What causes unburned hydrocarbons?
Sources of unburned hydrocarbon. Unburned hydrocarbons (UHC) are typically an output of incomplete combustion due to unfavorable engine design, low fuel quality or failure in the control system.
What happens to unburned hydrocarbons?
Sometimes unburned hydrocarbons are released into the air during incomplete combustion. Burning fossil fuels, including gasoline in automobile engines, releases some hydrocarbons into the air.
What emission is caused by unburned fuel?
3 Carbon monoxide. The incomplete combustion of carbon produces CO. Operationally, this is used to optimize the combustion process as it indicates that there is a nonoptimum mixing of combustion air with the fuel.
How are hydrocarbons formed in an engine?
A small fraction of the fuel oil, which consists of hydrocarbons, will pass through the engine unburned and other hydrocarbons are formed during the combustion process. The hydrocarbons are thus mainly particles of unburned and partly burned original fuel.
What will happen to the unburnt hydrocarbons when it passes through catalytic converters?
As the exhaust passes through the catalytic converter, unburnt hydrocarbons are converted into carbon dioxide and water, and carbon monoxide and nitric oxide are changed to carbon dioxide and nitrogen gas, respectively.
Why are hydrocarbons highly flammable?
Hydrocarbons are flammable because the carbon in their structure is in the most reduced form.
How do hydrocarbons combust?
Hydrocarbon fuels can undergo complete combustion or incomplete combustion, depending on the amount of oxygen available. Complete combustion happens when there is a good supply of air. Carbon and hydrogen atoms in the hydrocarbon fuel react with oxygen in an exothermic reaction: carbon dioxide and water are produced.
What is the percentage of wasted fuel through incomplete combustion?
An approximate relationship between the percentage of wasted fuel through incomplete combustion and the ppm of HC is about 1/200 ( 1.0% partially burned fuel produces 200 ppm HC, 10%=2000 ppm HC, 0.1%=20 ppm HC )
What does HCHC mean on an exhaust?
HC = Hydrocarbons, concentration of the exhaust in parts per million (ppm). = Unburned Petrol, represents the amount of unburned fuel due to incomplete combustion exiting through the exhaust. This is a necessary evil. We don’t want it so try to keep it as low as possible.
What is an example of incomplete combustion?
One example of Incomplete Combustion is raw gasoline (HC) which goes in, then comes out, and isn’t burnt up in the process. Another example is Carbon Monoxide (CO). It doesn’t create smog, but it’s deadly, so you don’t want it around.
What are the major factors that contribute to vehicle exhaust emissions?
The following major factors contribute to the overall increase in exhaust emissions levels and degraded vehicle driveability: Lack of scheduled maintenance: Sub-system failures Combination of multiple marginal sub-systems
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