Study On The Heat Transfer Performance Of New Combinational Insulation(SOFI/VD-MLI) For Cryogenic Storage Tank

As the essential technology of cryogenic storage tank, the thermal protection technology has serious influence on the heat leakage of the tank, especially in the aerospace, the using of efficient thermal protection technology will significantly reduce the heat leakage of the tank and the evaporation loss of cryogenic propellant, then, the zero boil-off storage of cryogenic propellant will be realized. New combional insulation(SOFI/VD-MLI), which is the reasonable combination of foam insulation(SOFI) and variable multilayer insulation(VD-MLI), is a kind of efficient thermal protection technology of cryogenic storage tank and has the advantages of exercellent heat insulation and light weight. SOFI/VD-MLI not only can minimize the heat leakage of cryogenic storage tank in the ground, launching and on-orbit stages of aircraft, but also helps to reduce the quality of the tank.The SOFI/VD-MLI of cryogenic storage tank was taken as the research object. For SOFI/VD-MLI, the heat transfer calculation models were established by analysing the heat transfer mechanisms, and the heat leakage was calculated based on the heat transfer calculation models, then, the temperature fields were numerically simulated.Firstly, the heat transfer mechanisms of SOFI/VD-MLI in the ground and space stages were analyzed. In the ground stage, SOFI/VD-MLI mainly accounts for the thermal conduction of SOFI, and the thermal radiation between adjacent reflectors, the gas conduction between adjacent reflectors and the solid conduction through the separator materials between adjacent reflectors of VD-MLI. In the space stage, SOFI/VD-MLI mainly considers the thermal conduction of SOFI, and the thermal radiation between adjacent reflectors, the residual gas conduction between adjacent reflectors and the solid conduction through the separator materials between adjacent reflectors of VD-MLI. Both in the ground stage and in the space stage, the influences of separator materials and gas on the thermal radiation are neglected. On the basis of the heat transfer processes of SOFI/VD-MLI in the ground and space stages, the heat transfer calculation models of SOFI/VD-MLI in the ground and space stages were obtained.Secondly, based on the heat transfer calculation models of SOFI/VD-MLI in the ground and space stages, the heat leakage was calculated. The result shows that the heat insulation effect of SOFI in the ground stage is far better than in the space stage and SOFI plays the main heat insulation role in the ground stage, the heat insulation effect of VD-MLI in the space stage is far better than in the ground stage and VD-MLI plays the main heat insulation role in the space stage. So SOFI/VD-MLI not only solves the heat leakage problem of cryogenic storage tank in the ground stage, but also plays an exercellent role to the heat insulation of the tank in the space stage.Finally, the temperature fields of SOFI/VD-MLI in the ground and space stages were numerically simulated. The result shows that in the ground stage, the temperature variation of SOFI is obvious and the temperature of VD-MLI remains unchaged along the direction of insulation layer thickness. In the space stage, the temperature variation of VD-MLI is obvious and the temperature of SOFI remains unchaged along the direction of insulation layer thickness. Therfore, SOFI plays the main heat insulation role in the ground stage and VD-MLI plays the main heat insulation role in the space stage.