How do exhaust systems work?
The purpose of the exhaust/emission system is to deaden the sound made by the internal combustion engine, reduce the temperature of the exhaust, and control the emissions that come out of your vehicle. Vehicles create harmful gases during the combustion of fuel. The catalytic converter in the exhaust system turns these gases into mostly harmless ones that do much less damage to the environment. Some of the harmful gases that the exhaust system controls are:
- Hydrocarbons (unburned)
- Carbon Dioxide
- Sulfur Dioxide
- Carbon Monoxide
- Nitrogen Oxides
- Lead and Other Metals
The exhaust manifold conducts gases from the combustion chambers of the engine to the exhaust pipe. It is usually constructed of cast iron and smooth curves to improve the flow of exhaust.
The catalytic converter reduces harmful emissions from engine exhaust. It uses a combination of heat and metals that act as catalysts. A catalyst is a metal (or chemical) that causes other chemicals to go through a reaction without being affected itself. The inside of the catalytic converter consists of metals like aluminum oxide, platinum palladium. These metals cause the carbon monoxide and hydrocarbons to react and produce water vapor and carbon dioxide which are much less harmful to the atmosphere.
The muffler alone cannot always quiet all the engine noise. Many exhaust systems also include a resonator which is like a mini muffler. They are usually straight pipes filled with sound muffling materials. The resonator can be either before or after the muffler in the exhaust system.
Exhaust pipe connects all the other parts of the exhaust system.
The muffler quiets the noise of the engine. There are two kinds of mufflers. One uses baffled chambers to reduce noise. As sound waves move through this type of muffler, they bounce off the baffles and expend their energy inside the muffler, losing force and volume. The other type forces the exhaust straight through a perforated pipe that contains metal, fiberglass, or some other kind of sound-absorbing material. This muffler is designed to reduce back pressure (exhaust going back up the pipes) and consequently makes a little more noise.
The tail pipe comes out of the muffler, past the rear bumper of the vehicle, directing exhaust gases away from the vehicle. On many newer cars it also serves as a decorative function and is tipped in chrome.