy in graphene-based composite thermal interface materials, advancing beyond previous efforts by simultaneously reducing thermal contact resistance and eliminating leakage, thereby enhancing the reliability of high-performance electronic and energy systems.
{"title":"Enhancing wettability and reducing thermal contact resistance of liquid metal–graphene film interfaces via metal coating modification","authors":"Hailang Kuang , Hao Bai , Chonghao Yuan , Feng Guo , Ziyi Zheng , Yu Zhao , Zongyu Wang , Chunrong Yu , Jifeng Zhang","doi":"10.1016/j.applthermaleng.2026.129702","DOIUrl":"10.1016/j.applthermaleng.2026.129702","url":null,"abstract":"<div><div>As electronic devices become smaller and more powerful, effective heat dissipation has become a critical challenge, particularly at solid-solid interfaces where thermal contact resistance impedes heat flow. Graphene films, known for their high thermal conductivity and mechanical flexibility, are promising candidates for thermal interface materials. However, their low surface energy leads to poor wetting and liquid metal leakage, limiting their effectiveness. In this study, we use magnetron sputtering to deposit tungsten films of controlled thickness onto graphene, aiming to enhance the liquid metal-graphene interface. Our results show that the tungsten coating increases the surface energy of graphene, reducing the liquid metal contact angle by 25.9° and improving adhesion. The optimized coating, achieved after 40 min of sputtering, lowers the total thermal contact resistance to 5.49 ± 0.18 mm<sup>2</sup>K/W. Additionally, leakage tests under applied pressure demonstrate that the modified graphene films prevent liquid metal escape while maintaining stable solid-liquid contact. This work presents a novel strategy for engineering surface energy in graphene-based composite thermal interface materials, advancing beyond previous efforts by simultaneously reducing thermal contact resistance and eliminating leakage, thereby enhancing the reliability of high-performance electronic and energy systems.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"288 ","pages":"Article 129702"},"PeriodicalIF":6.9,"publicationDate":"2026-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922331","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}
Pub Date : 2026-01-03DOI: 10.1016/j.applthermaleng.2025.129606
Juan Ríos-Arriola, Nicolás Velázquez-Limón
Reducing energy consumption for cooling and desalination processes is an important issue in hot climates and water-stressed regions. The growing water scarcity problem has increased the relevance of the absorption cycle capability to produce cooling and water, nevertheless its performance has not been thoroughly evaluated. This study presents a parametric analysis of a single-effect (lithium bromide-water) absorption cooling and desalination system in order to determine its operational limits and optimal operating conditions. The thermodynamic modeling of the system was simulated using Aspen Plus® software to evaluate its performance varying mass flow rates, concentration levels, pressure levels and external water supply temperatures (hot, cooling and chilled water). Results indicate that a system designed for 35 kW cooling capacity and activated by low-grade thermal energy (<100 °C) produces 1.26 m3/day of freshwater with a coefficient of performance (COP) of 0.77, a global COP (COPG) of 1.61, and a recovery ratio (RR) of 0.88. The open absorption cycle COP is 2.69 % higher compared to a conventional closed cycle (operating under similar conditions) because in the open cycle the refrigerant (seawater) enters in a subcooled state, whereas in the closed cycle the refrigerant is throttled at the condenser saturation temperature. The main advantage of the open cycle is its wider operating range, because the amount of refrigerant inside the system is not fixed, unlike in the closed cycle. The proposed system enhances for implementing absorption systems in regions with a hot climate and water scarcity.
{"title":"Performance assessment and optimization of an absorption cooling and desalination system","authors":"Juan Ríos-Arriola, Nicolás Velázquez-Limón","doi":"10.1016/j.applthermaleng.2025.129606","DOIUrl":"10.1016/j.applthermaleng.2025.129606","url":null,"abstract":"<div><div>Reducing energy consumption for cooling and desalination processes is an important issue in hot climates and water-stressed regions. The growing water scarcity problem has increased the relevance of the absorption cycle capability to produce cooling and water, nevertheless its performance has not been thoroughly evaluated. This study presents a parametric analysis of a single-effect (lithium bromide-water) absorption cooling and desalination system in order to determine its operational limits and optimal operating conditions. The thermodynamic modeling of the system was simulated using Aspen Plus® software to evaluate its performance varying mass flow rates, concentration levels, pressure levels and external water supply temperatures (hot, cooling and chilled water). Results indicate that a system designed for 35 kW cooling capacity and activated by low-grade thermal energy (<100 °C) produces 1.26 m<sup>3</sup>/day of freshwater with a coefficient of performance (COP) of 0.77, a global COP (COP<sub>G</sub>) of 1.61, and a recovery ratio (RR) of 0.88. The open absorption cycle COP is 2.69 % higher compared to a conventional closed cycle (operating under similar conditions) because in the open cycle the refrigerant (seawater) enters in a subcooled state, whereas in the closed cycle the refrigerant is throttled at the condenser saturation temperature. The main advantage of the open cycle is its wider operating range, because the amount of refrigerant inside the system is not fixed, unlike in the closed cycle. The proposed system enhances for implementing absorption systems in regions with a hot climate and water scarcity.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"289 ","pages":"Article 129606"},"PeriodicalIF":6.9,"publicationDate":"2026-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145924529","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}
A novel latent heat thermal energy storage system that integrated Tesla valve structure flow channels was developed to improve the energy efficiency of cold energy storage unit. The system utilized phase change materials to store cooling capacity during off-peak hours, which was then used to supplement the cooling load during peak periods. This paper employed a combined experimental and numerical simulation method to compare the Tesla valve structure with a conventional plate-fin structure in terms of cold storage and release times, effective discharge time, and energy storage efficiency. The results indicated that the asymmetric Tesla valve structure enhanced heat transfer and reduced solidification time by 54.6 %. Under an inlet velocity of 0.2 m/s and a charging time of 6 h, the cold storage rate increased by 12.6 %. At a discharge velocity of 0.025 m/s, the system achieved an energy storage efficiency of 89.9 % and a discharge duration of 8.01 h, which significantly outperformed the plate-fin structure with 54.9 % and 4.39 h, respectively. The system also exhibited higher sustained output power and temperature (both at least 1.5 times the reference case with plate-fin structure).
{"title":"Realizing rapid energy storage and efficient release in a tesla valve integrated cold energy storage unit for data center cooling","authors":"Hao Ling , Yongjian Wu , Yunlong Gu , Yanqi Zhao , Xiaolei Zhu , Feng Jiang , Yulong Ding , Xiang Ling , Daining Fang","doi":"10.1016/j.applthermaleng.2025.129683","DOIUrl":"10.1016/j.applthermaleng.2025.129683","url":null,"abstract":"<div><div>A novel latent heat thermal energy storage system that integrated Tesla valve structure flow channels was developed to improve the energy efficiency of cold energy storage unit. The system utilized phase change materials to store cooling capacity during off-peak hours, which was then used to supplement the cooling load during peak periods. This paper employed a combined experimental and numerical simulation method to compare the Tesla valve structure with a conventional plate-fin structure in terms of cold storage and release times, effective discharge time, and energy storage efficiency. The results indicated that the asymmetric Tesla valve structure enhanced heat transfer and reduced solidification time by 54.6 %. Under an inlet velocity of 0.2 m/s and a charging time of 6 h, the cold storage rate increased by 12.6 %. At a discharge velocity of 0.025 m/s, the system achieved an energy storage efficiency of 89.9 % and a discharge duration of 8.01 h, which significantly outperformed the plate-fin structure with 54.9 % and 4.39 h, respectively. The system also exhibited higher sustained output power and temperature (both at least 1.5 times the reference case with plate-fin structure).</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"289 ","pages":"Article 129683"},"PeriodicalIF":6.9,"publicationDate":"2026-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145915253","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}
Pub Date : 2026-01-03DOI: 10.1016/j.applthermaleng.2025.129614
Xianyan Lin , Hongzhang Zhu , Zewen Li , Haoyun Yuan , Yong Guo , Tao Qin , Bin Liao , Zheng Chen
In response to the global demand for cleaner and more efficient energy systems, the novel elliptical rotary engines (EREs) in the aviation offer a promising solution due to their compact design and high efficiency. However, super-knock at ultra-high compression ratios (CR) limits the full potential of EREs. A novel low-pressure hydrogen-assisted direct water injection (LPHA-DWI) strategy is proposed to mitigate super-knock and co-optimize ERE performance. Comprehensive numerical simulations were conducted, incorporating combustion dynamics, energy distribution, and mechanical load analysis. A quantitative function analysis evaluated the relationships between CR, spark timing, water-fuel ratio (WFR), and hydrogen mass fraction (HMF), focusing on their impacts on knock suppression, efficiency, and emission reduction. Results show that as CR increases from 9.26 to 17, both the knock intensity (KI) and the maximum pressure rise rate (MPRR) increase exponentially, accelerating knock escalation with multi-site ignition and pressure wave convergence, particularly in the end-slit region. The optimized strategy (20 % WFR and 2 % HMF) successfully suppresses super-knock, improving indicated thermal efficiency (ITE) by 18.92 % relative to the baseline engine (CR9.26), while significantly reducing soot, HC, and CO emissions, with a slight increase in NOₓ. A newly defined power-vector field analysis reveals localized mechanical vulnerabilities near the end radial seals caused by pressure wave convergence and increased thermal stress. These findings indicate that LPHA-DWI can significantly enhance the overall performance of EREs and provide a feasible solution for cleaner, more sustainable, and more efficient energy systems. The hydrogen-water synergistic mechanism and its optimization provide valuable insights for cleaner and more sustainable energy in EREs.
{"title":"Superknock mitigation and multi-objective performance optimization in ultra-high-compression elliptical rotary engines: integrating novel hydrogen-assisted direct water injection","authors":"Xianyan Lin , Hongzhang Zhu , Zewen Li , Haoyun Yuan , Yong Guo , Tao Qin , Bin Liao , Zheng Chen","doi":"10.1016/j.applthermaleng.2025.129614","DOIUrl":"10.1016/j.applthermaleng.2025.129614","url":null,"abstract":"<div><div>In response to the global demand for cleaner and more efficient energy systems, the novel elliptical rotary engines (EREs) in the aviation offer a promising solution due to their compact design and high efficiency. However, super-knock at ultra-high compression ratios (CR) limits the full potential of EREs. A novel low-pressure hydrogen-assisted direct water injection (LPHA-DWI) strategy is proposed to mitigate super-knock and co-optimize ERE performance. Comprehensive numerical simulations were conducted, incorporating combustion dynamics, energy distribution, and mechanical load analysis. A quantitative function analysis evaluated the relationships between CR, spark timing, water-fuel ratio (WFR), and hydrogen mass fraction (HMF), focusing on their impacts on knock suppression, efficiency, and emission reduction. Results show that as CR increases from 9.26 to 17, both the knock intensity (KI) and the maximum pressure rise rate (MPRR) increase exponentially, accelerating knock escalation with multi-site ignition and pressure wave convergence, particularly in the end-slit region. The optimized strategy (20 % WFR and 2 % HMF) successfully suppresses super-knock, improving indicated thermal efficiency (ITE) by 18.92 % relative to the baseline engine (CR9.26), while significantly reducing soot, HC, and CO emissions, with a slight increase in NOₓ. A newly defined power-vector field analysis reveals localized mechanical vulnerabilities near the end radial seals caused by pressure wave convergence and increased thermal stress. These findings indicate that LPHA-DWI can significantly enhance the overall performance of EREs and provide a feasible solution for cleaner, more sustainable, and more efficient energy systems. The hydrogen-water synergistic mechanism and its optimization provide valuable insights for cleaner and more sustainable energy in EREs.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"289 ","pages":"Article 129614"},"PeriodicalIF":6.9,"publicationDate":"2026-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145915195","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}
Maintaining a stable and adequate outlet air temperature under fluctuating weather conditions remains a critical challenge in solar air heater applications. This study presents an experimental investigation of a novel hybrid double-pass solar air heater equipped with wavy fins featuring air gaps and a latent heat thermal storage unit, with a particular focus on improving outlet temperature stability. Indoor experiments considering various fin inclination angles (30°, 45°, and 60°) were initially conducted to determine the optimal fin inclination angle in order to enhance thermal performance, revealing 45° as the most effective. Following this phase, outdoor experiments evaluated the influence of the electric auxiliary heater's position on thermal behavior and energy consumption, where the auxiliary heater was installed either at the U-turn section (configuration 1) or at the outlet section (configuration 2). The findings indicate that configuration 2 achieved a more stable outlet temperature of 54 ± 1.3 °C. This configuration provided a maximum temperature rise of 32 °C, from an ambient temperature of 24 °C, and exhibited lower top heat losses. Further, configuration 2 reduced the electrical energy consumption by 4.2 % compared to configuration 1. Furthermore, the system demonstrated average thermal efficiencies of 65.6 % and 68.1 % for configurations 1 and 2, respectively, with a favorable energy payback time of 0.49 years, making it a simple and sustainable solution for various agricultural and industrial applications.
{"title":"An experimental investigation on the influence of auxiliary heater position and wavy fin inclination on the performance of a novel hybrid solar air heater with phase change material","authors":"Noureddine Embarek , Hocine Guellil , Abdel Illah Nabil Korti , Ibrahim Sulimieh , Müslüm Arıcı","doi":"10.1016/j.applthermaleng.2026.129704","DOIUrl":"10.1016/j.applthermaleng.2026.129704","url":null,"abstract":"<div><div>Maintaining a stable and adequate outlet air temperature under fluctuating weather conditions remains a critical challenge in solar air heater applications. This study presents an experimental investigation of a novel hybrid double-pass solar air heater equipped with wavy fins featuring air gaps and a latent heat thermal storage unit, with a particular focus on improving outlet temperature stability. Indoor experiments considering various fin inclination angles (30°, 45°, and 60°) were initially conducted to determine the optimal fin inclination angle in order to enhance thermal performance, revealing 45° as the most effective. Following this phase, outdoor experiments evaluated the influence of the electric auxiliary heater's position on thermal behavior and energy consumption, where the auxiliary heater was installed either at the U-turn section (configuration 1) or at the outlet section (configuration 2). The findings indicate that configuration 2 achieved a more stable outlet temperature of 54 ± 1.3 °C. This configuration provided a maximum temperature rise of 32 °C, from an ambient temperature of 24 °C, and exhibited lower top heat losses. Further, configuration 2 reduced the electrical energy consumption by 4.2 % compared to configuration 1. Furthermore, the system demonstrated average thermal efficiencies of 65.6 % and 68.1 % for configurations 1 and 2, respectively, with a favorable energy payback time of 0.49 years, making it a simple and sustainable solution for various agricultural and industrial applications.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"288 ","pages":"Article 129704"},"PeriodicalIF":6.9,"publicationDate":"2026-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922106","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}
Pub Date : 2026-01-03DOI: 10.1016/j.applthermaleng.2025.129659
Mengjie Xu , Qianqian Jin , Yeben Gong , Yahui Sun , Wei Wu , Chong Zhai
Global freshwater scarcity necessitates the development of sustainable atmospheric water harvesting (AWH) technologies. Absorption-based AWH systems are promising due to their adaptability and compatibility with solar energy, but conventional designs suffer from low efficiency and large system footprints. This study presents a solar-powered membrane-based microchannel AWH (SMA-AWH) device that integrates desorption, condensation, and regeneration within a compact architecture. Experimental investigations reveal that solution concentration is the dominant factor influencing productivity, with yields decreasing from 1.06 to 0.31 kg/(m2·h) as concentration rises from 40 % to 55 %. Regeneration performance is highly sensitive to solution temperature and air mass flow rate, with efficiency deteriorating when air flow drops below 0.12 kg/s or solution temperature exceeds 36 °C. A validated physical model (error < 5 %) was employed to conduct parametric simulations, demonstrating that channel width, length, and number positively affect harvesting rates, whereas channel height shows an inverse effect. Optimal performance is achieved with a 2 mm width, 0.4 m length, and 5 mm air gap. Seasonal evaluations under Nanjing's climate indicate that the device produces up to 3.5 kg/day in summer but only 1.2 kg/day in winter, highlighting the need for auxiliary heating during low-insolation periods. An economic assessment shows that the long-term cost of freshwater can be controlled at 740 mL per yuan, confirming both the affordability and competitiveness of the system. Overall, the proposed SMA-AWH device demonstrates efficient, low-carbon, and cost-effective water harvesting, offering a viable pathway for deployment in water-stressed regions.
{"title":"Solar-powered membrane-microchannel device for efficient and cost-effective atmospheric water harvesting","authors":"Mengjie Xu , Qianqian Jin , Yeben Gong , Yahui Sun , Wei Wu , Chong Zhai","doi":"10.1016/j.applthermaleng.2025.129659","DOIUrl":"10.1016/j.applthermaleng.2025.129659","url":null,"abstract":"<div><div>Global freshwater scarcity necessitates the development of sustainable atmospheric water harvesting (AWH) technologies. Absorption-based AWH systems are promising due to their adaptability and compatibility with solar energy, but conventional designs suffer from low efficiency and large system footprints. This study presents a solar-powered membrane-based microchannel AWH (SMA-AWH) device that integrates desorption, condensation, and regeneration within a compact architecture. Experimental investigations reveal that solution concentration is the dominant factor influencing productivity, with yields decreasing from 1.06 to 0.31 kg/(m<sup>2</sup>·h) as concentration rises from 40 % to 55 %. Regeneration performance is highly sensitive to solution temperature and air mass flow rate, with efficiency deteriorating when air flow drops below 0.12 kg/s or solution temperature exceeds 36 °C. A validated physical model (error < 5 %) was employed to conduct parametric simulations, demonstrating that channel width, length, and number positively affect harvesting rates, whereas channel height shows an inverse effect. Optimal performance is achieved with a 2 mm width, 0.4 m length, and 5 mm air gap. Seasonal evaluations under Nanjing's climate indicate that the device produces up to 3.5 kg/day in summer but only 1.2 kg/day in winter, highlighting the need for auxiliary heating during low-insolation periods. An economic assessment shows that the long-term cost of freshwater can be controlled at 740 mL per yuan, confirming both the affordability and competitiveness of the system. Overall, the proposed SMA-AWH device demonstrates efficient, low-carbon, and cost-effective water harvesting, offering a viable pathway for deployment in water-stressed regions.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"288 ","pages":"Article 129659"},"PeriodicalIF":6.9,"publicationDate":"2026-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922237","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}
Pub Date : 2026-01-02DOI: 10.1016/j.applthermaleng.2025.129554
Wenlian Ye , Qingpeng Song , Tiangang Wang , Lingxuan Kong , Yingwen Liu
Accurate performance prediction of composite insulation structures for liquid hydrogen (LH2) storage remains challenging due to strong parameter coupling and inherent nonlinearities. This study develops a novel predictive framework integrating Response Surface Methodology (RSM) with four deep neural network (DNN) algorithms (CNN, CNN-GRU, CNN-LSTM, and CNN-biLSTM) to predict the thermal performance of HGMs-VDMLI composite insulation systems. For the first time, this framework systematically analyzes key input parameters including low, intermediate, and high layer densities, warm boundary temperature, and inner material thickness, with their interaction effects, establishing regression models for heat flux and effective thermal conductivity. All models were comprehensively evaluated using multiple metrics. Interaction analysis identified the warm boundary temperature as the most influential factor. The RSM model demonstrated exceptional accuracy, consistently outperforming all DNN algorithms across every evaluation metric, with R2 values of 1.0000 for heat flux and 0.9996 for effective thermal conductivity, along with adjusted R2 values of 1.0000 and 0.9993, and predicted R2 values of 0.9999 and 0.9972, respectively. Overall, this study provides a reliable predictive methodology and offers innovative insights for the optimization of composite insulation systems in LH2 storage.
{"title":"Predictive modeling of composite insulation for LH2 storage: A comparative study of response surface methodology and deep learning algorithms","authors":"Wenlian Ye , Qingpeng Song , Tiangang Wang , Lingxuan Kong , Yingwen Liu","doi":"10.1016/j.applthermaleng.2025.129554","DOIUrl":"10.1016/j.applthermaleng.2025.129554","url":null,"abstract":"<div><div>Accurate performance prediction of composite insulation structures for liquid hydrogen (LH<sub>2</sub>) storage remains challenging due to strong parameter coupling and inherent nonlinearities. This study develops a novel predictive framework integrating Response Surface Methodology (RSM) with four deep neural network (DNN) algorithms (CNN, CNN-GRU, CNN-LSTM, and CNN-biLSTM) to predict the thermal performance of HGMs-VDMLI composite insulation systems. For the first time, this framework systematically analyzes key input parameters including low, intermediate, and high layer densities, warm boundary temperature, and inner material thickness, with their interaction effects, establishing regression models for heat flux and effective thermal conductivity. All models were comprehensively evaluated using multiple metrics. Interaction analysis identified the warm boundary temperature as the most influential factor. The RSM model demonstrated exceptional accuracy, consistently outperforming all DNN algorithms across every evaluation metric, with R<sup>2</sup> values of 1.0000 for heat flux and 0.9996 for effective thermal conductivity, along with adjusted R<sup>2</sup> values of 1.0000 and 0.9993, and predicted R<sup>2</sup> values of 0.9999 and 0.9972, respectively. Overall, this study provides a reliable predictive methodology and offers innovative insights for the optimization of composite insulation systems in LH<sub>2</sub> storage.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"289 ","pages":"Article 129554"},"PeriodicalIF":6.9,"publicationDate":"2026-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145915248","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}
Pub Date : 2026-01-02DOI: 10.1016/j.applthermaleng.2026.129701
Qitao Zhang , Arash Dahi Taleghani , Zhuochen Zhan , Guoqiang Li
Enhanced Geothermal Systems using supercritical CO2 (CO2-EGS) offer superior thermophysical properties and dual benefits of energy generation with carbon sequestration. However, CO2's inherent buoyancy creates severe thermal short-circuiting through intra-fracture channeling (gravity override) and inter-fracture channeling in the reservoir with non-uniform fracture system. These phenomena cause premature thermal breakthrough and significantly reduce energy recovery efficiency. This study introduces the concept of temperature-sensitive proppants as an autonomous solution to mitigate CO2 flow channeling. These “smart” proppants dynamically reduce fracture conductivity in cooled zones while maintaining high conductivity in hot regions, intelligently redirecting CO2 flow to achieve uniform thermal sweep. Through comprehensive 3D numerical simulations of a horizontal well doublet system over 30 years, we quantify substantial performance improvements. In uniform fracture networks, temperature-sensitive proppants increased cumulative heat extraction by 20 % and sustained production temperatures 22 K higher after three decades. More significantly, in non-uniform fracture systems prone to severe channeling, the technology delivered a 45 K temperature increase and 55 % improvement in heat extraction efficiency compared to conventional proppants. Results demonstrate that temperature-sensitive proppants provide transformative, self-regulating flow control that maximizes energy recovery while extending system longevity. This technology addresses the critical challenge of thermal short-circuiting in CO2-EGS, significantly improving economic viability while advancing dual goals of clean energy generation and large-scale geological carbon sequestration.
{"title":"Enhanced heat recovery in CO2-enhanced geothermal systems: A temperature-sensitive proppant approach","authors":"Qitao Zhang , Arash Dahi Taleghani , Zhuochen Zhan , Guoqiang Li","doi":"10.1016/j.applthermaleng.2026.129701","DOIUrl":"10.1016/j.applthermaleng.2026.129701","url":null,"abstract":"<div><div>Enhanced Geothermal Systems using supercritical CO<sub>2</sub> (CO<sub>2</sub>-EGS) offer superior thermophysical properties and dual benefits of energy generation with carbon sequestration. However, CO<sub>2</sub>'s inherent buoyancy creates severe thermal short-circuiting through intra-fracture channeling (gravity override) and inter-fracture channeling in the reservoir with non-uniform fracture system. These phenomena cause premature thermal breakthrough and significantly reduce energy recovery efficiency. This study introduces the concept of temperature-sensitive proppants as an autonomous solution to mitigate CO<sub>2</sub> flow channeling. These “smart” proppants dynamically reduce fracture conductivity in cooled zones while maintaining high conductivity in hot regions, intelligently redirecting CO<sub>2</sub> flow to achieve uniform thermal sweep. Through comprehensive 3D numerical simulations of a horizontal well doublet system over 30 years, we quantify substantial performance improvements. In uniform fracture networks, temperature-sensitive proppants increased cumulative heat extraction by 20 % and sustained production temperatures 22 K higher after three decades. More significantly, in non-uniform fracture systems prone to severe channeling, the technology delivered a 45 K temperature increase and 55 % improvement in heat extraction efficiency compared to conventional proppants. Results demonstrate that temperature-sensitive proppants provide transformative, self-regulating flow control that maximizes energy recovery while extending system longevity. This technology addresses the critical challenge of thermal short-circuiting in CO<sub>2</sub>-EGS, significantly improving economic viability while advancing dual goals of clean energy generation and large-scale geological carbon sequestration.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"289 ","pages":"Article 129701"},"PeriodicalIF":6.9,"publicationDate":"2026-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145915256","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}
Pub Date : 2026-01-02DOI: 10.1016/j.applthermaleng.2025.129649
Mohamed Egiza , Mohamed Ragab Diab , Mahmoud Nassar , Mohamed Alhosary , Mohamed Rozza , Ammar H. Elsheikh , Fadl A. Essa
This study introduces a novel solar still configuration that integrates multiple natural materials within a geometry-optimized inverted pyramid aluminium basin and presents the first systematic evaluation of their combined thermal behavior using a comprehensive 4E framework encompassing energy, exergy, economic, and environmental criteria. Although previous work has investigated individual natural materials, the synergistic influence of stones, a cotton wick, and luffa on heat transfer dynamics, evaporation behavior, and overall system efficiency has not been examined, particularly within an optimized basin geometry. The present design couples geometric solar intensification with material-driven thermal enhancement to create a low-cost and energy-efficient desalination system. Experimental findings showed that the integrated configuration delivered the highest performance among all tested cases: stones provided thermal storage to stabilize temperature, the wick promoted capillary-driven thin-film evaporation, and luffa facilitated uniform water distribution while reducing thermal losses due to its porous structure. The inverted pyramid geometry further improved solar energy concentration and reduced convective heat losses, strengthening thermal utilization. Under identical operating conditions, the optimal configuration achieved a maximum daily distilled yield of 4.18 kg/m2, corresponding to a 58.3% enhancement over the reference still. Thermal efficiency increased from 26.1%to 41.3% (58.2%improvement), and exergy efficiency rose from 2.03% to 2.92% (43.8% increase). The cost of desalinated water decreased from 0.020 to 0.014 USD per liter, a reduction of 30%, while annual CO₂ mitigation increased from 6.01 to 9.52 tons, indicating a 58.4%improvement. The 4E analysis further revealed a 29.1% reduction in embodied energy and a marked improvement in energy payback time. These results confirm the effectiveness of integrating multifunctional natural materials within an optimized basin as a practical and sustainable pathway for decentralized solar desalination.
{"title":"Multifunctional passive enhancement of solar desalination using natural materials in an inverted Pyramid Basin: Thermal and 4E performance analysis","authors":"Mohamed Egiza , Mohamed Ragab Diab , Mahmoud Nassar , Mohamed Alhosary , Mohamed Rozza , Ammar H. Elsheikh , Fadl A. Essa","doi":"10.1016/j.applthermaleng.2025.129649","DOIUrl":"10.1016/j.applthermaleng.2025.129649","url":null,"abstract":"<div><div>This study introduces a novel solar still configuration that integrates multiple natural materials within a geometry-optimized inverted pyramid aluminium basin and presents the first systematic evaluation of their combined thermal behavior using a comprehensive 4E framework encompassing energy, exergy, economic, and environmental criteria. Although previous work has investigated individual natural materials, the synergistic influence of stones, a cotton wick, and luffa on heat transfer dynamics, evaporation behavior, and overall system efficiency has not been examined, particularly within an optimized basin geometry. The present design couples geometric solar intensification with material-driven thermal enhancement to create a low-cost and energy-efficient desalination system. Experimental findings showed that the integrated configuration delivered the highest performance among all tested cases: stones provided thermal storage to stabilize temperature, the wick promoted capillary-driven thin-film evaporation, and luffa facilitated uniform water distribution while reducing thermal losses due to its porous structure. The inverted pyramid geometry further improved solar energy concentration and reduced convective heat losses, strengthening thermal utilization. Under identical operating conditions, the optimal configuration achieved a maximum daily distilled yield of 4.18 kg/m<sup>2</sup>, corresponding to a 58.3% enhancement over the reference still. Thermal efficiency increased from 26.1%to 41.3% (58.2%improvement), and exergy efficiency rose from 2.03% to 2.92% (43.8% increase). The cost of desalinated water decreased from 0.020 to 0.014 USD per liter, a reduction of 30%, while annual CO₂ mitigation increased from 6.01 to 9.52 tons, indicating a 58.4%improvement. The 4E analysis further revealed a 29.1% reduction in embodied energy and a marked improvement in energy payback time. These results confirm the effectiveness of integrating multifunctional natural materials within an optimized basin as a practical and sustainable pathway for decentralized solar desalination.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"288 ","pages":"Article 129649"},"PeriodicalIF":6.9,"publicationDate":"2026-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922174","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}
Pub Date : 2026-01-02DOI: 10.1016/j.applthermaleng.2025.129667
Tianen Chen , Yue Liu , Zifei Fang , Tao Shen , Yuanhao Wang , Shifeng Wang
To address the issue of reduced photovoltaic conversion efficiency and heat waste caused by excessive temperatures under sunlight, this study developed a cooling system (CTW-MPCM) that combines paraffin-based phase-change energy storage microcapsules with waste heat recovery for cooling and thermal energy recovery in photovoltaic panels. The results show that by adjusting the irradiance intensity (400 W/m2 ∼ 800 W/m2) with a solar simulator, the PV panels with the CTW-MPCM system demonstrated an average temperature reduction of 14.6 °C ∼ 23.3 °C on the front surface and 24.3 °C ∼ 30.6 °C on the back, with a photoelectric conversion efficiency increase of 5.07 ∼ 13.84 %. At 800 W/m2, the thermal recovery efficiency was 82.1 %. The system maintained high cooling performance even under real environmental conditions and the heat transfer process of the system was simulated at both macro and micro scales using finite element analysis. This work combines phase-change energy storage microcapsules with a waste heat recovery system, solving the common leakage problem of traditional phase-change materials and providing a more efficient solution for thermal regulation and waste heat recovery in photovoltaic panels.
{"title":"Synthesis of paraffin-based phase change energy storage microcapsules and their application in thermal regulation of photovoltaic panels","authors":"Tianen Chen , Yue Liu , Zifei Fang , Tao Shen , Yuanhao Wang , Shifeng Wang","doi":"10.1016/j.applthermaleng.2025.129667","DOIUrl":"10.1016/j.applthermaleng.2025.129667","url":null,"abstract":"<div><div>To address the issue of reduced photovoltaic conversion efficiency and heat waste caused by excessive temperatures under sunlight, this study developed a cooling system (CTW-MPCM) that combines paraffin-based phase-change energy storage microcapsules with waste heat recovery for cooling and thermal energy recovery in photovoltaic panels. The results show that by adjusting the irradiance intensity (400 W/m<sup>2</sup> ∼ 800 W/m<sup>2</sup>) with a solar simulator, the PV panels with the CTW-MPCM system demonstrated an average temperature reduction of 14.6 °C ∼ 23.3 °C on the front surface and 24.3 °C ∼ 30.6 °C on the back, with a photoelectric conversion efficiency increase of 5.07 ∼ 13.84 %. At 800 W/m<sup>2</sup>, the thermal recovery efficiency was 82.1 %. The system maintained high cooling performance even under real environmental conditions and the heat transfer process of the system was simulated at both macro and micro scales using finite element analysis. This work combines phase-change energy storage microcapsules with a waste heat recovery system, solving the common leakage problem of traditional phase-change materials and providing a more efficient solution for thermal regulation and waste heat recovery in photovoltaic panels.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"289 ","pages":"Article 129667"},"PeriodicalIF":6.9,"publicationDate":"2026-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145975123","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}
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