Question 4 MODE02 - Assistant MODU Engineer

The Correct Answer is A. Proper atomization of fuel is crucial in a diesel engine combustion chamber because it involves breaking the injected fuel into extremely fine droplets. This highly increases the total surface area of the fuel exposed to the high-temperature, high-pressure air. When the surface area is maximized, the fuel can vaporize and mix with the air much more rapidly and uniformly, leading to a complete and efficient burning process. Therefore, **proper atomization significantly improves combustion** efficiency and quality, which in turn maximizes power output and minimizes harmful emissions. ### Why the other options are incorrect: **B) It decreases power output:** This is incorrect. Improved combustion (as a result of proper atomization) ensures more energy is extracted from the fuel, leading to an **increase** (or maximization) of power output and engine efficiency, not a decrease. **C) It changes the injection pressure:** This is incorrect. Atomization is the *result* of the injection system operating at a high pressure through a specific nozzle design. Atomization itself does not change the pressure; rather, high injection pressure is a prerequisite for achieving proper atomization. **D) It reduces compression pressure:** This is incorrect. Compression pressure is determined by the mechanical design of the engine (e.g., the compression ratio, piston rings, and valves). Fuel injection and atomization occur *after* the air has been compressed and have no direct influence on the maximum compression pressure achieved during the compression stroke.