Hello,
As part of simulation of gases mixture and water, I need to calculate viscosity of the fluid components and I am using relationships proposed by Chung et al. (1988).
The irony is while I am able to validate that I have coded the relationships well for gases like methane, oxygen but when I am trying to do with water, there is drastic difference, especially for T between 300 K and 700 K.
In order to check if it is only in my case, I was able to find an article where the authors are closer than NIST/CoolProp data base.
I also need to evaluate conductivity and I have same issues for water. In the temperature range mentioned, the conductivity even goes negative in some regions.
I am not able to understand how come it shows this anomaly only in case of water.
May some one help in this regard.
Thanks
(P.S: I can share more info if required. Thanks)
Chung thermophysical models are valid for gases, if my memory serves. Couldn't you model water viscosity differently ?
Refik Alper Tuncer
Yes, I also thought so but looking at original paper, it seems they have evaluated for water also ( 273-973 K and 1-800 bar).
Moreover, I recently came across an article (Article High-fidelity numerical analysis of non-premixed hydrotherma...
)where they have compared with standard database. ( above ~300 K) figure 2 in their paper ( sent to you by message in order to avoid any copy. issues) . Black line as calculated by authors.
I am doing multicomponent system and would like to do as suggested in literature was thus wondering why the case of water is behaving so badly.
Thanks
I think that is actually water vapor, which is a combustion reaction product. In order to get a result that is close to NIST, you need to calculate the density properly. How do you calculate your density ? With Peng-Robinson ?
Yes, infact I get same output for density as in paper using PR ( fig. 2). That's why I was more concerned.
Only thing that comes to my mind is that you are within a critical region where PREOS actually yields two "reasonable" results(in fact three, but we disregard middle one), one for vapor and other for liquid phase. If your density calculator script chooses the vapor phase, where it is expected to be liquid then the discrepancy in viscosity (and likely all other thermodynamic properties) makes sense.
- Badges
- Science topic