| With the intelligence of the technology,the consumption of oil,known as "industrial blood",is also increasing.With the gradual depletion of offshore oil resources,oil exploitation has gradually shifted to deep seas and far seas.For deep-sea oil exploration,thermal insulation of oil pipelines has become a top priority.In the deep sea,the temperature is usually low and the pressure is extremely high,which puts forward extremely high requirements on the oil pipeline.Although there is already a heating technology for pipes,it is not applicable in the deep sea.The traditional foam insulation materials used in the deep sea also have problems such as low strength,susceptibility to moisture,and poor heat resistance.Therefore,we designed and prepared a double-layer thermal insulation material composed of graphene/lauric acid phase change material and hollow aluminum sphere/epoxy resin cell material.The phase change material in the inner layer can be stored and released by the temperature change of crude oil.The outer layer of hollow aluminum ball epoxy composite material is a high-strength,low-density thermal insulation material to resist the pressure and low temperature of the deep sea.The main research contents are as follows:1.Home-made GO was used as the raw materials,dinonyl carbonyl iron and ethylenediamine as reducing agents,reduced graphene oxide aerogel(r GOA)was prepared by directional freezing and then freeze-drying.Directional freezing controls the arrangement of dinonyl carbonyl iron products to prepare magnetic thermally conductive graphene aerogels(r GO-Fe A)with anisotropic thermal conductivity.Preparation of magnetically thermally conductive graphene/lauric acid phase change materials by impregnation.The research results show that the phase change composite has a high phase change enthalpy of 172.9 J/g under the optimum magnetic powder addition of 20 wt%,with good cycle stability and shape stability.The variable enthalpy decays by only 5.63%,the vertical in-plane thermal conductivity is 1.175 W/m·K,and the anisotropic thermal conductivity is 5.269.Anisotropic thermal conductivity increases heat transfer efficiency.2.Using expanded polystyrene microspheres as a template,powder metallurgy method,and ethyl orthosilicate and polyvinyl butyral as binders,at a relatively low temperature of 720 ℃(slightly higher than the melting point of aluminum 60 ℃)prepared high-strength metal-aluminum hollow spheres.The aluminum hollow sphere has a complete structure,and the yield stress is9.7 times that of the ordinary stainless steel metal hollow sphere.The aluminum hollow sphere/epoxy resin composite cellular material was prepared by curing the metal aluminum hollow sphere and epoxy resin E44.By changing the arrangement of the aluminum hollow spheres in the epoxy resin,it is found that the thermal conductivity of the aluminum hollow spheres/epoxy foam material is only 0.2089 W/m·K,when the aluminum hollow spheres are arranged in a body-centered cubic in the epoxy resin.less than one thousandth of the thermal conductivity of aluminum,is 86% of the thermal conductivity of pure epoxy resin.The density of the aluminum hollow sphere/epoxy resin composite cell material is only 77% of that of pure epoxy resin,and the elastic modulus is almost the same as that of pure epoxy resin,which is about 97% of that of pure epoxy resin.3.A double-layer composite thermal insulation material is prepared by bonding the prepared aluminum hollow sphere/epoxy resin cell material and the magnetic thermally conductive graphene/lauric acid phase change material.The influence of the relative proportions of aluminum hollow sphere/epoxy resin cell material and magnetic thermally conductive graphene/lauric acid phase change material on the overall thermal conductivity of the material was studied.The results show that the composite thermal insulation material has excellent thermal insulation properties,and the minimum thermal conductivity can be reduced to 0.2140 W/m·K. |
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