首页
登录
职称英语
Fire can be thought of as any combustion process intense enough to emit light
Fire can be thought of as any combustion process intense enough to emit light
游客
2024-06-10
13
管理
问题
Fire can be thought of as any combustion process intense enough to emit light. It may be a quietly burning flame or the brilliant flash of an explosion.
A typical combustion process is the burning of gasoline in an automobile engine. The vaporized fuel is mixed with air, compressed in the engine’s cylinder, and ignited by a spark. As the fuel flames up, the heat produced flows into the adjacent layer of unburned fuel and ignites it. In this way a zone of first spreads throughout the fuel mixture until the combustion wave.
The speed at which such a combustion wave travels through a fuel mixture is called the burning velocity of the mixture. The burning velocity of a gas such as methane quietly burning in air is only about one foot per second. By comparison, the burning velocity of more reactive combinations such as the rocket fuels, hydrogen and fluorine, can be hundreds of feet per second.
If the fuel flows at the same speed as the combustion wave, the result is a stationary flame, like the one in your kitchen gas burner. In the kitchen burner a jet of gas mixed with airflows from the openings in the head of the burner. If the velocity of the fuel mixture flowing from the opening is greater than its burning velocity, the flame blows out.
In jet engines speeding through the air at 500 to 600 miles per hour, the engine’s flame is sometimes blown out by the blast of air entering the combustion chamber at high speeds. Jet pilots call this condition "flameout."
Combustion can sometimes occur very slowly. A familiar example of slow combustion is the drying of ordinary oil based paint. In this chemical reaction, called oxidation, the oxygen in the air reacts with the drying oil in the paint to provide a tough film. The linseed oil molecules link together, forming an insoluble coating. Another example is the hardening, and cracking of rubber with age. One way to avoid this is to incorporate certain chemicals called inhibitors into the compound.
How can the chemical reaction involved in such a quiet process as the drying of paint also produce spectacular flames and explosions? The main difference between the two is the temperature at which they occur.
At lower temperatures the reaction must take place over a long time. The heat, which is slowly produced, is dissipated to the surroundings and does not speed up the reaction. When the heat produced ’by the low temperature reaction is retained instead of being dissipated, the system breaks into flame. This is the process that accounts for a major fire hazard, spontaneous combustion, as when oily rags suddenly burst into flame.
In a flame or explosion, the reactions are extremely fast. In many chemical processes, however, such a rapid oxidation process would be extremely destructive. [br] All the following could be defined as combustion EXCEPT ______.
选项
A、a quietly burning flame
B、an explosion
C、a radiator giving off heat
D、the drying of oil based paint
答案
C
解析
细节定位题。从第1段中得知,不论是静静的燃烧还是非常耀眼的爆炸都属于燃烧。这里包括选项A和B。而从第6段第2句得知,缓慢燃烧的一个典型例子就是普通油漆涂料的干燥,这里提到了选项D,唯有c没有被提到,故C正确。
转载请注明原文地址:https://tihaiku.com/zcyy/3627263.html
相关试题推荐
【S1】[br]【S10】many∧the→as根据上一行中的is及本行中的by可确定thought正确;breadwinner意为“挣钱养家的人”;be
Thefatherthought______(他可以说服女儿改变决定).hecouldtalkhisdaughterintochanging
【B1】[br]【B16】A、demonstrationB、processionC、bodyD、marchD本题考查考生对名词的辨析。据上下文“…a
【S1】[br]【S5】A、intensiveB、absorbedC、intenseD、concentratedC词义辨析题。intense意为“强
【S1】[br]【S7】在popular后加enough“形容词+enough+动词不定式”的固定结构常用于表示“……得足够……”,结合句意可知,应在pop
【S1】[br]【S7】popular∧→enough“形容词+enough+动词不定式”的固定结构常用于表示“……得足够……”,结合句意可知,应在popu
【S1】[br]【S9】as—if/thoughthefactthat...outsidethehome是我们在日常生活中曾经提到过的,为过去时态,
【S1】[br]【S11】A、thoughtB、relatedC、interpretedD、translatedC动词词义辨析以及固定搭配。这句话的
Culturalnormssocompletelysurroundpeople,sopermeatethoughtandaction,
Languageisthemeansbywhichthethoughtsandfeelingsofonepersonareca
随机试题
Whatisthepassagemainlyabout?[br]Whichofthefollowingisnotmentioneda
______wasthoughttobeimpossibleinthepasthasnowbecomeareality.A、WhatB
全波整流、滤波电路如图所示,如果输入信号ui=sin(ωt+30°)V,则开关
A. B. C. D.
某教育机构招聘讲师,有5位评委打分,平均分需要达到85分才能正式通过。小王应聘时
公司经理对( )负责。A.董事会 B.股东大会 C.监事会 D.职代会
若1年期即期利率4%,市场预测未来的1年期预期利率均等于其前期的利率加上1%,则
在开标时,被判定为无效投标文件的有() A.投标文件未按照招标文件的要求予以
在选择电力变压器时,下列哪些电压等级的变压器,应按超高压变压器油标准选用?()
背景: 某房屋建筑工程,建筑面积26800m2,地下二层,地上七层,钢筋混凝土
最新回复
(
0
)