The influence of nitrogen doping on self-ignition of hydrogen during high-pressure release into air - numerical investigation

摘要

Hydrogen is expected to be a future alternative fuel. However, its implementation as a widely used energy carrier is difficult because of its tendency for leakage and ignition during pressurized release into air - hydrogen must be stored in tanks under high pressure. Up to now, in the studies on hydrogen self-ignition the influence of the nitrogen addition was not taken into account. This phenomenon is numerically investigated in this paper. The computations were conducted using a commercial CFD code AVL Fire. Examined domain was formed of two tanks - one filled with fuel (H_2-N_2 mixture) and second filled with oxidizer (air) connected by a tube. The length of the tube ranged from 10 mm to 80 mm. Conducted numerical simulations show that for longer tubes the ignition occurs inside the tube and initial pressure necessary for ignition decreases as the tube length increases. It is also demonstrated that rising initial pressure decreases the ignition delay time.