TITLE.PM5

198 ENGINEERING THERMODYNAMICS

dharm

/M-therm/Th4-6.pm5

(^1) x 1
a
2
p 2
p 1
h
s
(c)
Fig. 4.66. Reversible adiabatic or isentropic process.
+Example 4.57. 1 kg of steam at 120 bar and 400°C expands reversibly in a perfectly
thermally insulated cylinder behind a piston until the pressure is 38 bar and the steam is then
dry saturated. Calculate the work done by the steam.
Solution. Mass of steam, m = 1 kg
Initial pressure of steam, p 1 = 120 bar = 120 × 10^5 N/m^2
Initial temperature of steam, t 1 = 400°C.
Fig. 4.67