it deals about thermodynamics

1. Availability & Irreversibility

2. Non flow processes

23. Availability Function for Non-Flow
process:-
• Let P0 be the ambient pressure, V1 and V0 be
the initial and final volumes of the system
respectively.
• If in a process, the system comes into
equilibrium with the surroundings, the work
done in pushing back the ambient atmosphere
is P0(V0-V1).

24. • Availability= Wuseful=Wmax-P0(V0-V1)
• Consider a system which interacts with the
ambient at T0. Then,
• Wmax=(U1-U0)-T0(S1-S0)
• Availability= Wuseful=Wmax-P0(V0-V1)
• = ( U1-T0 S1)- ( U0-T0 S0)- P0(V0-V1)
• = ( U1+ P0V1-T0 S1)- ( U0+P0V0-T0 S0)
• = f1-f0

25. • where f=U+P0V-T0S is called the availability
function for the non-flow process. Thus, the
availability: f1-f0
• If a system undergoes a change of state from
the initial state 1 (where the availability is (f1-
f0) to the final state 2 (where the availability is
(f2-f0), the change in the availability or the
change in maximum useful work associated
with the process, is f1-f2.

36. Steady flow or open system