How can I caculate flowrate for recangular copper tube?

[DavidE]

Hello All!

Can you please advise me how to calculate the water flow through different sizes of rectangular copper tube? I need to use the following information.
1. Input water pressure of 2kg/cm2 (This is the normal value, but could vary between 1 and 3kg/cm2)
2. Various lengths or rectagular copper tube from 500mm to 5000mm.
3. Various sizes of rectangular copper tube from 6 x 6mm, 6 x 8mm, 12 x 10mm up to 45 x 45mm in all combinations.

Many thanks in advance!
DavidE

[admin]

For rectangular cross section of pipe you should use hydraulic radius like:
Dh=4A/P, A - cross section area, P - wetted perimeter, and for rectangle is Dh=4*L*W/2(L+W) = 2 * L * W / (L+W), where is L, W dimensions of rectangle.

This hydraulic radius than should be used in pressure drop calculator at:
http://www.pipeflowcalculations.com/pressuredrop/

For it you must enter pressure on the start of pipe and pressure on the end of pipe in order to calculate flow rate, together with other values.
Select "calculate for flow rate", than enter other values for L, D, kr, rho, p1 and pressure drop or p2 and you will get results for flow rate.

[DavidE]

Dear Admin,
Many thanks for your reply and detailed instructions. I have been trying to get an answer on the flowrate from your pressure drop calculator, but it doesn't appear to be working! After filling in the boxes as requested, and that are not greyed out, I click on Report, which shows all of the values that I have input, plus the greyed out values, but nothing changes in the output area. All the values are the same as before I clicked on the Report button. Am I doing something wrong? or is there a fault with the calculator?

Regards,
DavidE

[DavidE]

Hello again. I have tried again this evening and it is working well now. Thanks very much!

Regards,
DavidE

[admin]

Glad you have solved it and don't forget to press "calculate" button.

[DavidE]

Hello!

Now I need to know how many litres per minute are needed to disipate 1kw of heat, and then after the 1kw is disipated, how much the temperature of the water will rise?

Actually the kws will be variable between say 10 and 30, but I assume the formular for 1kw can be multiplied by 10 to 30 as required.

Not sure if one of your calculators can be used, but and advice will be gratefully received.

By the way, your flowrate calculator worked really well, so thanks very much again!

Regards,
DavidE

[admin]

Thank you for nice word.

Heater calculator should be used at:
http://www.pipeflowcalculations.com/heater/

There you should choose calculate for flow rate and enter heat power of 1kW, but you also have to know temperatures if you want to calculate flow rate.

Here is the report that I have:

Heater/Chiler calculator
CALCULATION REPORT
1. mass flow rate (w): w = 43.000446 kg/h
2. volumetric flow rate (q): q = 0.011944576 l/s
3. density (ρ): ρ = 1000.0 kg/m3
4. diameter (D): D = 60 mm
5. velocity (V): V = 0.0042245295 m/s
6. specific heat (c): c = 4186 J/kgK
7. thermal power (P): P = 1 KW
8. inlet tempearture (T1): T1 = 70 C
9. outlet tempearture (T2): T2 = 90 C
10. tempearture difference (Δ T): Δ T = 20.0 C

[DavidE]

Hello!

Many thanks for your detailed reply! I have been busy, so only just started to look at it. I'll let you know how I get on. Apart from this, I am quite interested to know who you are and where you are, and how is it that you have such a great website and calculators, but make no charge?

Regards,
DavidE

[admin]

I am mechanical engineer living and working in Serbia. First calculators I have made for me and decided to make as applet and put on web. As it became popular I made even more with additional featurs so now, 10 years after, it is looking as it is and will be better in time to come. As long as advertisers are willing to pay I will not charge, as I think that majority of users are occasional and charging them will not be effective.

[DavidE]

Hello again!

Many thanks for the interesting story about you and your webpage, and sorry for the late reply. I am also an engineer, an Induction Heating specialist, and have spent quite a bit of time commissioning equipment in the former Yugoslavia. One company I can remember at the moment is Viz Viscana (not sure if the spelling is correct)

I wonder if you could help me again, by rechecking a flow rate that I have from your pipe flow calculator. Your calculator is giving a different flow rate from a flow rate that a colleague is coming up with, using his own method. I'm not sure if I am putting in a wrong values, or his calculation is incorrect.

Quite simply, I need to know the flow through 11m of smooth rectangular copper tube 34mm x 17mm x 3.5mm wall thickness. Taking off the wall thickness, I input 27mm x 10mm for the tube size, and 2 bar at P1 and 0.3 bar at P2, so 1.7 bar forward pressure. The other values I have input are: V = 1.004. K = 0.001. Kr = 0.1. I did not change any other default values.

I am getting about 55 L/min, and my colleague is getting 82 L/min, who is correct? Many thanks in advance!

Regards,
DavidE