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!

Y of water at 1000 C

  1. Jan 10, 2014 #1
    I am trying to find the heat capacity ratio of water at 1000C or 1273.15K.
    I have tried to find it through various website but have yet to find anything past 375C. I could find the gamma if I was given any of the two types of heat capacity ratios (volumetric or pressure) I could get it myself. I would like to find this out because it is useful for a rocket engine I am trying to design.
  2. jcsd
  3. Jan 10, 2014 #2
    The heat capacities are known from experiments and documented in the NASA polynomial databases, e.g. here:

    There, you see that heat capacity can be calculated using
    Cp/R = a1 + a2 T + a3 T^2 + a4 T^3 + a5 T^4
    where the coefficients a are given in the thermodynamic database:

    In the thermodynamic database mentioned there, the H2O entry is:
    H2O L 8/89H 2O 1 G 200.000 3500.000 1000.000 1
    3.03399249E+00 2.17691804E-03-1.64072518E-07-9.70419870E-11 1.68200992E-14 2
    -3.00042971E+04 4.96677010E+00 4.19864056E+00-2.03643410E-03 6.52040211E-06 3
    -5.48797062E-09 1.77197817E-12-3.02937267E+04-8.49032208E-01 4

    the coefficients a1..a5 for the high temperature range 1000 K - 3500 K are given in line 2
  4. Jan 10, 2014 #3
    Thank you for the help bigfooted but I am sorry to say that I don't really understand the differences in the different a# coeffficients. I understand what to do with them but do not really know which a is which
  5. Jan 10, 2014 #4

    You are familiar with E format for representing powers of 10, correct?
  6. Jan 10, 2014 #5
    Yes I am Chestermiller thank you for clarifying the constants for me.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook