1 reply to this topic

[pamjacinto]

Hi.

I am looking for equations which could calculate the overall viscosity of a liquid mixture. Is the Refutas equation a reliable one?

Also, if anybody knows the kinematic viscosity of the following, please tell me! Thanks so much.
glucose
xylose
KCl
KH2PO4
tetracycline

Edited by pamjacinto, 20 March 2011 - 12:20 AM.

[MrShorty]

Usually the first place I look when I have a question of this type is the text The Properties of Gases and Liquids by Prausnitz and others. In this text, Prausnitz states that, "Irving surveyed more than 50 equations for binary liquid viscosities and classified them by type. He points out that only very few do not have some adjustable constant that must be determined from experimental mixture data and the few that do not require such a parameter are applicable only to systems of similar components with comparable viscosities."

I'm not an expert on such things, but I notice that the Refutas equation does not have a mixture parameter. I also notice that references (on Wikipedia and such) are to petroleum refining texts. I'm guessing the Refutas equation is an acceptable methode for calculating the viscosity of hydrocarbon/hydrocarbon mixtures.

I expect the list of chemicals you gave is not random, but components in the liquid (aqueous??) mixture for which you want to determine the viscosity. It is my uneducated opinion that no expression as simple as the Refutas equation is going to correctly predict the viscosity of an aqueous mixture of electrolytes and sugars. Too many hydrogen bonds and such for a simple equation to account for.

As for tabulated values for the viscosity of those compounds, I don't know of any, and part of that probably is that you are asking for the viscosity of "normally" solid compounds (whatever viscosity means to a solid).

Because this is in the student forum, I expect this is part of some assignment you've been given. Perhaps if you could be more specific in the description of what you need the viscosity for, what the mixtures look like, etc. Someone with more experience in fluid dynamics could guide you better.