What is the Enthalpy of Water at 45 Degrees and 1.2 Bar Pressure?

  • Thread starter Thread starter target
  • Start date Start date
  • Tags Tags
    Compressed Water
target
Messages
2
Reaction score
0

Homework Statement


Finding the enthalpy of water with the following known data:
Water, temperature 45 degrees, pressure 1.2 bar


Homework Equations


Q' = m'(steam) * h(gas) - m'(steam) - h(fluid)


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?
 
Physics news on Phys.org
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
 
Thread 'Need help understanding this figure on energy levels'
This figure is from "Introduction to Quantum Mechanics" by Griffiths (3rd edition). It is available to download. It is from page 142. I am hoping the usual people on this site will give me a hand understanding what is going on in the figure. After the equation (4.50) it says "It is customary to introduce the principal quantum number, ##n##, which simply orders the allowed energies, starting with 1 for the ground state. (see the figure)" I still don't understand the figure :( Here is...
Thread 'Understanding how to "tack on" the time wiggle factor'
The last problem I posted on QM made it into advanced homework help, that is why I am putting it here. I am sorry for any hassle imposed on the moderators by myself. Part (a) is quite easy. We get $$\sigma_1 = 2\lambda, \mathbf{v}_1 = \begin{pmatrix} 0 \\ 0 \\ 1 \end{pmatrix} \sigma_2 = \lambda, \mathbf{v}_2 = \begin{pmatrix} 1/\sqrt{2} \\ 1/\sqrt{2} \\ 0 \end{pmatrix} \sigma_3 = -\lambda, \mathbf{v}_3 = \begin{pmatrix} 1/\sqrt{2} \\ -1/\sqrt{2} \\ 0 \end{pmatrix} $$ There are two ways...
Back
Top