High School

What is the purpose of the EVAP system?

1) To prevent the escape of HC vapors into the atmosphere
2) To reduce NOx emissions
3) To increase fuel efficiency
4) To control exhaust gas temperature

Answer :

Final answer:

The EVAP system's purpose is to capture and prevent fuel vapor emissions into the atmosphere, significantly reducing the contribution to smog and ground-level ozone. The correct option is 1.

Explanation:

The purpose of the EVAP (Evaporative Emission Control) system is to prevent the escape of HC vapors (hydrocarbons) into the atmosphere, which is option 1. This system captures fuel vapors from the fuel tank and directs them back into the combustion process of the engine rather than letting them escape to the environment.

This is crucial because HC vapors contribute to smog and ground-level ozone formation, which are harmful to both the environment and human health.

While the EGR (Exhaust Gas Recirculation) system reduces NOx emissions by recirculating a portion of an engine's exhaust gas back to the engine cylinders, and the catalytic converter further helps by converting NOx into N₂ and O₂, the EVAP system is specifically designed to address volatile hydrocarbons, not NOx or fuel efficiency.