ОңТҮстік қазақстан медицина академиясы, хабаршы №4 942, 2021 жыл, том 2
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ОҢТҮСТІК ҚАЗАҚСТАН МЕДИЦИНА АКАДЕМИЯСЫ, ХАБАРШЫ №4(942, 2021 жыл, ТОМ 2 113 geographic characteristics influence the impact of these air pollutants. Ozone formation e.g. occurs more easily during hot weather. Also toxic air pollutants are more evident under hot weather conditions. They can be emitted either by the engine exhausts or by evaporation from fuel storage and fuel handling since ethanol has high volatility and generally increases evaporative emissions of gaseous hydrocarbons. As opposed to this, carbon monoxide is a larger problem in cold weather and at high altitudes. To asses the environmental impact of substituting petrol with ethanol, both fuels have to be compared regarding their emissions. Therefore a detailed comparison between emissions of ethanol and petrol combustion will be done. Harmful engine exhaust emissions from combustion of ethanol are generally lower when compared to the tailpipe emissions of fossil petrol. Thus ethanol can reduce certain vehicle pollutant emissions which exacerbate air quality problems, particularly in urban areas. Among the biggest benefits from using ethanol is the high reduction potential of carbon monoxide (CO) emissions. The use of E10 is reported to achieve a 25% or greater reduction in carbon monoxide emissions due to the increased oxygen content of ethanol (OECD/IEA 2004 p. 112). Ethanol contains approximately 35 % oxygen which promotes a more complete combustion of the fuel. Thus, in some countries, ethanol is used as oxygenate for fossil petrol and is increasingly replacing the oxygenate MTBE due to the high ground water contamination potential of MTBE. On the other hand ethanol-blended petrol emits higher evaporative hydrocarbons (HC) and other volatile organic compounds (VOCs) than petrol. When ethanol is added to gasoline, evaporative VOCs can increase due to the higher vapor pressure, measured as Reid Vapor Pressure (RVP) of the ethanol mixture. Generally, adding the first few per cent of ethanol triggers the biggest increase in volatility. Raising the ethanol concentration further does not lead to significant further increases (and in fact leads to slight decreases), so that blends of 2%, 5%, 10% and more have a similar impact. Impacts of ethanol on жүктеу/скачать 3,39 Mb. Достарыңызбен бөлісу:
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