Hi everybody,
I am a mechanical engineering performing a process design. I am a novice in this and need your help.
Problem: I have a incoming stream containing crude oil + water. I know only the following for both the fluids separately:
a) Mass flow rate
Incoming temperature and pressure
c) Density
d) Dynamic Viscosity
e) Specific Heat
Requirement: To know the Density, Dynamic Viscosity and Specific Heat of the mixture. Aim is to calculate the pressure drop when this fluid is flowing in a pipe with numerous bends.
How i tried to solve the problem:
1. For density and Specific Heat I believe the value for the mixture shall be the mass weighted average of the individual fluid values. Please correct me if I am wrong.
2. For Viscosity I searched the internet and found 2-3 references to the following:
a) There is a mentod of calculating the 'Kinematic' viscosity of a mixture using viscosity blending number method. Please see: https://neutrium.net...ty-of-mixtures/
For this method, first I converted the available dynamic viscosity values to kinematic viscosity for both the fluids. Then I used the above formula to calculate the kenimetic viscosity of the mixture. Then I reconverted this to the dynamic viscosity of the mixture by multiplying the vaue with the average density. This seems to be too convoluted. Am I doing it correctly?
Perry mentions that the dynamic vicosity (nu) of liquid mixtures can be calculated using:
ln numix = sum(i=1 to C) [xi * ln nui] + 0.5 * sum(i = 1 to C)[sum (j=1 to C) [xi * xj * Gij] ]
However, to use this method, I need the value of the constant G for each fluid which I have not been able to find.
Further, I tried to use two opensource process simulation software. COCO and DWSIM. These would easily provide me the physical properties of the mixture of the fluids. However, here I am faced with another problem - Crude oil is not a pure compound, and I dont know the exact constituents of this particular crude. All I know is the physical properties data mentioned above. How to model the crude in such a case in process simulation applications? Can I create a new compound with only the physical properties I know (only for the purpose of calculating the final mixture properties)?
Please help.