Question

A sealed rigid tank .4m^3 filled with steam at 6.5 bar and is at 300 o C. It is cooled until contents become saturated vapor. Find mass of steam, final T/P of tank, and how much heat must be removed if cooling is reversible??

Answer 1

P = 6.5 bar

T = 300 oC

at this state points the enthalpy and and quality of steam from steam property table is

State = overheated steam

Specific enthalpy= 3060.78 KJ/Kg

specific volume = 0.4 m3/Kg

Mass of steam = 0.4/0.4 = 1 Kg

now the tank is cooled so the Volume will remain unchanged and the state is saturated vapor

Hence we will look in the steam table for saturated vapor with this specific volume of 0.4 m3/Kg

From steam table

P =4.7 bar

T =149.51 oC

H = 2745.340 KJ/Kg

Heat removed =3060.78 -2745.340 =315.44 KJ/Kg (since we have 1 kg of steam) = 315.44 KJ of heat is removed