Text 4. Gasoline

Gasoline is one of the most important fuels used for transportation. Most gasoline is used in engines that move automobiles and trucks. Gasoline engines also power such vehicles and machines as airplanes, motorboats, tractors, and lawn movers. People in the United Kingdom and some other countries call gasoline petrol because it is made from petroleum.

The widespread use of gasoline began in the early 1900’s, when the mass production of cars started. Gasoline-powered cars made travel easier. People no longer had to live near their jobs, and they could reach remote vacation spots more easily. Gasoline-powered farm machinery allowed for improved crop production.

Through the years, the increasing use of gasoline gave rise to a gigantic industry employing millions of people. However, the use of gasoline has also caused serious problems. For example, transporting petroleum and the manufacture and use of gasoline contribute heavily to air and water pollution.

1. Most gasoline is made by separating and chemically changing the different compounds in petroleum.

2. One of the most promising sources of gasoline for the future involves processing the oil contained in shale rock.

3. To solve the problems, gasoline manufactures are developing gasolines that pollute the environment less.

Exercise 20. Memorize the following words and word combinations to text 5.

Heavy-duty – 1) інтенсивний; потужний; надпотужний; 2) з важким режимом роботи

freight truck - вантажівка

road-building equipment– шляхобудівне знаряддя

submarine – підводний човен

emergency – аварія, аварійна ситуація; непередбачуваний випадок

ignite - запалювати

spark-ignition engine – двигун з іскровим запалюванням

spark plug – запальна свічка

compression-ignition – запалювання завдяки компресії

rod – шток, стрижень

inject- упорскувати

spray - розпилювати

supercharge - наддувати, нагнітати

throttle - дросель

thereby – таким чином

Exercise 21. Read, translate and give the gist of text 5.

Text 5. Diesel Engine

Diesel engine is a type of internal-combustion engine used chiefly for heavy-duty work. Most of the locomotives in the United States are diesel powered. Diesel engines drive huge freight trucks, large buses, tractors, and heavy roadbuilding equipment. They are also used to power submarines and ships, the generators of electric-power stations in small cities, and emergency electric-power generators. Some automobiles are powered by diesel engines.

There are two main types of internal-combustion engines: gasoline engines and diesel engines. The gasoline engine, found in most cars, is a spark-ignition engine. It uses electricity and spark plugs to ignite the fuel and air mixture in the engine cylinders. The diesel engine is a compression-ignition engine. It compresses the air in the cylinders, causing the temperature of the air to rise. Fuel injected into the hot, compressed air immedi­ately ignites.

During the combustion process, the stored chemical energy in the fuel is converted to thermal, or heat, en­ergy. The temperature in each cylinder rises as high as 2,480ºC and creates pressures of 1,500 pounds per square inch. The pressure pushes against the tops of the pistons, forcing them to the other end of their cylinders. The pistons are connected by a rod or other mechanism to a crankshaft that they turn. In this way, a diesel engine supplies rotary power to drive vehicles and other machines.

To ignite the fuel, the compressed air must have a certain temperature. The degree to which the tempera­ture of the air rises depends on the amount of work done by the piston in compressing it. This work is meas­ured as a ratio between the volume of uncompressed air and the volume of the air after compression. The compression ratio necessary to ignite the fuel depends on the size of the engine cylinders. In large cylinders, the compression ratio is about 13 to 1. For small cylin­ders, it may be as high as 22 to 1.

Near the end of the piston compression stroke, the fuel is injected into the cylinder. In order for the fuel and air to mix well, the fuel is injected under high pres­sure as a spray. Combustion usually starts just before the piston ends its compression stroke. The power of diesel engines can be increased by supercharging, or forcing air under pressure into the cylinder.

Diesel engines have a high thermal efficiency, or abil­ity to convert the stored chemical energy in the fuel into mechanical energy, or work. In the spark-ignition en­gine, the amount of power produced is determined by a throttle that regulates how much air and fuel enter the cylinder. The throttle may operate in a partly closed po­sition much of the time, thereby reducing the engine air intake and efficiency. Diesel engines do not require a throttle, making them more efficient than gasoline en­gines.

A cycle begins with the intake stroke when the piston moves down and draws air into the cylinder. The piston rises and compresses the air. During the compression stroke, the air temperature rises to about 480ºC. When fuel is injected into the cylinder, it mixes with the hot air and burns explosively. Gases produced by this combustion push the piston down for the power stroke. Dur­ing the exhaust stroke, the piston moves up and forces the burned gases out of the cylinder.

Exercise 22. Match the words in A with their synonyms in B

A	B
1) spray	a) at once
2) heavy	b) provide
3) duty	c) boat
4) truck	d) obligation
5) ship	e) atomize
6) internal	f) decrease
7) ignite	g) turn into
8) compression	h) amount
9) immediately	i) pressure
10) convert	j) fire
11) supply	k) inner
12) rise	l) lorry
13) volume	m) weighty
14) start	n) increase
15) reduce	o) commence

Exercise 23. Complete the following sentences with the words from text 5.

1. Most of the locomotives in the United States are ____.

2. There are two main types of internal-combustion engines: ____.

3. The diesel engine is a ___ engine.

4. The diesel engine compresses the air in the cylinders, causing _.

5. During the combustion process, ___ in the fuel is converted to thermal, or heat, energy.

6. The pressure pushes against the tops of the pistons, forcing them ____.

7. To ignite fuel ___ must have a certain temperature.

8. The work done by the piston is measured as a ratio between __ an the volume of the air after compression.

9. ___ usually starts just before the piston ends its compression stroke.

10. The amount of power produced is determined by throttle that regulates ___ enter the cylinder.

Exercise 24. Say what is true and what is false. Correct the false sentences using the expressions of agreement or disagreement given below.

I don’t agree with the statement.

I disagree with this.

I am afraid I can’t agree with you here.

I am afraid (I think) you are mistaken.

I see your point, but … .

On the contrary.

Nothing of the kind, I am afraid.

I am sure, that ...

1. Diesel engines drive huge freight trucks, large buses, tractors, and heavy road-building equipment.

2. The gasoline engine found in most railway trains is a spark-ignition engine.

3. The diesel engine compresses water in tanks, causing the temperature of the air to rise.

4. During the combustion process, the electrical power is converted to thermal or heat energy.

5. The pistons are connected by a rod to a crank-shaft that they turn.

6. As soon as the piston compression stroke starts, the fuel is injected into the cylinder.

7. Combustion usually stops just before the piston ends its compression stroke.

8. The throttle may operate in a partly closed position, thereby increasing the engine air intake.

Exercise 25. Answer the following questions on text 5.

1. What work are diesel engines chiefly used for?

2. What means of transport use diesel engines?

3. Where else can these engines be used?

4. What are two main types of internal-combustion engines?

5. What causes the temperature rise in the engine?

6. What is converted into the thermal or heat energy in the internal combustion engine?

7. Why is it necessary to ignite the fuel?

8. What does the pressure ratio come to in large and small cylinders?

9. What determines the spark-ignition engine?

10. How does a four-cycle diesel engine work?

Exercise 26. Translate into English.

1. Дизельні двигуни використовуються майже в усіх транспортних засобах.

2. Більшість сучасних авто використовують бензинові двигуни з іскровим запаленням.

3. Накопичена в паливі хімічна енергія перетворюється в процесі згоряння в теплову енергію.

4. Ступінь стискання, необхідний для запалення пального, залежить від розміру циліндрів двигуна.

5. В невеликих за розміром циліндрах ступінь стискання може дорівнювати 22 до 1.

6. Процес горіння зазвичай починається перед тим, як поршень закінчує стадію компресії.

7. Дизельні двигуни не потребують дроселя, що робить їх ефективнішими за бензинові.

8. Дизельні двигуни більше підходять для виконання важких робіт, ніж бензинові двигуни однакової потужності, оскільки вони можуть витримувати великі навантаження.

9. Дизельне пальне потребує менше очищення і є дешевшим, ніж паливо вищої якості, таке, як бензин.

Exercise 27. Make up a dialogue on diesel engines.

Exercise 28. Read text 6 filling the spaces with the words given below in brackets.

(provides, compresses, a cycle, upstroke, draws, stroke, differ, exhausts, downstroke, valves, piston, intake, occur, ports, injected)