h Fig 6-5 Isochoric Process of Water Vapor Fig 6-6 Isobaric Process of Water Vapor 6.5.2 Isobaric Process On h-s diagram, the isobaric(constant-pressure) process is depicted by the curve 1-2 in Fig. 6-6 The change in internal energy of the steam is v2=v 1) The work output is w=p(V2-n)=q-△ The technical work available is PI-p The amount of heat addition is 6.5.3 Isothermal Process On h-s diagram, the isothermal (constant-temperature) process is depicted by the curve 1-2 in Fig. 6-7 The change in internal energy of steam is Fig 6-7 Isothermal Process M=l2-l1=(h2-P22)-(-P1n1) The amount of heat addition is 7(S2-S1) The expansion work output is The technical work available is 6.5. 4 Adiabatic Process The adiabatic process is realized without heat addition or rejection and the entropy of the working medium during a reversible adiabatic(isentropic) process remains constant. That is, s=const(as shown by a straight line 1-2 in Fig. 6-8). Superheated steam turns into saturated vapor, and further into wet vapor. An irreversible process is shown by the dotted line 1-2 in Fig. 6-9. During an adiabatic expansion process, the pressure and the temperature of the steam decreases, however, the entropy Icreases Under isentropic conditions, it is easy to determine the final state properties on h-s diagram The amount of heat addition is equal to zero, that is105 Fig .6-5 Isochoric Process of Water Vapor Fig. 6-6 Isobaric Process of Water Vapor Fig. 6-7 Isothermal Process 6.5.2 Isobaric Process On h s − diagram, the isobaric (constant-pressure) process is depicted by the curve 1-2 in Fig.6-6. The change in internal energy of the steam is ( ) 2 1 2 1 2 1 u = u −u =h −h − p v −v The work output is w= p(v2 − v1 ) = q − u The technical work available is = − = − 2 1 1 2 w vdp v( p p ) t The amount of heat addition is q = h2 − h1 6.5.3 Isothermal Process On h s − diagram, the isothermal (constant-temperature) process is depicted by the curve 1-2 in Fig.6-7. The change in internal energy of steam is ( ) ( ) 2 1 2 2 2 1 1 1 u = u −u = h −p v − h − p v The amount of heat addition is ( ) 2 1 q =T s − s The expansion work output is w= q −u The technical work available is wt = q − h 6.5.4 Adiabatic Process The adiabatic process is realized without heat addition or rejection and the entropy of the working medium during a reversible adiabatic (isentropic) process remains constant. That is, s = const (as shown by a straight line 1-2 in Fig. 6-8). Superheated steam turns into saturated vapor, and further into wet vapor. An irreversible process is shown by the dotted line 1-2 in Fig. 6-9. During an adiabatic expansion process, the pressure and the temperature of the steam decreases, however, the entropy increases. Under isentropic conditions, it is easy to determine the final state properties on h s − diagram. The amount of heat addition is equal to zero, that is