Design Of Composite CNG Cylinder Structure And Study On The Temperature Rise During The Fast Filling Process

Compressed natural gas cylinders for automobiles have the development trends of high pressure,lightweight,low cost and high reliability.Non-metallic inner-liner composite fullwinding cylinders have been paid more and more attention and applied abroad,but there is still a lack of research and discussion in this field in China.So it is very important to study the performance of non-metallic inner-liner composite cylinder.Based on the research status at home and abroad,the following work has been carried out:(1)The structure design of 30 MPa composite cylinder with non-metallic inner liner was carried out by combining relevant standards and parameters,and the structural parameters of inner liner were determined.Combining with the grid theory and filament winding process requirements,the structure design of filament winding layer of gas cylinder is carried out,including determining filament winding angle,filament winding thickness,filament winding layer number,etc.(2)Thermodynamic theory analysis was made on the influencing factors of temperature rise during the filling process of composite cylinders.In the process of natural gas filling into the cylinder rapidly,there are four factors that cause the temperature rise of the cylinder: throttling effect,heat generated by gas compression,internal energy conversion of system kinetic energy,and environmental heat transfer.(3)The finite element model of the cylinder under design pressure and minimum blasting pressure is established by using the subprogram of ABAQUS software(WCM).The stress analysis and strength check of the cylinder structure are carried out.The cylinder structure meets the strength requirement under the working pressure of 30 MPa,thus verifying the rationality of the cylinder structure.(4)By establishing a numerical simulation model considering turbulence,real gas effect and solid heat transfer,the process of rapid filling temperature rise of gas cylinder was simula ted.The temperature distribution of gas inside the cylinder and the wall of the cylinder during filling process was obtained,and the safety of gas cylinder filling under this condition was confirmed.The validity of the simulation model is verified by comparing with the existing experiments.(5)By using the established numerical simulation model,the gas charging process of several groups of cylinders was simulated,and the performance of the 30 MPa non-metallic inner cylinder designed in this paper was analyzed.The gas volume of 30 MPa non-metallic inner-liner cylinder designed in this paper is 1.4 times that of 20 MPa cylinder of 80 L on the market when it is inflated for 2 minutes.The cylinder self-weight is only 1/2 of that of composite inner-liner cylinder of the same volume as that of the cylinder designed in this paper.