Research On Flow Field Characteristics And Optimization Design Of High Pressure Pipeline Of CNG Bus

At present, there is little Process specification on the high pressure pipeline, the influence of the vehicle high pressure pipeline layout, the selection of pipe length, pipe diameter and other design parameters on the utilization rate of gas storage and the pipeline in the gas supply stability is lack of in-depth study. Numerical simulation of computational fluid dynamics(CFD) suggests that not only length, curvature and radius of the pipeline, but also structure of the cylinder valve are the main causes of the flow field characteristic. Further study the effects of technical parameters of high pressure pipeline and pipeline shape on the internal flow field of high pressure pipeline. After the analysis, the conclusion is obtained:?The pressure drop of the inlet and outlet of the high pressure pipeline is large. The pressure drop of the flow field in the straight pipe is proportional to the length of the pipeline;?Pipeline of Coil between two gas cylinder sand gas cylinder valve pressure drop accounted for a large proportion of the total inlet pressure drop;?In the case of constant supply air quality,the pressure drop of the inlet and outlet of the pipeline increases with the decrease of the supply pressure;?The pipeline internal flow velocity increasing, the pipeline entrance pressure drop greater and greater speed, the greater the pressure drop changes;?The pressure loss of a plurality of gas cylinders at the same time is less than that of a single gas storage cylinder;?The greater the diameter, the lower the pressure drop of the flow field inside the high pressure pipeline;?The greater the curvature radius of the elbow, the smaller the pressure drop of the unit length of the flow field inside the pipeline;?When the cylinder valve diameter and diameter are not the same, the gas cylinder valve will produce a greater pressure drop, The pressure drop generated by the gas cylinder valve whose diameter is less than the pipe diameter is less than the pressure drop caused by the gas cylinder valve whose diameter is greater than the pipe diameter. The high pressure pipeline of the original CNG bus is optimized: After optimization, the length of the high pressure pipeline is 6.93 m, which is shorter than that of the original pipeline 5.95m; Stainless steel tubes with a diameter of 10 instead of 8 of the stainless steel tubes; The curvature radius of elbow is increased to 50mm;The structure of the gas cylinder valve is optimized, and the diameter of the gas cylinder valve is increased to 8mm; Gas cylinders between the connecting pipe with U shape pipe,curvature radius of 50 mm. After optimization, the pressure drop of the inlet and outlet of the high pressure pipeline is decreased obviously, the total pressure drop of the front entrance and exit is reduced by 131.2 Kpa, The utilization ratio of natural gas in the gas storage bottle can be increased by 0.65%.