Heat energy is a source of power, but （） will cause damage to the engine.

相似题目

• Each cylinder is closed at the top by a （）, made of a special heat-resistant steel.

  A . cylinder liner B . coupling flange C . cylinder cover D . piston crow

  查看最佳答案

• Which statement concerning reserve sources of energy for GMDSS is FALSE（）.

  A . While the ship is at sea，there must be available at all times a supply of electrical energy sufficient to operate the radio installations and to charge any batteries used as part of a reserve source of energy B . Both the VHF and MF/HF installations must be simultaneously supplied C . A means of ensuring a continuous supply of electrical power must be provided to all GMDSS equipment that could be affected by an interruption in power D . If a UPS or equivalent is used to supply power to the ship's GPS receiver or other source of positional information，a means must be provided to ensure the continuous supply of the information in the event of a failure to the ship's main or emergency source of power

  查看最佳答案

• The transmission time duration of a single pulse of radio-frequency energy is a function of the（）.

  A . persistence B . pulse repetition rate C . pulse length D . resolutio

  查看最佳答案

• The essential part of the diesel engine, whose function is to convert the heat energy into the mechanical power, is the （）.

  A . crankshaft B . piston C . connecting rod D . bearing

  查看最佳答案

• Besides heat, fuel, and oxygen, which of the following is necessary for a fire to exist?（）

  A . Chain reaction B . Thermal action C . Chemical occlusion D . Pyrotechnical reactio

  查看最佳答案

• The heat required to change a substance from a solid to a liquid while at its freezing temperature, is known as the latent heat of （）.

  A . fusion B . vaporization C . condensation D . sublimatio

  查看最佳答案

• The rate of heat transfer from a hot region to a cold region is affected most by the （）.

  A . size of the heat sink B . temperature difference between the regions C . size of the heat source D . total heat of the system

  查看最佳答案

• A SECONDARY function of a waste heat boiler is to （）.

  A . reduce engine exhaust noise B . reduce engine back pressure C . increase engine cycle efficiency D . increase turbocharger efficiency

  查看最佳答案

• Which of the lists forms of heat transfer, if any, is illustrated by the flow of combustion gases through a boiler?（）

  A . Natural convection only B . Forced convection only C . Both natural convection and forced convection D . None

  查看最佳答案

• The latent heat of evaporation is dissipated in the （） in a compression refrigeration system.

  A . evaporator B . condenser C . expansion valve D . compressor

  查看最佳答案

• A condenser is a vessel in which（） is deprived of its latent heat of vaporization and so changed to its liquid state.

  A . sea water B . fresh water C . vapour D . ga

  查看最佳答案

• The general purpose of a heat exchanger is to （）.

  A . eliminate hot air from the condenser B . maintain steady pressure in a system C . heat, or cool one fluid by means of another fluid D . reduce the engine room temperature in tropical climate

  查看最佳答案

• The movement of heat within a fluid, caused by the application of thermal energy, is called （）.

  A . radiation B . conduction C . convection D . condo-radiatio

  查看最佳答案

• The spreading of fire as a result of heat being carried through a vessels ventilation system, is an example of heat transfer by （）.

  A . conduction B . convection C . radiation D . windage

  查看最佳答案

• b. The only function of fat in the body is to act as a source of potential energy.

  查看最佳答案

• The energy released by the chemical reaction is ( ) heat.

  查看最佳答案

• The device capable of doing this is called a capacitor. The ability of a capacitor to store electrical energy is termed capacitance.（）

  查看最佳答案

• In a diesel engine, offers the heat energy directly; works as working medium and changes the heat energy to mechanical energy.

  A.the burning of the fuel; medium shaft B.fuel spray; fresh air C.fuel; fuel spray D.the burning of the fuel; the burned gas mixture

  查看最佳答案

• 听力原文： Most industrialized nations have gone through two major energy transitions. By energy transition we mean a change from one major source of energy to another.

  The first major energy transition was from wood to coal. For many centuries people used wood as a primary source of energy. By burning wood people were able to heat their homes, cook their food, and produce basic items. Most early societies grew up near a sufficient supply of wood. The main advantage of wood was that it was easy to get and easy to bum. During the early 1800's, some towns and villages began to make a transition from wood to coal as a basic source of energy, because they found that coal generally burns longer and at a higher temperature than wood, and a long-burning and hot-burning fuel was badly needed for the machines that were being used at that time. Another advantage of coal was that there was a lot of it and it was also easy to get. Besides, it could be easily shipped to faraway places. As a result of the transition from wood to coal, industry developed very rapidly. People were able to get more things and their standard of living went up. The second major energy transition was from coal to oil. We'll discuss it next week. Why did most early societies grow up near a sufficient supply of wood？ A．Because wood was safer than coal. B．Because wood burned longer than coal. C．Because there was more wood than coal. D．Because they used wood as primary source energy.

  查看最佳答案

• Solar-generated electricity docs not carry the health or environmental risks of nuclear energy. We can never run out of solar energy, because the sun is a renewable energy source.

  Two kinds of systems generate solar energy: passive and active. A passive solar energy system generates energy from fixed glass plates built into the structure, without the use of mechanical devices. A greenhouse is a good example of a building heated by passive solar energy. The sun's rays penetrate the glass panels to heat the interior of the greenhouse, and the heat is retained through tight construction. The same principle can be applied to heating homes and other buildings on sunny days. An active solar energy system makes use of mechanical devices and moving parts to maximize the amount of energy collected. For example, solar energy can be generated with photovoltaic cells, which are made from silicon, an abundant element. A bank of photovoltaic cells can be encased in glass and wired together to produce electricity. The bank of cells can be mounted on the roof at an angle that maximizes exposure to direct sunlight. Another device to generate solar energy is a flatplate collector, which is an insulated glass box, typically placed on the sun-facing roof. Inside the box are pipes filled with air or water. The heat that builds up in the pipes can be used for home heating and hot-water supplies. Two questions persist about solar energy: How can solar energy be used in colder climates？ How can solar energy be used on cloudy days？ Scientists have the technological means to overcome both problems, but the solutions may make solar energy more expensive for many people than other alternatives. The energy released from the sun is about 10,000 degrees F, but by the time the rays reach the earth the temperature is considerably lower, because the sun's energy has diffused over a large area during its long journey. To be useful energy in colder climates, the sun's diffused rays must be concentrated. The process of concentrating the sun's rays is not difficult. Scouts learn that sunlight focused with a lens at the proper angle can burn a piece of paper. In warmer climates, the sun's rays can provide heat and hot water with little concentration. In colder climates, compensation is made simply by collecting more of the sun's rays by building a larger collecting device and rotating the lenses as the sun's position in the sky changes. In cloudy weather, another system can store the energy generated from the sun. For example, water heated by the sun can be retained in protected storage containers. Because of high installation coasts, solar energy is more expensive than other sources of energy for most consumers. At this time, electricity provided by a solar power plant costs two or three times the amount of a coal-fired plant. But solar equipment is generally installed on the consumer's roof rather than at a central power plant, as is the case with other energy sources. A family must pay several thousand dollars to construct a solar energy system capable of providing virtually all household heat and electricity. The family is also responsible for maintenance and repair of the system. While initial construction costs are much higher, monthly heating and electricity bills are much lower once the system begins operation. Users of solar energy do not face rising monthly electricity bills from a power company, which passes to its consumers the increasing costs of purchasing fossil fuels and constructing new facilities. Solar energy is economical for consumers who remain in the same house for many years and can benefit from low monthly operating costs. For most families, solar energy will become more attractive when other energy sources become more expensive. One indication of solar energy's bright future is that petroleum companies have bought the m A．The technical problem of providing heat on cloudy days are not yet solved. B．It costs much to have a solar energy system installed at home. C．There are basically two types of solar energy. D．Solar energy is clean, inexhaustible and free of risk.

  查看最佳答案

• Renewable energy sources can be replenished in a short period of time. The five renewable sources used most often include hydropower (water), solar, wind, geothermal, and biomass. Renewable energy's impact on the world's energy picture is significant. Many important events have occurred during the history of using renewable sources to generate electricity--but the overall consumption from renewable energy sources has declined by about 15 percent from their I996 peak to about 6 quads in 2005.

  The use of renewable energy is not new. Five generations (125 years) ago, wood supplied up to 90 percent of our energy needs. Due to the convenience and low prices of fossil fuels, wood use has fallen. Now, the biomass which would normally present a disposal problem is converted into electricity (e.g., manufacturing wastes, rice hulls, and black liquor from paper production). Historically, low fossil fuel prices, especially for natural gas, have made growth difficult for renewable fuels. The deregulation and restructuring of the electric power industry could have a major impact on renewable energy consumption. Demands for cheaper power in the short term would likely decrease demand for renewable energy, while preferences for renewables included in some versions of proposed electricity restructuring legislation would breathe new life into this industry. Use of renewables in the United States is not currently expected to approach that of the major fuels, and due to their limitatious (e.g., their intermittent nature-cloudy days have no solar gain, quiet days mean no wind blows to drive wind turbines, dams are primarily for flood control, so hydroelectricity production varies as dams' water levels change), renewables may never provide "the" answer to all energy problems. Around the world, renewable energy is proving to be of great value. In 2005, about 6.1 Quadrillion Btu (Quads) of U.S. energy came from renewable fuels. Each of the energy sources we use is measured, purchased, and sold in a different form. Many units of measurement are used to measure the energy we use each day. From 1996 to 2005, the trend of the consumption from renewable energy was ______. A．increasing B．decreasing C．irregular D．not mentioned

  查看最佳答案

• There are different ways in which people try to deal with the problem of energy. One way is the greater production of common energy sources, such as coal, oil and gas. The trouble with these sources, however, is that they are not renewable.

  Another way is energy conservation (节能 ), which means using energy more efficiently (有效地 ). In some very cold countries people build special houses to save energy. They place materials between the inside and the outside of the walls of the house to keep the cold out and the warmth in. The house is heated by the lights, the body heat of the people and the other equipment in it. Finally, renewable energy sources are used even though they are often expensive to develop. One form. of these is geothermal energy. In certain parts of the world the temperature of the earth increases thirty degrees centigrade with each kilometer down. At six kilometers, therefore, it rises to nearly two hundred degrees. To get the heat, water is pumped (压;抽 ) down into the rocks and back up to the surface. Heat from the earth is already used in certain countries. 1、How many ways of dealing with the energy problem are discussed in the text？ () A、Two. B、Three. C、Four. D、Five. 2、From the text we learn that coal(). A、is quite easy to produce B、is not used most efficiently C、is the most common source of energy D、could be renewed only by new technology 3、The writer tells about the "special houses" because they(). A、show the excellent skills of the builders B、serve as an example of energy conservation C、are heated by different sources of energy D、are warmer than other types of houses 4、The underlined words "geothermal energy" in the third paragraph mean (). A、renewable source B、 underground source C、 heat inside the earth D、 temperature of the earth 5、At a place where the surface temperature is 15°C, how deep do you have to dig so as to get a temperature of 75 °C ？ () A、One km. B、 Two km. C、 Three km. D、 Four km

  查看最佳答案

• 英语翻译 .,unlike alternative energy sources such as wind,solar,and geothermal power opponents of nuclear energy would like to be implemented. unlike前面是 Another point they raise is that nuclear energy is both readily available and reliable,unlike......

  查看最佳答案

• There are many problems in our modern world. One very()serious problem is energy. We get a great () of energy we need from coal, gas, and oil. However, the () of energy which we use is () every year, and we only have enough coal, gas, and oil for the next twenty or thirty years. How will we live () the energy which these things give us？ Scientists are looking for () to this problem. They are looking for new () to produce energy. For example, they are working with new ways to () energy from the light and heat of the sun. They are also working with plans which produce energy from () of the oceans. All of the new methods () scientists are finding are still very expensive, but perhaps they will help solve our energy problems () the future.

  1.A.number B.group C.price D.deal 2.A.effect B.amount C.course D.program 3.A.increase B.increasing C.had increased D.is increasing 4.A.without B.improve C.producing D.strength 5.A.key B.a direction C.a solution D.service 6.A.cost B.method C.branch D.pound 7.A.Show B.pay C.save D.produce 8.A.property B.remedy C.welfare D.movements 9.A.So that B.which C.whose D.Of which 10.A.at B.for C.In D.from

  查看最佳答案