# Compressed water enthalpy

1. Feb 18, 2010

### target

1. The problem statement, all variables and given/known data
Finding the enthalpy of water with the following known data:
Water, temperature 45 degrees, pressure 1.2 bar

2. Relevant equations
Q' = m'(steam) * h(gas) - m'(steam) - h(fluid)

3. The attempt at a solution
I need to find the enthalpy of water under the circumstances above, to calculate a quantity of heat transferred by condensing steam. However I seem to be unable to find the enthalpy of the fluid. All attempts to find the enthalpy, I end up with either tables of saturated water or compressed water at pressures way above 1.2bar. Anybody can help me with the problem?

2. Feb 18, 2010

### CFDFEAGURU

Just look the values up in the steam tables.

I am assuming that you are using degree C because your pressure is in bars. From my copy of the NBS/NRC Steam Tables I have the following value.

h for compressed water is 188.51 kJ/kg @ 45 C and 1.2 bars.

You haven't specified at quality and you clearly do not have superheated steam because the saturation temperature @ 1.2 bar is 104.81 C and you are well below that temperature. Therefore, you have a liquid-vapor mixture which means that you need a quality value in order to determine the other enthalpy value that you need.

Do you follow?

Thanks
Matt