equations for pressure drop for flow in spirals

[jmelia]

I have a tank bottom's spiral jacket and I need to estimate the pressure drop for water flow.
I looked in Perry's:
"the pressure drop for flow in spirals es discussed by Srinivasan...." but there is no formula and I'm not able to found it in any article.
Could anyone help me?
thanks in advance

j

 

[25362]

I'll give herebelow the formulas that professor Lydersen gives in his book Fluid Flow and Heat Transfer, John Wiley and Sons.

The friction factor:

f=0.076Re[sup]-1/4[/sup]+0.0073(D/D[sub]c[/sub])[sup]0.5[/sup] +/- 10%​

Where D (m) is the inner tube diameter, and D[sub]c[/sub] (m) is the coil diameter.

The formula applies when 0.34<Re(D/D[sub]c[/sub])[sup]2[/sup]<300

and the friction drop:

P[sub]f[/sub], N/m[sup]2[/sup]=4(f)(L/D)(density of fluid)V[sup]2[/sup]/2,​

L: length of coil, m
density of fluid: for water, 1000 kg/m[sup]3[/sup]
V: fluid velocity, m/s

As a reference Professor Lydersen also mentions Srinivasan et al.: &quot;Friction factors for coils&quot;, Trans. Instn. Chem. Engrs., 48, T156-T 161 (1970)

I hope this is of help.

 

[jmelia]

thanks 25362,
these are the same formulas proposed on Perry's handbook.
but what happens in a spiral pipe with a increasing/decreasing diameter?

thanks
j