(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A well-insulated closed tank is of volume 70 m^3. Initially, it contains 25000 kg of water distributed between liquid and vapor phases at 30 deg C. Saturated steam at 11 bar is admitted to the tank until pressure reaches 7 bar. What mass of steam is added?

2. Relevant equations

m' = m2 - m1 (where m' is mass of steam, m2 is final mass in tank and m1 is initial mass in tank, m1 = 25000 kg)

m2H2 - (m1H1 + m'H') = 0

m2/m1 = (U1 - H')/(U2 - H') = (H' -U1)/(H' - U2)

3. The attempt at a solution

Q = 0 if well insulated

Assume W = 0

Kinetic and potential energies can be ignored

V(tank) = constant and is taken to be the control volume

H' = 2779.7 kJ/kg (from steam tables)

I know m1 and H'. I thought if volume of tank is constant than i can calculate P1 from P1V1=P2V2 but then that just gives me that the pressure is constant too. I need to figure out the enthalpies of the contents in the tank before and after the addition of the sat. steam and then I should be okay. Can anyone help? Thanks!

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Thermodynamics: Addition of saturated steam to closed tank

**Physics Forums | Science Articles, Homework Help, Discussion**