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.om,-H.om +0+W=du Steady state 8W=0 System boundary Adiabatic 80=0 δm im=im。 H,=H Adiabatic process Isenthalpic expansion 绝热过程 SJTU Thermodynamics of Materials Fall 2012 ©X.J.Jin Lecture 2 First Law llPhase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Fall 2012 © 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 mi mo System: valve at steady state Hi mi  Ho mo Q W  dU Adiabatic Q  0 W  0 Steady state mi  mo Hi  Ho Adiabatic process Isenthalpic expansion 绝热过程