Phase-change material(PCM)is widely used in thermal management due to their unique thermal behavior.However,related research in thermal rectifier is mainly focused on exploring the principles at the fundamental device...Phase-change material(PCM)is widely used in thermal management due to their unique thermal behavior.However,related research in thermal rectifier is mainly focused on exploring the principles at the fundamental device level,which results in a gap to real applications.Here,we propose a controllable thermal rectification design towards building applications through the direct adhesion of composite thermal rectification material(TRM)based on PCM and reduced graphene oxide(rGO)aerogel to ordinary concrete walls(CWs).The design is evaluated in detail by combining experiments and finite element analysis.It is found that,TRM can regulate the temperature difference on both sides of the TRM/CWs system by thermal rectification.The difference in two directions reaches to 13.8 K at the heat flow of 80 W/m^(2).In addition,the larger the change of thermal conductivity before and after phase change of TRM is,the more effective it is for regulating temperature difference in two directions.The stated technology has a wide range of applications for the thermal energy control in buildings with specific temperature requirements.展开更多
The objective of this work is to develop new biosourced insulating composites from rice husks and wood chips that can be used in the building sector. It appears from the properties of the precursors that rice chips an...The objective of this work is to develop new biosourced insulating composites from rice husks and wood chips that can be used in the building sector. It appears from the properties of the precursors that rice chips and husks are materials which can have good thermal conductivity and therefore the combination of these precursors could make it possible to obtain panels with good insulating properties. With regard to environmental and climatic constraints, the composite panels formulated at various rates were tested and the physico-mechanical and thermal properties showed that it was essential to add a crosslinker in order to increase certain solicitation. an incorporation rate of 12% to 30% made it possible to obtain panels with low thermal conductivity, a low surface water absorption capacity and which gives the composite good thermal insulation and will find many applications in the construction and real estate sector. Finally, new solutions to improve the fire reaction of the insulation panels are tested which allows to identify suitable solutions for the developed composites. In view of the flame tests, the panels obtained are good and can effectively combat fire safety in public buildings.展开更多
The rapid growth of the global population,coupled with increasing pollution levels,highlights the urgent need for sustainable and eco-friendly construction materials,such as unfired clay bricks.However,their widesprea...The rapid growth of the global population,coupled with increasing pollution levels,highlights the urgent need for sustainable and eco-friendly construction materials,such as unfired clay bricks.However,their widespread adoption remains limited due to certain performance drawbacks,particularly in thermal insulation,a critical factor in addressing climate change challenges.In this study,a plant-based waste-derived biopolymer was incorporated into unfired clay bricks to enhance their physicochemical and thermomechanical properties.The biopolymer was added at six different weight fractions(0%,1%,3%,7%,15%,and 20%)to systematically evaluate its impact on bulk density,porosity,capillary water absorption,thermal conductivity,specific heat capacity,and compressive strength.The results revealed a gradual decrease in porosity as the biopolymer content increased,leading to a 41%improvement in thermal conductivity at 20 wt%.However,the optimal balance between thermal efficiency and compressive strength was achieved at 7 wt%biopolymer;this result has been verified through a combination of experimental methods and modeling.Additionally,TRNSYS simulations confirmed the enhanced thermal performance,demonstrating a 9.74%increase in time lag and a 16%reduction in decrement factor,both of which contribute to optimizing building energy efficiency.Overall,this approach not only helps reduce environmental pollution but also enhances insulation capacity while lowering heating and cooling demands,thereby improving overall building performance.Biopolymer-reinforced unfired clay bricks thus represent a promising solution for advancing a low-carbon and sustainable construction industry,aligning with the United Nations Sustainable Development Goals(SDGs)for climate change mitigation and responsible resource management.展开更多
基金This work was supported in part by Tsinghua University-Zhuhai Huafa Industrial Share Company Joint Institute for Architecture Optoelectronic Technologies(JIAOT KF202204)in part by STI 2030—Major Projects under Grant 2022ZD0209200+2 种基金in part by National Natural Science Foundation of China under Grant 62374099,Grant 62022047in part by Beijing Natural Science-Xiaomi Innovation Joint Fund under Grant L233009in part by the Tsinghua-Toyota JointResearch Fund,in part by the Daikin-Tsinghua Union Program,in part sponsored by CIE-Tencent Robotics XRhino-Bird Focused Research Program.
文摘Phase-change material(PCM)is widely used in thermal management due to their unique thermal behavior.However,related research in thermal rectifier is mainly focused on exploring the principles at the fundamental device level,which results in a gap to real applications.Here,we propose a controllable thermal rectification design towards building applications through the direct adhesion of composite thermal rectification material(TRM)based on PCM and reduced graphene oxide(rGO)aerogel to ordinary concrete walls(CWs).The design is evaluated in detail by combining experiments and finite element analysis.It is found that,TRM can regulate the temperature difference on both sides of the TRM/CWs system by thermal rectification.The difference in two directions reaches to 13.8 K at the heat flow of 80 W/m^(2).In addition,the larger the change of thermal conductivity before and after phase change of TRM is,the more effective it is for regulating temperature difference in two directions.The stated technology has a wide range of applications for the thermal energy control in buildings with specific temperature requirements.
文摘The objective of this work is to develop new biosourced insulating composites from rice husks and wood chips that can be used in the building sector. It appears from the properties of the precursors that rice chips and husks are materials which can have good thermal conductivity and therefore the combination of these precursors could make it possible to obtain panels with good insulating properties. With regard to environmental and climatic constraints, the composite panels formulated at various rates were tested and the physico-mechanical and thermal properties showed that it was essential to add a crosslinker in order to increase certain solicitation. an incorporation rate of 12% to 30% made it possible to obtain panels with low thermal conductivity, a low surface water absorption capacity and which gives the composite good thermal insulation and will find many applications in the construction and real estate sector. Finally, new solutions to improve the fire reaction of the insulation panels are tested which allows to identify suitable solutions for the developed composites. In view of the flame tests, the panels obtained are good and can effectively combat fire safety in public buildings.
文摘The rapid growth of the global population,coupled with increasing pollution levels,highlights the urgent need for sustainable and eco-friendly construction materials,such as unfired clay bricks.However,their widespread adoption remains limited due to certain performance drawbacks,particularly in thermal insulation,a critical factor in addressing climate change challenges.In this study,a plant-based waste-derived biopolymer was incorporated into unfired clay bricks to enhance their physicochemical and thermomechanical properties.The biopolymer was added at six different weight fractions(0%,1%,3%,7%,15%,and 20%)to systematically evaluate its impact on bulk density,porosity,capillary water absorption,thermal conductivity,specific heat capacity,and compressive strength.The results revealed a gradual decrease in porosity as the biopolymer content increased,leading to a 41%improvement in thermal conductivity at 20 wt%.However,the optimal balance between thermal efficiency and compressive strength was achieved at 7 wt%biopolymer;this result has been verified through a combination of experimental methods and modeling.Additionally,TRNSYS simulations confirmed the enhanced thermal performance,demonstrating a 9.74%increase in time lag and a 16%reduction in decrement factor,both of which contribute to optimizing building energy efficiency.Overall,this approach not only helps reduce environmental pollution but also enhances insulation capacity while lowering heating and cooling demands,thereby improving overall building performance.Biopolymer-reinforced unfired clay bricks thus represent a promising solution for advancing a low-carbon and sustainable construction industry,aligning with the United Nations Sustainable Development Goals(SDGs)for climate change mitigation and responsible resource management.
