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: Internal Energy of Natural Gas

  1. Apr 6, 2008 #1
    1. The problem statement, all variables and given/known data
    I have liquid natural gas, or LNG, at -165degrees Celsius. I want to know the total energy required to heat the gas up 50ml to 5 degrees Celsius.

    2. Relevant equations
    Not sure.
    Im assuming I need information regarding specific heat etc. Heat of vaporization maybe?

    3. The attempt at a solution
    Tried to hunt down some more data on LNG but couldn't find it. I do remember a formula from my highschool days a long the lines of Q=MC(T2-T1). Not sure however if that only applies to solids?
  2. jcsd
  3. Apr 6, 2008 #2
    total energy = H1 + H2 + H3

    H1 = (Cp x mass x (bp - (-165oc))
    H2 = (heat of vap x mass)
    H3 = (Cp x mass x (5oC - bp)

    Yes you will need density, specific heat and Heat of vap of the LNG (and b.p of course) - don't know if it will be good enough to use the methane values though
  4. Apr 7, 2008 #3
    Ok I needed a fair amount of safety, so I used worst case scenarios of Cp being 2.5J/kg.K and Vap being approx 600kJ/kg. The specific gravity was 0.6.

    I calculated it to being approx. 30kJ. Does that sound correct?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook