Skip to main content

EMISSION SYSTEM IN VEHICLES AND MUFFLERS

 

Contents of Exhaust gas:

  • The largest part of most combustion gas is
    • Nitrogen (N2 ), 
    • Water vapor (H2O) and 
    • Carbon-dioxide (CO2 ) these are not toxic

  • A relatively small part of combustion gas is toxic substances, such as 
    • Carbon Monoxide (CO) from incomplete combustion, 
    • Hydrocarbon (HC) from un-burnt fuel, 
    • Nitrogen Oxide (NOx ) from excessive combustion temperatures 
    • Particulate matter (PM). 

Treatment of Exhaust gas:

  • The Exhaust gas has more pollutant so that it should be reduced to prevent the pollution form the exhaust gas
  • There are some treatment carried out for Exhaust gases are below    

    • Exhaust Gas Recirculation(EGR)
    • Selective Catalytic Reduction(SCR)

Exhaust gas Recirculation(EGR) : 

  • The diesel engines to run more efficiently cause them to run at higher temperature this leads to the creation of Nitrogen Oxides (NOx).

  • The Combination of Nitrogen and Oxygen in the air to form Nitrogen Oxide.
  • In order to reduce NOx an engine should run at a lower temperature this can be achieved by Reducing the amount of Oxygen in the cylinder
  • Exhaust Gas Recirculation is an efficient method to reduce NOx emissions from the engine. 
  • It works by recirculating a quantity of exhaust gas back to the engine cylinders.

Working Principle

  • EGR works by recirculating a portion of an engine's exhaust gas back to the engine cylinders.
  • This dilutes the Oxygen in the incoming air stream and provides gases inert to combustion to act as absorbents of combustion heat to reduce peak in cylinder temperatures.

  • NOx is produced in high temperature mixtures of atmospheric nitrogen and oxygen that occur in the combustion cylinder, and this usually occurs at cylinder peak pressure

Selective Catalytic Reduction(SCR) :

  • Selective Catalytic Reduction (SCR) is an emissions control technology system that injects a liquid-reductant agent through a special catalyst into the exhaust stream of a diesel engine.
  • The reductant source is usually automotive-grade urea, otherwise known as Diesel Exhaust Fluid (DEF).
  • The DEF sets off a chemical reaction that converts nitrogen oxides into nitrogen, water and tiny amounts of carbon dioxide (CO2).
  • Natural components of the air we breathe, which is then expelled through the vehicle tailpipe.
  • SCR technology is designed to permit nitrogen oxide (NOx) reduction reactions to take place in an oxidizing atmosphere.
  • It is called "selective" because it reduces levels of NOx using ammonia as a reductant within a catalyst system.
  • The chemical reaction is known as "reduction" where the DEF is the reducing agent that reacts with NOx to convert the pollutants into nitrogen, water and tiny amounts of CO2.
  • The DEF can be rapidly broken down to produce the oxidizing ammonia in the exhaust stream.

The Schematic diagram of Exhaust system.  

Catalytic Converter 

  • Catalytic converter makes use of two catalysts to convert harmful gases to harmless gases. • 
  • They are: 
    • Reduction Catalyst and 
    • Oxidation Catalyst

  • The reduction catalyst is made of platinum and rhodium
  • The oxidation catalyst is made of platinum and palladium
  • Both the catalysts have a ceramic honeycomb structure. 


  • The exhaust gases are first sent over the reduction catalyst.
  • It converts oxides of nitrogen (NOx ) to nitrogen (N2 ) and oxygen (O2 ).
  • Exhaust gases that are free of oxides of nitrogen (NOx ) are then sent over the oxidation catalyst
  • The oxidation catalyst coverts carbon-monoxide (CO) and hydrocarbons (HC) in the gases into carbon-di-oxide (CO2 ) and water (H2O).

Muffler

  • The purpose of the Muffler (silencer) is to reduce the noise of the exhaust gas before it is released to the atmosphere.
  • This leads not only to discharge noise at the exhaust outlet, but also to noise radiation from exhaust pipe and silencer surfaces.
  • The muffler is a set of tubes. These tubes are designed to create reflected waves that interfere with each other or cancel each other out.

  • The exhaust gases and the sound waves enter through the center tube.
  • They bounce off the back wall of the muffler and are reflected through a hole into the main body of the muffler.
  • They pass through a set of holes into another chamber, where they turn and go out the last pipe and leave the muffler.

*******Thanks*******





 


Comments

Post a Comment

Popular posts from this blog

JIT(JUST IN TIME)

 What is the objective? To achieve zero inventory in APTICS dictionary. JIT is defined as," A philosophy of manufacturing based on elimination of all waste and continuous improvement of productivity." APICS-         " American production of inventory control and society" JIT is also defined as an approach with objective of producing a right part in right time  at right place. JIT was developed by TOYOTA in 1950.(1950-1970). 1980 - GEC ( General electric company ) Country -USA OTHER NAMES OF JIT- Toyota production system Lean production Stockless production Elements of JIT- Stabilize and level the MPS with uniform plant loading (Heijunka). Reduce set up time(Ex- Nascar pit screw) Reduce lot size Preventive maintenance  Reduce lead time Flexible workplace-Respect for people Require supplier quality assurance and implement a zero defect quality program (JIDOKA) QAT - Quality at Source M.P.S. - Master Production System Advantage of JIT-  Less inventory Minimum was
Post a Comment
Read more

IGNITION SYSTEMS

Ignition system is a system in an internal combustion engine that produces the spark to ignite the mixture of fuel and air.  It includes the battery, ignition coil, distributor, spark plugs, and associated switches and wiring.  It is a part of the electrical system which carries the electrical current to a current plug.  It gives the spark to ignite the air-fuel mixture at the correct time Ignition Function:   It produces 30,000 volt spark across spark plug  It Distributes high voltage spark to each spark plug in correct sequence  Time of the spark occurs when piston is near to top dead center  Spark timing varies with load, speed, and other conditions Basic Ignition System: The components in ignition system are as follow:  Battery,  Switch ignition distributor  Ignition coil  Spark plugs and  Necessary wiring Ignition System types: A battery of 12 volts is generally employed. However, a very high voltage surge (of about 25,000 volts in modern engines) is required for ign
Post a Comment
Read more

Trouble shooting of Cooling System

Check the coolant level in your vehicle if it is overheating . If there is insufficient coolant in the vehicle, overheating will occur while driving. Add the appropriate amount of coolant to the coolant reservoir. Inspect your vehicle's thermostat to determine if it is stuck. If your thermostat is stuck, your vehicle will overheat almost immediately after driving a short distance. Another way to check the thermostat is to start the car, open the hood and feel the radiator hose. If the lower part of the radiator hose is hot and the upper part is cool, the thermostat is stuck.  Look at your fan belt to determine if it is broken or loose . Tighten the connections for the fan belt or replace it if necessary. Determine if the cooling system is clogged. Drain and flush the coolant from the cooling system to unclog it. Check the water pump to see if it is faulty and replace it if necessary *******Thanks*******
Post a Comment
Read more