Y of water at 1000 C

1. Jan 10, 2014

dbmorpher

Hello,
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. Jan 10, 2014

bigfooted

The heat capacities are known from experiments and documented in the NASA polynomial databases, e.g. here:
http://www.me.berkeley.edu/gri-mech/data/nasa_plnm.html

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:
http://www.me.berkeley.edu/gri-mech/version30/files30/thermo30.dat

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

3. Jan 10, 2014

dbmorpher

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

4. Jan 10, 2014

Staff: Mentor

a1=3.03399249E+00
a2=2.17691804E-03
a3=-1.64072518E-07
a4=9.70419870E-11
a5=1.68200992E-14

You are familiar with E format for representing powers of 10, correct?

5. Jan 10, 2014

dbmorpher

Yes I am Chestermiller thank you for clarifying the constants for me.