ОңТҮстік қазақстан медицина академиясы, хабаршы №4 942, 2021 жыл, том 2
жүктеу/скачать 3,39 Mb. Pdf көрінісі
|
№4942021том2
| E20-E100
) conventional engines have to be refitted with more efforts. This is due to the characteristics of ethanol to dissolve certain rubber and plastic materials. Further, engines running with high blends of ethanol have to be refitted as pure ethanol has a much higher octane rating (116 AKI, 129 RON) than ordinary petrol. Therefore changes to the compression ratio and spark timing are needed to obtain maximum benefits. To refit an engine which will be fueled with pure ethanol, larger carburetor jets, which are about 30-40% larger by area, have to be installed. Additionally, below temperatures of 13 °C, ethanol engines also need a cold-starting system to maximize combustion and minimize uncombusted non- vaporized ethanol. Depending on the particular customization requirements, refitting costs may run from a few euros for substitution of fuel lines to more than €500 if the fuel-supply system is fully upgraded (fuel lines, tank, pump, filter, etc) [3-4]. As an example, in Brazil some vehicles are exclusively running with pure ethanol. They are equipped with ethanol compatible materials and with on-board electronic engine management systems, which can adjust engine operation to ethanol fuelled conditions. Recently an increasing number of vehicles are manufactured with engines which can run on any petrol/bioethanol ratio from 0% ethanol up to 85% ethanol. Sensors of these flexible fuel vehicles ( E85 FFV ) can automatically detect the type of the fuel and adapt engine running. They adjust the air/fuel ratio and the ignition timing to compensate the different octane levels of the fuel in the engine cylinders. The main reason to limit ethanol content to 85 % is to enhance volatility conditions for cold start, particularly in cold climates. Therefore the technology does not need any cold start ancillary system. Worldwide, in February 2006, there were an estimated six million E85 FFVs on the road (WWI 2006). In Europe FFVs are used especially in Sweden, but also in other countries, e.g. in Germany or the United Kingdom, these vehicles are introduced. Pioneers in the European market are the manufacturers Ford and Saab. As opposed to Europe, in Brazil so called E100 FFV s were introduced in 2003. This variant of the E85 FFV technology is capable to operate either within the E20/E25 range, exclusively with hydrous ethanol (E100), or with any blend between E20/E25 and E100. The ethanol sensors used in the E85 versions are replaced in this technology by an advanced software component in the engine’s electronic control unit. This uses inputs from conventional oxygen sensors in the exhaust system (lambda sensors) and self-calibrates the engine to fuel requirements. This technology has proved feasible in Brazil in large part because the warm climate allows blending of hydrous ethanol to E20/E25 without the risk of phase separation. E100 FFVs have becom e a sales phenomenon since their introduction in the Brazilian marketplace, in part because E100 is significantly less expensive than E20/E25 in much of the country (WWI 2006). |