2.2 Entropy not Conserved S.J.T.U. Phase Transformation and Applications Entropy is not conserved in natural processes,in contrast to the energy function(U) Steady state and no extraneous heat losses. 2=-Qu Energy is conserved. △U+n=△U,+△Um=Q,+Qn=0 The process of heat transfer at the boundaries of reservoirs I and II is considered to be reversible. AS-AS,+AS,-O+OL--0u.+0-Qu T-Tn ≠0 The irreversibility TTT Tu TTu gave rise to an entropy increase. T SJTU Thermodynamics of Materials Spring 2010 ©X.J.Jin Lecture 3 Second law IPhase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2010 © X. J. Jin Lecture 3 Second law I 2.2 Entropy not Conserved Entropy is not conserved in natural processes, in contrast to the energy function (U). TI TII Steady state and no extraneous heat losses. QI  QII Energy is conserved. UI II  UI UII  QI QII  0 The process of heat transfer at the boundaries of reservoirs I and II is considered to be reversible.  0                    I II I II II II II I II II II I I I II I II T T T T Q T Q T Q T Q T Q S S S The irreversibility gave rise to an entropy increase