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Двигатели Стирлинга

Сайт о двигателях Роберта Стирлинга. История, описание, конфигурация, принцип работы... А также о других двигателях, тепловых машинах, двигателях внешнего и внутреннего сгорания, новинках в машиностроении. More »

Двигатели Стирлинга

Сайт о двигателях Роберта Стирлинга. История, описание, конфигурация, принцип работы... А также о других двигателях, тепловых машинах, двигателях внешнего и внутреннего сгорания, новинках в машиностроении. More »

Двигатели Стирлинга

Сайт о двигателях Роберта Стирлинга. История, описание, конфигурация, принцип работы... А также о других двигателях, тепловых машинах, двигателях внешнего и внутреннего сгорания, новинках в машиностроении. More »

 

Архивы рубрики: An Introduction to Engine Testing and Development

NOx Analyzers

NOx (chemiluminescence) analyzers measure NO by detecting the light emitted when NO is reacted with ozone (03). The intensity of the light is proportional to the amount of NO in the sample gas. The intensity of the light is measured and converted to an electrical signal, mixed together in a reaction chamber. This chamber normally

Flame Ionization Detector

In the flame ionization detector (FID), a sample of exhaust gas is passed through a flame. The flame bums any hydrocarbons present in the sample gas. When an electri­cal current is passed across the flame, the current changes in proportion to the amount of hydrocarbons contained in the sample gas. The electrical signal from the

Non-Dispersive Infrared Analyzer

A gas will absorb light energy of a frequency band that generally is peculiar to the gas. If this frequency band is narrow and is not shared by any of the other gases that are likely to be present in the sample, then the amount of energy within a certain frequency band that is absorbed

Back Flushing

To prevent the sampling system from becoming contaminated too quickly, it is important to back flush the system between readings. The back flush blows contaminants back down the sample line and into the engine exhaust pipe. It also drains any water that has been trapped below the cooling coil.

Leak Checking

Sampling additional air from the surroundings probably is the most common form of measurement error. Small leaks are difficult to detect because the exhaust gas usually contains some oxygen. Leaks are common because the joints in the sample line often are disturbed (i. e., when connecting a sample line to a new vehicle or when

Sample Pump

The sample pump must be able to generate a sufficient and stable flow rate, the wetted parts must be resistant to attack from the sample gas, and it must not add to, or lose, any of the components being measured.

Solid Particles

Solid particles can cause measurement errors by blocking capillaries and absorbing infrared radiation. A filter usually removes the solid particles. The filter normally is the first component in the sampling system after the connecting line in order to protect as much of the sampling system as possible.

Dryness

Water vapor can cause measurement errors by condensing on optical lenses, absorbing infrared radiation, and reducing the concentration of some gases by absorption. Water vapor in the sample normally is reduced to a low level by passing the sample gas through a coil cooled to 4°C. The water usually is collected in a reservoir at

Flow Rate

The time taken for the sample gas to pass from the vehicle exhaust to the analyzer must be kept constant to time-align the continuous results to the drive cycle. The high bypass flow rate helps to shorten the response time and to lessen the time-alignment error due to partial filter blockage.

Pressure Control

Many analyzers are sensitive to changes in sample pressure and flow rate. The sample gas must be presented to the analyzers at the same pressure and flow rate as the span and zero gases. Therefore, the sampling system must be able to compensate for any change in sample pressure or flow rate caused by changes