| With the development of the economy and the expansion of industrial scale,China's demand for oil is increasing.But after a long period of exploitation,the decreasing phenomenon of China's oil fields has been very serious.In order to enable China's oil economy to develop steadily,we must import a large number of oil.Oil is generally transported through oil tanker cargo tank,and it is easy to condense during transportation or handling because of its high viscosity and high freezing point,so it needs to be heated to keep in a liquid state.However,in the conventional steam heating method,if the time of heating is too early or the temperature is too high,the energy is wasted so that the economy of the ship is poor;and if the time of heating is too late or the temperature is too low,it is difficult to take the oil off.Phase change materials(PCMs)have the advantages of large latent heat,wide phase change temperature and environmental.When it is used as heat-insulating material in cargo tanks,it can reduce or increase the temperature by absorbing or releasing energy to allow oil to stay in a relatively constant temperature environment for a for a longer period of time during transportation.However,the phase change materials also have defects such as poor thermal conductivity and easy to leak.In order to solve these problems,this paper uses the material composite technology to prepare the novel shaped phase change materials and analyse their properties.The main contents of this paper include the following points:1.Take the preferred stearic acid(SA)as the core material and onion-like mesoporous silicon(MOS)as the support material to prepare a novel shaped composite phase change material SA/MOS through the physical adsorption method.And analyze its morphology,chemical components,thermal stability,heat storage properties,and etc.by the tests of SEM,TEM,XRD,FT-IR,TGA and DSC.The results show that the porous structure of MOS makes SA adsorbed firmly in the pores,and the best adsorption rate is 70%,and the latent heat of the composite phase change material gradually increases with the increasing of the content of SA.The melting and solidification temperature of 70% SA/MOS were72.72 °C and 63.87 °C,respectively,with the enthalpies of 108.0 J/g and 126.0 J/g,whichwere higher than those of prepared by SA and other support materials.And there was no leakage after 50 thermal cycles,indicating that SA/MOS has good thermal stability and heat storage properties.2.In order to improve the enthalpy of the composite phase change materials,dopamine(Dop)was used to modify the support material to synthesize Dop-MOS,and then it was used as support material to prepare the novel shaped composite phase change material SA/Dop-MOS with the core material of SA through the physical adsorption method,and its properties were tested by SEM,BET,XRD,FT-IR,TGA and DSC.The results show that the specific surface area,cumulative volume and pore size of Dop-MOS are lower than that of MOS.The maximum adsorption of SA to the Dop-MOS was also70% and the melting and solidification temperature of 70%SA/Dop-MOS were 70.9 °C and 64.2 °C with the enthalpies of 127.2 J/g and 124.9 J/g,respectively.And the enthalpies increased by 28.6% and 21.0% compared with 70% SA / MOS,indicating that dopamine's modification of MOS is effective,and SA/Dop-MOS has better heat storage performance. |
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