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1、基本概念基本概念 Basic Concepts Objectives 1.1 熱力系統(tǒng)熱力系統(tǒng) Definition of Thermodynamic System 1.2 熱力狀態(tài)熱力狀態(tài) Concepts of State and its properties Pressure,Temperature and Specific Volume 1.3 熱力過程熱力過程 Quasi-equilibrium Process and Reversible Process Thermodynamic Cycle 熱力系統(tǒng)熱力系統(tǒng) System,surroundings and boundary 熱力

2、學(xué)分析的對(duì)象叫熱力學(xué)分析的對(duì)象叫熱力系統(tǒng)熱力系統(tǒng)。A quantity of matter or a region in space chosen for study.系統(tǒng)之外部分稱為系統(tǒng)之外部分稱為環(huán)境或者外界環(huán)境或者外界。The mass or region outside the system.系統(tǒng)和環(huán)境系統(tǒng)和環(huán)境(外界外界)的分界面叫做的分界面叫做邊界或者控制面邊界或者控制面。The real or imaginary surface separates the system from its surroundings.熱力系統(tǒng)分類熱力系統(tǒng)分類 Classification 按有無物質(zhì)

3、交換按有無物質(zhì)交換 封閉系統(tǒng)封閉系統(tǒng) Closed System 敞開系統(tǒng)敞開系統(tǒng) Open System 按工質(zhì)狀況按工質(zhì)狀況 單組分系統(tǒng)單組分系統(tǒng) Single Component System 多組分系統(tǒng)多組分系統(tǒng) Multi-Component System 單相系統(tǒng)單相系統(tǒng) Single Phase System 多相系統(tǒng)多相系統(tǒng) Multi-phase System 按能量交換形式按能量交換形式 簡(jiǎn)單系統(tǒng)簡(jiǎn)單系統(tǒng) Simple System 絕熱系統(tǒng)絕熱系統(tǒng) Adiabatic System 孤立系統(tǒng)孤立系統(tǒng) Isolated System 有緣學(xué)習(xí)更多+謂y g d 3 0 7

4、6 考證資料或關(guān)注桃報(bào)：奉獻(xiàn)教育（店鋪）熱力系統(tǒng)熱力系統(tǒng) 封閉系統(tǒng)封閉系統(tǒng):與外界只有熱或功的能與外界只有熱或功的能量交換而無物質(zhì)交換的系統(tǒng)量交換而無物質(zhì)交換的系統(tǒng)。Mass cannot cross the boundaries of a closed system,but energy can.因其質(zhì)量恒定因其質(zhì)量恒定，又叫又叫控制質(zhì)量系統(tǒng)控制質(zhì)量系統(tǒng)。A closed system with a moving boundary.邊界可以是固定的邊界可以是固定的，也可以有位也可以有位移或變形的移或變形的。熱力系統(tǒng)熱力系統(tǒng) 敞開系統(tǒng)敞開系統(tǒng):與外界既有能量交換又有與外界既有能量交換又有物質(zhì)交

5、換的系統(tǒng)物質(zhì)交換的系統(tǒng)。An open system with one inlet and one exit.因其體積固定因其體積固定，又叫又叫控制容積系統(tǒng)控制容積系統(tǒng)。A control volume with real and imaginary boundaries.A control volume with fixed and moving boundaries.熱力系統(tǒng)熱力系統(tǒng) 孤立系統(tǒng)孤立系統(tǒng) 簡(jiǎn)單系統(tǒng)簡(jiǎn)單系統(tǒng) 絕熱系統(tǒng)絕熱系統(tǒng) 與外界只交換熱量和一種形式功的熱與外界只交換熱量和一種形式功的熱力系統(tǒng)。力系統(tǒng)。與外界沒有熱量交換的熱力系統(tǒng)與外界沒有熱量交換的熱力系統(tǒng)。與外界既無能量交

6、換也無物質(zhì)交換的與外界既無能量交換也無物質(zhì)交換的熱力系統(tǒng)熱力系統(tǒng)。No heat can cross its boundary.Neither mass nor energy can cross its boundary.Only heat and one type of work can cross its boundary.Simple Adiabatic Isolated 熱力狀態(tài)熱力狀態(tài) 系統(tǒng)變化過程的某一瞬間所呈現(xiàn)的宏觀物理狀況。系統(tǒng)變化過程的某一瞬間所呈現(xiàn)的宏觀物理狀況。狀態(tài)狀態(tài) 狀態(tài)參數(shù)狀態(tài)參數(shù) 用來描述系統(tǒng)所處狀態(tài)的宏觀物理量。用來描述系統(tǒng)所處狀態(tài)的宏觀物理量。The cond

7、ition,or the state,of the system as characterized by values of its properties.Any characteristic of a system is called a property.基本參數(shù)基本參數(shù) Basic Property 導(dǎo)出參數(shù)導(dǎo)出參數(shù) Derived Property 直接測(cè)量直接測(cè)量 directly measured 計(jì)算獲得計(jì)算獲得 calculated from basic ones State Property 壓力壓力(Pressure)沿垂直方向上作用在沿垂直方向上作用在單位面積上的力單位面

8、積上的力。A normal force exerted on a fluid per unit area.2NPam=5bar10 Pa=SI Pressure Measurement Absolute,Gage and Vacuum Pressures Absolute Vacuum Absolute Vacuum bp大氣壓大氣壓 gp表壓表壓 ap絕對(duì)壓力絕對(duì)壓力 vp真空度真空度 ap絕對(duì)壓力絕對(duì)壓力 bp大氣壓大氣壓 bpAtmosphere abgppp=+abvppp=-0ap=絕對(duì)真空絕對(duì)真空 溫度溫度(Temperature)表示物體表示物體冷熱程度冷熱程度的參數(shù)。的參數(shù)。A

9、 measure of“hotness”or“coldness”.熱力學(xué)第零定律熱力學(xué)第零定律 如果兩個(gè)系統(tǒng)分別與另一系統(tǒng)處于如果兩個(gè)系統(tǒng)分別與另一系統(tǒng)處于熱平衡熱平衡，這兩個(gè)系統(tǒng)，這兩個(gè)系統(tǒng)也處于也處于熱平衡熱平衡。The zeroth law of thermodynamics If two bodies are in thermal equilibrium with third body,they are also in thermal equilibrium with each other.Two objects in thermal equilibrium are at the sa

10、me temperature.溫溫 標(biāo)標(biāo)(Temperature Scale)212.00 671.67 100.00 373.15 0-273.15-459.67 273.16 273.15 0.00 491.69 491.67 0.01 32.02 32.00 水的水的沸點(diǎn)沸點(diǎn) Boiling or steam point 水的冰點(diǎn)水的冰點(diǎn) Freezing or ice point 水三相點(diǎn)水三相點(diǎn) Triple point 攝氏溫標(biāo)攝氏溫標(biāo) Celcius scale 華氏溫標(biāo)華氏溫標(biāo) Fahrenheit scale oC 熱力學(xué)溫標(biāo)熱力學(xué)溫標(biāo) K氏溫標(biāo)氏溫標(biāo) Kelvin scal

11、e oF K R 朗肯溫標(biāo)朗肯溫標(biāo) Rankine scale 0 SI British SI British H2O 1 atm Temperature Scale Comparisons oo(K)(C)273.15(R)(F)459.67TtTt=+=+o(R)1.8(C)TtD=Doo(K)(C)(R)(F)TtTtD=DD=Doo(F)1.8(C)32(R)1.8(K)ttTT=+=Density,Specific Volume and Specific Gravity 密度密度(Density):比容比容(Specific Volume):比重比重(Specific Gravity

12、):3(kg/m)mVr=1vr=WaterSGrr=mass per unit volume Volume per unit mass,the reciprocal of density the ratio of densities between a substance and water at 4oC.a dimensionless quantity 狀態(tài)參數(shù)的特性狀態(tài)參數(shù)的特性(Characteristics of State Property)1 2 A C B 積分特性積分特性(integral)微分特性微分特性(differential)數(shù)學(xué)上數(shù)學(xué)上(Mathematically

13、)狀態(tài)參數(shù)是狀態(tài)的狀態(tài)參數(shù)是狀態(tài)的單值函數(shù)單值函數(shù)。狀態(tài)參數(shù)的變化狀態(tài)參數(shù)的變化只與初始和終了狀態(tài)有關(guān)，只與初始和終了狀態(tài)有關(guān)，與過程無關(guān)。與過程無關(guān)。狀態(tài)確定，參數(shù)全部確定；狀態(tài)變化，狀態(tài)確定，參數(shù)全部確定；狀態(tài)變化，至少一個(gè)參數(shù)變化。至少一個(gè)參數(shù)變化。22110fdfffdfD=-=22()()yxffdfdxdyxyffx yy x抖=+抖抖=抖抖強(qiáng)度參數(shù)與廣度參數(shù)強(qiáng)度參數(shù)與廣度參數(shù)(intensive&extensive properties)強(qiáng)度參數(shù)強(qiáng)度參數(shù) 廣度參數(shù)廣度參數(shù) 與所含物質(zhì)數(shù)量無關(guān)。與所含物質(zhì)數(shù)量無關(guān)。與所含物質(zhì)數(shù)量有關(guān)。與所含物質(zhì)數(shù)量有關(guān)。independent of

14、 the quantity of the system proportional to the quantity of the system Example:temperature,pressure,Example:volume,energy,比參數(shù)比參數(shù) Specific property 兩個(gè)廣度參數(shù)之比，是強(qiáng)度參數(shù)。兩個(gè)廣度參數(shù)之比，是強(qiáng)度參數(shù)。An extensive property per unit extensive property Example:density,specific volume,Extensive Intensive 量綱與單位量綱與單位(Dimensions

15、 and Units)量綱量綱 單位單位 Any physical quantity can be characterized by dimensions.The magnitudes assigned to the dimensions are called units.Secondary or derived dimensions such as volume,velocity,energy,Dimensional Homogeneity,SI system 平衡狀態(tài)平衡狀態(tài)(Equilibrium state)系統(tǒng)的宏觀系統(tǒng)的宏觀狀態(tài)不隨時(shí)間而變狀態(tài)不隨時(shí)間而變。A state in w

16、hich the system is not capable of spontaneous change from one state to another state.In an equilibrium state there are no unbalanced driving forces(or potentials)within the system.系統(tǒng)內(nèi)系統(tǒng)內(nèi)推動(dòng)力或者勢(shì)差為推動(dòng)力或者勢(shì)差為 0。Note：動(dòng)態(tài)平衡，動(dòng)態(tài)平衡，宏觀狀態(tài)不變。宏觀狀態(tài)不變。平衡平衡 均勻均勻 平衡平衡 時(shí)間時(shí)間 均勻均勻 空間空間 A closed system reaching thermal equ

17、ilibrium.A system at two different states.平衡狀態(tài)平衡狀態(tài)(Equilibrium state)平衡的平衡的充分必要條充分必要條件件(Sufficient and Necessary Conditions)熱平衡熱平衡 Thermal 力平衡力平衡 Mechanical 相平衡相平衡 Phase 化學(xué)平衡化學(xué)平衡 Chemical 系統(tǒng)內(nèi)系統(tǒng)內(nèi)無溫差無溫差 No difference of temperature 系統(tǒng)內(nèi)系統(tǒng)內(nèi)無壓差無壓差 No difference of pressure 相間相間無化學(xué)勢(shì)差無化學(xué)勢(shì)差 No difference of

18、 chemical potential 反應(yīng)物生成物反應(yīng)物生成物間間無化學(xué)勢(shì)差無化學(xué)勢(shì)差 No difference of chemical potential 有緣學(xué)習(xí)更多+謂y g d 3 0 7 6 考證資料或關(guān)注桃報(bào)：奉獻(xiàn)教育（店鋪）狀態(tài)方程狀態(tài)方程 (Equation of State)熱力系統(tǒng)中描述狀態(tài)所需的熱力系統(tǒng)中描述狀態(tài)所需的獨(dú)立獨(dú)立強(qiáng)度強(qiáng)度變量數(shù)變量數(shù)。自由度自由度(degree of freedom)The number of intensive properties required to fix the state of a system.相律相律(Phase rul

19、e)2fab=-+fab-number of independent properties number of components of a system number of phases of a system 狀態(tài)方程狀態(tài)方程 (Equation of State,EOS)(,)0f p v T=描述流體描述流體p-v-T性質(zhì)的關(guān)系式。性質(zhì)的關(guān)系式。A relation connecting p,v,and T of a fluid.The state of nitrogen is fixed by two independent,intensive properties.(,)pf v

20、 T=or 狀態(tài)方程狀態(tài)方程 (Equation of State)熱力過程熱力過程 系統(tǒng)從一個(gè)狀態(tài)到另一個(gè)狀態(tài)的系統(tǒng)從一個(gè)狀態(tài)到另一個(gè)狀態(tài)的變化歷程變化歷程。Any change that a system undergoes from one equilibrium state to another.the series of states through which a system passes during a process.Path:A process between states 1 and 2 and the process path.準(zhǔn)靜態(tài)過程準(zhǔn)靜態(tài)過程(Quasi-Equ

21、ilibrium Process)一切一切不平衡勢(shì)差無限小不平衡勢(shì)差無限小，進(jìn)行得，進(jìn)行得無限緩慢無限緩慢的的過程過程。A process proceeds in such a manner that the system remains infinitesimally close to an equilibrium state at all times.狀態(tài)變化速度小于系統(tǒng)恢復(fù)平衡態(tài)速度的狀態(tài)變化速度小于系統(tǒng)恢復(fù)平衡態(tài)速度的過程過程。A sufficiently slow process that allows the system to adjust itself to a new equ

22、ilibrium state from previous state.A quasi-equilibrium process is an idealized process and is not a true representation of an actual process.Quasi-equilibrium processes serve as standards to which actual processes can be compared.Note：可逆過程可逆過程(Reversible Process)當(dāng)系統(tǒng)完成某一過程后，如果令其沿相同的路徑逆行而當(dāng)系統(tǒng)完成某一過程后，如果

23、令其沿相同的路徑逆行而能恢復(fù)到原來的狀態(tài)，而且不留下任何痕跡，這一過程能恢復(fù)到原來的狀態(tài)，而且不留下任何痕跡，這一過程稱為稱為可逆過程可逆過程。A reversible process is that the system and surroundings can be restored to their initial states without any change in the system or surroundings.實(shí)現(xiàn)可逆過程的充要條件：實(shí)現(xiàn)可逆過程的充要條件：過程是準(zhǔn)靜態(tài)的過程是準(zhǔn)靜態(tài)的(Quasi-Equilibrium)；過程不存在耗散過程不存在耗散(No dissip

24、ation)。Note：只有系統(tǒng)和外界均無不可逆因素時(shí)，才是可逆過程。只有系統(tǒng)和外界均無不可逆因素時(shí)，才是可逆過程。熱力循環(huán)熱力循環(huán)(Thermodynamic Cycle)A system is said to have undergone a cycle if it can return to its initial state at the end of the process.系統(tǒng)從某一狀態(tài)出發(fā)，經(jīng)歷一系列過程之后又回到初始系統(tǒng)從某一狀態(tài)出發(fā)，經(jīng)歷一系列過程之后又回到初始狀態(tài)，稱為狀態(tài)，稱為循環(huán)循環(huán)。p v 1 2 3 4 正向循環(huán)正向循環(huán)12341:Heat Work 逆向循環(huán)逆向循環(huán)14321:Work Heat(由熱產(chǎn)功由熱產(chǎn)功)(耗功生熱耗功生熱)順時(shí)針順時(shí)針(clockwise)逆時(shí)針逆時(shí)針(counterclockwise)有緣學(xué)習(xí)更多+謂y g d 3 0 7 6 考證資料或關(guān)注桃報(bào)：奉獻(xiàn)教育（店鋪）The end of this chapter 習(xí)題習(xí)題 第一章第一章1，2，3，4題。題。