Design And Finite Element Analysis Of LNG Composite Cylinders

LNG cylinder is a key component of LNGV as an energy storage container.The traditional cylinder is made of metal.On the one hand,the problem of high energy consumption caused by high metal density,on the other hand,because of the good thermal conductivity of metal also makes the insulation layer of the production cost higher.With development of aeronautics and astronautics,the technique of composite cryogenic tank is very advanced and mature.If this technique can be used in time to make composite cylinders,the quality of LNGV will greatly reduce,thus greatly saving energy consumption.Firstly,under premise of the cylinder working condition,this paper selects the molding process of the winding cylinder by summarizing the standards,and determines the important parameters of the cylinder including the winding thickness,the winding angle,and the thickness of the thermal insulation layer.Then the finite element simulation of the pressure test of the cylinder was carried out to verify the safety of the cylinder.Also,the finite element simulation of the working conditions of the cylinder was performed.It was found that filling the cylinder after precooling can reduce the stress peaks comparing to filling at room temperature.The critical failure pressure and the dangerous position of the cylinder are also predicted.Finally,the temperature field of the cylinder was simulated and the thermal insulation performance of the cylinder was studied.According to the simulation results combined with the Hashin failure criterion,the following results are obtained.The precooling filled cylinders can work normally under the working conditions of 0.8MPa internal pressure and-162?.When the internal pressure is 4.4MPa,the cylinder fails to work properly.At the same time,under this working condition,there is no significant change in the temperature of LNG in the cylinder within 55 hours.The simulation results show that the designed cylinder can be used normally under working condition and have good safety and thermal insulation.