Cooling system
Cooling system is an apparatus employed to keep the temperature of a structure or device from exceeding limits imposed by needs of safety and efficiency. If overheated, the oil in a mechanical transmission loses its lubricating capacity, while the fluid in a hydraulic coupling or converter leaks under the pressure created. In an electric motor, overheating causes deterioration of the insulation. The pistons in an overheated internal-combustion engine may seize (stick) in the cylinders. Cooling systems are employed in automobiles, industrial plant machinery, nuclear reactors, and many other types of machinery. The cooling agents customarily employed are air and a liquid (usually water), either alone or in combination. In some cases, direct contact with ambient air (free convection) may be sufficient; in other cases, it may be necessary to employ forced convection, created either by a fan or by the natural motion of the hot body. In a transmission, if the surface area of the housing (container) is sufficiently large compared with the power lost, or if the transmission is in a moving vehicle, no artificial cooling means may be necessary. To augment the cooling effect by increasing the surface area, the housing may be provided with thin metal fins. On some stationary mechanical transmissions, it may be necessary to circulate the lubricating oil through pipes surrounded by cold water or to use a fan to blow air through pipes surrounded by the oil in the reservoir. On many electric motors, cooling is provided by a fan that is attached to the rotating element and creates a current of air through the housing. In an automobile, the motion of the vehicle provides sufficient forced-convection cooling for the transmission and the gears in the rear axle; in the engine, however, so much energy is released that, except for some early models and certain small cars with low-powered engines, air cooling has not been employed. A typical automotive cooling system comprises (1) a series of channels cast into the engine block and cylinder head, surrounding the combustion chambers with circulating liquid to carry away heat; (2) a radiator, consisting of many small tubes equipped with a honeycomb of fins to radiate heat rapidly, that receives and cools hot liquid from the engine; (3) a water pump, usually of the centrifugal type, to circulate the liquid through the system; (4) a thermostat to control temperature by varying the amount of liquid going to the radiator; and (5) a fan to draw fresh air through the radiator. To prevent freezing, an antifreeze solution is either added to or substituted for water. To raise the boiling point of the solution, the cooling system is usually pressurized by means of a pressure cap on the radiator with valves that open outwardly at a prescribed pressure and inwardly to prevent a vacuum as the system cools.
Essential vocabulary: 1. to employ - применять 2. to exceed - превышать 3. to impose – навязывать, налагать 4. to lubricate – смазывать 5. capacity – ёмкость, возможность 6. coupling (converter) - преобразователь 7. deterioration of the insulation – улучшение изоляции 8. internal-combustion engine – двигатель внутреннего сгорания 9. to seize - захватывать 10. to stick – втыкать, приклеивать 11. machinery - оборудование 12. customarily - привычно 13. ambient air – окружающий воздух (среда) 14. sufficient - достаточный 15. housing – корпус 16. artificial - искусственный 17. to augment - прибавлять 18. thin - тонкий 19. fin – плавник (пластина) 20. stationary - неподвижный 21. to surround - окружать 22. to attach – крепить, прикреплять 23. gear – шестерня, зубчатая передача, передаточный механизм, привод 24. rear axle – задняя ось 25. to release - выпускать 26. to comprise - включать 27. to cast – 1) бросать, 2) лить, отливать (металлы), 3) распределять 28. combustion chamber – камера сгорания 29. honeycomb- сотовый 30. to radiate - излучать 31. antifreeze solution – антифризовый раствор 32. outwardly - внешне 33. to prescribe - задавать
I. Answer the following questions: 1. What is cooling system? 2. What are the usual cooling agents employed? 3. Why are in some cases no cooling means needed? 4. What is cooling in many electric motors provided by? 5. What does a typical automotive cooling system comprise? 6. What is an antifreeze solution used for?
II. Translate the following phrases: - выходить за пределы - двигатель внутреннего сгорания - ядерный реактор - постоянно используемый (задействованный) - естественное движение тела - металлические пластины - прикрепленный к вращающемуся элементу - окруженный водой - маломощный двигатель - увеличение площади поверхности - точка кипения - искусственные средства охлаждения - перегретый двигатель - вызванный необходимостью
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