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Applied mechanics |Прикладная механика

Lesson 7

Read the text: Battery-electric vehicle

          Battery Electric Vehicles (BEVs) are electric vehicles whose main energy storage is in the chemical energy of batteries. BEVs are the most common form of what is defined by the California Air Resources Board (CARB) as zero emission (ZEV) passenger automobiles, because they produce no emissions while being driven. The electrical energy carried onboard a BEV to power the motors is obtained from a variety of battery chemistries arranged into battery packs. For additional range genset trailers or pusher trailers are sometimes used, forming a type of hybrid vehicle. Batteries used in electric vehicles include "flooded" lead-acid, absorbed glass mat, NiCd, nickel metal hydride, Li-ion, Li-poly and zinc-air batteries.

The Henney Kilowatt, the first modern (transistor-controlled) electric car.

Attempts at building viable, modern battery-powered electric vehicle began in the 1950s with the introduction of the first modern (transistor controlled) electric car - the Henney Kilowatt. Despite the poor sales of the early battery-powered vehicles, development of various battery-powered vehicles continued through the 1990s (notably General Motors with the EV1), but cost, speed and inadequate driving range continued to make them impractical. Battery powered cars have primarily used lead-acid batteries and NiMH batteries. Lead-acid batteries' recharge capacity is considerably reduced if they're discharged beyond 75% on a regular basis, making them a less-than-ideal solution. NiMH batteries are a better choice, but are considerably more expensive than lead-acid. Lithium-ion battery powered vehicles such as the Venturi Fetish have recently demonstrated excellent performance and range, but they remain very expensive.

          An early poster, prior to flexi-fuel engines, promoting alcohol fuel warns Brazilians not to mix standard petrol with alcohol fuel, and not to use alcohol in unconverted engines. The use of alcohol as a fuel for internal combustion engines, either alone or in combination with other fuels, has been given much attention mostly because of its possible environmental and long-term economical advantages over fossil fuel. Both ethanol and methanol have been considered for this purpose. While both can be obtained from petroleum or natural gas, ethanol may be the most interesting because many believe it to be a renewable resource, easily obtained from sugar or starch in crops and other agricultural produce such as grain, sugarcane or even lactose. Since ethanol occurs in nature whenever yeast happens to find a sugar solution such as overripe fruit, most organisms have evolved some tolerance to ethanol, whereas methanol is toxic.

           Other experiments involve butanol, which can also be produced by fermentation of plants.When alcohol fuel is mixed into gasoline, the result is known as gasohol and labelled with an 'E' followed by the percentage of Ethanol. E10 is commonly found throughout the southern United States, E20 will be mandated by the U.S. state of Minnesota by 2013. and E85 (containing 85% ethanol and just 15% of gasoline) is slowly becoming available. E100 is straight ethanol, which is most widely used in Brazil and Argentina.Use of pure ethanol and ethanol/gasoline mixtures is not without problems however. Ethanol has the unfortunate property of slowly decomposing certain rubber compounds such as are found in the fuel lines and seals in vehicles produced before the mid 1980s. There are claims that even E10 can have a significantly deleterious effect on older vehicles and after prolonged use may cause dangerous fuel leaks in affected cars. Because gasoline is more volatile than Ethanol, it can be harder to start some engines using higher Ethanol percentages than they were designed to use - especially when the engine is cold - and even modern vehicles may be unable to run more than 20% ethanol for this reason.

            Because of the difficulty of starting engines using ethanol, it is common practice in E100 countries such as Brazil to have a small gasoline reservoir in addition to the normal fuel tank with a switch to allow the driver to switch over to gasoline when the car has difficulties starting on ethanol alone. Ethanol is also electrically conductive (gasoline is an effective insulator) which can cause problems with some early electric fuel pump designs and fuel tank sensors. Corrosion of magnesium and aluminium parts is also a concern at higher ethanol percentages. Ethanol has less energy per volume than gasoline so miles-per-gallon ratings with ethanol mixtures are significantly worse than with pure gasoline - although ethanol has a higher octane rating which is beneficial to high compression ratio engines. Many cars that currently use gasoline can run on ethanol, a fuel made from plant sugars. Most cars that are designed to run on gasoline are capable of running with up to 15% ethanol mixed into gasoline. With a small amount of redesign, gasoline-powered vehicles can run on ethanol concentrations as high as 85%. Most gasoline fuelled vehicles can be modified to run on LPG but there has been some concern that the ethanol-gasoline mixtures prematurely wear down seals and gaskets. Theoretically, the lower energy content of alcohol should lead to considerably reduced efficiency and range when compared with gasoline. However, EPA testing has actually shown only a 20-30% reduction in range. Therefore, if the vehicle is capable of doing 750 kilometers on a 50 liter tank (15 kilometers per liter), its range would be reduced to approximately 600 kilometers (12 kilometers per liter). Measures are available to increase this efficiency, such as different camshaft configurations, altering the timing/spark output of the ignition, increasing compression, or simply using a larger fuel tank.In the United States, alcohol fuel was produced in corn-alcohol stills until Prohibition criminalized the production of alcohol in 1919. Interest in alcohol as an automotive fuel lapsed until the oil price shocks of the 1970s. Reacting to the high price of oil and its growing dependence on imports, in 1975 Brazil launched a huge government-subsidized effort to manufacture ethanol fuel (from its sugar cane crop) and ethanol-powered automobiles. These ethanol-only vehicles were very popular in the 1980s, but became economically impractical when oil prices fell - and sugar prices rose - late in that decade. In recent years Brazil has encouraged the development of flex-fuel automobiles, where the owner can use any mixture of ethanol and gasoline based on their individual cost and performance goals.

1. Match the left part with the right:

2. Complete the sentences with the suggested words: significantly, concern, volume, beneficial

Corrosion of magnesium and aluminium parts is also a _______ at higher ethanol percentages. Ethanol has less energy per ______ than gasoline so miles-per-gallon ratings with ethanol mixtures are _______ worse than with pure gasoline - although ethanol has a higher octane rating which is _______ to high compression ratio engines.