化工热力学基本概念和重点.doc

* * * * * * * * * * * * (system)(surrounding)* * * ()(isolated system) * (closed system )* (open system)* * ()* Vm = V / nVm=m / v, * * (thermal equilibrium)* (mechanical equilibrium)* (phase equilibrium)* (chemical equilibrium)* * * state functionstate equation T,p,V T=fp,Vp=fT,VV=fp,TpV=nRT* 1molH2 ()298K* T1 T2 () T* dV=0* * P1 P2 () P* Q=0()* * U=0* P=* P=0* (heat)QQQQ 0, QQ 0JouleJworkWWeWfW0J JKJ QW dVAdlFPAWe -Fdl-PAdl-PdVWe =-PdVPWe = -P SV -P (V2V1 )* -PdV-PdVP P Pe * We -PdVPdV * * * 1850* 12()3 U * * * * J12QWU* QWW* QWQ + WU = Q + WUQWU = Q + WU* Q = 0W = 0U = 0()* W = 0U = QV pVT * * * (guasistatic process)PePidPdt* (reversible process)III()(irreversible process)(1) (2) (3) (1) (2) (1) S, G(2) (enthalpy)* * * QVUQPH:dV=0Wf0QV kJJ(dV0Wf0): dp=0Wf=0QpkJJ U,QVUQPH(1) QV QP QV QP UH(H)HUQVUQPH(2) UH 20molp=750mmHg10002000352kJQWU H Qp=352kJH =Qp=352kJWe=-pe(V2-V1)=-(750/760)* 101325*(2000-1000)*10-3=-100kJU=Qp+We=352-100=252kJorH=U+pV=U+peVU=Qp-peV =-100kJ (heat capacity)* * * * * ,Wf0CJK-11KgJKKg1mol()JKmol* 273.15KC(,l)11.5JKmolC(,l)75.29JKmolC(,g)33.58JKmolCC* K T KT1 T2 * 1molWf0 CVm JKmol T1 T2 CV,m (Wf0PVT)1molWf 0CPm JKmol T1 T2 CP,m (Wf 0PVT )C Pm C Vm C PmfTCp,m Cp =nCp,m C Vm1.5R C Pm2.5R C Vm2.5R C Pm3.5R C Vm3R C Pm4R * * CP,m CV,m* Gay-Lussac-JouleGay-Lussac-JouleGay-Lussac-JouleGay-Lussac-Joule* Gay-Lussac-JouleGay-Lussac-JouleGay-Lussac-Joule* Gay-Lussac-JouleGay-Lussac-Joule CP,m CV,mC p, mC V, mC p,mC V, m CP,m CV,m CP,m CV,m CP,m CV,m Carnot * * * - * -