HC emission

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HC emissions is a collective term for volatile organic substances ( hydrocarbons , engl. H ydro c arbons ) in the organic chemistry and in the automotive industry .

Chemical meaning

Volatile organic substances from hydrocarbons or (HC) can arise in natural products such as wood or in plastics through raw materials and processing.

In the chemical industry, these volatile organic compounds are often assigned to the VOC .

HC emissions in the automotive industry

Because diesel and petrol consist of a mixture of hydrocarbons, hydrocarbons remain in the exhaust gas even after combustion. Together with nitric oxide (NO x ) and solar radiation, these substances can be converted into organic compounds that irritate the mucous membranes and significantly promote the emergence of summer smog.

In many parts of the world there are therefore upper limits that limit the emission of volatile hydrocarbons. In the USA, the so-called CARB ( California Air Resources Board ) legislation in the state of California has the strictest legislation, CARB-LEV II, in force worldwide.

According to the origin of the HC emissions

  • fuel emissions as emissions from the fuel or the fuel system and
  • non-fuel emissions as emissions that are not from the fuel or the fuel system

originate, differentiated.

Test procedures in the automotive industry

The individual test procedures for HC emissions are specified either by the licensing authority or by the vehicle manufacturers or their association standards such as the VDA .

Some test methods are also offered as a service by approved test institutes.

A conversion or transfer of quantitative measurement results to other test methods is usually not possible due to different test conditions. Under certain circumstances, conclusions can only be drawn about the occurrence of a substance.

CARB laws in California

Here, the emissions of organic substances are recorded quantitatively over a defined period of time in a one-year-old vehicle in a climate chamber .

Fogging according to DIN 75201

In fogging according to DIN 75201, the proportion of volatile substances is determined from a material sample. A determination of individual organic compounds with their share in the total emission does not take place here.

Odor test according to VDA 270 (pickle jar method)

In the odor test according to VDA 270, the odor of a material is determined by a test group and rated with grades.

Bottle method for determining formaldehyde according to VDA 275

Here, a mass-related formaldehyde value in mg / kg is determined from a material sample.

Thermal desorption (TDS) according to VDA 278

With thermal desorption, the proportion of volatile substances is determined from a very small material sample in two temperature ranges 90 ° C VOC and 120 ° C FOG. Here the organic compounds are determined individually and their share in the total emission is determined.

Chamber measurement method according to VDA 276 and summer test according to BMW GS 97014-3

With the chamber measurement method according to VDA 276 and the summer test according to BMW GS 97014-3, the proportion and the volatile individual substances of real material samples or components are determined at 65 ° C. Here the organic compounds are determined individually and their share in the total emission is determined. This complex procedure offers a high level of informative value and real test conditions for components and material samples about the behavior in the vehicle compared to one of the TDS according to VDA 278.

Manufacturer-specific chamber measurement methods

With the manufacturer-specific chamber measurement methods, vehicles or components are subjected to HC tests in a test chamber . However, the vehicle manufacturers in Germany use different test methods, the qualitative results of which cannot be compared with one another.

Health significance of hydrocarbons

Some hydrocarbon compounds (aromatic HC) have carcinogenic properties, while others (e.g. alkanes ) are not known to have any harmful properties.

Fuels with special HC properties

In the case of fuels, there are mixtures that consist of almost 100% alkanes. The HC emissions from such fuels contain almost only alkanes. At the same time, the proportion of aromatics and polyaromatic hydrocarbons (PAHs) is greatly reduced after these fuels have been burned and the exhaust gases are therefore less harmful to health. Such fuels are z. B. Eco-Par (or EcoPar) and alkylate petrol .

See also

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