Experimental study of minimum ignition energy of methane/air mixtures at elevated temperatures and pressures

The minimum ignition energy (MIE) is an important parameter when describing explosion characteristics. While the minimum ignition energy of methane has been studied by many researchers, little information is available for elevated temperatures and elevated pressures. In our study, firstly, the minimum ignition energy of methane/air mixtures was measured for different temperatures (30-150 °C) and different pressures (0.1-0.9 MPa). Then, our experimental results were compared with the ignition prediction model previously used by Coronel et al. Results indicate that in our experimental setup, the sensitive electrode gap is 1 mm and the sensitive methane equivalence ratio is 1. With increasing pressure or temperature, the MIE decreases. The MIE has a high order linear relationship with 1/P2, but an approximately linear relationship with 1/T. With increasing temperature, the influence of pressure on the MIE becomes smaller. In addition, with increasing pressure, the effect of the temperature on the MIE also decreases. The fitting formula for the MIE at elevated temperatures and pressures is able to predict the MIE accurately. The prediction model used by Coronel et al. is valid for predicting the minimum ignition energy of methane at various initial pressures. Overall, the calculated results by prediction model are about 1.5 times as large as the experimental values, which is acceptable when predicting the MIE of methane at elevated pressures.