Simulation and Analysis of HCNG Laminar Burning Velocity
【摘要】：This work is about spark ignition engines fuelled by hydrogen enriched compressed natural gas (HCNG). Nowadays this fuel becomes more and more important because the addition of hydrogen has many advantages and improves the HCNG engine characteristics. One of the most important factors is the laminar burning velocity of a fuel. The first section of this work is about the determination of the laminar burning velocity with the help of CHEMKIN using the GRI-Mech 3.0 code. The simulation is based on CNG and hydrogen mixtures, beginning at a volumetric fraction of 0% hydrogen to 100% hydrogen. Different equivalent ratios, pressures and temperatures were also investigated.
The second section deals with the fundamentals of the two-zone thermodynamic model, the turbulent flame propagation model and introduces related equations. With the help of pressure data diagrams for various hydrogen blending ratios made on the Tsinghua test bench along with the mentioned model, the turbulent burning velocity and the turbulent intensity can be calculated. Eleven tests with different operating conditions were compared. Furthermore the laminar burning velocity was calculated. In the third section the laminar burning velocity is calculated with the help of a Le Chatelier’s Rule-like formula.
The comparison of the laminar burning velocity show that even under different operating conditions, the CHEMKIN simulation and two zone thermodynamic model results have the same tendency and even match quite well with the chosen constants. Comparing the calculated laminar burning velocity with CHEMKIN and the two-zone model the tendency at different conditions is also the same, but the difference of the laminar speeds is higher.