Calculating drop in gas pressure

AI Thread Summary
The discussion focuses on calculating gas pressure drop using Poles Formula, with specific parameters provided for flow rate, pipe diameter, length, and gas density. The calculated pressure drop of 2.2459 mbar appears consistent; however, the user raises a concern about the relationship between flow rate and pressure drop. It is clarified that a lower flow rate results in less friction, leading to a higher pressure at the pipe's end, which aligns with fluid dynamics principles. This indicates that higher flow rates indeed cause greater pressure loss due to increased friction. Understanding this relationship is crucial for accurate pressure drop calculations in gas systems.
Cardigan9
Messages
1
Reaction score
0
Poles Formula (see page 10 of attachment)

www.mech.hku.hk/bse/MEBS6000/mebs6000_1011_04_steam.pdf

Where have I gone wrong?

• q = flow (m3/h)
• d = diameter of pipe (mm)
• h = pressure drop (mbar)
• l = length of pipe (m)
• s = specific gravity of gas (density of gas / density of air)

h = ( q^2 * s * l ) / ( 0.0071^2 * d^5 )

q = 6 m3/h
d = 20mm
l = 19M
s = 0.58

The result is 2.459 i.e. the pressure drops by 2.2459 mb, which on the face of it looks fine, the problem is that if I reduce the flow rate the loss of pressure over the length of the pipe drops. Which in theory means that if I start with 21mb gas pressure and have a lower flow rate I end up with a higher pressure at the end of the pipe; that can't be right can it?
 
Last edited by a moderator:
Physics news on Phys.org
Yes, that is correct. Higher flow causes more friction and more pressure loss.
 
Thread 'Collision of a bullet on a rod-string system: query'
In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
Thread 'A cylinder connected to a hanged mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top