Internal Combustion Engines
The two reference fuels used for cetane rating are

Cetane and normal heptane
Cetane and tetra ethyl lead
Cetane and iso-octane
Cetane and alpha-methyl naphthalene

ANSWER DOWNLOAD EXAMIANS APP

Internal Combustion Engines
In a typical medium speed 4-stroke cycle diesel engines

Exhaust valve opens at 35° before bottom dead center and closes at 20° after top dead center
Exhaust valve opens at bottom dead center and closes at top dead center
May open and close anywhere
Exhaust valve opens just after bottom dead center and closes just before top dead center

ANSWER DOWNLOAD EXAMIANS APP