Study On The Insulation Performance Of Composite Multilayer Insulation

Compared to conventional propellants in space propulsion system,cryogenic propellant(liquid hydrogen/oxygen)has highest specific impulse and efficiency of any known rocket propellant.It is also non-toxic and pollution free.Storage of cryogenic propellant on-orbit requires efficient thermal insulation technology in storage,the most common solution is composite high vacuum Multilayer Insulation(MLI),mainly a compound of foam and multilayer insulation.High vacuum multilayer insulation material has the best performance among cryogenic insulation materials.But its performance is easily affected by the interstitial gas pressure,layer thickness,layer density,boundary temperature and etc.There are many limitations in theoretical calculation methods as well.Therefore,building a reliable testing system for measuring insulation performance of composite multilayer insulation,and establishing a procedure to calculate the performance of multilayer insulation has important practical significance for standardized measurement and engineering applications.With these objectives in mind,the following work is discussed in this paper:A comparison of performance,advantages and disadvantages of several common cryogenics insulation materials is conducted.History of high vacuum MLI and key factors affecting the performance is summarized.Several typical Calorimeter platforms are analyzed in detail,and the latest platform based on refrigerator is introduced.A theoretical model of calculating high vacuum MLI performance is established based on latest theoretical model,and combined with gas heat transfer theory of high vacuum MLI,heat conduction and radiation.A MatLab program is written based on the theoretical model.A high vacuum multilayer insulation test system has been set up,consisting of a calorimeter,vacuum system,data acquisition system and auxiliary system.The reliability of the test system is verified by experiment results and theoretical calculation.Pre-stressed high vacuum MLI material was tested following requirements of applications.The performance of high vacuum multi MLI performs better than Polyurethane foam.Measured thermal conductivity of the best performing MLI is 2.58×10-4 W/m·K.Per the experimental results,the model is revised predict the performance of the composite multilayer insulation material.