Ammonia (NH 3), has been considered as a promising alternative energy carrier for automobile engines and gas turbines due to its production from renewable sources using concepts such as power-togas. Knowledge of the combustion characteristics of NH 3 /air and the formation of pollutants, especially NO x and unburned NH 3 , at intermediate temperatures is crucially important to investigate. Detailed understanding of ammonia reaction mechanism is still lacking. The present study reports ignition delay times of NH 3 /air mixtures over a temperature range of 1100-1600 K, pressures of 20 and 40 bar, and equivalence ratios of 0.5, 1.0, and 2.0. The experimental results are compared to the literature mechanism of Mathieu and Petersen (2015), and reasonable agreement is observed. Detailed modeling for ammonia emissions is performed, and the NH 3 /air combustion is found to be potentially free from NO x and unburned NH 3 at fuel-rich conditions.

No abstract

No abstract

No abstract

Liquefied natural gas (LNG) and liquefied biogas (LBG) as transport fuels constitute one of the pillars of the European clean fuel strategy. LNG and LBG often contain higher hydrocarbons up to C 5 , which leads to more complex ignition properties when utilizing them in gas engines. Therefore, it is essential to understand their combustion behavior and to quantify the abnormal combustion such as knocking propensity in correlation to the methane number (MN). Currently, there is no traceable standard to define the MN, and the literature algorithms give no consistent results for the same LNG/LBG mixtures. In this study, the correlation between the MN and ignition delays of several LNG/LGB mixtures containing C 1 -C 5 alkanes and nitrogen was investigated at temperatures between 870 and 1,550 K, at 10, 20, and 40 bar, and with equivalence ratios of 0.4 and 1.2. Good correlations have been observed for mixtures with MN 50-90 at high temperatures. At intermediate temperatures, discrepancies were found between mixtures with same MN but different C 1 -C 3 compositions. Moreover, the addition of butane and propane isomers at low vol.% showed no effect on the ignition delay times (IDTs) at intermediate temperatures.