Ignition of methane and ethane blends with oxygen at engine conditions

Shock-tube experiments and chemical kinetics modeling were performed to characterize the chemistry for mixtures of methane and ethane with significant levels of ethane, which are not currently well known. Experiments were conducted in three different shock tubes on ten mixtures ranging from 100% methane to 100% ethane at pressures of 1 and 12 atm and from temperatures between 1154 and 2248 K. The percentage by volume variation and equivalence ratios for the mixtures studied were determined by way of a comprehensive design of experiments technique that reduces the necessary experimentation while still covering the full parameter space. This study shows that while current chemistry models predict ignition delay times well for mixtures most like natural gas, improvements can be made to model methane with larger amounts of ethane (greater than 20% by volume).