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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.
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