热能与动力工程专业外语_热能与动力工程英语
热能与动力工程专业外语由刀豆文库小编整理，希望给你工作、学习、生活带来方便，猜你可能喜欢“热能与动力工程英语”。
For both situation shown in Fig.1.2,we expre the overall effect of convection,we use New-ton”s law of cooling: Q=Ha(Tw-T8横)
在图1.2所示的两种情况，我们对对流的整体效果，我们使用的冷却新吨级“定律为: Q=Ha(Tw-T8横)
Thermodynamic considerations show that an idea thermal radiator ,or blackbody ,will emit energy at a rate proportional to the fourth power of the absolute temperature of the body and directly proportional to its surface area.Thus q(emitted)=σAT4(1-6)
热力学规律揭示出一个理想的热辐射体或黑体，所散发出能量的速度与其自身的绝对温度的四次方和其表面积成正比。即（公式）
Where σ is the proportionality constant and is called the Stefan-Boltzmann constant with the value of 5.669*10-8 W/m2k4.Equation(1-6)is called the Stefan-Boltzmann law of thermal radiation, and it applies only to blackbodies.It is important to note that this equation is valid only for thermal radiation;other types of electromagnetic radiation may not be treated so simply.其中σ是比例常数，值为5.669*10-8 W/m2k4称为斯蒂凡玻尔兹曼常数。公式（1-6）被称为热辐射斯蒂凡玻尔兹曼定律，它仅适用于黑体。重要的是要注意这个公式只适用于热辐射;其他类型的电磁辐射可不能如此简单对待。
Combustion of gaseous fuels occurs by the laws of branched chain reactions which where discovered by Soviet Academician N.N.Semenov and C.N.Hinshelwood.The conversion of the original substances to the final products paes through a sequence of reaction links which are connected in succeion with one another and develop in the volume of a combustible mixture like the branches of a tree develop from its trunk.This results in the formation of the final reaction products and of even greater number of active centres which further ensure the development of the reaction in the confining volume.气体燃料燃烧时由苏联院士NNSemenov和CNHinshelwood发现支链反应法。通过反应与另一个连接在继承和发展的一个可燃混合气的体积，像一棵树的树枝从树干的链接序列的原始物质转化为最终产品。在最终的反应产物和更活跃的中心，进一步确保围体积的反应发展形成这样的结果。
Let us consider the mechanism of branched chain reactions,taking as an example the combustion of hydrogen in air.By the stoichiometric equation
让我们考虑支链反应的机制，作为一个例子，在空气中燃烧的氢。通过计量公式 2H2+O2=2H2O
The rate of reaction between molecules of the combustible substance的可燃物质的分子之间的反应率
(Wh2o=K0e….)
Cannot be very large.Actually ,however, combustion of hydrogen at temperatures above 500℃ is an explosive chain reaction proceeding at a very high rate.Indeed, according to N.N.Semenov, the beginning of the active reaction is preceded by the formation of active centres:
其实不能非常大。然而，在500℃以上温度，氢的燃烧是一个爆炸性的连锁率非常高的反应程序。事实上，根据NNSemenov的积极反应开始之前活性中心的形成：
(H2+M…)
(H2+O….)Where M and Q2 are active molecules which poe high energy levels in the volume
其中，M和Q2拥有量高的能量水平的积极分子
Atoms and radicals formed by this mechanism actively enterthe reactions which
surrounding molecules,i.e.chains of succeive reactions develop which result in the formation of the final reaction products and ever greater number of active centres.这一机制所形成的原子和自由基积极进入反应，周围的分子，即连续反应链的发展，从
而最终反应产物的形成和活动中心的数目越来越大的。Fig.1.17 schematically shows the combustion of a liquid fuel droplet in stagnant air.A
vapourcloud forms around the droplet and diffuses into the environment ,with the
diffusion of oxygen of the air occurring in opposite direction.As a result ,the stoichiometric relationship between the combustible gases and oxygen is established at a certain distance from the droplet , i.e.the burning fuel vapours form a spherical combustion front around it.The magnitude of rst is equal to 4-10 droplet radii, i.e.rst = 4-10 rd, and depends heavily on the droplet size and the temperature in the combustion zone.In the zone where vapours prevail, but their combustion zone.The highest temperature is established in the
reaction zone.Although at both sides of this zone the temperature decreases gradually, its
decrease is more intensive in the inside direction, i.e.on approaching the droplet ,since some
heat is spent there for heating fuel vapours.Fig.1.17示意图显示了一个停滞的空气中的液体燃料液滴燃烧。蒸气云周围形成液滴扩散
到环境中，在相反的方向发生空气中的氧气扩散。因此，之间的可燃气体和氧气的化学计
量关系是建立在一定的距离RST从液滴，即燃烧燃料蒸汽形成一个围绕它的球形的燃烧
前。RST幅度等于4-10液滴半径，即RST =4-10路，很大程度上取决于墨滴的大小和燃烧
区的温度。在R
虽然双方在此区域的温度逐渐降低，其跌幅更密集的方向在里面，即在接近液滴，因为有
一定的热量是用于取暖燃料蒸汽。
Thus, the burning rate of a liquid fuel droplet is determined by the rate of evaporation
from its surface, the rate of chemical reaction in the combustion zone.And the rate of oxygen
diffusion to this zone.As stated earlier, the reaction rate in a gaseous medium is very high
and cannot limit the total rate of combustion.The quantity of oxygen diffused through the
spherical surface is proportional to the square of sphere diameter, and therefore, a slight
removal of the combustion zone from the surface of the droplet(under oxygen deficiency)
noticeably increases the ma flow rate of supplied oxygen.Thus, the rate of combustion of
the droplet is mainly determined by evaporation from its surface.The combustion rate of
liquid fuels is increased by atomizing the fuel just before burning, which substantially
increase the total surface of evaporation.Besides all this, as the size of the droplets decreases,the intensity of evaporation per unit area of their surface increases.Fine liquid fuel droplets
suspended in an air flow move at low Reynolds numbers, Re
through a spherical surface is determined solely by the conductivity 入 through the
boundary layer, which is much thicker than the droplet diameter.Under such conditions, the
heat-transfer co-efficient a is given by Sokolsky’s formula:Nu = ad/入=2whence a = 2入/d = 入/rWhere Nu is the Nuelt number.因此，一个液体燃料液滴的燃烧率是由从它的表面，在燃烧区域的化学反应速率的蒸发率。率氧气扩散到该区域。如前所述，在气体介质中的反应速度是非常高的，可以没有限制的燃烧率。通过球面扩散的氧气量是球体直径的平方成正比，因此，一个轻微去除表面的液滴（缺氧）从燃烧区明显增加提供氧气的质量流量。因此，液滴的燃烧率主要取决于其表面的蒸发。液体燃料的燃烧率增加了雾化的燃料，只是在刻录之前，这大大增加蒸发表面。除了这一切，为液滴的跌幅，其表面增加单位面积蒸发强度大小。精细液体燃料液滴，悬浮在空气流移动低雷诺数RE
As follows from formula(1-13), the heat exchange between a droplet and the surrounding medium increases as the size of the droplet decreases, i.e.with a decrease in its ma.It turns out that the evaporation time of the droplet decreases, i.e.with a decrease in its ma.It turns out that the evaporation time of a droplet is proportional to the square of its initial diameter.按以下公式（1-13），液滴和液滴的大小减小周围介质之间的热交换，即减少其质量。事实证明，液滴降低蒸发时间，即减少其质量。事实证明，液滴的蒸发时间是其初始直径的平方成正比。
When combined with air in a furnace, pulverized coal first paes through the stage of thermal preparation(Fig.1.18), which consists in the evaporation of residual moisture and separation of volatiles.Fuel particles are heated up to a temperature at which volatiles are evolves are evolves intensively(400-600C)in a few tenths of a second.The volatiles are then ignited, so that the temperature around a coke particle increases rapidly and its heating is accelerated(III”).The intensive burning of the volatiles(II)takes up 0.2-0.5s.A high yield of volatiles(brown coal, younger coals, oil shales , peat), produces enough heat through combustion to ignite coke particles.When the yield of volatiles is low, the coke particles must be heated additionally form an external source(III”).The final stage is the combustion of coke particles at a temperature above 800-1000C(4).This is a heterogeneous proce whose rate is determined by the oxygen supply to the reacting surface.The burning of a coke particle proper takes up the greater portion(1/2 to 2/3)of the total time of combustion which may constitute 1 to 2.5s , depending on the kind of fuel and the initial size of particles.当于一炉的空气相结合，煤粉首先通过热的准备阶段（图1.18），包括残留水分的蒸发和挥发物的分离。燃料颗粒被加热到温度下挥发物的发展是集中发展的第二个零点几秒（400-600C）。然后点燃的挥发，使焦炭颗粒周围的温度迅速上升，并加速其加热
（三）。密集的挥发物燃烧
（二）占用0.2-0.5s的。一个高产挥发物（褐煤，年轻的煤，油页岩，泥炭），产生足够的热量通过燃烧焦炭颗粒点燃。当挥发物的产量低，焦炭颗粒必须加热此外形成外部源
（三）“。最后一个阶段是焦炭颗粒的燃烧温度在800-1000C（4）以上，这是一种异质性的过程，其速率是反应表面的氧气供应决定。焦炭颗粒适当的燃烧占据了较大部分的总燃烧时间可能构成1至2.5S（1 / 2至2 / 3），燃料种类和粒子的初始大小而定。
Capacitive or inductance电容或电感
The movement aociated with one of the mechanical sensors already described can be used to influence an electrical property such as capacitance affecting a measured signal.Forexample ,under changing preure a diaphragm causes a change in capacitance or inductance.与前面介绍的机械传感器之一相关的运动可以用来影响，如影响测量信号的电容的电气性能。例如，在不断变化的压力隔膜导致电容或电感的变化。
Resistive, strain gauge电阻，应变计
The electrical resistance of a metal wire depends on the strain applied to the wire.Deflection of the diaphragm due to the applied preure cause strain in the wire, and the electrical resistance can be measured and related to preure.金属丝的电阻取决于应用的隔膜由于所施加的压力线的原因应变线。偏转应变，电阻可以测量和压力有关。
Piezoelectric压电
A piezoelectric material, such as quartz, generates a voltage output when preure is applied on it.Force can be applied by the diaphragm to a quartz crystal disk that is deflected by proce preure.压电材料，如石英，它适用于当压力产生的电压输出。队可应用于隔膜过程压力偏转石英晶体的磁盘.Thermocouple Theory热电偶理论
A thermocouple circuit has at least two junctions: the measurement junction and a reference junction.Typically, the reference junction is created where the two wires connect to the measure device.This second junction it is really two junctions: one for each of the two wires, but because they are aumed to be at the same temperature(isothermal)they are considered as one(thermal)junction.It is the point where the metals change-from the thermocouple metals to what ever metals are used in the measuring device-typically copper.热电偶电路至少有两个路口：它们是测量交界处和参考结。通常情况下，我们把连接到测量设备的两条线定义为参考的交界处。这第二个路口，它才是真正的两路口：为每个两条线之一，但因为他们都被假定为在相同的温度（温），他们被认为是（热）交界处。它是金属的变化，从热电偶金属什么都在测量设备通常是铜使用的金属。
The output voltage is related to the temperature difference between the measurement and the reference junctions.This is phenomena is known as the Seebeck effect.The Seebeck effect generates a small voltage along the length of a wire ,and is greatest where the temperature gradient is greatest.If the circuit is of identical material, then they will generate identical but opposite Seebeck voltages which will cancel.However, if the wire metals are different the Seebeck voltages will be different and will not cancel.输出电压是关系到测量和参考路口之间的温差。这是现象称为塞贝克效应。塞贝克效应产生一个小的电压，沿线的长度和最大温度梯度最大。如果电路是相同的材料，那么他们就会产生相同，但方向相反的塞贝克电压，将取消。但是，如果是不同的金属丝塞贝克电压将有所不同，并不会取消。
In practice the Seebeck voltage is made up of two components: the Peltier voltage generated at the junctions, plus the Thomson voltage generated in the wires by the temperature gradient, as shown in Fig.1.22.在实践中，Seebeck电压由两部分组成：在交界处产生的电压的佩尔蒂埃，加上汤姆森电压导线所产生的温度梯度，在Fig.1.22所示。
The Peltier voltage is proportional to the temperature of each junction while the Thomson voltage is proportional to the square of the temperature difference between the two junctions.It is the Thomson voltage that accounts for most of the observed voltage and non-linearity in
thermocouple response.佩尔蒂埃电压是每个交界处的温度成正比，而汤姆森电压的两路口之间的温度差的平方成正比。这是汤姆逊电压占大部分观测到的电压和热电偶响应非线性。
Each thermocouple type has its characteristic Seebeck voltage curve.The curve is dependent on the metals, their purity ,their distribution in the wire is also important.These potential inhomogeneous characteristics of metal are why thick wire thermocouples can be more accurate in high temperature applications, when the thermocouple metals and their impurities become more mobile by diffusion.每个热电偶类型有其特有的Seebeck电压曲线。曲线上的金属，其纯度，他们分布在电线也很重要。这些潜在的金属不均匀的特点是为什么粗丝热电偶，可以更准确地在高温应用中，当热电偶金属及其杂质的扩散变得更加移动。
Pitot tube and annubar皮托管和阿牛巴:
The pitot tube, shown in Fig.1.26 below, measures the static and dynamic preures of the fluid at one point in the pipe.The flow rate can be determined from the difference between the static and dynamic preures which is the velocity head of the fluid flow.An annubar consists of several pitot tubes placed acro a pipe to provide an approximation to the velocity profile, and the total flow can be determined based on the multiple measurements.Both the potit tube and annubar contribute very small preure drops, but they are not physically strong and should be used only with clean fluids.Fig.1.26下面所示，皮托管，流体在一个管道中的点的静态和动态压力措施。流速可确定这是流体流动的速度头的静态和动态压力之间的差异。由阿牛巴放在整个管道提供了一个近似的速度剖面的几个皮托管，并可以多次测量的基础上确定的总流量。potit管和阿牛巴的贡献非常小的压力下降，但它们不是身体强壮，只应使用清洁的流体
The following flow sensors are based on physical principles other than head.头比其他物理原理是基于以下的流量传感器。
Turbine涡轮: As fluid flows through the turbine, it causes the turbine to rotate with an angular velocity that is proportional to the fluid flow rate.The frequency of rotation can be measured and used to determine flow.This sensor should not be used for slurries or systems experiencing large, rapid flow or preure variation.作为通过涡轮的流体流动，它会导致涡轮的旋转角速度，流体流速成正比。可旋转的频率测量和用于确定流。该传感器不应该用于泥浆或遇到大的，快速的流量或压力变化的系统。
Controlled Variable and Manipulated Variable.The controlled variable is the quantity or condition that is measured and controlled.The manipulated variable is the quantity or condition that is varied by the controller so as to affect the value of the controlled variable.Normally ,the controlled variable is the output of the system.Control means measuring the value of the controlled variable of the system and applying the manipulated variable to the system to correct or limit deviation of the measured value from a desired value.控制变量和操纵变量。控制变量是测量和控制的数量或条件。操纵变量的数量或条件变化，从而影响控制变量的值是由控制器。通常情况下，控制变量是系统的输出。控制意味着测量系统的控制变量的值和调节变量的应用系统所需的值的测量值的偏差纠正或限制。
In studying control engineering, we need to define additional terms that are neceary to describe control systems.在研究控制工程，我们需要定义来描述控制系统所必需的附加条款。
Open loop control systems.Those systems in which the output has no effect on the control action are called open loop control systems.In other words, in an open loop control system the control system the output is neither measured nor fed back for comparison with the input, One practical example is a washing machine, Soaking, and rinsing in the washer operate on a time basis.The machine does not measure the output signal, that is, the cleanline of the clothes.开环控制系统，输出对控制行为没有影响的系统被称为控制系统。话句话说，在开环系统中与输出相比控制系统既不衡量也不反馈.一个实际的例子是一个洗衣机、浸泡,并冲洗洗衣机里运作一个时间的基础上。这台机器不检测输出信号,那就是,洁净的衣服。
In any open loop control system the output is not compared with the reference input.Thus, to each reference input there corresponds a fixed operating condition, as a result, the accuracy of the system depends on calibration, In the presence of disturbances, an open loop control system will not perform the desired task, Open loop control can be used, in practice, only in the relationship between the input and output is known and if there are neither internal nor external disturbances.Clearly, such systems are not feed back control systems.Note that any control system that operates on a time basis is open loop.For instance, traffic control by means of signals operated on a time basis is another example of open-loop control.在任何开环控制系统的输出与参考输入是不能相比。因此，每个参考输入对应一个固定的经营状况，因此，该系统的准确性取决于校准干扰的存在，一个开环控制系统将不执行所需的任务，可用于开环控制在实践中，只有在输入和输出之间的关系是已知的和如果有既不是内部还是外部干扰。显然，这样的系统不反馈控制系统。请注意，任何时间的基础上运作的控制系统是开环。例如，交通控制时间的基础上运作的信号是开环控制的另一个例子。
第八章 空调与制冷8.1 空调空调是一个可以同时进行多种处理的组合过程。它可以处理空气、输送空气并把空气送入被调空间中。空调可以从中央设备或屋顶单元提供热与冷。为了......
2.2 Development of Utility Boiler现代660MW燃煤锅炉有大约6000吨的压力部件，包括500千米的受热面管材，3.5千米连接管与联箱和30000个管接头焊口。这是经过大约50年发展的结......
一直希望自己能够从事一种富有挑战性的事业，去实现自己的人生价值。为了实现它，我从小就养成了勤奋好学的习惯。从小学到初、高中几乎年年获奖。97年我以优异的成绩考入吉林工......
对热能与动力工程学科的认识一、对本专业的培养目标的认识本专业主要培养从事汽车动力工程、制冷与低温技术、暖通空调，能源与环境工程、电厂热能动力、燃气工程、流体机械等......
热能与动力工程专业热能与动力工程专业业务培养目标：业务培养目标：本专业培养具备热能工程、传热学、流体力学、动力机械、动力工程等方面基础知识，能在国民经济各部门，从事动力......
