$3\mathrm{.}1$ List any two differences between the otto and the diesel engines.

$3\mathrm{.}2$ An oil engine running on the dual combustion cycle starts to compress the air at $102$kPa and $23C.$ The maximum pressure is $6850$kPa and geometric compression ratio is $18$:$1.$ The heat added at constant volume is the same as that added at constant pressure. If the initial volume is $1m^3,$ calculate the:

$3\mathrm{.}2\mathrm{.}1$ temperature, pressure and volume at state points

$3\mathrm{.}2\mathrm{.}2$ air standard efficiency and the mean effective pressure.

$(6)$

$[28]$