有机相变储热复合材料的储/放热性能研究

Investigation on Thermal Sotrage and Release Property with Organic Phase Change Heat Storage Composite Material

以高孔隙率泡沫石墨材料作为骨架在真空环境下吸附石蜡,制备而成新型有机相变储热复合材料。利用HotDisk热常数分析仪和差示扫描量热仪(DSC)研究了其热性能,结果证明复合材料的导热能力得到了极大强化。对分别填充了复合材料和纯石蜡的以水作为热媒的储热槽进行了实验研究,重点考察了两者在储热和放热过程中的温度均匀性、储能速率及泡沫石墨对石蜡相变的影响,同时就泡沫石墨的孔隙率大小对复合材料导热性能和储能速率的影响规律进行了对比分析。研究表明,复合材料的相变温度区间基本不变,导热性能提高了21倍,相变时间缩短了56%以上,相变界面移动加快,储热槽的储热、放热性能和储能密度有了很大提高;不同孔隙率会影响复合材料的导热系数、储能速率和储能容量,在提高储能速率和保证储能容量两者之间,选择孔隙率为91%的泡沫石墨作为复合材料骨架应是一最佳值。

A new organic composite phase change material（PCM） was manufactured by melting and perfusing the paraffin into the porous graphite foam in the vacuum environment.Thermal properties of the composite material were tested by using Hot Disk and differential scanning calorimeter（DSC）,and the test results show that the capacity of heat transmission of composite material was greatly enhanced due to the inducing of graphite foam with its pores network and high thermal conductivity.Simultaneously,experiments of the heat storage and release characteristics in two heat storage tanks which were respectively filled with composite PCM and pure paraffin were carried on,and water as heat transfer fluid.Uniformity of temperatures,energy storage efficiencies and influence of graphite foam were investigated,meanwhile,the influences of different porosity of graphite foam on the thermal conductivity enhancement and energy storage were compared and discussed.The study indicates that the heat conduction performance is improved of 21 times and the phase change time is obviously advanced of 56% in the composite PCM heat storage tank,which gets large improvement on the properties of thermal storage and release and the energy storage density.It is also concluded that the porosity will influence the thermal conductivity,energy storage rate and energy storage capacity of composite materials,as a result,91% will be a optimal value in consider of both improving energy storage rate and ensuring energy storage capacity.