# Heat-release analysis

To discuss the combustion speed, heat release was estimated from the in-cylinder pressure waveform.

First, the heat-release rate was calculated by Eq. using combustion analysis software (Ono Sokki, DS0328). And other softwares such as Python, MatLab can calculate it, too.

The change in the specific heat ratio during combustion was considered.

The accumulated heat release was calculated from the heat-release rate.

The combustion phase “CAn” is defined as the n% heat-release point of the total heat release.

The combustion duration “CAm-n” indicates the duration from the combustion phase “CAm” to “CAn”.

$\frac{\mathit{dQ}}{d\theta }=\frac{1}{\kappa –1}{V}_{\mathit{CYL}}\frac{\mathit{dP}}{d\theta }+\frac{\kappa }{\kappa –1}P\frac{d{V}_{\mathit{CYL}}}{d\theta }$