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jay January 12, 1999 19:44

Ratio of specific heats

Can anyone tell me the value of gamma (Cp/Cv) for:

Ammonia (NH3), and Carbon Dioxide (CO2) and Carbon Monoxide (CO)

Thanks in advance.


Glenn Horrocks January 13, 1999 00:06

Re: Ratio of specific heats

The gamma for: CO2 = 1.289 CO = 1.400 (at 300K)

From Fundamentals of Classical Thermodynamics by Van Wylan & Sonntag.

I don't seem to be able to find NH3. Its Cp is 2.158 kJ/kgK at 300K, that's the best I can do. (From Fundamentals of Heat and Mass Transfer by Incropera and De Witt)

Maybe try the SI Chemical Data Book?

Regards, Glenn

Jens I. Madsen January 13, 1999 05:40

Re: Ratio of specific heats
I could not find the ratio of specific heats (gamma) for NH3 in a table either, but the value is easily deductable if you recall your basic thermodynamics:

R= Cp-Cv gamma = Cp/Cv

Combining these expressions, gamma can be computed from quantities that I did find, namely those for Cp and R.

gamma = Cp/(Cp-R) Cp = 2219 J/kgK (at 20 deg. Celsius) R = 488,3 J/kgK

=> gamma = 1.28

Table values where taken from "Bosnjakovic: Technische Thermodynamik"

jay January 13, 1999 10:50

Re: Ratio of specific heats
Glenn and Jens,

Many thanks for your replies, and for the references both of you provided.



Erwin Platvoet January 13, 1999 12:20

Re: Ratio of specific heats
Ratio of specific heats

ammonia = 1.310 carbon dioxide = 1.304 carbon monoxide = 1.404

at 15 deg.C and 1 atm.

Source: Perry's Chem. Eng. Handbook, table 3-185

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