A LiBr/LiOH non-eutectic mixture shows a potentially outstanding heat energy density of 800 J/g at a constant temperature,which makes it a very promising candidate for heat storage applications around 300℃.However,sa...A LiBr/LiOH non-eutectic mixture shows a potentially outstanding heat energy density of 800 J/g at a constant temperature,which makes it a very promising candidate for heat storage applications around 300℃.However,salt-based phase change materials are known for their too low thermal conductivity which can question the thermal storage systems effective feasibility.The objective here is to infiltrate a carbon felt of high porosity(>93%)with the LiBr/LiOH mixture to anticipate this deficiency.The device has to be adapted according to the properties and the characteristics of the studied storage and host materials.The developed procedure for the carbon felt infiltration with the synthesized binary system is presented.The optimised working conditions allow(1)minimizing the interaction time duration between the quartz tube and the salt-based mixture and,(2)verifying the good chemical compatibility of the mixture with the host matrix after infiltration.展开更多
The first carbon aerogels prepared by autocondensation of condensed(flavonoid)tannin,a cheap renewable resource extracted from Mimosa barks,are presented.Mixing aqueous solutions of tannin and sodium silicate indeed p...The first carbon aerogels prepared by autocondensation of condensed(flavonoid)tannin,a cheap renewable resource extracted from Mimosa barks,are presented.Mixing aqueous solutions of tannin and sodium silicate indeed produced the very fast gelation of tannins,thus leading to organic hydrogels which were first converted into organic aerogels by supercritical drying,and then into carbon aerogels after pyrolysis at 900℃.Subsequent dissolution of the silica nanoparticles thus formed within the carbon structure further increased significantly the porosity of the materials.Silica thus appeared to be both the gelation catalyst and a pore-directing agent.In this work,the influence on the porosity of the silica/tannin ratio and of the nature of the etching agent used for removing the silica was thoroughly investigated by combining several techniques.The conditions for producing either the most porous materials or those with the highest surface areas were identified and discussed.展开更多
文摘A LiBr/LiOH non-eutectic mixture shows a potentially outstanding heat energy density of 800 J/g at a constant temperature,which makes it a very promising candidate for heat storage applications around 300℃.However,salt-based phase change materials are known for their too low thermal conductivity which can question the thermal storage systems effective feasibility.The objective here is to infiltrate a carbon felt of high porosity(>93%)with the LiBr/LiOH mixture to anticipate this deficiency.The device has to be adapted according to the properties and the characteristics of the studied storage and host materials.The developed procedure for the carbon felt infiltration with the synthesized binary system is presented.The optimised working conditions allow(1)minimizing the interaction time duration between the quartz tube and the salt-based mixture and,(2)verifying the good chemical compatibility of the mixture with the host matrix after infiltration.
基金The authors gratefully acknowledge the financial support of the CPER 2007–2013“Structuration du Pole de Competitivite Fibres Grand’Est”(Competitiveness Fibre Cluster,France)through local(Conseil General des Vosges),regional(Region Lorraine)national(DRRT and FNADT)and European(FEDER,France)funds.
文摘The first carbon aerogels prepared by autocondensation of condensed(flavonoid)tannin,a cheap renewable resource extracted from Mimosa barks,are presented.Mixing aqueous solutions of tannin and sodium silicate indeed produced the very fast gelation of tannins,thus leading to organic hydrogels which were first converted into organic aerogels by supercritical drying,and then into carbon aerogels after pyrolysis at 900℃.Subsequent dissolution of the silica nanoparticles thus formed within the carbon structure further increased significantly the porosity of the materials.Silica thus appeared to be both the gelation catalyst and a pore-directing agent.In this work,the influence on the porosity of the silica/tannin ratio and of the nature of the etching agent used for removing the silica was thoroughly investigated by combining several techniques.The conditions for producing either the most porous materials or those with the highest surface areas were identified and discussed.
