In a diesel engine, an injection nozzle is used for _________.

• A. Atomizing the Fuel
• B. Lubricating the Journal Bearings
• C. Igniting the Fuel
• D. Scavenging the Cylinder

Answer: (A)

The injection nozzle’s job is to atomize the fuel and deliver it into the combustion chamber as a fine spray at the right moment and pressure. Atomizing the fuel creates many tiny droplets, which have a large surface area and vaporize quickly when sprayed into the hot, compressed air. This rapid vaporization and mixing with air is essential for efficient combustion in a diesel engine, which relies on compression ignition rather than a spark. The nozzle also helps control how much fuel is injected and when, influencing ignition timing and the overall efficiency and emissions of the engine.

Lubricating journal bearings is done with engine oil, not the fuel nozzle. Ignition in a diesel is achieved by the high temperature of the compressed air, not by the nozzle. Scavenging the cylinder refers to clearing exhaust and filling with fresh air, a process separate from injecting fuel.