Hence, S2 S1 for a Reversible Adiabatic Process

First law Second law

This is also called the law of conservation of energy The entropy of an isolated system increases in all real processes and is conserved in reversible processes. OR Chapter 5. 1st Law for control mass Chapter 6 The AVAILABLE energy of an isolated system decreases in all real processes (and is conserved in reversible processes) 1st Law for control volume Q12  W12  E2  E1 E  U  PE  KE The 2nd law says that work and heat energy are not the same. It is easier to convert all of work to heat energy, but not vis versa. i.e. work energy is Qin  Win  mih  PE  KEi  more valuable than heat energy. Heat can not be converted completely and continuously into work. Qout  Wout  meh  PE  KEe  m2u2  m1u1 

Chapter 5.5 Chapter 5.6 So, 2nd law dictates the direction at which a system state will change. It enthalpy Cv Cp will move to a state of lesser available energy H  U  PV Specific heat is the Steady Transient amount of heat required Entropy is constant in a reversible adiabatic process. h  u  Pv state State to raise the temp. of a 2 Q S2 S1   Sgen Sgen  0 Derived from first Law unit mass by one degree  1 T by setting P constant u Sgen  0  reversible process Cv   Adiabatic process Q W m u u T v      2  1  Q  0  adiabatic process C h Q  P dV  mu2  u1  p  Wnet  he  hi  T p Hence, S2  S1 for a reversible adiabatic process Q  PV2  V1   mu2  u1  Solids and liquids: Use Wnet average specific heat C. q  P2  1   u2  u1  Wlost   T dSgen q  P2  u2  P1  u1  Cv  Cv For solids and liquids  hi h e Actual boundary work W12   P dV  Wlost 1q2  h2  h1 Gibbs relations Note: Even though enthlapy was derived by the T ds du P dv assumption of constant P, it is a property of a   system state regardless of the process that lead T ds  dh  v dp to the state. Ideal Gas dh  du  dP v 0 T Cp0 sT   dT dh  du  v dP  P dv Solids, Liquids T0 T 0 0 P2 s2  s1  s  s  R ln Using table A.7 or A.8 T2 T1 P1 T2 T2 P2 s2  s1  Cln s2 s1  Cp0 ln R ln Constant Cp,Cv T1  T  P For solids and liquids For ideal gas 1 1 T2 v 2 s2  s1  Cv ln  R ln v Constant Cp,Cv T1 1 C k  p0 For solids and liquids, dv  0 Cv0 du  Cv0 dT since almost incompressible, hence Polytrpic process dh  Cp0 dT PVn constant dh  du  v dP For Solids and Liquids P V n Cp0  Cv0  R 2  1 Also for solids and liquids, v is very small, hence P1 V2 n P T dh du For Solids and Liquids 2  2 n1  P1 T1 Hence for solids/liquids, dh  du  C dT specific work (work is moving boundary work,  P dv 1 R w1 2  P2v2 P1v1   T2 T1  n 1  1n  1n   By Nasser M. Abbasi Image1.vsd v 2 v 2 P1 w12  P1v1 ln v  RT1 ln v  RT1 ln n  1 1 1 P2