第二组The only attention that heat exchanger should require is to ensure that the heat transfer surfaces remain substantially clean and the flow passages generally clear of obstruction. Indication that undue fouling is occurring is given by a progressive inc

题目

第二组

The only attention that heat exchanger should require is to ensure that the heat transfer surfaces remain substantially clean and the flow passages generally clear of obstruction. Indication that undue fouling is occurring is given by a progressive increase in the temperature difference between the two fluids, over a period of time, usually accompanied by a noticeable rise in pressure loss at a given flow.

Fouling on the sea-water side is the most usual cause of deterioration in performance. The method of cleaning the sea water-side surfaces depends on the type of heat exchanger. With shell-and-tube heat exchangers, the removal of the header covers or, m the case of the smaller heat exchangers, the headers themselves, will provide access to the tubes. Obstructions, dirt, scale etc., can then be removed, using the tools provided by the heat exchanger manufacturer. Flushing through with fresh water is recommended before a heat exchanger is returned to service. In some applications, such as piston oil cooling, progressive fouling may take place on the outside of the tubes. Most manufactures recommend a chemical flushing pr6cess to remove this in situ~ without dismantling the heat exchanger.

Plate heat exchangers may be cleaned by unclamping the stack of plates and mechanically cleaning the surface of each plate as recommended by the manufacturers. The plate seals may require replacement from time to time and here the manufacturers&39; instructions should be closely followed

By which of the following indication, can we conclude that the lube oil-sea water heat exchanger is unduly fouled?

A.the heat exchanger lube oil inlet temperature lowering

B.the heat exchanger sea-water outlet pressure rise

C.the heat exchanger temperature difference between lube oil and sea water increasing

D.the heat exchanger pressure difference between sea water inlet and outlet decreasing

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3.Space is a dangerous place,not only because of meteors but also because of rays from the sun?and other stars.The atmosphere again acts as our protective blanket on earth.Light gets through,and?this is essential for plants to make the food which we eat.Heat,too,makes our environment endurable.Various kinds of rays come through the air from outer space,but enormous quantities of radiation from the sun are screened off.As soon as men leave the atmosphere they are exposed to this radiation.But their spacesuits or the walls of their spacecraft,if they are inside,do prevent a lot of radiation damage. Radiation is the greatest known danger to explorers in space.The unit of radiation is called"rein".Scientists have reason to think that a man can put up with far more radiation than 0.1 rem?without being damaged;the figure of 60 rems has been agreed on.The trouble is that it is extremely?difficult to be sure about radiation damage—a person may feel perfectly well,but the cells of his or?her sex organs may be damaged,and this will not be discovered until the birth of deformed(畸形的)children or even grandchildren.Missions of the Apollo flights have had to cross belts of high radiation?and,during the outward and return journeys,the Apollo crew accumulated a large amount of rems.So?far,no dangerous amounts of radiation have been reported,but the Apollo missions have been quite?short.We simply do not know yet how men are going to get on when they spend weeks and months?outside the protection of the atmosphere,working in a space laboratory.Drugs might help to decrease?the damage done by radiation,but no really effective ones have been found so far.We know from the passage that__A.exposure to even tiny amounts of radiation is fatal B.the effect of exposure to radiation is slow in coming C.radiation is avoidable in space exploration D.astronauts in spacesuits needn't worry about radiation damage

4.单词pig和heat所包含的元音相同。()此题为判断题(对，错)。

更多“第二组 The only attention that heat exchanger should require is to ensure that the heat tr ”相关问题

  • 第1题：

    Space is a dangerous place,not only because of meteors but also because of rays from the sun?and other stars.The atmosphere again acts as our protective blanket on earth.Light gets through,and?this is essential for plants to make the food which we eat.Heat,too,makes our environment endurable.Various kinds of rays come through the air from outer space,but enormous quantities of radiation from the sun are screened off.As soon as men leave the atmosphere they are exposed to this radiation.But their spacesuits or the walls of their spacecraft,if they are inside,do prevent a lot of radiation damage.
    Radiation is the greatest known danger to explorers in space.The unit of radiation is called"rein".Scientists have reason to think that a man can put up with far more radiation than 0.1 rem?without being damaged;the figure of 60 rems has been agreed on.The trouble is that it is extremely?difficult to be sure about radiation damage—a person may feel perfectly well,but the cells of his or?her sex organs may be damaged,and this will not be discovered until the birth of deformed(畸形的)children or even grandchildren.Missions of the Apollo flights have had to cross belts of high radiation?and,during the outward and return journeys,the Apollo crew accumulated a large amount of rems.So?far,no dangerous amounts of radiation have been reported,but the Apollo missions have been quite?short.We simply do not know yet how men are going to get on when they spend weeks and months?outside the protection of the atmosphere,working in a space laboratory.Drugs might help to decrease?the damage done by radiation,but no really effective ones have been found so far.

    It can be inferred from the passage that__

    A.the Apollo mission was very successful
    B.protection from space radiation is no easy job
    C.astronauts will have deformed children or grandchildren
    D.radiation is not a threat to well-protected space explorers

    答案：B
    解析：
    【考情点拨】推理判断题。【应试指导】由最后一句“Drugs might…but no?really effective ones have been found So far．”可知，目前人类还没有找到有效的方法去避免辐射的危害，所以免受辐射危害并非易事，故选B。

  • 第2题：

    下列提供交通大数据的网站有（）。

    A．腾讯位置大数据（https://heat.qq.com）

    B．高德交通大数据（http://data.chongbuluo.com/）

    C．百度地图|人气（http://renqi.map.baidu.com/）

    D．淘宝（http://www.taobao.com）


    B. 腾讯位置大数据（https://heat.qq.com ）;C. 高德交通大数据（ https://data.chongbuluo.com/ ）;D. 百度地 图| 人气（ https://renqi.map.baidu.com/ ）

  • 第3题：

    利用Heat进行设计和定义编排极为方便，请你写出Heat的编排方式


    A

  • 第4题：

    以下每组单词划线的元音字母组合中，有一个与其他单词的元音字母组合读音不同，请把它找出来。

    A．beard

    B．deer

    C．area

    D．heat


    autumn;board

  • 第5题：

    以下哪一项表达最为准确？

    A.Both bombs produce the same three effects: heat, blast, and radiation. The first of which usually causes the most fatalities.#B.Both bombs produce the same three effects: heat, blast, and radiation, the first of them usually causes the most fatalities.#C.Both bombs produce the same three effects: heat, blast, and radiation, the first of which usually causes the most fatalities.#D.Both bombs produce the same three effects
    Both bombs produce the same three effects: heat, blast, and radiation , t he first of which usually causes the most fatalities.

  • 第6题：

    Heat有两个API组件，分别是


    Memo

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