Prediction of burn rate,knocking and cycle-to-cycle variations of binary compressed natural gas substitutes in consideration of reaction kinetics influences

Abstract

Since zero-dimensional/one-dimensional simulations of natural gas spark-ignition engines use model theories similar to gasoline engines, the impact of changing fuel characteristics needs to be taken into consideration in order to obtain results of higher quality. For this goal, this article proposes some approaches that consider the influence of binary fuel mixtures such as methane with up to 40 mol% of ethane, propane, n-butane or hydrogen on laminar flame speed and knock behavior. To quantify these influences, reaction kinetics calculations are carried out in a wide range of the engine operation conditions. Obtained results are used to update and extend existing sub-models. The model quality is validated by comparing simulation results with measured heat release rates and knock limit. The benefit of the new sub-models is demonstrated by predicting the influence the fuel takes on engine operating limits in terms of knocking and lean misfire limits, the latter being determined using a cycle-to-cycle variation model.