Overall Review Basic Concept Thermodynamic System A quantity
总复习 (Overall Review)
Basic Concept 系统 (Thermodynamic System): A quantity of matter or a region in space chosen for study. （系统就是指被选做研究对象的物体或空间。） 2. 平衡状态(Equilibrium State) 1. A system in equilibrium experiences no changes with time when it is isolated from its surroundings. 所谓平衡状态就是指在没有外界影响的情况下，系统 的状态不随时间而发生变化。
3. 准 静 态 过 程( Q u a s i - s t a t i c P r o c e s s ) 在无限小势差推动下的由连续平衡态组成的过 程，就是准静态过程。 When a process proceeds in such a manner that the system remains infinitesimally close to an equilibrium state at all times, it is called a quasistatic or quasi-equilibrium process.
4. 可逆过程(Reversible process) 系统经历某一过程后，如果能使系统与外界同时恢 复到初始状态，而不留下任何痕迹，则此过程为可 逆过程。 A process that can reversed without leaving any trace on the surroundings. That is, both the system and the surroundings are returned to their initial states at the end of the reverse process.
o 自发过程(Spontaneous Process) 不需要任何外界作用而自动进行的过程。 A process which can happy naturally without the interference from the surroundings.
5. 稳态稳定流动(Steady-flow process) A process during which a fluid flows through a control volume steadily. That is, the properties remain the same at a fixed point during the entire process.
6. 循环 (Cycle) If a system returns to its initial state at the end of the process, it is said a system have undergone a cycle. 系统经历了一系列状态变化过程，又回到了原来状态， 称为热力循环。
7. 比热容（Specific Heat) 将单位物量的物质温度升高 1 K所需加入的热量。 The energy required to raise the temperature of a unit quantity of a substance by one degree
10. 焓（Enthalpy） Enthalpy, a state function, is defined as follows, h= u + pv This energy is composed of two parts: the internal energy of the fluid (u) and the flow work (pv) associated with pushing the mass of fluid across the system boundary. 对开口系统而言，焓指流动 质所携带能量的一部 分，这部分能量取决于热力状态
15. 未饱和湿空气(Unsaturated Air) Dry air+ Superheated water vapor 干空气和过热水蒸汽的混合物。 饱和湿空气(Saturated Air) Dry air+ Saturated water vapor 干空气和饱和水蒸汽的混合物。
16. 露点温度(Dew-point Temperature) It is defined as the temperature at which condensation begins when the air is cooled at constant pressure. 17. 相对湿度φ (Relative Humidity of Air) It is defined as the ratio of the amount of moisture in the air to the maximum amount of moisture the air can hold at the same temperature. 湿空气中实际包含的水蒸汽量与同温度下最多能包 含的水蒸汽量的百分比。
18. 含湿量(Humidity ratio) 含湿量d：以干空气为基准，包含 1千克干空气 的湿空气中中所含有的水蒸汽的质量。 The mass of water vapor present in a unit mass of dry air is called humidity Ratio.
19. 马赫数：（The Mach number） M, It is the ratio of the flow speed, c, to the velocity of sound in the same fluid at the same state. It is denoted as M. (流体在某一点的运动速度和该点当地声速之比, 以M表示)
20. 滞止参数(Stagnation Properties) 气体速度为零时的状态称为滞止状态, 该状态的参数称为滞止参数. Stagnation properties represent the enthalpy of a fluid when it is brought to rest adiabatically
21. Critical Pressure Ratio(临界压力比)
Critical Point(关键点）: 1. Pressure (压力） o o Absolute pressure （绝对压力） Relative pressure （相对压力） Gage pressure （表压力） Vacuum pressure （真空度）
绝对压力与相对压力 absolute pressure 当 p > pb 当 p < pb relative pressure 表压力 pe Gage pressure 真空度 pv Vacuum pressure pe p pb pv p
Exercise. 1 (练习 1）---压力的测量 As shown in the following figure，it is known that pb=101325 Pa, the height difference is H=300 mm for mercury liquid. The gauge pressure of B is 0. 2543 MPa, Then what is the pressure for side A, and what is the value of Pg, A? 已知大气压pb=101325 Pa，U型管内 汞柱高度差H=300 mm，气体表B读数为 0. 2543 MPa，求：A室压力p. A及气压表A的读数pg. A
解： Emphasis (强调)： pb is the pressure of environment in which the gauge is located (是测压仪表所在环境压力)
2. Equation of State for Ideal Gas （理想气体的状态方程 的应用） Pv=RT Example. Determine the mass of air in a room whose dimensions are 4 m× 5 m× 6 m at 100 k. Pa and 25℃
3. 平均比热 Mean specific heat c 求O 2在 100 -500℃平均定压热容 (cp , cv) c=f (t) t 1 t 2 t
5. 闭口系统能量方程 Point function---Exact differentials--- d 一般式 Path function---Inexact differentials--- W Q Q = d. U + W Q = U + W q = du + w q = u + w 单位 质 适用条件： 1）任何 质 2) 任何过程
6. Corollaries of the First Law （热力学第一定律的推论） (1) Work done in any adiabatic (Q=0) process is path independent. (2) For a cyclic process heat and work transfers are numerically equal or
Exercise (练习) Correct the error in the following equations. (纠正下列各式中的错误) 1. (1) (2) (3) (4) (5)
2. Make a statement of suitable conditions under which the following equations can be adopted. ( 叙述下列各公式的适用条 件) (1) (2) (3) (4)
3. Initially, there is m 1 working fluid in an adiabatic and rigid container, its state is denoted as ‘ 1’. Then m 2 working fluid of state ‘ 2’ is charged into the container. The process finished until the state of the working fluid reaches ‘ 3’. Write out the energy equation for the process.
8. The procedures adopted (所采取的步骤) Pv=RT
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9. 单级压气机 (1) Work consumption (耗功量） If it is isothermal compression, then (若压缩过程为可逆定温过程，则：) If it is isentropic compression, then (若压缩过程为可逆绝热压缩，则: )
If it is polytropic compression, then (若压缩过程为可逆多变过程，则 : ) （2） Discharge Temperature (排气温度）
10. The influence of residual volume of inter-space. (余隙容积的影响) （1）The influence on discharge volume( 对排气量的影响） （2） The influence on compression work（ 对耗功量的影响） There is no influence on compression work. (对耗功量无影响)
11. Multistage Compression with inter-cooling （多级压缩、中间冷却）
12. 克劳修斯表述 Clausius statement 不可能将热从低温物体传至高温物体而不引起 其它变化。 It is impossible to construct a device that operates in a cycle and produces no effect other than the transfer of heat from a lower-temperature body to a higher-temperature body.
12. Carnot‘s Theorems (卡诺定理) 在相同的高温热源和相同的低温热源间 作的 可逆热机的热效率恒高于不可逆热机的热效率； The efficiency of an irreversible heat engine is always less than that of a reversible one operating between the same two thermal reservoirs.
o 在相同的高温热源和相同的低温热源间 作 的一切可逆热机有相同的热效率，而与 质 无关。 The efficiencies of all reversible heat engines operating between the same two thermal reservoirs are the same.
13. The significance of the Carnot Theorems (卡诺定理的意义) (1)卡诺定理指明了热变功的最高效率 The Carnot Theorem indicates the maximum thermal efficiency of heat engine, which converts heat into work.
(2)卡诺定理指明可以通过提高高温热源的温度, 降低低温冷源的温度或减少过程的不可逆因素 等方式来提高热效率 The Carnot Theorem point out thermal efficiency can be improved by means of raising the temperature of high temperature thermal reservoir, lowering the temperature of lower temperature reservoir, or reducing irreversibilities.
(3) 卡诺热效率表明了热量的最大可用能 The Carnot thermal efficiency value reveals the maximum amount of high temperature thermal energy which can be converted to work. (4)卡诺定理表明能量不仅有数量的差别，还有品质 的高低 The Carnot Theorem indicates that energy has quality as well as quantity.
热源温度越高，热量的品质就越高, 其可转化 为的可用能就越大。 The higher the temperature, the higher u the quality of thermal energy. (5) 基于卡诺定理, 才证明熵是一个状态参数 It is based on Carnot theorem that entropy is investigated to be a property. ()
(4). > , for irreversible process (不可逆过程)。 =, for reversible process (可逆过程)
15. The increase principle of Entropy (孤立系统的熵增原理) For isolated system The entropy of an isolated system during a process always increases or, in the limiting case of a reversible process remains constant. In other word, it never decreases. (孤立系统中的过程总是向着熵增大的过程进行, 若为可逆过程, 则 熵不变。换句话说，即孤立系统的熵不会减小）
16. Entropy generation and Entropy flow (熵产与熵流) (1) Entropy generation is caused by any irreversibility. ( 熵产是由不可逆因素引起的熵变) (2) Entropy Flow/Transfer (熵流) Entropy transfer by heat transfer (热量熵流) Entropy transfer by mass flow (质量熵流)
For closed system (对于闭口系统) o o For steady-flow system (对于稳态稳定流动系统） For single stream, adiabatic, steady flow （对于 单股绝热的稳态稳定流动系统）
17. Significance of Entropy and its application (熵的意义及应用) Heat absorption and heat rejection during a reversible processcan be calculated by resorting to Entropy. (可逆过程中的吸热或放热量可借助熵来计算） （2） Entropy generation indicates the direction of process in isolate System. (熵产是孤立系统中过程进行方向的标志） （1）
heat transfer across a finite temperature difference （温差传热） Free or unrestrained expansion（自由膨胀） （3）Entropy is a measurement of the amount of thermal energy which can not be converted to work. (熵是热量不可用能大小的量度） T TH T 0 s 1 s 2 s (4) Entropy Generation indicates the amount of loss in energy which can be converted to work. (熵产是做功能 力损失的量度）
18. Types of Property Tables (水蒸汽表的分类) (1) Saturated water Tables (饱和水和饱和蒸汽表) Saturated water---T Tables(以温度t为独立变量排列) o Saturated water---p Tables(以压力p为独立变量排列) (2) Subcooled water and Superheated vapor Table (未 饱和水和过热水蒸汽表) P and t are dependent variables (以p和t为自变量) o
（4） Consulting property tables of water vapor to determine the state of each point and their h， s，x. (利用水蒸气表判断下列各点的状态，并确定其h，s， x的值。)
19. Thermodynamic Processes of Water Vapor (水蒸气的热力过程) (1) Based on the given conditions, determine the initial state and its properties . (根据已知条件，确定初始状态，查出其余参数。) (2) Based on the characteristics of the process and one of the properties of the final state, determine the final state and its properties. ( 根据过程特点和一个终态参数，确定终态，再查出其余 终态参数。) (3) Based on the initial and final state, calculate the q、Δu、w during the process。 (根据初、终态参数，计算q、Δu、w等。)
(1) Constant Volume Process ( 定容过程, v=定值。) Constant volume Process (定容过程)
(2) Constant Pressure Process (定压过程 p=定值) Constant Pressure Process (定压过程)
(3) Constant Temperature Process (定温过程 T=定值) Isothermal Process (定温过程)
(4) Adiabatic Process ( 绝热过程) Isentropic Process (定熵过程)
Example: 1 kg water vapor, initially, ℃ undertakes an isentropic expansion process and reaches the final state of Calculate the amount of work done by the water vapor during the process.
20. Example: The atmospheric air is at ℃. （１）If is relative humidity is equal to 60%, then calculate such properties as （２）If ℃, then calculate such properties as Discussion: To determine the state of moist air, it need three state properties at least. (为了确定湿空气的 状态，至少需要３个状态参数）
21. 湿空气的焓湿图 The Psychrometric Chart (h-d图) Saturation Line (饱和湿空气线） In addition, there are other lines(还有下列曲线：） 1. Lines of constant enthalpy (定焓线，与y轴成 45 o. C角向下) 2. Lines of constant humidity ratio (定含湿量线，垂直直线) 3. Lines of constant temperature (定温线) 4. Lines of constant volume ( 定容线) 5. Lines of constant relative humidity line( 定相对湿度线。) 6. Lines of constant pv和d. (水蒸汽分压力pv和d关系曲线 )
22. 湿空气的热力过程 （Thermodynamic Process of Moist Air ） (1) Sensible Heating Process (加热过程) 加热过程 B A The load on the heater is:
(2) Sensible Cooling Process at Constant Moisture Content (单纯冷却过程) If the temperature of the cooling medium is still above its dew point temperature, then (若冷却介质温度没有降到露点以下，则过程前后)： 冷却过程 A B
(3) Sensible Cooling with Dehumidification (冷却去湿) If the air is continuously cooled to a temperature which below its dewpoint temperature, then water vapor will condense. (温度下降到露点以后，继续降温，析出水分，减小含湿量。) A C B
(2) Isothermal Humidification Process (等温加湿)
(5) Mixing of Two Air Streams (混合过程)
25. 蒸汽再热循环 (reheat cycle) 1 T 5 6 b 4 3 s
26. Otto循环(定容加热循环）_ 1’ - 2 Compress mixture quasi-statically and adiabatically 2 - 3 Ignite and burn mixture at constant volume (heat is added) 3 (4)- 5 Expand mixture quasi-statically and adiabatically 5 - 1’’ Cool mixture at constant volume
27. The Diesel Cycle (狄塞尔循环)
p p-v图和T-s图 逆勃雷登循环 T 2 3 3 4 1 2 Reversed Brayton Cycle 2 3 1 4 v 绝热压缩 s 等压冷却 p 3 4 2 T 0 1 T 2 s 4 绝热膨胀 s 1 等压吸热 p
lnp-h图及计算 lnp 4 3 2 T 2 3 4 5 1 5 h 1 s
压焓图 P-h diagram
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