Question 4
a) The wet exhaust gas analysis of a diesel engine operating at 2000 rev/min and
500 Nm load with n-cetane ($C_{16}H_{34}$) fuel found 5% oxygen by volume. Determine
the air-fuel ratio by mass of the engine at this operating condition. Also, calculate
the mass percentage of moisture in the exhaust.
(15 marks)
b) Discuss THREE factors that affect the volumetric efficiency of an engine.
(6 marks)
c) Engine noise is the term used to describe the audible and tactile disturbances that
engines generate which are experienced by vehicle occupants and bystanders.
i. Explain the THREE major sources of engine noise;
(3 marks)
ii. Discuss SIX possible methods to reduce the engine noise.
(6 marks)
