Flow Nozzel Pressure Drop
Flow Nozzel Pressure Drop
(OP)
Hi all,
I want to calculate the pressure drop over an ISA (short radius) flow nozzle. I've followed three different approaches to model the pressure drop, but all three delivered different answers.
I have a 250mm pipe, with a 191.76mm nozzle. The upstream pressure of the steam is 171 bar @ 540ÂșC, flowing at 126.7 kg/s.
If I follow the ISO 5167-3 code, I calculate a pressure drop of 9.5 bar.
If I apply isentropic expansion theory (in conjunction with the discharge coefficient used above) I calculate a pressure drop of 2.2 bar.
I have also calculated a K-loss factor from the discharged coefficient and applied it to K_loss*0.5*rho*Vel_nozzel^2. From this approach I've calculated a pressure drop of 1.2 bar.
Could anyone please give me some insight into this problem.
Regards
I want to calculate the pressure drop over an ISA (short radius) flow nozzle. I've followed three different approaches to model the pressure drop, but all three delivered different answers.
I have a 250mm pipe, with a 191.76mm nozzle. The upstream pressure of the steam is 171 bar @ 540ÂșC, flowing at 126.7 kg/s.
If I follow the ISO 5167-3 code, I calculate a pressure drop of 9.5 bar.
If I apply isentropic expansion theory (in conjunction with the discharge coefficient used above) I calculate a pressure drop of 2.2 bar.
I have also calculated a K-loss factor from the discharged coefficient and applied it to K_loss*0.5*rho*Vel_nozzel^2. From this approach I've calculated a pressure drop of 1.2 bar.
Could anyone please give me some insight into this problem.
Regards
Philip Oosthuizen
Company info:
SteinMuller Engineering Services
http://www.steinmuller.co.za/





RE: Flow Nozzel Pressure Drop
Get to the above online calculator and type in the word
"free" in the code box. You will need to convert your
units.
RE: Flow Nozzel Pressure Drop
dP = (1+0.014Beta?2.06Beta^2+1.18Beta^3) *W^2/rho1/(0.126447*K*Beta^2*D^2*Y1)^2
Beta = 191.76/250 = 0.767
W = 126.7*3600 = 456120 kg/h
rho1 = 51.78 kg/m3
K = 0.98/sqrt(1-Beta^4) = 1.21
D = 250 mm
Y1 = 0.99 (approx, from graphs)
dP = 0.331 * 130 kPa
= 43 kPa (permanent)
Groete
CKruger