Abstract: In order to obtain the temperature change rules of the composite CNG cylinder during inflation, the inflation process of the cylinder under 30 MPa was numerically simulated by Fluent 17.0. And the temperature distribution and change rules of the internal gas during the inflation process and the wall temperature rise were obtained through analysis. The simulation results were analyzed for the gas cylinder with heat conducting medium added to the outer wall under the same conditions. The results show that the high temperature area of the gas cylinder is distributed in the head section of the bottle tail; the low temperature area is distributed in the inlet position; and the temperature distribution at the inlet presents a plume shape. The gas temperature continues to rise, but it has a nonlinear relationship with time. The highest temperature rise rate of the fiber layer of the gas cylinder has been significantly increased, while the average temperature rise rate of the cylinder has a small increase, but the temperature rise rate of the inner bladder layer slightly decreases as the filling progresses. The temperature rise of the wall has not been linearly related to the inflation time. The thermal conductive paste keeps the temperature rise of the cylinder wall stable, and its temperature is reduced at the end of inflation.

Key words: composite material, CNG cylinder, Fluent 17.0, numerical simulation, temperature rise