Answer:
work is 130.5 kJ/kg
entropy change is 1.655 kJ/kg-k
maximum theoretical work is 689.4 kJ/kg
Explanation:
piston cylinder assembly
100 bar, 360°C to 1 bar, 160°C
to find out
work and amount of entropy and magnitude
solution
first we calculate work i.e heat transfer - work = specific internal energy @1 bar, 160°C - specific internal energy @ 100 bar, 360°C .................1
so first we get some value from steam table with the help of 100 bar @360°C and 1 bar @ 160°C
specific volume = 0.0233 m³/kg
specific enthalpy = 2961 kJ/kg
specific internal energy = 2728 kJ/kg
specific entropy = 6.004 kJ/kg-k
and respectively
specific volume = 1.9838 m³/kg
specific enthalpy = 2795.8 kJ/kg
specific internal energy = 2597.5 kJ/kg
specific entropy = 7.659 kJ/kg-k
now from equation 1 we know heat transfer q = 0
so - w = specific internal energy @1 bar, 160°C - specific internal energy @ 100 bar, 360°C
work = 2728 - 2597.5
work is 130.5 kJ/kg
and entropy change formula is i.e.
entropy change = specific entropy ( 100 bar @360°C) - specific entropy ( 1 bar @160°C )
put these value we get
entropy change = 7.659 - 6.004
entropy change is 1.655 kJ/kg-k
and we know maximum theoretical work = isentropic work
from steam table we know specific internal energy is 2038.3 kJ/kg
maximum theoretical work = specific internal energy - 2038.3
maximum theoretical work = 2728 - 2038.3
maximum theoretical work is 689.4 kJ/kg
