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catalyst consists of a stainless steel canister that contains a honeycomb structure called a substrate or catalyst support. There are no moving parts, just large amounts of interior surface area. The interior surfaces are coated with catalytic metals such as platinum or palladium. It is called an oxidation catalyst because the device converts exhaust gas pollutants into harmless gases by means of chemical oxidation. In the case of diesel exhaust, the catalyst oxidizes CO, HCs, and the liquid hydrocarbons adsorbed on carbon particles. In the field of mobile source emission control, liquid hydrocarbons adsorbed on the carbon particles in engine exhaust are referred to as the soluble organic fraction (SOF) -- the soluble part of the particulate matter in the exhaust. Diesel oxidation catalysts are efficient at converting the soluble organic fraction of diesel particulate matter into carbon dioxide and water.
this is my project so i need pick one of the car to be my topic .so i choose 2008 nissa tiida so can u tell me . National Environment (AUS)Protection Measure for Diesel Vehicles (Guidelines)• Give a brief explanation of what this involves.
Originally called a "Lambda Sensor" when it was first used in fuel-injected European cars, the oxygen sensor monitors the level of oxygen (O2) in the exhaust so an onboard computer can regulate the air/fuel mixture to reduce emissions. The sensor is mounted in the exhaust manifold downpipe(s) before the catalytic converter or between the exhaust manifold(s) and the catalytic converter(s). It generates a voltage signal proportional to the amount of oxygen in the exhaust.
The sensing element on nearly all oxygen sensors in use is a zirconium ceramic bulb coated on both sides with a thin layer of platinum. The outside of the bulb is exposed to the hot exhaust gases, while the inside of the bulb is vented internally through the sensor body or wiring to the outside atmosphere.
When the air/fuel mixture is rich and there is little O2 in the exhaust, the difference in oxygen levels across the sensing element generates a voltage through the sensor's platinum electrodes: typically 0.8 to 0.9 volts. When the air/fuel mixture is lean and there is more oxygen in the exhaust, the sensor's voltage output drops to 0.1 to 0.3 volts. When the air/fuel mixture is perfectly balanced and combustion is cleanest, the sensor's output voltage is around 0.45 volts.
The oxygen sensor's voltage signal is monitored by the onboard engine management computer to regulate the fuel mixture. When the computer sees a rich signal (high voltage) from the oxygen sensor, it commands the fuel mixture to go lean. When it receives a lean signal (low voltage) from the oxygen sensor, it commands the fuel mixture to go rich. Cycling back and forth from rich to lean averages out the overall air/fuel mixture to minimize emissions and to help the catalytic converter operate at peak efficiency, which is necessary to reduce hydrocarbon (HC), carbon monoxide (CO) and oxides of nitrogen (NOX) levels even further.
The speed with which the oxygen sensor reacts to oxygen changes in the exhaust is very important for accurate fuel control, peak fuel economy and low emissions. The air/fuel mixture in an older carbureted engine doesn't change as quickly as that in a throttle body fuel-injected vehicle, so response time is less critical. But, in new engines with multipoint fuel injection, the air/fuel mixture can change extremely fast, requiring a very quick response from the oxygen sensor.
catalytic converter, there are two different types of catalyst at work, a reduction catalyst and an oxidation catalyst. Both types consist of a ceramic structure coated with a metal catalyst, usually platinum, rhodium and/or palladium. The idea is to create a structure that exposes the maximum surface area of catalyst to the exhaust stream, while also minimizing the amount of catalyst required, as the materials are extremely expensive. Some of the newest converters have even started to use gold mixed with the more traditional catalysts. Gold is cheaper than the other materials and could increase oxidation, the chemical reaction that reduces pollutants
catalytic converter is a device that uses a catalyst to convert three harmful compounds in car exhaust into harmless compounds.
The three harmful compounds are:
Carbon monoxide is a poison for any air-breathing animal. Nitrogen oxides lead to smog and acid rain, and hydrocarbons produce smog.
In a catalytic converter, the catalyst (in the form of platinum and palladium) is coated onto a ceramic honeycomb or ceramic beads that are housed in a muffler-like package attached to the exhaust pipe. The catalyst helps to convert carbon monoxide into carbon dioxide. It converts the hydrocarbons into carbon dioxide and water. It also converts the nitrogen oxides back into nitrogen and oxygen.
okay thats great .cheers
this info is universal can work on any car
this info is universal can work on any car and use it as reffernce
thx but do u know why is the
Catalytic Converter emission control system. if u know can u locate that part for if u have photo will be good idea?~
thx so can you hlep me answer 5 more question i will add bouns for you!
which emission(s) the system controls
here is the info
how the emissions are formed:
Car emissions are biproducts of the internal combustion engine of a car, which is released into the atmosphere via the car's exhaust system. These emissions are significant contributors to air pollution and also form the main ingredients required to create smog in many of the larger cities around the world. In this respect, emissions are of importance as they have been found to have many detrimental effects on both public health and the environment.
Hydrocarbons are toxins which form the main ingredient in smog (see also ‘Smog' section). They are formed when fuel is burned in the car and are can be described as burned or partially burned fuel
Carbon Monoxide (CO) is an odourless, colourless and tasteless gas which is highly toxic to humans. It is responsible for the majority of fatal air poisoning incidents in developed countries, In cars, carbon monoxide is produced as a result of incomplete combustion of the fuel.
Mono-nitrogen oxides can be either nitrogen oxide (NO) or nitrogen dioxide (NO2). Consequently, they are often generically referred to as "NOx" pollutants (effectively,
NOx is a mixture of NO and NO2).They are generated when nitrogen in the air reacts with oxygen under the conditions of high temperature and pressure in the engine. NOx is a precursor to smog and acid rain. NO and NO2 react with water, ammonia and a number of other compounds to form (amongst other nasties), nitric acid vapour.Nitric acid vapour can penetrate deep into lung tissue and damage it
Generally the emission of Carbon dioxide from a car is considered a "best case scenario" (it means that fuel is being burned effectively), it is still a greenhouse gas. Motor vehicle Carbon Dioxide emissions form a significant part of the man made contribution to the growth of Carbon dioxide concentrations in the atmosphere which is believed by a majority of scientists to play a significant part in climate change
A photochemical smog is the chemical reaction of sunlight, nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the atmosphere, which leaves airborne particles (called particulate matter) and ground-level ozone. Nitrogen oxides are released by nitrogen and oxygen in the air reacting together under high temperature and pressure of the car engine (as well as industrial manufacturing factories). VOCs are released from man-made sources such as gasoline (petrol) as well as paint, solvents and pesticides
how theirements emission(s) are controlled:
The need to control car emissions, such as hydrocarbons, NOx and carbon monoxide, has lead to the development of a number of pollution control devices in the car. The desire to reduce emissions has also, over the course of time, necessitated the computerisation of the car. In 1981, the first of a series of advancements as a "self adjusting engine" which featured a feedback control system. This consisted of an oxygen sensor fitted on the exhaust system, which would measure the oxygen content of the emissions. It would then send a signal back to a computer which would analyse the oxygen value and adjust the air / fuel mix accordingly.As the onboard computer systems advanced, they were also able to adjust things like ignition spark timing and control other emission monitoring systems on the vehicle. Now, computer systems are so advanced that they are capable of self - diagnosing, alerting the driver to any outages with a warning light on the dash. At the same time, the computer logs the issue internally with other diagnostic information which can later be examined by a technician. Generally, emissions are controlled in three ways:1. To promote more complete combustion in the engine, so there are generally less bi products such as carbon monoxide and hydrocarbons to be emitted.2. To reintroduce hydrocarbons back into the engine and give the a "second chance" of complete combustion and conversion into less harmful compounds.3. To provide an additional area for combustion to take place (this is how catalytic converters function).
Explain how the system/components are tested:
The electronic emissions control unit or computer monitorscertain powertrain functions and controls various operating parametersto help the vehicle run efficiently and with the lowest possibleemissions. Ignition, transmission function, air injection, exhaustgas recirculation (EGR), engine operating temperature and fuel systemparameters are some of the systems monitored and/or controlled by theelectronic emissions control unit car computer .The onboard emissions diagnostic device monitors the operation ofa vehicle's emission control system and alerts the driver with adashboard light when malfunctions occur. The system will record wherethe problem is occurring and assist automotive technicians indiagnosing and repairing emission control malfunctions. Since someemission control malfunctions do not have an adverse effect on vehicleperformance, they can go undetected by the driver for quite some time.The onboard diagnostic device will help catch malfunctions early,preventing a significant output of harmful exhaust emissions from yourvehicle, and possibly in time to be covered by the emissions controlwarranty. Often this "device" is part of the electronic control unitmentioned above.
EMISSION CONTROL PARTSExhaust Gas Conversion Systemsoxygen sensor thermal reactorcatalytic converter dual-walled exhaust pipeExhaust Gas Recirculation SystemEGR valve thermal vacuum switchEGR solenoid EGR spacer plateEGR backpressure transducer Sensor and switches use tocontrol EGR flowEvaporative Emission Control Systempurge valve fuel filler cappurge solenoid vapor storage canister and filterPositive Crankcase Ventilation (PCV) SystemPCV valve PCV solenoidAir Injection SystemAir pump diverter, bypass, or gulp valvereed valve anti-backfire or deceleration valveEarly Fuel Evaporative (EFE) SystemEFE valve thermal vacuum switchheat riser valveFuel Metering Systemelectronic control module (unit) or EFI air flow meter, computercommand module or mixture control unit, deceleration controls,electronic choke, fuel injectors, fuel injection units and fuelaltitude compensator sensor, bars or rails for EFI or TBI systems,mixture settings on sealed fuel mixture control solenoid, diaphragmor other systems, fuel metering components that achieve closed/otherfeedback control sensors/loop operation switches and valvesAir Induction Systemthermostatically controlled air cleaner, air boxIgnition Systemselectronic spark advance timing advance/retard systems,high energy electronic ignitionMiscellaneous Partshoses, gaskets, brackets, clamps and other accessories used in theabove systemsEMISSION RELATED PARTSThese are examples of other parts of your vehicle which have aprimary purpose other than emissions control but which neverthelesshave significant effects on your vehicle's emissions. If any of theseparts fail to function or function improperly, your vehicle'semissions may exceed federal standards. Therefore, when any of theparts of the following systems are defective in materials orworkmanship and have failed in a way that would be likely to causeyour vehicle's emissions to exceed federal standards, they should berepaired or replaced under the emissions warranty:
faulty system when emisson are not controlled dash warrning light will turn on and that is sign the emission are out of control to test the part system has obd2 diagnositc
and early 1980's manufacturers started using electronic means to control engine functions and diagnose engine problems. This was primarily to meet EPA emission standards. Through the years on-board diagnostic systems have become more sophisticated. OBD-II, a new standard introduced in the mid-'90s, provides almost complete engine control and also monitors parts of the chassis, body and accessory devices, as well as the diagnostic control network of the car.
The service industry calls the Check Engine light on your dash an "MIL" or Malfunction Indicator Light. It shows three different types of signals. Occasional flashes show momentary malfunctions. It stays on if the problem is of a more serious nature, affecting the emissions output or safety of the vehicle. A constantly flashing MIL is a sign of a major problem which can cause serious damage if the engine is not stopped immediately. In all cases a "freeze frame" of all sensor readings at the time is recorded in the central computer of the vehicle.
Hard failure signals caused by serious problems will cause the MIL to stay on any time the car is running until the problem is repaired and the MIL reset. Intermittent failures cause the MIL to light momentarily and they often go out before the problem is located. The freeze frame of the car's condition captured in the computer at the time of the malfunction can be very valuable in diagnosing these intermittent problems. However, in some cases if the car completes three driving cycles without a re-occurrence of the problem, the freeze frame will be erased.
service repair after the system indicated the failed part like oxygen sensor or catalytic converter you test with scanner and read output radings and repalce parts as needed
let me know if ican help you more thank you
which emission(s) the system controls
Choose another 2 emission control systems and repeat the requirements as for the catalytic converter.