Which area of the indicator diagram illustrated, indicates the afterburning period in a diesel engine cylinder? Illustration MO-0033

Correct Answer: Option D — K

Area 'K' on the indicator diagram represents the expansion phase following peak combustion. Afterburning occurs when fuel continues to burn late into the expansion stroke due to poor atomization or late injection timing. This results in a slower pressure drop than expected, indicating inefficient combustion and increased exhaust gas temperatures.