# Viscosity of select species at atmospheric pressure for very large temperatures?

I'm dealing with hot combustion products flowing through heat exchangers and I'd like to perform some calculations regarding the flow properties (velocity, temperature, pressure and density) as it passes trough the heat exchanger.

I've a 1D model already built and I'd like to test it and validate it, but I'm lacking some critical information.

Is there any place where I can find the absolute viscosity [Pa*s] as a function of temperature (for pressures of 1atm, or close to it) for some select gases?

I need to know the viscosity between 300K and 2500K for gaseous CO2, H2O, N2 and O2. In polynomial form (something similar to the NASA/JANAF polynomials) would be nice, but in table would also be good.

I've already tried NIST, but it doesn't have that information for the temperature range I'm interested in.

Is it possible to run a macro for FLUENT, Star ccm+ or OpenFOAM and get those values from those programs? I have legal access to all of them.

• Can't you generate the table yourself using NASA polynomials? Most probably any table containing these data will be generated this way. – Algo May 8 '16 at 11:58
• You can also check the CoolProp library. – Algo May 8 '16 at 12:00
• Thanks, I'l check the library. The problem is not being able to generate the polynomials. The problem is that I'm not being able to find data for high temperatures. – André Almeida May 8 '16 at 13:33
• The method used in chemkin should take care of this pretty well. Described here. Equations and tables. – Dan May 9 '16 at 10:25
• Thanks! Can you put the link to the equations? I'm not finding them. – André Almeida May 12 '16 at 16:40

See NASA's computer program CEA (Chemical Equilibrium with Applications). From this site you can download an application to perform calculations. This application contains a text file called trans.inp with coefficients, $A$ through $D$, for an empirical dynamic viscosity equation: $$\ln\eta=A\ln T+\frac{B}{T}+\frac{C}{T^2}+D$$ and for thermal conductivity: $$\ln\lambda=A\ln T+\frac{B}{T}+\frac{C}{T^2}+D$$
with $T$ in Kelvin, $\eta$ in $\mu$P (or $10^{-7}$Pa s), and $\lambda$ in $\mu$W/cm K (or $10^{-4}$W/m K).
The file contains coefficients for multiple temperature ranges (up to 10,000 K for CO$_2$ and 15,000 K for H$_2$, N$_2$, and O$_2$) and also for binary interaction parameters, e.g., $\eta_{ij}$ for species $i$ and $j$, required for obtaining the viscosity of mixtures.
Unfortunately I didn't found any information regarding the high temperature values for the viscosity nor the conductivity for those gases. I used a very crude method to get around the issue. Basically, I interpolated the available data using some functions up to the upper temperature limit of the available data (usually around 1000K), and then used the obtained functions to extrapolate up to 2000K. The functions where selected on the basis that "they maintained the general tendency on the behavior of the available data up to the maximum limit of 2000K, not allowing for any sharp inflexions or other oscillatory phenomenon". This method is extremely crude, but my application did not require very high precision. You can read it further in my Master's thesis (the work where I used this information). When the document is available to the general public I'll post the link here. Bellow is a figure of the used equations and the available data vs. interpolating/extrapolating functions. Note some discontinuity where the data from NIST (full lines) meet the extraplations (dashed lines): 