[STEM] The Emissions Hysteria Industry

Because of the debate about emissions from internal combustion engines decisions such as driving bans have already been taken. With this in mind the technical background and statistical developments should always be taken into account.

Otto-Process
Diesel-Process
NOx-Ruß-Trade-Off and Catalytic-Converters
Epidemiology
Particulates
NOx
SOx

Otto-Process

The Otto process (Nicolaus August Otto June 10, 1832 - January 26, 1891) is the thermodynamic comparison process for internal combustion engines which works with a constant-volume-combustion (isochoric combustion). The procedure was developed in the years 1861 to 1876 by Otto. In reality a combustible mixture is compressed during compression and electrically ignited (spark ignition).

Prior to gasoline direct injection the torque was adjusted by throttling the intake mixture with a throttle. In addition Otto and Diesel were distinguished on the basis of the outer mixture formation by means of carburetor for gasoline engines and internal mixture formation in the case of the diesel engines.

The combustion takes place virtually explosively but not at a constant volume. Therefore petrol engines tend to have lower efficiencies than comparable diesel engines. With the faster combustion the Otto process thus offers worse conditions for the formation of nitrogen oxides (NOx) than the diesel process. The petrol engine can work according to the two-stroke and according to the four-stroke process.

Diesel-Process

The Diesel Process (Rudolf Christian Karl Diesel March 18, 1858 - September 29, 1913) is the thermodynamic comparison process for internal combustion engines that work with a constant-pressure-combustion (isobaric combustion). The process was successfully commenced in 1897 by Diesel. In reality during the compression air is compressed and after the injection a combustible mixture that spontaneously ignites at the appropriate pressure (autoignition).

Since the diesel works without spark ignition the combustible mixture must be compressed so high that the temperature after compression reaches the ignition temperature of the fuel. This ignition temperature is about 550 ° C to 620 ° C.

The combustion takes place virtually explosively but slower than the gasoline engine and not at a constant pressure. Therefore diesel engines tend to have higher efficiencies than comparable gasoline engines. With the slower combustion the diesel process offers better conditions for the formation of nitrogen oxides (NOx) than the Otto process. The diesel engine can work according to the two-stroke and according to the four-stroke process.

NOx-Ruß-Trade-Off and Catalytic-Converters

Incineration of hydrocarbons (CxHy) inevitably produces carbon dioxide (CO2) and water (H2O). Carbon dioxide (CO2) and water (H2O) are natural products of that combustion. Depending on the fuel, the process and the treatment of the exhaust gases harmful combustion products such as nitrogen oxides (NOx), carbon monoxide (CO), unburned hydrocarbons (CxHy) and fine particles are produced. The latter can be in the form of soot (C) or by the agglomeration of other radicals such as nitrogen oxides (NOx).

In Otto engines a 3-way-catalytic-converter for exhaust gas treatment can be installed. This converts harmful combustion products into natural products of combustion. In the 3-way-catalytic-converter nitrogen oxides (NOx) are reduced to nitrogen (N2). The released oxygen (O2) then converts carbon monoxide (CO) to carbon dioxide (CO2) and burns hydrocarbons (CxHy) to water (H2O) and carbon dioxide (CO2).

In diesel engines the emissions depend on the driving style of the engine. In the case of a lack of air or a rich mixture the diesel produces more soot (C) and less nitrogen oxides (NOx). And with an excess of air or a lean mixture the diesel produces less soot (C) and more nitrogen oxides (NOx). Diesel engines usually operate with an excess of air or a lean mixture because the direct injection leaves less time for the mixing of air and fuel. So the fuel finds enough oxygen for the combustion despite the short time.

For this reason diesel engines can use an SCR-catalytic-converter (Selective-Catalytic-Reduction) for the exhaust gas treatment. Nitrogen oxides (NOx) are reduced by means of ammonia (NH3) to nitrogen (N2) and water (H2O).

Since ammonia (NH3) is an aggressive gas the little aggressive liquid diaminomethanal CO(NH2)2 (AdBlue, Diesel Exhaust Fluid) is used. In the city however an SCR-catalytic-converter (Selective-Catalytic-Reduction) reaches its limits because the temperature required for the formation of ammonia (NH3) in the case of interrupted traffic is not always reached. [Schreiner,p.30ff] [Merker, Teichmann,p.506ff] [Mollenhauer, Tschöke,p.672ff] [Pischinger, Klell, Sams,p.283ff]

Epidemiology

Epidemiology is the science of the distribution, causes and consequences of health-related conditions in populations. One method is the comparison of health damage.

Harmful combustion products such as nitrogen oxides (NOx), carbon monoxide (CO), unburned hydrocarbons (CxHy) and fine particles such as soot (C) are hazardous. But only for that people do not die. Epidemiology thus compares the damage to health with an equivalent number of deaths.

However the results can be influenced or even superimposed by different confounding factors. When assessing harmful combustion products other factors such as a significantly different proportion of smokers or weather conditions can affect the incidence of illness or death much more than differences in air quality.

Particulates

Particulate matter (PM10, PM2.5) is a particle that has a separation efficiency of 50% when classified with an air inlet for an aerodynamic diameter of 10 microns (PM10) or 2.5 microns (PM2.5). The degree of separation is the proportion of the dispersed phase (particulate matter) of a certain particle size (PM10, PM2.5) which is deposited. However the weight and size of the particles gives no information about its composition and consequently its toxicity.

Fine dust is produced during combustion processes such as in vehicles and heaters, in brake and tire wear, in construction work or in the processing of metal. In Germany particulate matter emissions have fallen by 50% (PM2.5) and 40% (PM10) since 1995 respectively. However the biggest emitters of particulate matter are industrial processes, households and small consumers but not vehicles. [pm25] [pm25,alt] [pm10] [pm10,alt] [Merker, Teichmann,p.486ff] [Mollenhauer, Tschöke,p.465ff] [Pischinger, Klell, Sams,p.286ff]

NOx

Nitrogen oxides (NOx) is a collective term for various gaseous compounds of nitrogen (N) and oxygen (O). Nitrogen oxides (NOx) irritate and damage the respiratory tract. Nitric oxides (NOx) also produce nitric acid (HNO3) which also pollutes the environment.

Nitrogen oxides (NOx) are mainly produced during combustion processes such as in vehicles and heaters. Particularly vulnerable are diesel engines as they operate with the modern direct injection and an excess of air.

In Germany nitrogen oxide emissions have fallen by 60% since 1990. The biggest emitters of nitric oxide are vehicles. [NOx] [NOx,alt] [Schreiner,p.30ff] [Merker, Teichmann,p.495ff/506ff] [Mollenhauer, Tschöke,p.469ff/672ff] [Pischinger, Klell, Sams,p.283ff]

SOx

Sulfur oxides (SOx) is a generic term for various gaseous compounds of sulfur (S) and oxygen (O). Sulfur oxides (SOx) are harmful to health. In addition sulfuric acid (H2SO4) is produced by sulfur oxides (SOx) which also pollutes the environment.

Sulfur oxides (SOx) are formed during the combustion of sulfur-containing fuels. Since sulfur-containing fuels are increasingly not being used sulfur dioxide emissions in Germany have fallen by 95% since 1990. [SOx] [SOx,alt] [Mollenhauer, Tschöke,p.86ff/401ff]

Einfache Standards

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