Shanghai Tunnel Engineering Interview Questions and Answers

Piston rings are used in engines to seal the gap between the piston and cylinder wall, preventing leakage of combustion gases and oil.

• Piston rings create a seal between the piston and cylinder wall to prevent leakage of combustion gases and oil

• They help maintain compression within the combustion chamber

• Piston rings also aid in heat transfer from the piston to the cylinder wall

• They reduce friction between the piston and cylinder wall, improving engine efficiency

P-V and T-S diagrams are used to analyze the thermodynamic processes in Otto and Diesel engines.

• P-V diagram shows the pressure-volume relationship during the engine cycle.

• T-S diagram shows the temperature-entropy relationship during the engine cycle.

• Otto cycle is used in gasoline engines while Diesel cycle is used in diesel engines.

• Both cycles consist of four processes: intake, compression, power, and exhaust.

• The efficiency of the cycles can be analyzed using these diagrams.

Comparison ratio in a diesel engine refers to the ratio of the volume of the combustion chamber when the piston is at the bottom of its stroke to the volume when the piston is at the top of its stroke.

• Comparison ratio is a key factor in determining the efficiency and performance of a diesel engine.

• Higher compression ratios typically result in better fuel efficiency and power output.

• Common diesel engine comparison ratios range from 14:1 to 23:1.

• The comparison ratio is calculat...read more