Research On The Structure Design And Heat Transfer Model Of Phase Change Microcapsule Low-temperature Protective Composite Fabric

With the development of science and technology,the environmental conditions of human contact are more complicated,and it is inevitable to work in a low temperature environment.Such as low-temperature experiments in biomedicine,daily training of frontier soldiers,and operating experimental instruments in low temperature environment etc.Even if some operations last for a short period of time,the low temperature environment may cause harm to the human body,so it is necessary to wear protective clothing for work.However,the traditional low temperature protective clothing usually has the heavy form,which limits the human body's activity and affects the work efficiency.In order to work flexibly in a short time under the low temperature environment,the paper combined passive thermal insulation with active thermal production to designed and prepared a three-layer structure low temperature protective composite fabric,which includes a far-infrared nonwoven fabric,a phase change microcapsule functional layer and an aerogel insulation layer.This composite fabric can effectively reduce the internal microclimate temperature change ratio of the composite fabric in a low temperature environment for a certain period of time.Therefore,the fabric can prolong the time of temperature reduction and satisfy the low temperature protection requirement.The research results can provide theoretical basis and feasible technical solutions for the development of lightweight low-temperature protection products in the future,and have broad application prospects.Firstly,the heat storage and temperature regulating phase change microcapsules which can be applied reasonably and efficiently on low temperature protective materials was studies.Microencapsulation technology was used to encapsulate phase change materials,and the effects of emulsifier dosage,emulsification speed,melamine and formaldehyde ratio,core wall ratio on phase change microcapsule morphology,heat storage performance and mechanical properties were discussed.The phase change microcapsules with complete morphology,excellent heat storage performance and certain mechanical properties were obtained by in-situ polymerization.Based on the reinforcing and toughening theories of polymer composites,organic-inorganic composite wall-material phase-change microcapsules were prepared by adding inorganic particles(plasma-treated carbon nanotubes,diatomite),which the mechanical properties of the microcapsules were significantly improved and reduced the damage ratio of the microcapsules in practical application,so that the microcapsules could better fulfilled the application requirements of the low temperature protection.In addition,if only used phase change material to prepare the low temperature protective fabric,when the phase change material was contacted with low temperature environment in direct,the phase transition duration was shortened and protective performance was also been affected.The paper designed and prepared a three-layer structure low temperature protective composite fabric containing thermal insulation layer,and the protective performance of the composite fabric in low temperature environment was studied.According to the PID algorithm,the thermal insulation performance test equipment was designed and manufactured.The test and evaluation of the thermal insulation performance of materials under low temperature environment are realized.Finally,based on the principle of heat transfer,the heat transfer mode of composite fabric in low temperature environment was analyzed and the mathematical model of heat transfer was established by finite element ANSYS Workbench.The prediction model for low temperature resistance was established.The finite element model established could be used for the optimal design of low temperature protective composite fabrics,and it also could analyze and predicte the low temperature protection effect in the actual environment.