Currently,people pay more and more attention to the transitional resettlement of victims after various natural disasters.There is an urgent need for a large number of temporary houses to resettle the victims after nat...Currently,people pay more and more attention to the transitional resettlement of victims after various natural disasters.There is an urgent need for a large number of temporary houses to resettle the victims after natural disasters.Disaster-relief temporary houses(DTHs)played an important role in the post-disaster resettlement in the past,which can not only be produced on a large scale,but also can be quickly and conveniently erected,which were the main means to solve the problem of transitional resettlement.However,due to their temporary nature,there was no extra energy consuming system installed in the DTHs generally.Hence the indoor thermal environment inside the DTHs was severe in summer.In this study,combined with the field experimental tests of the DTHs in Wenchuan Earthquake and Lushan Earthquake and the experimental study of the full-size DTH,it found that the thermal environment inside the DTH was intolerably high in summer.It had negative impact on victims.In order to improve the thermal environment inside DTHs during post-disaster period which lacked of extra energy resources,this study used the method of combining phase change materials(PCMs)with walls of the DTH to explore its feasibility and effectiveness.The results showed that PCMs could effectively improve the thermal environment inside the DTH in summer.Furthermore,the difference of the composite positions between PCMs and the wall affected the improvement effect.The energy release rate of the PCMs assembly system(PAS)varied according to the positions of the PCMs.展开更多
Refrigeration systems are essential across various sectors,including food preservation,medical storage,and climate control.However,their high energy consumption and environmental impact necessitate innovative solution...Refrigeration systems are essential across various sectors,including food preservation,medical storage,and climate control.However,their high energy consumption and environmental impact necessitate innovative solutions to enhance efficiency while minimizing energy usage.This paper investigates the integration of Phase Change Materials(PCMs)into a vapor compression refrigeration system to enhance energy efficiency and temperature regulation for food preservation.A multifunctional prototype was tested under two configurations:(1)a standard thermally insulated room,and(2)the same room augmented with eutectic plates filled with either Glaceol(-10℃ melting point)or distilled water(0℃ melting point).Thermocouples were calibrated and deployed to record air and PCM temperatures during freeze–thaw cycles at thermostat setpoints of and Additionally,a-30℃ -35℃ .defrosting resistor and timer were added to mitigate frost buildup,a known cause of efficiency loss.The experimental results show that PCM-enhanced rooms achieved up to 10.98℃ greater temperature stability during defrost cycles and reduced energy consumption by as much as 7.76%(from 0.4584 to 0.4231 kWh/h).Moreover,the effectiveness of PCMs depended strongly on thermostat settings and PCM type,with distilled water demonstrating broader solidification across plates under higher ambient loads.These findings highlight the potential of PCM integration to improve cold-chain performance,offering rapid cooling,moisture retention,and extended product conservation during power interruptions.展开更多
对 Si 含量为10%～13%的 Al-Si 合金进行了加速氧化、热循环和掺 Fe 实验,研究了其在不同热循环条件下的相变储热性能和可靠性．结果表明,在空气中经几百 h 的高温氧化后,氧化率小于0．01%,其影响可以忽略不计．经过0,4,23,60, 100,200,...对 Si 含量为10%～13%的 Al-Si 合金进行了加速氧化、热循环和掺 Fe 实验,研究了其在不同热循环条件下的相变储热性能和可靠性．结果表明,在空气中经几百 h 的高温氧化后,氧化率小于0．01%,其影响可以忽略不计．经过0,4,23,60, 100,200,300,400,500,600,700次熔化-凝固循环后,相变温度的变化为3．8～11．8℃,相变潜热从484．86 kJ/kg下降到432．62 kJ/kg．当 Al-Si 合金的掺铁量为0．5%时,相变潜热下降6．5%；对于缓冷的储能过程,偏析较小并在循环多次后趋于缓和和稳定．Al-Si 合金成份和结构的变化对材料的储热性能影响较小,在长期的热循环过程中有良好和稳定的储热性能．展开更多
Phase change materials(PCMs)have great potential in thermal energy management,but their low ther-mal conductivity,easy leakage,and poor thermal stability limit their wide application.After constructing the biomimetic ...Phase change materials(PCMs)have great potential in thermal energy management,but their low ther-mal conductivity,easy leakage,and poor thermal stability limit their wide application.After constructing the biomimetic leaf-vein-like three-dimensional(3D)structure of boron nitride(BN)and impregnated with polyethylene glycol(PEG),the comprehensive properties of phase change composites were effec-tively enhanced under low filler content.The PEG is stored in the 3D structure of BN,which can prevent leakage at high temperatures and enhance the composites’thermal stability and storage modulus.As a fast channel of transmission of phonons,the BN skeleton can effectively reduce thermal resistance.When the amount of filler is 10 vol%,the highest thermal conductivity of the composite PCMs is 2.62 W m-1 K-1,which is 10.1 times than that of pure PEG.Under the infrared camera,the composite PCMs yielded excellent battery thermal management performance,indicating that the material has great potential in thermal management.展开更多
This paper proposes a modified Kelvin model for high mechanical property open-cell metal foams and investigates its application in thermal simulations. The thermal conductivity is simulated based on the steady state m...This paper proposes a modified Kelvin model for high mechanical property open-cell metal foams and investigates its application in thermal simulations. The thermal conductivity is simulated based on the steady state method and the results are consistent with experimental values. The melting process of phase change materials (PCMs) in Kelvin model and its modified model is numerically investigated under a temperature constant heat resource. By detecting the temperature variations, it shows that the metal foam greatly improves the heat transfer in energy storage systems. Besides, the comparison of the melting process in two foam models indicates that the systems based on high mechanical property metal foams have a shorter melting time. The melting process of paraffin in modified Kelvin metal foam models with three different porosities (65%, 70% and 75%) are numerically analyzed and compared.展开更多
The rapid commercialization of Phase Change Materials(PCMs)for HVAC applications effectively leverages ambient temperature fluctuations to meet growing energy demands in buildings.This study outlines a systematic appr...The rapid commercialization of Phase Change Materials(PCMs)for HVAC applications effectively leverages ambient temperature fluctuations to meet growing energy demands in buildings.This study outlines a systematic approach to passively integrate PCM into building roofs for cooling load reduction.The process involves PCM selection,characterization,analysis of melting front propagation,and thermal performance assessment.Thermal/digital imaging approach tracks the melting front's propagation,revealing significant natural convection due to heat flux from modules bottom surface.Melting front propagation occurs primarily in one dimension.Two identical roof slab units are fabricated and tested in Rupnagar City,India,for assessing thermal performance,with one unit equipped with PCM(PSU)and the other as a conventional reinforced slab unit(CSU).Various energetic and thermal performance metrics,including Maximum Temperature Reduction(MTR),Operative Temperature Difference(OTD),Heat transfer,electricity cost savings(Esc),Discomfort Hours Reduction(DHR),and Maximum Heat Gain Reduction(MHGR),are evaluated.PCM integration results in a significant MTR of 4℃and a 60%reduction in heat flux compared to the conventional unit.Moreover,the PCM room exhibits an 11.2%and 34.8%enhancement in thermal comfort,as indicated by DHR and MHGR,respectively,compared to the reference unit.In addition,considering heating and cooling spaces,it offers a maximum daily saving of 0.06 USD/(kWh·m^(2)).These findings highlight PCM's potential to mitigate temperature fluctuations,enhance thermal comfort,and reduce energy consumption in severe climatic conditions.展开更多
The use of porous skeletons for encapsulating phase change materials(PCMs)is an effective approach to addressing issues such as leakage,low thermal conductivity,and poor photothermal conversion efficiency.Inspired by ...The use of porous skeletons for encapsulating phase change materials(PCMs)is an effective approach to addressing issues such as leakage,low thermal conductivity,and poor photothermal conversion efficiency.Inspired by the hollow skeletal structure found in birds in nature,high-quality 3D interconnected hollow diamond foam(HDF)was fabricated using a series of processes,including microwave plasma chemical vapor deposition(CVD),laser perforation,and acid immersion.This HDF was then used as a scaffold to encapsulate PEG2000.The results demonstrate that HDF significantly reduces the supercooling degree and latent heat discrepancy of PEG2000.Compared to pure PEG2000,the thermal conductivity of the HDF/PEG increased by 378%,while its latent heat reached 111.48 J/g,accompanied by a photothermal conversion efficiency of up to 86.68%.The significant performance improvement is mainly attributed to the combination of the excellent properties of the diamond with the inherent advantages of the 3D interconnected structure in HDF,which creates a high-conductivity transport network inside.Moreover,the HDF/PEG composite extends the temperature cycling time of electronic components by 4 times for heating and 2.3 times for cooling,thereby prolonging the operational lifetime of electronic devices.HDF/PEG offers an integrated solution for solar energy collection,photothermal conversion,heat dissipation in electronic components,and thermal energy transfer/storage.This innovative approach provides innovative ideas for the design and fabrication of composite PCMs and has great application potential,such as solar energy utilization,thermal management,and thermal energy storage.展开更多
Phase change materials(PCMs)play a leading role in overcoming the growing need of advanced thermal management for the storage and release of thermal energy which is to be used for different solar applications.However,...Phase change materials(PCMs)play a leading role in overcoming the growing need of advanced thermal management for the storage and release of thermal energy which is to be used for different solar applications.However,the effectiveness of PCMs is greatly affected by their poor thermal conductivity.Therefore,in the present review the progress made in deploying the graphene(Gr)in PCMs in the last decade for providing the solution to the aforementioned inadequacy is presented and discussed in detail.Gr and its derivatives((Gr oxide(GO),Gr aerogel(GA)and Gr nanoplatelets(GNPs))based PCMs can improve the thermal conductivity and shape stability,which may be attributed to the extra ordinary thermo-physical properties of Gr.Moreover,it is expected from this review that the advantages and disadvantages of using Gr nanoparticles provide a deep insight and help the researchers in finding out the exact basic properties and finally the applications of Gr can be enhanced.In this work,Gr and its derivatives based PCMs was characterized by Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction spectroscopy(XRD),and scanning electron microscopy(SEM)by which crystal structure was known,phase was identified along with the knowledge of surface structure respectively.The increase in the mass fraction(%)of the filler(Gr and its derivatives)led to even better thermo-physical properties and thermal stability.The thermal characterization was also done by differential scanning calorimetry(DSC),thermo gravimetric analysis(TGA)and thermal conductivity tests.The enthalpy of freezing and melting showed that Gr and its derivatives based PCMs had a very high energy storage capability as reflected in its various applications.展开更多
文摘Currently,people pay more and more attention to the transitional resettlement of victims after various natural disasters.There is an urgent need for a large number of temporary houses to resettle the victims after natural disasters.Disaster-relief temporary houses(DTHs)played an important role in the post-disaster resettlement in the past,which can not only be produced on a large scale,but also can be quickly and conveniently erected,which were the main means to solve the problem of transitional resettlement.However,due to their temporary nature,there was no extra energy consuming system installed in the DTHs generally.Hence the indoor thermal environment inside the DTHs was severe in summer.In this study,combined with the field experimental tests of the DTHs in Wenchuan Earthquake and Lushan Earthquake and the experimental study of the full-size DTH,it found that the thermal environment inside the DTH was intolerably high in summer.It had negative impact on victims.In order to improve the thermal environment inside DTHs during post-disaster period which lacked of extra energy resources,this study used the method of combining phase change materials(PCMs)with walls of the DTH to explore its feasibility and effectiveness.The results showed that PCMs could effectively improve the thermal environment inside the DTH in summer.Furthermore,the difference of the composite positions between PCMs and the wall affected the improvement effect.The energy release rate of the PCMs assembly system(PAS)varied according to the positions of the PCMs.
基金supported in entire part by the Biomaterials and Transport Phenomena Laboratory Agreement No.30303-12-2003,at the University of Medea.
文摘Refrigeration systems are essential across various sectors,including food preservation,medical storage,and climate control.However,their high energy consumption and environmental impact necessitate innovative solutions to enhance efficiency while minimizing energy usage.This paper investigates the integration of Phase Change Materials(PCMs)into a vapor compression refrigeration system to enhance energy efficiency and temperature regulation for food preservation.A multifunctional prototype was tested under two configurations:(1)a standard thermally insulated room,and(2)the same room augmented with eutectic plates filled with either Glaceol(-10℃ melting point)or distilled water(0℃ melting point).Thermocouples were calibrated and deployed to record air and PCM temperatures during freeze–thaw cycles at thermostat setpoints of and Additionally,a-30℃ -35℃ .defrosting resistor and timer were added to mitigate frost buildup,a known cause of efficiency loss.The experimental results show that PCM-enhanced rooms achieved up to 10.98℃ greater temperature stability during defrost cycles and reduced energy consumption by as much as 7.76%(from 0.4584 to 0.4231 kWh/h).Moreover,the effectiveness of PCMs depended strongly on thermostat settings and PCM type,with distilled water demonstrating broader solidification across plates under higher ambient loads.These findings highlight the potential of PCM integration to improve cold-chain performance,offering rapid cooling,moisture retention,and extended product conservation during power interruptions.
文摘对 Si 含量为10%～13%的 Al-Si 合金进行了加速氧化、热循环和掺 Fe 实验,研究了其在不同热循环条件下的相变储热性能和可靠性．结果表明,在空气中经几百 h 的高温氧化后,氧化率小于0．01%,其影响可以忽略不计．经过0,4,23,60, 100,200,300,400,500,600,700次熔化-凝固循环后,相变温度的变化为3．8～11．8℃,相变潜热从484．86 kJ/kg下降到432．62 kJ/kg．当 Al-Si 合金的掺铁量为0．5%时,相变潜热下降6．5%；对于缓冷的储能过程,偏析较小并在循环多次后趋于缓和和稳定．Al-Si 合金成份和结构的变化对材料的储热性能影响较小,在长期的热循环过程中有良好和稳定的储热性能．
基金Lanzhou Science and Technology Plan Project Funding(Project No.:2021-1-44)and Project Funding of Fangda Carbon New Material Co.,Ltd.
文摘Phase change materials(PCMs)have great potential in thermal energy management,but their low ther-mal conductivity,easy leakage,and poor thermal stability limit their wide application.After constructing the biomimetic leaf-vein-like three-dimensional(3D)structure of boron nitride(BN)and impregnated with polyethylene glycol(PEG),the comprehensive properties of phase change composites were effec-tively enhanced under low filler content.The PEG is stored in the 3D structure of BN,which can prevent leakage at high temperatures and enhance the composites’thermal stability and storage modulus.As a fast channel of transmission of phonons,the BN skeleton can effectively reduce thermal resistance.When the amount of filler is 10 vol%,the highest thermal conductivity of the composite PCMs is 2.62 W m-1 K-1,which is 10.1 times than that of pure PEG.Under the infrared camera,the composite PCMs yielded excellent battery thermal management performance,indicating that the material has great potential in thermal management.
文摘This paper proposes a modified Kelvin model for high mechanical property open-cell metal foams and investigates its application in thermal simulations. The thermal conductivity is simulated based on the steady state method and the results are consistent with experimental values. The melting process of phase change materials (PCMs) in Kelvin model and its modified model is numerically investigated under a temperature constant heat resource. By detecting the temperature variations, it shows that the metal foam greatly improves the heat transfer in energy storage systems. Besides, the comparison of the melting process in two foam models indicates that the systems based on high mechanical property metal foams have a shorter melting time. The melting process of paraffin in modified Kelvin metal foam models with three different porosities (65%, 70% and 75%) are numerically analyzed and compared.
文摘The rapid commercialization of Phase Change Materials(PCMs)for HVAC applications effectively leverages ambient temperature fluctuations to meet growing energy demands in buildings.This study outlines a systematic approach to passively integrate PCM into building roofs for cooling load reduction.The process involves PCM selection,characterization,analysis of melting front propagation,and thermal performance assessment.Thermal/digital imaging approach tracks the melting front's propagation,revealing significant natural convection due to heat flux from modules bottom surface.Melting front propagation occurs primarily in one dimension.Two identical roof slab units are fabricated and tested in Rupnagar City,India,for assessing thermal performance,with one unit equipped with PCM(PSU)and the other as a conventional reinforced slab unit(CSU).Various energetic and thermal performance metrics,including Maximum Temperature Reduction(MTR),Operative Temperature Difference(OTD),Heat transfer,electricity cost savings(Esc),Discomfort Hours Reduction(DHR),and Maximum Heat Gain Reduction(MHGR),are evaluated.PCM integration results in a significant MTR of 4℃and a 60%reduction in heat flux compared to the conventional unit.Moreover,the PCM room exhibits an 11.2%and 34.8%enhancement in thermal comfort,as indicated by DHR and MHGR,respectively,compared to the reference unit.In addition,considering heating and cooling spaces,it offers a maximum daily saving of 0.06 USD/(kWh·m^(2)).These findings highlight PCM's potential to mitigate temperature fluctuations,enhance thermal comfort,and reduce energy consumption in severe climatic conditions.
基金supported by the National Natural Science Foundation of China(Grant Nos.52176054,52236006,52172037,and 52350362)the Natural Science Foundation of Guangdong Province,China(Grant No.2024A1515012033).
文摘The use of porous skeletons for encapsulating phase change materials(PCMs)is an effective approach to addressing issues such as leakage,low thermal conductivity,and poor photothermal conversion efficiency.Inspired by the hollow skeletal structure found in birds in nature,high-quality 3D interconnected hollow diamond foam(HDF)was fabricated using a series of processes,including microwave plasma chemical vapor deposition(CVD),laser perforation,and acid immersion.This HDF was then used as a scaffold to encapsulate PEG2000.The results demonstrate that HDF significantly reduces the supercooling degree and latent heat discrepancy of PEG2000.Compared to pure PEG2000,the thermal conductivity of the HDF/PEG increased by 378%,while its latent heat reached 111.48 J/g,accompanied by a photothermal conversion efficiency of up to 86.68%.The significant performance improvement is mainly attributed to the combination of the excellent properties of the diamond with the inherent advantages of the 3D interconnected structure in HDF,which creates a high-conductivity transport network inside.Moreover,the HDF/PEG composite extends the temperature cycling time of electronic components by 4 times for heating and 2.3 times for cooling,thereby prolonging the operational lifetime of electronic devices.HDF/PEG offers an integrated solution for solar energy collection,photothermal conversion,heat dissipation in electronic components,and thermal energy transfer/storage.This innovative approach provides innovative ideas for the design and fabrication of composite PCMs and has great application potential,such as solar energy utilization,thermal management,and thermal energy storage.
文摘Phase change materials(PCMs)play a leading role in overcoming the growing need of advanced thermal management for the storage and release of thermal energy which is to be used for different solar applications.However,the effectiveness of PCMs is greatly affected by their poor thermal conductivity.Therefore,in the present review the progress made in deploying the graphene(Gr)in PCMs in the last decade for providing the solution to the aforementioned inadequacy is presented and discussed in detail.Gr and its derivatives((Gr oxide(GO),Gr aerogel(GA)and Gr nanoplatelets(GNPs))based PCMs can improve the thermal conductivity and shape stability,which may be attributed to the extra ordinary thermo-physical properties of Gr.Moreover,it is expected from this review that the advantages and disadvantages of using Gr nanoparticles provide a deep insight and help the researchers in finding out the exact basic properties and finally the applications of Gr can be enhanced.In this work,Gr and its derivatives based PCMs was characterized by Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction spectroscopy(XRD),and scanning electron microscopy(SEM)by which crystal structure was known,phase was identified along with the knowledge of surface structure respectively.The increase in the mass fraction(%)of the filler(Gr and its derivatives)led to even better thermo-physical properties and thermal stability.The thermal characterization was also done by differential scanning calorimetry(DSC),thermo gravimetric analysis(TGA)and thermal conductivity tests.The enthalpy of freezing and melting showed that Gr and its derivatives based PCMs had a very high energy storage capability as reflected in its various applications.
