Total friction loss through parallel streamlines
Total friction loss through parallel streamlines
(OP)
Hi,
Lets say I have two parallel streamlines for gas between point A and point B, and two parallel streamlines for liquid between point A and point B. Further, I know the friction losses for all 4 streamlines. Then, how can I calculate the total friction loss for the gas, and the total friction loss for the liquid?
PS I suspect that parallel electrical circuit laws can be used somehow [1/RT = Σ(1/Ri) or 1/√RT=Σ(1/√Ri)]
\Carl
Lets say I have two parallel streamlines for gas between point A and point B, and two parallel streamlines for liquid between point A and point B. Further, I know the friction losses for all 4 streamlines. Then, how can I calculate the total friction loss for the gas, and the total friction loss for the liquid?
PS I suspect that parallel electrical circuit laws can be used somehow [1/RT = Σ(1/Ri) or 1/√RT=Σ(1/√Ri)]
\Carl





RE: Total friction loss through parallel streamlines
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist
RE: Total friction loss through parallel streamlines
I have roughly estimated the frictional losses based on geometry and velocities. The velocities are "first guesses" in the Bernoulli equation, and I will use iteration to find the end solution. But before I can do that, I need to combine the two frictional streamlines for the gas and liquid phase.
Hope you guys can help me out.
\Carl
RE: Total friction loss through parallel streamlines
Katmar Software - AioFlo Pipe Hydraulics
http://katmarsoftware.com
"An undefined problem has an infinite number of solutions"
RE: Total friction loss through parallel streamlines
RE: Total friction loss through parallel streamlines
The only thing you actually know is the pressure drop between your points A and B is the same for each pipe. I hope by streamline you actually mean pipe. Please confirm or otherwise this post is talking rubbish.
You say parallel, but are the two pipes for each fluid the same size?
For any given pipe size and lengthy, resistance to flow is more or less proportional to the square of the velocity.
Energy loss is head loss times flew times density.
Is this what you want to find?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Total friction loss through parallel streamlines
I'm asking for a formula to calculate total friction loss for parallel pipes.
I have tried to illustrate it in the picture. Upstream point A and downstream point B, there is a common pipe.
RE: Total friction loss through parallel streamlines
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist
RE: Total friction loss through parallel streamlines
RE: Total friction loss through parallel streamlines
Richard A. Cornelius, P.E.
WWW.amlinereast.com
RE: Total friction loss through parallel streamlines
dicksewerrat: Taking one of the pipes out of service is not an option.
RE: Total friction loss through parallel streamlines
What do you mean by total friction drop? Pressure drop is often the same thing.
Your first point is the fact that your pressure drops in all the pipes is the same. Your variables are many, but flowrate is the first one to resolve.
Depending how long these pipes are the density of your gas might change from one end to the other.
You really nerd to start putting some dimensions to this to have any chance of solving it. I don't think threes any easy formulae.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Total friction loss through parallel streamlines
RE: Total friction loss through parallel streamlines
RE: Total friction loss through parallel streamlines
I'm thinking the two upper pipes (Are the upper two vent pipes of some kind - connected somehow on both ends to liquid service pipes below? ) are going to start vaporizing first, and will be probably mostly gas at saturation conditions for most of the length. If they drain - maybe back to the first reservoir - then they'd be a mix of vapor on the bottom flowing with gravity, and vapor on top flowing with pressure. The condensate could be pushed along though - depends if the upper pipe would ever "plug up" with too much liquid to let the gas go by. Depends too on delta P, and if my guess about drain direction is right.
Lower pipe seems a mix of vapor in the upper pipe and liquid in the lower, unless the pump suction from reservoir 1 is always below the condensate level. Then you'd only have flashing problem down low. Same guess as above: I'd need to a complete 3D model or drawing to begin doing anything but guessing.
RE: Total friction loss through parallel streamlines
What about single phase flow through the pipes? Is there any way to determine the total friction loss with a simpler approach?
RE: Total friction loss through parallel streamlines
If you mean the energy expended, then you can use the pump hydraulic power equation
P = Q x Dens x g x h / 3.6x10^6
P - kW
Q- m3/hr
Dens = density in kg/m3
g = 9.81
h hydraulic head loss in m of fluid (you can get this from your pressure drop)
For the same pressure drop, flow through different size pipes is around (d/D)^2
Look at this threads and scroll down to the post by Katmar
http://www.eng-tips.com/viewthread.cfm?qid=402971
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Total friction loss through parallel streamlines
RE: Total friction loss through parallel streamlines
To TenPenny - we all agree with what you are saying, however, the subtle intent of the original OP is to mix two phases presumably flowing at different rates and pressures.