1.17 Adiabatic Compression or Expansion (4) S.J.T.U. Phase Transformation and Applications Helium,ideal gas Valve First gas, Insulated 50-liter,25 C,20 atm → Quench chamber,?10 atm (L,)im,-(H。)m。+Q+δW=dU=0 System boundary om, H,=H。 T,=T, H(T,P)=H(T) Quench chamber,?10 atm,Close system Define the system as the quantity of gas remaining in the tank when T the pressure reaches 10 atm Adiabatic expansion T=T(0.758)=298×0.758=226K 226K/-47C SJTU Thermodynamics of Materials Spring 2006 ©X.J.Jin Lecture 3 Second law IPhase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2006 © X. J. Jin Lecture 3 Second law I 1.17 Adiabatic Compression or Expansion (4) Helium, ideal gas Insulated 50-liter, 25 °C, 20 atm Quench chamber, ?, 10 atm − )()( + + = dUWQmHmH = 0 i δ i o δ o δ δ Valve = HH oi ( ) 25 4.0 1 2 1 2 )5.0() 2010 == ()( = R R CR P PP TT = TT 12 = × = 226758.0298)758.0( K 226K / -47 °C System boundary δmi δmo First gas, ? Ti = To Quench chamber, ?, 10 atm， Close system H(T, P) = H(T) Define the system as the quantity of gas remaining in the tank when the pressure reaches 10 atm Adiabatic expansion