Emission Control System Purpose● The emission control systems are installed toreduce the amount of CO, HC and Nox exhausted from the engine.● To prevent the atmospheric release of blow bygas HC and evaporated fuel containing HC being released from the tank.
Function of each system 1. PCV – Reduce HC 2. EVAP – Reduce evaporative HC 3. EGR – Reduce NOx 4. TWC – Reduce CO, HC, NOx
Type of Exhaust Emission Pollutants Carbon Monoxide (CO) ● Carbon monoxide is a colorless, odorless, tasteless and toxic gas produced as a by- product of combustion. ● A product of incomplete combustion. ● The main source of CO in our air is vehicles emission.
Health Effects ● CO reduce the blood’s ability to carry oxygen to body tissue including vital organs such as the heart and brain. ● It is most harmful to those who suffer from heart and respiratory disease.
Symptoms Associated With a Given Concentration of CO Over Time
Nitrogen Oxide (Nox) ● Generated when nitrogen in the air reacts with oxygen at the high temperature and pressure in side the engine. ● Nox gases are formed everywhere where there is combustion – like in an engine. ● In areas of high motor vehicle traffic, such as in large cities, the amount of nitrogen oxides emitted into the atmosphere as air pollution can be significant. ● Nox react to form smog and acid rain. ● Fuel NOx can contribute as much as 50% of total emissions when combusting oil and as much as 80% when combusting coal.
Health effects ● NOx reacts with ammonia, moisture, and other compounds to form nitric acid vapor and related particles. ● Small particles can penetrate deeply into sensitive lung tissue and damage it, causing premature death in extreme cases. ● Inhalation of such particles may cause or worsen respiratory diseases
Sulfur Oxide (Sox) ●A general term for oxide of sulphur, which are emitted from motor vehicle burning fuel containing sulphur.
Health effects ●Emissions harm human health depends primarily on ground-level ambient concentrations, the number of people exposed and duration of exposure.
hydrocarbon In chemistry, a hydrocarbon is any chemical compound that consists only of the elements carbon (C) and hydrogen (H).
Health effectHigh levels of hydrocarbons in theatmosphere can reduce the amountof available oxygen. Carcinogenic(cancer causing) forms ofhydrocarbons are consideredhazardous air pollutants, or airtoxins and can lead to thedevelopment of cancer.
Basic operation of EGR valve When a strong intake manifold vacuum was pulled (the less the throttle was opened ie. You took you foot off the pedal) the EGR valve opens to let exhaust gases into the intake manifold. As more throttle is applied, vacuum drops and the EGR valve closes.