Getting a Sanity Check on Calculating Combined Density of Gas & Liquid Flow

In summary, the conversation discusses a problem involving a pipe with a combination of gas and liquid flowing through it. The density of the gas and liquid are given, along with a vapor fraction and flow rate. The combined density is calculated using two different methods: one using the given densities and vapor fraction, and the other using the flow rates. The question arises about the interpretation of the vapor fraction and which approach is correct.
  • #1
MuzMond
2
0
Hello,
Long time lurker, 1st time poster.

I need a sanity check that I am solving this problem correctly.

I have a pipe with a combination of gas and liquid flowing through it, the density of the gas (ρg) is 5.5kg/m^3, the density of the liquid (ρL) is 435 kg/m^3.

I have a vapor fraction (vf) of 0.92
I also have a flow rate of 5000kg/hr.


The combined density ρc = ρg*vf + ρL(1-vf) = 5.5*0.92 + 435*0.08 = 5.06+34.8=39.86 kg/m^3.


Is the combined density per the method shown above, or do I use the volume flow rate Q to determine the combined density.

flow of liquid = 5000*0.08 = 400kg/hr
flow of gas = 5000*0.92 =4600 kg/hr
dividing by densitys to get volume flow,
Q liquid = 0.091 m^3/hr
Q gas = 836.36 m^3/hr

Combined volumetric flow = 836.36+0.091 = 836.451 m^3/hr
As total mass flow is 5000 kg/hr.
Density is mass/vol
Combined density = 5000/836.451 = 5.98 kg/M^3.

Any advice would be welcomed.

MM
 
Physics news on Phys.org
  • #2
in the first method, you assume that the vapor fraction is a volume fraction. In the second approach, you assume that it is a mass fraction.

Does 0.92 mean that 92% of the volume is gas or does it mean that 92% of the mass is gas?
 

1. What is the purpose of calculating the combined density of gas and liquid flow?

The combined density of gas and liquid flow is used to determine the overall density of a mixture, which is important for various industrial and scientific applications. It can also help in understanding the behavior and characteristics of the mixture.

2. How is the combined density of gas and liquid flow calculated?

The combined density is calculated by multiplying the density of the gas by its volume fraction and adding it to the density of the liquid multiplied by its volume fraction. The resulting value is the combined density of the mixture.

3. What factors can affect the accuracy of the calculated combined density?

Several factors can affect the accuracy of the calculated combined density, including temperature, pressure, and composition of the gas and liquid components. It is important to ensure that all these factors are taken into account when performing the calculation.

4. Can the combined density of gas and liquid flow be measured directly?

No, the combined density cannot be measured directly. It can only be calculated using the individual densities and volume fractions of the gas and liquid components.

5. How can I validate the accuracy of my calculated combined density?

The best way to validate the accuracy of your calculated combined density is by comparing it to experimental data. You can also perform sensitivity analyses by varying the input parameters and observing the impact on the calculated value.

Similar threads

  • Engineering and Comp Sci Homework Help
Replies
6
Views
4K
  • Engineering and Comp Sci Homework Help
Replies
1
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
1
Views
3K
  • Classical Physics
Replies
6
Views
1K
  • Introductory Physics Homework Help
Replies
6
Views
6K
  • Mechanical Engineering
Replies
4
Views
19K
Replies
2
Views
2K
Back
Top