Page - 51 - in Advanced Chemical Kinetics

of maximum heat-release rate. In addition, the higher To leads to lower in-cylinder charge density and thus the smaller amount of fuel when ϕo is constant. This can be explained by the data in Figure 6d for the accumulated heat release, which shows the lower accumu- lated heat release for the higher To. DME shows the highest accumulated heat release and methane the lowest. This is an important aspect that potentially can help to increase the higher power output. On the other hand, DME and n-heptane exhibit two-stage ignition with LTHR for this calculation condition, as shown in Figure 6c. The more advanced onset of LTHR than that of DME results from the higher To. As Figure 6a shows, the LTHR acceler- ates the temperature rise towards the end of the compression stoke. Therefore, To has to be reduced to achieve the same CA50. Figure 6. Comparison of (a) in-cylinder temperature, (b) heat-release rate, (c) magnified view of heat-release rate and (d) accumulated heat release for methane, DME, iso-octane and n-heptane. Autoignition and Chemical-Kinetic Mechanisms of Homogeneous Charge Compression Ignition... http://dx.doi.org/10.5772/intechopen.70541 51