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1、A thermodynamic system is a region in space or a quantity of matter bounded by a closed surface. The surroundings include everything external to the system, and the system is separated from the surroundings by the system boundaries. These boundaries can be movable or fixed, real or imaginary.一个热力学系统
2、是一个在空间或有事项的数量由一个封闭的表面范围热量Q与不同的温度，跨系统的边界传输能量总是向温度较低的机制。热是积极的，当能量被添加到系统中。功是指通过存在压差（任一种力）的系统边界传递能量的作用过程，总是指向低压，如果系统中产生的总效果能被简化为一个重物的提升，那么只有功通过了边界，当能量从系统中一出时，功是正的。A property of a system is any observable characteristic of the system. The state of a system is defined by listing its properties. The most c
3、ommon thermodynamic properties are temperature T, pressure p, and specific volume v or density . Additional thermodynamic properties include entropy, stored forms of energy, and enthalpy.Frequently, thermodynamic properties combine to form other properties. Enthalpy h, a result of combining properti
4、es, is defined as: h=u+pv where u is the internal energy per unit mass系统属性是系统的任何观察到的特征。系统状态的定义是通过列出其属性。最常见的热力学性质的温度T，压力P，和特定的体积V或密度。其他热力学性质包括熵，能量储存形式，和焓。通常情况下，热力学性质相结合，形成其他属性。焓H，一个属性相结合的结果，被定义为：H = U + PV其中u是每单位质量的内部能量Each property in a given state has only one definite value, and any property alway
5、s has the same value for a given state, regardless of how the substance arrived at that state.is a change in state that can be defined as any change in theproperties of a system. A process is described by specifying the initial and final equilibrium states, the path (if identifiable), and the intera
6、ctions that take place across system boundaries during the process.中的每一个给定的状态的属性只有一个定值，和任何财产总是有相同的值给定的状态，不管如何抵达该国的物质。一个进程是一个状态的改变，在系统属性的任何改变，可作为定义。一个过程是指定的初始和最终的平衡状态，路径（如果识别），并采取跨系统的边界，在这个过程中发生的相互作用。are identical. Therefore, at the conclusion of a cycle, all the properties have the same valueA pure
7、substance has a homogeneous and invariable chemical composition. It can exist in more than one phase, but the chemical composition is the same in all phases 一个周期进程的一个过程或一个系列，其中系统的初始和最终状态是相同的的。因此，在一个周期结束时，所有属性具有相同的价值，他们开始。纯物质均匀的和不变的化学成分。它可以存在于超过一个阶段，但在各个阶段的化学成分是一样的liquid. If the temperature of the li
8、quid is lower than the saturation temperature for the existing pressure, it is called either a subcooled liquid (the temperature is lower than the saturation temperature for the given pressure) or a compressed liquid (the pressure is 如果一种物质在饱和温度和压力的液体，它被称为饱和液体。如果液体的温度低于现有的压力的饱和温度，它被称为是过冷液体（温度低于给定压力的
9、饱和温度）或压缩液体（压力大于饱和为给定的温度压力）。exists as a vapor at saturation temperature and pressure, it is called a saturated vapor. When the vapor is at a temperature greater than the saturation temperature, it is a superheated vapor. Pressure and temperature of a superheated vapor are independent properties, beca
10、use the temperature can increase while pressure remains constant. Gases such as air at room temperature and pressure are highly 如果一种物质在饱和温度和压力的蒸气存在，它被称为饱和蒸气。当蒸汽温度大于饱和温度，它是一个热蒸气。过热蒸汽压力和温度是独立的属性，因为温度增加，而压力保持不变。如在常温常压下空气的气体是高度过热蒸汽。 and the irreversibility associated with the process. The concept of irr
11、eversibility provides added insight into the operation of cycles.热力学第二定律的区别和量化，只有在某一个方向，是可逆的（不可逆）进行的过程。第二定律可能在几个方面。一种方法是使用在一个开放的系统，并与进程关联的不可逆性的熵流的概念。不可逆转的概念到周期的运作提供额外的洞察力。The Carnot cycle, which is completely reversible, is a perfect model for a refrigeration cycle operating between two fixed temper
12、atures, or between two fluids at different temperatures and each with infinite heat capacity. Reversible cycles have two important properties: (1) no refrigerating cycle may have a coefficient of performance higher than that for a reversible cycle operated between the same temperature limits, and (2
13、) all reversible cycles, when operated between the same temperature limits, have the same coefficient of performance 卡诺循环，这是完全可逆的，是一个完美的模型之间的两个固定的温度，或在不同温度和热容量无限每个的两种流体之间的制冷循环的运行。可逆循环有两个重要的属性：（1）无制冷循环的性能系数之间相同的温度限制经营的可逆循环高于，（2）之间相同的温度极限运行时，所有可逆循环，同样的性能系数Flowing fluids in heating, ventilating, air-co
14、nditioning, and refrigeration systems can transfer heat, mass, and momentum. This chapter introduces the basics of fluid mechanics related to HVAC processes, reviews pertinent flow processes, and presents a general discussion of single-phase fluid flow analysis.流动的液体在加热，通风，空调和制冷系统，可以传递热量，质量和动量。本章介绍有
15、关暖通空调过程的流体力学，评论相关的流程，基础知识，并提出了一种单相流体流动分析的一般性讨论。Fluids differ from solids in their reaction to shearing. When placed under shear stress, a solid deforms only a finite amount, whereas a fluid deforms continuously for as long as the shear is applied. Both liquids and gases are fluids. Although liquids
16、and gases differ strongly in the nature of molecular actions, their primary mechanical differences are in the degree of compressibility and liquid formation of a free surface. In general, liquids are considered incompressible fluids; gases may range from compressible to nearly incompressible.流体与固体区别
17、在于他们对剪切力的反应作用。在施加剪切力时，固体只发生有限的变形，而只要有剪切力的作用流体就会连续变形。流体不同于固体剪切他们的反应。当剪切应力下了坚实的变形量只有有限的，而流体的剪切变形。液体和气体都是流体。虽然液体和气体的分子运动特性有着很大的区别，但是他们的主要的力学区别在于可压缩性的程度和液体自由表面（界面）的形成。在一般来说，液体被认为是不可压缩的流体，气体可能范围从可压缩到几乎不可。Viscosity is a measure of a fluids resistance to shear. Viscous effects are taken into account by cat
18、egorizing a fluid as either Newtonian or non-Newtonian. In Newtonian fluids, the rate of deformation is directly proportional to the shearing stress; most fluids in the HVAC industry (e.g., water, air, most refrigerants) can be treated as Newtonian. In non-Newtonian fluids, the relationship between
19、the rate of deformation and shear stress is more complicated.粘度是流体的抗剪切的措施。考虑采取分类流体为牛顿或非牛顿粘性的影响。在牛顿流体，变形率是成正比的剪应力;在暖通空调行业（如，水，空气，大部分制冷剂）牛顿流体可以作为治疗。在非牛顿流体，变形和剪切应力率之间的关系更为复杂。Heat is energy in transit due to a temperature difference. The thermal energy is transferred from one region to another by three
20、modes of heat transfer: conduction, convection, and radiation. Heat transfer is among a group of energy transport phenomena that includes mass transfer, momentum transfer or fluid friction and electrical conduction.热是由于温差在传输过程中的能量。热能是从一个地区转移到另一个传热的三种模式：传导，对流和辐射。传热之间的能源运输的现象，其中包括传质，动量传递或流体摩擦和导电。Therm
21、al conduction is the mechanism of heat transfer whereby energy is transported between parts of continuum by the transfer of kinetic energy between particles or groups of particles at the atomic level. In gases, conduction is caused by elastic collision of molecules; in liquids and electrically nonco
22、nducting solids, it is believed to be caused by longitudinal oscillations of the lattice structure. Thermal conduction in metals occurs, like electrical conduction, through the motion of free electrons. Thermal energy transfer occurs in the direction of decreasing temperature. In solid opaque bodies
23、, thermal conduction is the significant heat transfer mechanism because no net material flows in the process and radiation is not a factor.热传导传热，使能量是连续部分之间的运输粒子在原子水平上的颗粒或团体之间的动能转移的机制。气体中，分子的弹性碰撞引起的传导;电导电液体和固体，它被认为是造成晶格结构的纵向振荡。金属的热传导时，如导电，通过自由电子的运动。热能量转移发生在温度降低的方向。在坚实的不透明机构，热传导是显著的传热机制，因为没有净物资流动的过程中，
24、辐射是不是一个因素。When fluid currents are produced by external sources (for example, a blower or pump), the solid-to-fluid heat transfer is termed forced convection. If the fluid flow is generated internally by nonhomogeneous densities caused by temperature variation, the heat transfer is termed natural con
25、vection or free convection.When fluid currents are produced by external sources (for example, a blower or pump), the solid-to-fluid heat transfer is termed forced convection. If the fluid flow is generated internally by nonhomogeneous densities caused by temperature variation, the heat transfer is t
26、ermed natural convection or free convection.当流体的电流是由外部来源（例如，一个鼓风机或泵），固 - 液传热被称为强迫对流。如果是内部所产生的温度变化所造成的非均质密度的流体流动，传热称为自然对流或自然对流。当流体的电流是由外部来源（例如，一个鼓风机或泵），固 - 液传热被称为强迫对流。如果是内部所产生的温度变化所造成的非均质密度的流体流动，传热称为自然对流或自然对流。Equation 1 states that the heat flow rate q in the x direction is directly proportional to t
27、he temperature gradient dt/dx and the cross-sectional area A normal to the heat flow. The proportionality factor is the thermal conductivity k. The minus sign indicates that heat flow is positive the direction of decreasing temperature. Conductivity values are sometimes given in other units，but cons
28、istent units must be used in Equation 1 .Equation 1 states that the heat flow rate q in the x direction is directly proportional to the temperature gradient dt/dx and the cross-sectional area A normal to the heat flow. The proportionality factor is the thermal conductivity k. The minus sign indicate
29、s that heat flow is positive the direction of decreasing temperature. Conductivity values are sometimes given in other units，but consistent units must be used in Equation 1 .公式（1）在x方向的热流率q是成正比的温度梯度DT/ DX和横截面积一个正常的热流。比例系数，导热系数K。减号表示热流温度降低的方向积极。电导率值有时在其他单位，但一致的单位，必须在使用公式1。公式（1）在x方向的热流率q是成正比的温度梯度DT/ DX
30、和横截面积一个正常的热流。比例系数，导热系数K。减号表示热流温度降低的方向积极。电导率值有时在其他单位，但一致的单位，必须在使用公式1。Basic Parametersn Humidity ratio W (alternatively, the moisture content or mixing ratio) of a given moist air sample is defined as the ratio of the mass of water vapor to the mass of dry air in the sample: W = Mw/Mda (7)The humidity
31、 ratio W is equal to the mole fraction ratio xw/xda multiplied by the ratio of molecular masses:W = 0.621 98 xw /xda (8)n Specific humidity is the ratio of the mass of water vapor to total mass of the moist air sample: = Mw/(Mw + Mda) (9a)基本参数湿度比W（另外，水分含量或比例混合），一个给定的潮湿空气样品是干燥的空气质量比样品中的水蒸汽的质量定义为：W =
32、MW/ MDA（7）湿度比W是相等的摩尔分数比XW/ XDA分子群众的比例乘以：W =0.62198 XW/ XDA（8）具体的湿度潮湿的空气样本的总质量之比是水汽质量：= MW /（MW + MDA）（9A）In terms of the humidity ratio, = W/(1 + W) (9b)n Absolute humidity (alternatively, water vapor density) dv is the ratio of the mass of water vapor to total volume of the sample:dv = Mw/V (10)n D
33、ensity of a moist air mixture is the ratio of total mass to total volume: = (Mda + Mw )/V = (1/v)(1 + W) (11)where v is the moist air specific volume, m3/kgda, as defined by Equation (27). 湿度比例方面，= W /（1+ W）（9B）绝对湿度（另外，水蒸气密度）DV的水蒸气的质量样品总量的比例： DV = MW/ V（10）潮湿的空气混合物的密度总量的比例是总质量：=（MDA+ MW）/ V =（1 / V）
34、（1+ W）（11）其中V是潮湿的空气中特定卷，m3/kgda，由方程（27）定义。Thermodynamic wet-bulb temperature t* is the temperature at which water (liquid or solid), by evaporating into moist air at a given dry-bulb temperature t and humidity ratio W, can bring air to saturation adiabatically at the same temperature t* while the to
35、tal pressure p is maintained constant. This parameter is considered separately in the section on Thermodynamic Wet-Bulb and Dew-Point Temperature.热力学湿球温度T *是在水（液体或固体），潮湿的空气中蒸发，在一个给定的干球温度t和湿度比W的温度，可以使空气饱和绝热在同一温度T*而总压力p保持不变。此参数是在热力学湿球和露点温度的部分分开考虑。A principal purpose of heating, ventilating, and air-co
36、nditioning systems is to provideconditions for human thermal comfort. A widely accepted definition is, “Thermal Comfort is that condition of mind that expresses satisfaction with the thermal environment”. This definition leaves open what is meant by condition of mind or satisfaction, but it correctl
37、y emphasizes that the judgment of comfort is a cognitive process involving many inputs influenced by physical, physiological, psychological, and other processes.供暖，通风和空调系统的一个主要目的是提供人体热舒适的条件。一个被广泛接受的的定义是，“热舒适性，心理状况，与热环境表示满意”。这个定义叶开放的心态或满意的状况是什么意思，但它正确地强调，舒适的判断是一个认知的过程，涉及物理，生理，心理，和其他进程影响了许多投入。The cons
38、cious mind appears to reach conclusions about thermal comfort and discomfort from direct temperature and moisture sensations from the skin, deep body temperatures, and the efforts necessary to regulate body temperatures. In general, comfort occurs when body temperatures are held within narrow ranges
39、, skin moisture is low, and the physiological effort of regulation is minimized.意识的头脑似乎达到热舒适性和不适的结论，直接从皮肤，深部体温，以及必要的努力来调节体温的温度和水分的感觉。在一般情况下，舒适性发生时体温都在窄幅内举行，皮肤水分低，调节生理努力最小化。Air contaminants are generally either particles or gases. The distinction between particles and gases is important when determin
40、ing removal strategies and equipment. Although the motion of particles is described using the same equations used to describe gas movement, even the smallest of particles (approximately 1 nm) are much larger than individual gas molecules, have a much greater mass, and a much lower diffusion rate.空气污
41、染物一般是颗粒或气体。确定搬迁战略和设备时，粒子和气体之间的区别是重要的的。尽管粒子的运动是用相同的方程用来描述气体运动，甚至最小的粒子（约1纳米），远远高于单个气体分子较大，有更大的质量，扩散速率低得多。 。The particulate class covers a vast range of particle sizes, from dust large enough to be visible to the eye to submicroscopic particles that elude most filters. Particles may be liquid, solid, o
42、r have a solid core surrounded by liquid. They are present in the atmosphere at颗粒类，涵盖了从粉尘颗粒大小广阔的范围，足够大的眼睛躲避大多数过滤器的微观粒子，可见。粒子可能是液体，固体或液体包围了坚实的核心。他们中的浓度每立方厘米在受污染的城市环境的范围在清洁的环境中从100 particles/cm3百万的气氛。Also a central cooling and heating plant provides higher diversity and generally operates more efficie
43、ntly with lower maintenance and labor costs than a decentralized plant. However it does require space at a central location and a potentially large distribution system.This lesson address the design alternatives that should be considered when centralizing the cooling and heating sources in a facilit
44、y.此外，中央制冷和供热厂提供更高的多样性和一般的运作，更有效地与降低维护和劳动力成本比分散的工厂。然而，它需要在一个中央位置的空间和一个潜在的大分配制度。这节课的地址设计时应该考虑的替代品集中在设施的冷却和加热源。 Many electric utilities impose very high charges for peak power use or, alternatively, offer incentives for off-peak use. This policy has renewed interest in both water and ice thermal storag
45、e. The storage capacity installed for summer load leveling may also be available for use in the winter, making heat reclaim a more viable option.许多电力公司施加非常高的峰值功率使用收费，或者也可以提供非高峰期使用的激励机制。这一政策已重新在水和冰蓄冷的兴趣。存储容量为夏季负荷平衡安装，也可能是在冬季使用，高热不退更可行的选择。With ice storage, the low-temperature ice water can provide col
46、der air than that available from a conventional system that supplies air at 10 to 13. The use of a higher water temperature rise and a lower supply air temperature, lowers the required pumping and fan energy and, in some instances, offsets the energy penalty due to the lower temperature required to
47、make ice.冰蓄冷，低温冰水比，可提供从传统的系统提供在10至13的空气较冷的空气。使用较高的水温度上升和较低的送风温度，降低了所需的泵和风扇能源在某些情况下，抵消，由于冰所需温度较低的能量损失。Water from condensers is usually cooled by the atmosphere. Either natural draft or mechanical draft cooling towers or spray ponds are used to reject the heat to the atmosphere.Air-cooled condensers p
48、ass outdoor air over a dry coil to condense the refrigerant.Evaporative condensers pass outdoor air over coils sprayed with water.Water from condensers is usually cooled by the atmosphere. Either natural draft or mechanical draft cooling towers or spray ponds are used to reject the heat to the atmosphere.Air-cooled condensers pass outdoor air over a dry coil to condense the refrigerant. Evaporative condensers pass outdoor air over coils sprayed with water.通常是由大气冷却水从冷凝器。无论是自然通风或机械通风冷却塔或喷池塘用于拒绝到大气中的热量。风冷冷凝器越过室外空气凝结的制冷剂的干燥线圈。蒸发式冷凝器，通水喷洒线圈，室外空气。通常是由大气冷却水从冷凝器。无论是自然通风或机械通风冷却塔或喷池塘用于拒绝到
