Pub Date : 2026-01-02DOI: 10.1016/j.csite.2026.107642
Ying Li , Zhen Li , Mengdan Huo , Yajun Li , Jian-ming Gao
Molten salt phase change material(PCM) has great potential as a substitute for thermal energy storage, however, their widespread industrial adoption has been limited by issues of leakage. In this study, a shape-stabilized phase change material (SSPCM) with high temperature range (250–800 °C) was successfully synthesized. The fly ash (FA) was employed as the supporting skeleton material, while a ternary sulfate salt composed of Na2SO4, K2SO4, and MgSO4 served as the PCMs. The results indicate that the composite S-FS-45/55 shows excellent chemical compatibility and maintains a stable morphology. The maximum latent heat of the composite reaches 63.10 J/g. After 500 thermal cycles, the composite S-FS-45/55 still maintains excellent chemical compatibility, with a latent heat retention rate of 92.55 %. The excellent leakage prevention performance of the SSPCMs may benefit from the reinforcement of the innate mullite-quartz skeleton of the FA during high-temperature sintering process. In addition, the thermal conductivity was increased from 0.33 W/(m·k) to 2.58 W/(m·k) after adding 7.5 wt% silicon carbide (SiC) in the composite. This study provides a new way for high-value utilization of FA and the design of thermal energy storage materials, demonstrating significant application potential, particularly in the fields of industrial waste heat recovery and clean energy technology.
{"title":"Fly ash based shape-stabilized phase change materials for high-temperature thermal energy storage with enhanced thermal conductivity","authors":"Ying Li , Zhen Li , Mengdan Huo , Yajun Li , Jian-ming Gao","doi":"10.1016/j.csite.2026.107642","DOIUrl":"10.1016/j.csite.2026.107642","url":null,"abstract":"<div><div>Molten salt phase change material(PCM) has great potential as a substitute for thermal energy storage, however, their widespread industrial adoption has been limited by issues of leakage. In this study, a shape-stabilized phase change material (SSPCM) with high temperature range (250–800 °C) was successfully synthesized. The fly ash (FA) was employed as the supporting skeleton material, while a ternary sulfate salt composed of Na<sub>2</sub>SO<sub>4</sub>, K<sub>2</sub>SO<sub>4</sub>, and MgSO<sub>4</sub> served as the PCMs. The results indicate that the composite S-FS-45/55 shows excellent chemical compatibility and maintains a stable morphology. The maximum latent heat of the composite reaches 63.10 J/g. After 500 thermal cycles, the composite S-FS-45/55 still maintains excellent chemical compatibility, with a latent heat retention rate of 92.55 %. The excellent leakage prevention performance of the SSPCMs may benefit from the reinforcement of the innate mullite-quartz skeleton of the FA during high-temperature sintering process. In addition, the thermal conductivity was increased from 0.33 W/(m·k) to 2.58 W/(m·k) after adding 7.5 wt% silicon carbide (SiC) in the composite. This study provides a new way for high-value utilization of FA and the design of thermal energy storage materials, demonstrating significant application potential, particularly in the fields of industrial waste heat recovery and clean energy technology.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"78 ","pages":"Article 107642"},"PeriodicalIF":6.4,"publicationDate":"2026-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145894206","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.csite.2026.107644
Suresh Vellaiyan , Bassam S. Aljohani , Khalid Aljohani , Muralidharan Kandasamy , Nguyen Van Minh
This study addresses fuel scarcity and emission control in compression-ignition engines by integrating water–diesel emulsification with a surface-area engineered hybrid nanocomposite. Unlike conventional water–diesel emulsions using single-phase nanoparticles, this approach employs a surface-area-enhanced MWCNT–Al2O3 nanocomposite to improve heat transfer and catalytic oxidation. Nitrogen sorption analysis of the proposed nanocomposite confirmed a type-IV isotherm with H3 hysteresis, a modal pore size of ∼3 nm, a cumulative mesopore volume of 0.12–0.13 cm3 g−1, and a BET surface area exceeding 180 m2 g−1. These features provide a large density of accessible reactive sites at ultra-low additive loading. Water–diesel emulsions containing 5 % (E5W) and 10 % (E10W) water were prepared using a non-ionic surfactant, and the nanocomposite was dispersed at 100 ppm into the 10 % emulsion (E10W–NC). Engine analysis showed that E5W reduced peak in-cylinder pressure (ICP) and brake thermal efficiency (BTE) by 1.3 % and 7.1 %, respectively, while E10W caused larger reductions of 2.5 % and 11.1 %, accompanied by higher fuel consumption. In contrast, E10W–NC recovered combustion intensity and efficiency. Compared with E10W, the E10W–NC fuel increased peak ICP and net heat-release rate by 3 % and 13.3 %, respectively, while improving BTE by 12.8 % and reducing fuel consumption by 11.6 %. At the same time, it lowered NOx, hydrocarbon, carbon monoxide, and smoke emissions by 3 %, 4.8 %, 5.8 %, and 5.6 %, respectively. Overall, the results demonstrate that surface-area architecture governs the effectiveness of water–diesel emulsions, offering a practical pathway to cleaner and more efficient CI engine operation without hardware modification.
{"title":"Surface-area engineered nanocomposite for cleaner compression ignition combustion with water–diesel emulsions","authors":"Suresh Vellaiyan , Bassam S. Aljohani , Khalid Aljohani , Muralidharan Kandasamy , Nguyen Van Minh","doi":"10.1016/j.csite.2026.107644","DOIUrl":"10.1016/j.csite.2026.107644","url":null,"abstract":"<div><div>This study addresses fuel scarcity and emission control in compression-ignition engines by integrating water–diesel emulsification with a surface-area engineered hybrid nanocomposite. Unlike conventional water–diesel emulsions using single-phase nanoparticles, this approach employs a surface-area-enhanced MWCNT–Al<sub>2</sub>O<sub>3</sub> nanocomposite to improve heat transfer and catalytic oxidation. Nitrogen sorption analysis of the proposed nanocomposite confirmed a type-IV isotherm with H3 hysteresis, a modal pore size of ∼3 nm, a cumulative mesopore volume of 0.12–0.13 cm<sup>3</sup> g<sup>−1</sup>, and a BET surface area exceeding 180 m<sup>2</sup> g<sup>−1</sup>. These features provide a large density of accessible reactive sites at ultra-low additive loading. Water–diesel emulsions containing 5 % (E5W) and 10 % (E10W) water were prepared using a non-ionic surfactant, and the nanocomposite was dispersed at 100 ppm into the 10 % emulsion (E10W–NC). Engine analysis showed that E5W reduced peak in-cylinder pressure (ICP) and brake thermal efficiency (BTE) by 1.3 % and 7.1 %, respectively, while E10W caused larger reductions of 2.5 % and 11.1 %, accompanied by higher fuel consumption. In contrast, E10W–NC recovered combustion intensity and efficiency. Compared with E10W, the E10W–NC fuel increased peak ICP and net heat-release rate by 3 % and 13.3 %, respectively, while improving BTE by 12.8 % and reducing fuel consumption by 11.6 %. At the same time, it lowered NO<sub>x</sub>, hydrocarbon, carbon monoxide, and smoke emissions by 3 %, 4.8 %, 5.8 %, and 5.6 %, respectively. Overall, the results demonstrate that surface-area architecture governs the effectiveness of water–diesel emulsions, offering a practical pathway to cleaner and more efficient CI engine operation without hardware modification.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"78 ","pages":"Article 107644"},"PeriodicalIF":6.4,"publicationDate":"2026-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145894202","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.csite.2025.107590
Mohsen Fallah, Zahra Mohammadi
{"title":"Development, modeling, and optimization of a solar-assisted hybrid building energy system incorporating photovoltaic panels, thermal collectors, and energy storage using transient simulation and ANN–GA methods: a case study","authors":"Mohsen Fallah, Zahra Mohammadi","doi":"10.1016/j.csite.2025.107590","DOIUrl":"https://doi.org/10.1016/j.csite.2025.107590","url":null,"abstract":"","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"8 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2026-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145894203","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 : 2026-01-01DOI: 10.1016/j.csite.2025.107522
Cheng-Hung Huang, Kuan-Chieh Fang
A transient Inverse Conjugate Heat Transfer Problem (ICHTP) is experimentally investigated to estimate the spatially and temporally varying applied bottom heat flux in a three-dimensional plate-fin heat sink using infrared thermography. In this framework, the interface between the heat sink and the air domain is assumed to exhibit perfect thermal contact, thereby defining the problem as a transient conjugate heat transfer formulation. Unlike conventional inverse heat conduction problems, this approach necessitates the simultaneous solution of the continuity, momentum, and energy equations in the air domain, coupled with the heat conduction equation in the heat sink domain, significantly increasing its complexity. To the best of the authors’ knowledge, this work represents the first experimental investigation of an ICHTP aimed at estimating the unknown heat flux of a heat sink.
The accuracy of the estimated heat flux is verified experimentally under a prescribed inlet air velocity. Results indicate that, due to the singularity of the cost-function gradient at the terminal time, estimates near the final time must be discarded. For numerical simulations with error-free measurements and an inlet velocity of 5 m/s, highly accurate bottom-surface heat fluxes are recovered. The effect of measurement noise (σ = 0.3) is further examined in both numerical simulations and experimental evaluations. The average relative errors of the estimated heat fluxes are 2.82 % in the simulations and 9.6 % in the experiments, both achieved with only six iterations. The discrepancy arises because measurement noise in simulations can be precisely controlled, whereas experimental measurements inherently exhibit greater uncertainty. This underscores the inherent challenges associated with inverse problems and highlights the importance of obtaining accurate measurement data in the problem domain. Moreover, if the discrepancy principle is not employed as the stopping criterion, the estimation of heat flux deteriorates with additional iterations, despite the apparent reduction in temperature residuals between measured and estimated values.
{"title":"Experimental validation of an inverse method for bottom heat flux determination in a heat sink","authors":"Cheng-Hung Huang, Kuan-Chieh Fang","doi":"10.1016/j.csite.2025.107522","DOIUrl":"10.1016/j.csite.2025.107522","url":null,"abstract":"<div><div>A transient Inverse Conjugate Heat Transfer Problem (ICHTP) is experimentally investigated to estimate the spatially and temporally varying applied bottom heat flux in a three-dimensional plate-fin heat sink using infrared thermography. In this framework, the interface between the heat sink and the air domain is assumed to exhibit perfect thermal contact, thereby defining the problem as a transient conjugate heat transfer formulation. Unlike conventional inverse heat conduction problems, this approach necessitates the simultaneous solution of the continuity, momentum, and energy equations in the air domain, coupled with the heat conduction equation in the heat sink domain, significantly increasing its complexity. To the best of the authors’ knowledge, this work represents the first experimental investigation of an ICHTP aimed at estimating the unknown heat flux of a heat sink.</div><div>The accuracy of the estimated heat flux is verified experimentally under a prescribed inlet air velocity. Results indicate that, due to the singularity of the cost-function gradient at the terminal time, estimates near the final time must be discarded. For numerical simulations with error-free measurements and an inlet velocity of 5 m/s, highly accurate bottom-surface heat fluxes are recovered. The effect of measurement noise (σ = 0.3) is further examined in both numerical simulations and experimental evaluations. The average relative errors of the estimated heat fluxes are 2.82 % in the simulations and 9.6 % in the experiments, both achieved with only six iterations. The discrepancy arises because measurement noise in simulations can be precisely controlled, whereas experimental measurements inherently exhibit greater uncertainty. This underscores the inherent challenges associated with inverse problems and highlights the importance of obtaining accurate measurement data in the problem domain. Moreover, if the discrepancy principle is not employed as the stopping criterion, the estimation of heat flux deteriorates with additional iterations, despite the apparent reduction in temperature residuals between measured and estimated values.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"77 ","pages":"Article 107522"},"PeriodicalIF":6.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145690125","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 : 2026-01-01DOI: 10.1016/j.csite.2025.107534
Yingqi Liu , Lijie Shen , Elshan Mammadov , Xaotoli Megi , Jun Hao
The economic viability of lithium-ion batteries in portable and distributed power applications is increasingly constrained by premature degradation caused by irregular load profiles, mechanical vibration, and variable microclimatic exposure. These stressors elevate operational costs, shorten replacement cycles, and undermine return on investment across mobile energy systems. This study develops a multi-physics–driven degradation and economic assessment framework to quantify how coupled electrochemical, mechanical, and environmental effects translate into accelerated capacity loss and rising lifecycle costs in multi-cell battery modules. Moving beyond conventional thermal-centric analyses, the framework examines stress-induced solid electrolyte interphase (SEI) instability, lithium plating onset, and impedance growth under non-uniform operating conditions representative of hybrid and portable energy platforms. A dual-stage approach is employed: (i) electrochemical–mechanical coupling simulations using a pseudo-2D Newman model integrated with a stress–strain module in COMSOL to capture particle deformation, SEI cracking, and kinetic inefficiencies; and (ii) accelerated aging experiments combining vibration-assisted cycling, dynamic current ripple, and controlled humidity exposure on 18650-based modular packs. Results show that cyclic mechanical strain increases local overpotential by up to 18 %, accelerating lithium plating under low-state-of-charge, high-current regimes and reducing usable capacity retention, while high humidity conditions (>70 % RH) intensify electrolyte decomposition, increasing cell impedance by 22–34 % and raising energy losses per delivered kilowatt-hour. An economic degradation model coupled with a machine-learning prognostic algorithm predicts remaining useful life with an error below 6%, enabling optimization of operating envelopes to minimize replacement frequency and levelized battery cost. The findings demonstrate that mechanically induced electrochemical degradation constitutes a dominant driver of hidden economic loss, often exceeding thermal failure-related costs. The study concludes with economically oriented design and policy recommendations, including vibration-damping system architecture, humidity-adaptive battery management controls, and RUL-based operational limits, offering a scalable pathway to improve cost efficiency, asset longevity, and investment sustainability of lithium-ion battery systems.
{"title":"Policy and design recommendations for thermal safety and economic feasibility of lithium-ion battery","authors":"Yingqi Liu , Lijie Shen , Elshan Mammadov , Xaotoli Megi , Jun Hao","doi":"10.1016/j.csite.2025.107534","DOIUrl":"10.1016/j.csite.2025.107534","url":null,"abstract":"<div><div>The economic viability of lithium-ion batteries in portable and distributed power applications is increasingly constrained by premature degradation caused by irregular load profiles, mechanical vibration, and variable microclimatic exposure. These stressors elevate operational costs, shorten replacement cycles, and undermine return on investment across mobile energy systems. This study develops a multi-physics–driven degradation and economic assessment framework to quantify how coupled electrochemical, mechanical, and environmental effects translate into accelerated capacity loss and rising lifecycle costs in multi-cell battery modules. Moving beyond conventional thermal-centric analyses, the framework examines stress-induced solid electrolyte interphase (SEI) instability, lithium plating onset, and impedance growth under non-uniform operating conditions representative of hybrid and portable energy platforms. A dual-stage approach is employed: (i) electrochemical–mechanical coupling simulations using a pseudo-2D Newman model integrated with a stress–strain module in COMSOL to capture particle deformation, SEI cracking, and kinetic inefficiencies; and (ii) accelerated aging experiments combining vibration-assisted cycling, dynamic current ripple, and controlled humidity exposure on 18650-based modular packs. Results show that cyclic mechanical strain increases local overpotential by up to 18 %, accelerating lithium plating under low-state-of-charge, high-current regimes and reducing usable capacity retention, while high humidity conditions (>70 % RH) intensify electrolyte decomposition, increasing cell impedance by 22–34 % and raising energy losses per delivered kilowatt-hour. An economic degradation model coupled with a machine-learning prognostic algorithm predicts remaining useful life with an error below 6%, enabling optimization of operating envelopes to minimize replacement frequency and levelized battery cost. The findings demonstrate that mechanically induced electrochemical degradation constitutes a dominant driver of hidden economic loss, often exceeding thermal failure-related costs. The study concludes with economically oriented design and policy recommendations, including vibration-damping system architecture, humidity-adaptive battery management controls, and RUL-based operational limits, offering a scalable pathway to improve cost efficiency, asset longevity, and investment sustainability of lithium-ion battery systems.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"77 ","pages":"Article 107534"},"PeriodicalIF":6.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145786025","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 : 2026-01-01DOI: 10.1016/j.csite.2025.107574
Na Zhang , Chengxi Li , Tianxin Yuan , Liang Li , Yongfeng Cheng
To investigate the heat transfer mechanism of expanded polystyrene (EPS) concrete, this study was designed to experiment the thermal insulation performance of EPS concrete doped with fly ash. A random aggregate model of EPS concrete was also established to verify the accuracy of the model through experiments. The effects of aggregate volume rate, aggregate shape, aggregate distribution mode, interfacial transition zone and porosity on the thermal insulation performance of concrete were investigated. The heat flow and temperature fields of EPS concrete were analyzed to reveal the heat transfer mechanism of EPS concrete. Finally, a second-order heat transfer calculation model for EPS concrete was developed to predict the effective thermal conductivity. The results show that the thermal conductivity decreases with the increase in volume ratio and porosity of EPS particles, and is 0.24 W/(m·K) at the volume ratio of 40 % and porosity of 13.3 %. The lowest thermal conductivity was found in triangular EPS granular concrete and the highest in pentagonal. The reduction in thermal conductivity was most significant when the rotation angle of elliptical EPS particles ψa = 0°. As the number of EPS particles and pores increases, the thermal channels narrow, extending the duration of heat flow through the interior of the concrete, which leads to a decrease in thermal conductivity. The established second-order heat transfer model for EPS concrete enables effective prediction of its thermal conductivity. This study integrates experimental, numerical simulation, and theoretical analysis to establish a quantitative relationship between the characteristics of EPS concrete and its thermal performance. The proposed model offers a robust analytical basis for predicting the thermal properties of EPS concrete with fly ash.
{"title":"Heat transfer mechanism of EPS concrete with fly ash based on random aggregate model","authors":"Na Zhang , Chengxi Li , Tianxin Yuan , Liang Li , Yongfeng Cheng","doi":"10.1016/j.csite.2025.107574","DOIUrl":"10.1016/j.csite.2025.107574","url":null,"abstract":"<div><div>To investigate the heat transfer mechanism of expanded polystyrene (EPS) concrete, this study was designed to experiment the thermal insulation performance of EPS concrete doped with fly ash. A random aggregate model of EPS concrete was also established to verify the accuracy of the model through experiments. The effects of aggregate volume rate, aggregate shape, aggregate distribution mode, interfacial transition zone and porosity on the thermal insulation performance of concrete were investigated. The heat flow and temperature fields of EPS concrete were analyzed to reveal the heat transfer mechanism of EPS concrete. Finally, a second-order heat transfer calculation model for EPS concrete was developed to predict the effective thermal conductivity. The results show that the thermal conductivity decreases with the increase in volume ratio and porosity of EPS particles, and is 0.24 W/(m·K) at the volume ratio of 40 % and porosity of 13.3 %. The lowest thermal conductivity was found in triangular EPS granular concrete and the highest in pentagonal. The reduction in thermal conductivity was most significant when the rotation angle of elliptical EPS particles <em>ψ</em><sub><em>a</em></sub> = 0°. As the number of EPS particles and pores increases, the thermal channels narrow, extending the duration of heat flow through the interior of the concrete, which leads to a decrease in thermal conductivity. The established second-order heat transfer model for EPS concrete enables effective prediction of its thermal conductivity. This study integrates experimental, numerical simulation, and theoretical analysis to establish a quantitative relationship between the characteristics of EPS concrete and its thermal performance. The proposed model offers a robust analytical basis for predicting the thermal properties of EPS concrete with fly ash.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"77 ","pages":"Article 107574"},"PeriodicalIF":6.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145822875","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 : 2026-01-01DOI: 10.1016/j.csite.2025.107581
Yiyang Shen , Mengdan Qian , Kun Yu , Chunyu Deng , Yufang Liu
The rapid progress of modern detection technologies has placed stringent demands on multiband camouflage systems, rendering single-band designs inadequate for operational use. Metamaterial emitters, due to tunable electromagnetic characteristics, are regarded as highly promising candidates for multiband concealment. Yet, the precise realization of micro/nanostructures remains a persistent fabrication challenge. In this work, a femtosecond laser direct writing (FsLDW) method is employed to produce patterned metamaterial emitters with high accuracy and structural flexibility. Periodic gratings are generated on ultrathin metallic films without thermal diffusion, which ensures uniformity and reproducibility. Using this strategy, a Cu/SiO2/Cu nanosandwiched selective emitter is fabricated. It achieves dual-band infrared camouflage with high reflectance (R3–5 μm = 0.78 and R8–14 μm = 0.83) and CO2 laser camouflage via strong absorption at 10.6 μm. Moreover, enhanced emission in the non-atmospheric window (ε5–8 μm = 0.74) facilitates effective thermal management, leading to lower surface temperature compared with low emissivity materials under identical conditions. These findings demonstrate that FsLDW provides a versatile and reliable approach for the development of multiband emitters integrating camouflage and thermal management functionalities.
{"title":"Infrared selective emitter for multiband camouflage with thermal management via femtosecond laser direct writing of grating patterns","authors":"Yiyang Shen , Mengdan Qian , Kun Yu , Chunyu Deng , Yufang Liu","doi":"10.1016/j.csite.2025.107581","DOIUrl":"10.1016/j.csite.2025.107581","url":null,"abstract":"<div><div>The rapid progress of modern detection technologies has placed stringent demands on multiband camouflage systems, rendering single-band designs inadequate for operational use. Metamaterial emitters, due to tunable electromagnetic characteristics, are regarded as highly promising candidates for multiband concealment. Yet, the precise realization of micro/nanostructures remains a persistent fabrication challenge. In this work, a femtosecond laser direct writing (FsLDW) method is employed to produce patterned metamaterial emitters with high accuracy and structural flexibility. Periodic gratings are generated on ultrathin metallic films without thermal diffusion, which ensures uniformity and reproducibility. Using this strategy, a Cu/SiO<sub>2</sub>/Cu nanosandwiched selective emitter is fabricated. It achieves dual-band infrared camouflage with high reflectance (R<sub>3–5 μm</sub> = 0.78 and R<sub>8–14 μm</sub> = 0.83) and CO<sub>2</sub> laser camouflage via strong absorption at 10.6 μm. Moreover, enhanced emission in the non-atmospheric window (ε<sub>5–8 μm</sub> = 0.74) facilitates effective thermal management, leading to lower surface temperature compared with low emissivity materials under identical conditions. These findings demonstrate that FsLDW provides a versatile and reliable approach for the development of multiband emitters integrating camouflage and thermal management functionalities.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"77 ","pages":"Article 107581"},"PeriodicalIF":6.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145822879","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 : 2026-01-01DOI: 10.1016/j.csite.2025.107576
Wenhui Bao , Yini Tan , Zhen Jia , Guoliang Li , Daxin Liang , Wanke Cheng , Hui Chen
Rising global building energy consumption underscores the urgent need for sustainable materials capable of passive thermal regulation. Regenerated cellulose, a renewable and biodegradable polymer, presents promising potential for energy-efficient optical systems; however, achieving reversible light modulation with precise solvent responsiveness remains a significant challenge. This study introduces an optically switchable regenerated cellulose membrane fabricated through an ionic liquid-based dissolution-regeneration process. The material incorporates dioctyl phthalate (DBP) to dynamically generate and remove microdroplet scattering domains during solvent exchange. The membrane exhibits exceptional optical properties: a transparent state with 95.2 % transmittance in ethanol/DBP and a scattering state achieving 78.5 % visible reflectance in water. Mechanistic investigations reveal that DBP microdroplets (∼5 μm) form due to their hydrophobic characteristics and long carbon chain structure, creating dynamic light-scattering interfaces. Thermal performance evaluation demonstrates a remarkable 14 °C temperature modulation between transparent and scattering states during summer conditions. In winter operation, the transparent mode increases indoor temperature by 13.9 °C with a heating power density of 269.2 W m−2. By integrating biodegradability, mechanical flexibility, and reversible optical switching capabilities, this membrane offers a groundbreaking solution for energy-adaptive window materials and sustainable building thermal management systems.
{"title":"Solvent-induced microdroplet scattering interface switching in cellulose membranes enables all-season building thermal management","authors":"Wenhui Bao , Yini Tan , Zhen Jia , Guoliang Li , Daxin Liang , Wanke Cheng , Hui Chen","doi":"10.1016/j.csite.2025.107576","DOIUrl":"10.1016/j.csite.2025.107576","url":null,"abstract":"<div><div>Rising global building energy consumption underscores the urgent need for sustainable materials capable of passive thermal regulation. Regenerated cellulose, a renewable and biodegradable polymer, presents promising potential for energy-efficient optical systems; however, achieving reversible light modulation with precise solvent responsiveness remains a significant challenge. This study introduces an optically switchable regenerated cellulose membrane fabricated through an ionic liquid-based dissolution-regeneration process. The material incorporates dioctyl phthalate (DBP) to dynamically generate and remove microdroplet scattering domains during solvent exchange. The membrane exhibits exceptional optical properties: a transparent state with 95.2 % transmittance in ethanol/DBP and a scattering state achieving 78.5 % visible reflectance in water. Mechanistic investigations reveal that DBP microdroplets (∼5 μm) form due to their hydrophobic characteristics and long carbon chain structure, creating dynamic light-scattering interfaces. Thermal performance evaluation demonstrates a remarkable 14 °C temperature modulation between transparent and scattering states during summer conditions. In winter operation, the transparent mode increases indoor temperature by 13.9 °C with a heating power density of 269.2 W m<sup>−2</sup>. By integrating biodegradability, mechanical flexibility, and reversible optical switching capabilities, this membrane offers a groundbreaking solution for energy-adaptive window materials and sustainable building thermal management systems.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"77 ","pages":"Article 107576"},"PeriodicalIF":6.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145813775","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 : 2026-01-01DOI: 10.1016/j.csite.2025.107559
Gang Bai , Wei Wan , Xueming Li , Shuoshuo Wang , Bing Chen , Zaihua Yang
Due to the inadequacy of existing fire suppression technologies in liquor warehouses, this study demonstrates the applicability of liquid CO2 for extinguishing high-proof liquor fires. Full-scale fire suppression experiments using liquid CO2 were conducted. Results indicated a 100 % fire extinguishing success rate across all tested scales (4–60 m2). Under a valve opening of 28 % (approximately 450 kg/min), the suppression time was between 17 and 56 s, with amount of liquid CO2 agent ranges from 0.12 m3 to 0.38 m3(120∼356 kg). Upon extinguishment, the O2 concentration decreased to 11.4–12.5 %, while the CO2 concentration reached 17.8–22.6 %. After successful fire suppression, the warehouse environment was fully restored within 10 min through ventilation, significantly accelerating operational recovery. The cooling rate of the liquid CO2 system increased significantly with fire size expansion, demonstrating advantages in cooling and explosion suppression for large-scale, high-temperature fires. This study confirms the high efficacy and engineering applicability of liquid CO2 in suppressing liquor warehouse fires, provides theoretical support for fire prevention, and addresses a technical gap in practical implementations within this field.
{"title":"Liquid CO2 fire suppression in liquor warehouses: A full-scale experimental study","authors":"Gang Bai , Wei Wan , Xueming Li , Shuoshuo Wang , Bing Chen , Zaihua Yang","doi":"10.1016/j.csite.2025.107559","DOIUrl":"10.1016/j.csite.2025.107559","url":null,"abstract":"<div><div>Due to the inadequacy of existing fire suppression technologies in liquor warehouses, this study demonstrates the applicability of liquid CO<sub>2</sub> for extinguishing high-proof liquor fires. Full-scale fire suppression experiments using liquid CO<sub>2</sub> were conducted. Results indicated a 100 % fire extinguishing success rate across all tested scales (4–60 m<sup>2</sup>). Under a valve opening of 28 % (approximately 450 kg/min), the suppression time was between 17 and 56 s, with amount of liquid CO<sub>2</sub> agent ranges from 0.12 m<sup>3</sup> to 0.38 m<sup>3</sup>(120∼356 kg). Upon extinguishment, the O<sub>2</sub> concentration decreased to 11.4–12.5 %, while the CO<sub>2</sub> concentration reached 17.8–22.6 %. After successful fire suppression, the warehouse environment was fully restored within 10 min through ventilation, significantly accelerating operational recovery. The cooling rate of the liquid CO<sub>2</sub> system increased significantly with fire size expansion, demonstrating advantages in cooling and explosion suppression for large-scale, high-temperature fires. This study confirms the high efficacy and engineering applicability of liquid CO<sub>2</sub> in suppressing liquor warehouse fires, provides theoretical support for fire prevention, and addresses a technical gap in practical implementations within this field.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"77 ","pages":"Article 107559"},"PeriodicalIF":6.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145784670","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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