To find out pressure drop in a coil 2

[nvk123]

I have to design a coil for limiting the oil flow to 50 cc per minute using 1 mm dia tubing(coil) where upstream pressure is 70 bar and desired press is 38 bars.Whats the length,coil dia??? any help ???

 

[armonicman]

your coil must have a lenght of 39-40 cms

 

[chem55]

Hi Armonicman:

Could you pls explain me how did you calculate the length of the coil?

Thanks,
Chem55

 

[TD2K]

You just need to do a pressure drop. Basically, you'll need to estimate the oil's density and viscosity.

You have a tubing of a known ID and pressure drop (32 bar). Determine the length such that the flow is 50 cc/min. Since you know the flow, you know the Re and therefore the friction factor to solve the problem.

 

[quark]

TD2K is right and I want to add something from Perry's. When fluid flows in a coil, a secondary circulation perpendicular to the main flow occurs and this is called Dean Effect. This increases the friction relative to straight pipe flow and stabilizes laminar flow.

The new transition Reynolds No. can be calculated by the equation

Re(trans) = 2100[1+12(D/Dc)^1/2], where Dc is coil diameter and D is pipe diameter.

This formula is applicable in the range,
10<Dc/D<250.

Believe it or not : It is believed that Archimedis single handedly sailed the 4000 ton ship Syracusia from the dock when dock workers failed and quoted his famous saying.

 

[quark]

Sorry, I struck the button accidentally.

The Dean No. is given by De = Re/(Dc/D)^1/2

and the corrected friction factor is standard for laminar flow as in normal case and for turbulent flow,

fc/f = 1 + 0.09[De^1.5/(70+De)]

Regards,




Believe it or not : It is believed that Archimedis single handedly sailed the 4000 ton ship Syracusia from the dock when dock workers failed and quoted his famous saying.