1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Steam tables and enthalpy

  1. May 17, 2007 #1
    Hello again...i was wondering if you can help?

    I am using enthalpy equations to try and find h1 and h2 to work out 'work and heat transfers' for water, for a piston type question.

    I have calculated work done using: [w = -PDV]

    To find the heat transfer i need to use: [Q=m.(h2-h1)]

    i have obtained h1 using: h1 = hf + x(hg-hf) (using steam tables)

    This has been calculated at 1826 kg/m3, from a revision guide all it states to calculate h2 is:

    ''From the steam table using h1 find h2?''

    This is the only piece of information i need to complete the heat transfer calculation (to find h2) can you help at all? I dont now how to find h2.

    I know m = 0.15, and h1 is 1826kg/m3 and Q is 223 kj

    But h2?!?!?!

    Guidance on how to look this up would be appreciated.
  2. jcsd
  3. May 18, 2007 #2
    It would help if you could post the complete problem statement. For these types of problems, it usually helps to draw out the P-V and T-S diagrams. I suspect the equation relating enthalpy and work will help here, it should be somewhere in your text
  4. May 19, 2010 #3
    Posting the whole question would have got the job done but anyway have you tried these formulas

    since hf2 can be found on the tables and hfg

    or w=h1-h2
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook