1.14 Adiabatic flow through a valve: S.J.T.U. Joule-Thomson expansion Phase Transformation and Applications Adiabatic:no heat is added or removed from the system. Adiabatic fluid flow through a valve:insulated or the flow is so fast System:valve at steady state H,oin,-H,i。+dg+δW=dU Steady state w =0 System boundary Adiabatic 89=0 Sm; im,=dim。 H,=H。 Adiabatic process Isenthalpic expansion 绝热过程 SJTU Thermodynamics of Materials Spring 2006 ©X.J.Jin Lecture 2 First Law llPhase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2006 © X. J. Jin Lecture 2 First Law II 1.14 Adiabatic flow through a valve: Joule-Thomson expansion Adiabatic: no heat is added or removed from the system. Adiabatic fluid flow through a valve: insulated or the flow is so fast System boundary δmi δmo System: valve at steady state Hiδmi − Hoδmo +δQ +δW = dU Adiabatic δQ = 0 Steady state δW = 0 δmi = δmo Hi = Ho Adiabatic process Isenthalpic expansion 绝热过程