An exhaust gas analyzer or exhaust CO analyzer is an instrument for measuring carbon monoxide among other gases in the exhaust, caused by incorrect combustion, the measurement of the Lambda coefficient is the most common.
The principles used for CO sensors (and other types of gases) are infrared gas sensors (NDIRs) and chemical gas sensors. The carbon monoxide sensor is used to assess the amount of CO during the MOT test. In order to be used for such testing, it must be approved to be appropriate for use in the scheme. In the UK, the list of acceptable exhaust gas analyzers for use in the MOT test scheme is listed on the Department of Transport website.
Video Exhaust gas analyzer
Pengukuran koefisien Lambda
The presence of oxygen in the flue gas indicates that incomplete combustion combustion, resulting in contaminant gas. So measuring the proportion of oxygen in the exhaust from this machine can monitor and measure these emissions. This measurement is performed in the MOT test through the measurement of the Lambda coefficients.
The Lambda coefficient (?) Is obtained from the relationship between air and gasoline involved in mixed combustion. This is a measure of the efficiency of a gasoline engine by measuring the percentage of oxygen in the exhaust.
When the gasoline engine operates with a stoichiometric mixture of 14.7: 1, the value of LAMBDA (?) Is "1".
Mixing ratio = fuel weight/weight of air
- - Expressed as mass ratio: 14.7 kg air per 1 kg. fuel.
- - Disclosed as volume ratio: 10,000 liters of air per 1 liter of fuel.
With this connection theoretically perfect combustion of gasoline is achieved and greenhouse gas emissions will be minimal. The coefficient is defined as the Lambda coefficient
If Lambda & gt; 1 = slender mix, excess air. If Lambda & lt; 1 = rich mixture, excess gasoline.
- A sleek blend contains oxygen excess. The oxygen surplus will react with nitrogen to NOx (Nitrogen Oxide), if the temperature is high enough (about 1600 ° C) for sufficient time to allow so.
- A rich blend contains an oxygen deficit. This makes all fuels impossible to burn completely into carbon dioxide and water vapor. Therefore, some fuels will remain as hydrocarbons (HCs), or simply react to carbon monoxide (CO). The concentration of carbon monoxide in the flue gases is closely related, and is almost proportional to the ratio of air fuel in the rich region. Therefore, it is very valuable when setting the machine.
- The emitted carbon dioxide is theoretically proportional to the fuel consumed at a given and constant air fuel ratio. Less carbon dioxide will be emitted per liter of fuel if? & lt; 1, because some fuel will not be completely burned.
Maps Exhaust gas analyzer
Sensor type
Chemical CO Sensors
- Chemical CO gas sensors with sensitive layers based on polymer- or heteropolysiloxane have a major advantage of very low energy consumption, and can be reduced in size to fit microelectronic-based systems. On the downside, short-term and long-term effects and a rather low lifetime are the main obstacles when compared to the NDIR measurement principle.
- Another method (Henry's Law) can also be used to measure the amount of CO dissolved in a liquid, if the amount of foreign gas is not significant.
Nondispersive Infrared (NDIR) CO Sensor
The NDIR sensor is a spectroscopic sensor for detecting CO in a gas environment with its characteristic absorption. Its main components are infrared sources, light tubes, interference filters (wavelengths), and infrared detectors. The gas is pumped or diffuses into the light tube, and the electronics measure the absorption of the wavelength of the light characteristics. NDIR sensors are most commonly used to measure carbon monoxide. The best of these have a sensitivity of 20-50 PPM.
Most CO sensors are fully calibrated before shipping from the factory. Over time, the zero point of the sensor needs to be calibrated to maintain long-term sensor stability. New developments include using microelectromechanical systems to lower the cost of these sensors and to make smaller devices. Typical NDIR sensors cost in the range of (US) $ 100 to $ 1000.
Cambridge Indicator
Used by older aircraft, the Cambridge Mixture Indicator displays the air-fuel ratio by measuring the thermal conductivity of the flue gas. It was produced by Cambridge Instrument Company. The device was installed on planes in the 1930s, including Lockheed Model 10 Electra flown by Amelia Earhart on her last flight.
See also
- AFR sensor
- Oxygen sensor
References
Source of the article : Wikipedia
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