Numerical Study Of Fire Resistance Of Hydrogen Composite Cylinders Subjected To Fire Impingement

Hydrogen fuel vehicle is one of the main solutions to global energy shortage and environmental pollution.And composite cylinders are prevailingly used for onboard hydrogen storage of hydrogen fuel vehicle due to its high strength to weight ratio.In order to meet the needs of high vehicle endurance,the hydrogen pressure of composite cylinders is up to 35~70 MPa.Therefore,composite cylinders are vulnerable to fire impingement due to the explosive nature of hydrogen and the combustible nature of composite material.To reduce the risk of composite cylinder,it is essential to accurate predict the thermal response of the hydrogen composite cylinders subjected to fire impingement.Based on the existing research problems,a fully coupled conjugate heat transfer model based on a multi-region and multi-physics approach is proposed for modelling the transient heat transfer behaviour of composite cylinders subjected to fire impingement.The fire scenario is modelled using large eddy simulation,and three dimensional governing equations based on the finite volume method are written to model the heat transfer through the regions of composite laminate,liner and pressurized hydrogen respectively.The gas decomposition of composite material,its cooling effect resulting from the convection of gaseous products,the component and temperature dependent material properties are also included.The proposed conjugate heat transfer model is validated against a bonfire test of a commercial Type-4 cylinder.And the surface heat flux,temperature and decomposition are studied by numerical simulation based on the proposed model.The results reveal that the surface heat flux is highly transient and unevenly distributed at the outer surface.Convective heat transfer cannot be neglected for the modelling of the thermal response.It is also found that the melting point of the HDPE liner can be reached prior to the burst,leading to hydrogen leakage.Numerical simulation of the decomposition of composite make contribution to the prediction of the thermal response of the hydrogen composite cylinders.The effects of the important parameters such as installation height,composite thickness and thermal insulation coating on external thermal load and internal mechanical load are studied in order to improve the current design standards of the hydrogen composite cylinders.