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Saturday, 26 August 2017

A TINY DEVICE CONTROLS VEHICLE EMMISION UPTO 80% ,LEARN HOW....... WORKING OF CATALYTIC CONVERTER

WORKING TECHNIC 

 Before know about WORKING OF CATALYTIC CONVERTER , we need to know about...

    What is a catalyst??

            A catalyst is a substance that causes or accelerates a chemical reaction without itself being affected. Catalysts participate in the reactions, but are neither reactants nor products of the reaction they catalyze. 

TWO-WAY CATALYTIC CONVERTER-:

     A 2-way catalytic converter has two simultaneous tasks i.e
  • Oxidation of carbon monoxide to carbon dioxide.
  • Oxidation of hydrocarbons (unburned and partially burned fuel) to carbon dioxide and water.

This TWO-WAY  type of catalytic converter is widely used on diesel engines to reduce hydrocarbon and carbon monoxide emissions. They were also used on gasoline engines automobiles. Because of their inability to control oxides of nitrogen, they were superseded by three-way converters.

hoe-catalytic-converter-works
By Hastdutoene (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

THREE-WAY CATALYTIC CONVERTER-:

     Three-way catalytic converters have the additional advantage of controlling the emission of nitric oxide and nitrogen dioxide (both together abbreviated with NO and not to be confused with nitrous oxide), which are precursors to acid rain and smog.


In the catalytic converter, there are two different types of catalyst works, a reduction catalyst and oxidation catalyst. Usually platinum , rhodium or palladium is used for coating the ceramic structure of both catalyst.This is done so that maximum surface area of catalyst can be in contact with the exhaust stream.Due to the expensive cost , In some new developments Gold are mixed with traditional catalyst to reduce cost.This makes lower cost & increase oxidation(the chemical process that reduce pollutants up to 40%).

   Three-way catalytic converters means three regulated emissions it helps to reduce.Those are.....

1.reduction catalyst

It is also known as Selective Catalyst Reduction (SCR).

The  is the first stage of the catalytic converter. It uses platinum and rhodium to help reduce the NO emissions. When an NO or NO2 molecule came in touch with the catalyst, the catalyst attracts the nitrogen & hold on to it.There by causing the oxygen to be free in the form of O2 . Holded nitrogen mixed with the other nitrogens & forms N2 . 


 A system used on diesel vehicles that is designed to reduce emissions. A typical SCR system consists of a Diesel Exhaust Fluid (DEF) injection system and a catalytic converter. They are part of the exhaust system and placed between the engine and the mufflers.

In order to reduce harmful oxides of Nitrogen from diesel exhaust gases, an SCR system first injects DEF into the exhaust gases after they exit the engine. The DEF fluid vaporizes and forms ammonia and carbon dioxide before entering the catalytic converter. There the catalytic converter changes the ammonia, carbon dioxide and oxides of nitrogen into harmless nitrogen and water.


2.Oxidation Catalyst

The oxidation catalyst is the second stage of the catalytic converter. It reduces the unburned hydrocarbons and carbon monoxide by burning (oxidizing) them over a platinum and palladium catalyst.The reaction of  CO and hydrocarbons is improved by oxidisation catalyst. 

3.control system

The third stage of conversion includes monitoring the exhaust stream & through this information it controls the fuel injection system.An oxygen sensor is used in catalytic converter to sense the oxygen amount in exhaust stream & tells the engine computers about oxygen percentages .The engine computer uses this data to control the air-fuel ratio. This control scheme allows the engine computer to make sure that the engine is running at close to the stoichiometric point, and also to make sure that there is enough oxygen in the exhaust to allow the oxidization catalyst to burn the unburned hydrocarbons and CO.

Stoichiometric point
The stoichiometric point is the air to fuel ratio in a combustion engine. The stoichiometric air-fuel ratio for petrol (gasoline) is 14.7 to 1 by weight. Related concepts include: Air fuel ratio.


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4 comments:

  1. IT HELPED ME A LOT....THANK U

    ReplyDelete
  2. FOLLOW US FOR UPDATES .... THANK U

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  3. As mentioned previously the vehicle history is important but there are also more subtle indicators of what kind of life the vehicle may have had. automoves

    ReplyDelete
    Replies
    1. thanks for your reply.....Yes there are many variables responsible for exhaust pollution.

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