Help : HYSYS Properties of Liquid-Aqueous Mixture 2

[takiyasamsama]

Hi,

I am really not a chemical engineer but I received one HYSYS data sheet from my client to design a heat exchanger.

Below is what I'm trying to figure out, for example below, the viscosity for liquid and aqueous was below hundreds but when it combines the overall viscosity becomes more than hundreds. Any advise?

40.01 cP is the liquid viscosity and 0.9504 cP is the aqueous viscosity then 135 cP is the overall (mixture) viscosity

How did HYSYS get the 135 cP for the mixtures? Any special formula? Perhaps multiply by something i.e. molecular weight or etc.?

Any advise is highly appreciated.

 

[rense]

simulators can include several models for mixtures, for example my copy of Prode Properties includes several models discussed in The Properties of Gases and Liquids (which I adopt as reference in many cases).
Many different rules have been proposed (in literature) for example, for ideal liquid mixtures you may adopt a simple additivity rule (which would suggest a intermediate value as you noted) but for complex interations (as water-hydrocarbons which can be considered as immiscible fluids) things are more difficult, for example you may have a heavy oil in water emulsion etc. which require specific rules...
In general, emulsion's viscosity can be a lot higher than the one of water or oil, due to non-Newtonian behavior but take care that for these cases the automatic procedures available in most simulators can produce unreliable results...
Considering the importance of correct value of viscosity for heat exchanger design I would soggest to contact the client and discuss the value to adopt...

 

[takiyasamsama]

Thanks rense,

I agree that the best thing would just consult with client but my client told that they are having 3 phases at the exit terminal.

Okay, the unit we're about to design is a crude oil heater and the oil at the beginning (inlet) only consists of water and crude oil thus the liquid and aqueous stream. However, upon leaving or even half-way through the heating process the water content inside the mixture seems to have slightly evaporating.

Thus we have requested client to give the raw process data i.e. HYSYS data sheet but then on the outlet stream the program (HYSYS) unable to compute the viscosity hence I need to design this to cater for two-phase application where liquid and vapor would affect the sizing of the heat exchanger.

I was trying to figure out how to find the viscosity at the outlet since HYSYS data sheet splits the viscosity to individual viscosity, I know some might say just consider the heaviest/thickest viscosity but this kind of exchanger doesn't work that way or else we'd over-design them.

 

[rense]

the normal procedure is to divide exchanger in zones and then calculate conditions and transport proerties in each zone, with those values you can estimate velocities, Prandtl Numbers (or equivalen parameters and so on...)
for that you need to solve phase equilibria at specified H (with a H-P or equivalent flash operation) which gives the operating conditions (compositions of different phases at equilibria) and then estimate transport properties as viscosities...
With Prode Properties I am able to calculate all these values (compositions and transport properties in each zone) as a table in Excel for further processing, you may ask your client to do the same...

 

[georgeverghese]

This is probably a nonsense value produced by Hysis for this aqueous mix (like so many other predictions with these simulators when water gets in the way). There are some mixture physical property estimation methods in Perry, and some of them are valid for polar - non polar phase mixes.

 

[Iomcube]

takiyasamsama, it is possible shear-thinning & shear-thickening fluids (google it) ...but in your case these value are way of chart!


rense, Free PRODE version may not be able to do so but I will really appreciate if you can upload some screenshots regarding your procedure (which appeals to me greatly)

With Prode Properties I am able to calculate all these values (compositions and transport properties in each zone) as a table in Excel for further processing, you may ask your client to do the same...

 

[rense]

Iomcube,
Not sure if that is what you are looking for but there is a simple Excel page which calculates the properties in different zones (see image)

it works with all versions of Prode Properties, including free version