MDE 1 Q2,3

Answer: A) Through the connecting rod which converts the linear motion of the piston into rotational motion
Explanation: The force generated by the combustion gases acts on the piston crown and pushes the piston downward. This linear motion of the piston is transferred to the crankshaft through the connecting rod. The connecting rod converts this linear motion into rotational motion, which drives the crankshaft and ultimately powers the engine.

Answer: A) Piston crown, piston rings, and piston skirt
Explanation: In a cross-sectional view of a piston, you can typically see the piston crown (the top surface of the piston), the piston rings (which seal the combustion chamber and control oil consumption), and the piston skirt (the lower part of the piston that maintains alignment within the cylinder). Other components such as the camshaft or turbocharger are not visible in a cross-section of the piston itself.

Answer: A) Cylinder volume and piston design
Explanation: The compression ratio in an engine is determined by the ratio of the maximum cylinder volume (when the piston is at the bottom of its stroke) to the minimum cylinder volume (when the piston is at the top of its stroke). This is influenced by factors such as the design of the cylinder and piston, which define the total volume available for compression.

Answer: B) The distance fuel droplets travel into the combustion chamber before igniting
Explanation: Penetration refers to the distance that fuel droplets travel into the combustion chamber after being injected but before they ignite. Proper penetration is essential for ensuring that the fuel mixes well with air and spreads throughout the combustion chamber, allowing for efficient and complete combustion.

Answer: A) Fuel temperature and injection pressure
Explanation: Atomization of fuel is primarily influenced by factors such as fuel temperature and injection pressure. Higher injection pressures and optimal fuel temperatures help in breaking the fuel into fine droplets, which improves mixing with air and enhances combustion efficiency.

Answer: C) The ratio of the maximum to the minimum volume of the combustion chamber during the engine cycle
Explanation: The compression ratio is defined as the ratio of the cylinder's volume when the piston is at the bottom of its stroke (maximum volume) to the volume when the piston is at the top of its stroke (minimum volume). A higher compression ratio indicates that the air-fuel mixture is compressed more, leading to higher engine efficiency and power output due to more complete combustion.

Answer: B) The conversion of fuel into fine droplets to enhance combustion efficiency
Explanation: Atomization refers to the process of breaking down liquid fuel into fine droplets as it is injected into the combustion chamber. This increases the surface area of the fuel, allowing it to mix more effectively with air and burn more completely, which enhances combustion efficiency and reduces emissions.

Answer: A) Fuel temperature and injector nozzle design
Explanation: The penetration of fuel into the combustion chamber is mainly influenced by fuel temperature and the design of the injector nozzle. Higher fuel temperatures and optimized nozzle design can improve the penetration of fuel droplets, ensuring better mixing with air and more effective combustion.