Fundamental Study on the Influence of Additives on Ignition Control of Natural Gas HCCI Engine 18ICES/027
Authors
Mohamed H. Morsy - Suez Canal University
Suk Ho Chung - Seoul National University
Abstract
The influence of additives such as dimethyl ether (DME), formaldehyde (CH2O) and hydrogen peroxide (H2O2) for the control of ignition in natural gas HCCI engines have been investigated numerically by adopting a single-zone zero-dimensional model. Computations were first carried out in a constant volume bomb to demonstrate variations in ignition delay times with the additives by varying initial temperature, pressure, equivalence ratio, and composition. The effect of H2O2 addition in reducing the ignition delay was most pronounced as compared to the other two additives of DME and CH2O for all conditions examined. With engine-like conditions, calculations were done at a fixed equivalence ratio of 0.3 and initial mixture pressure of 1.5 bar. It was found that an additive-free mixture did not ignite for the intake temperature of 400 K. A mixture containing a small quantity of additives at the same temperature was ignited. For a fixed quantity of additive, it was found that H2O2 addition was effective in advancing the ignition timing as compared to the other two additives, which is consistent with the constant volume calculations. Furthermore, the addition of even 2.5% by volume of H2O2 could ignite a mixture at an intake temperature of 350 K, while at least the fractions of 10% and 15% by volume were needed for DME and CH2O, respectively.