Friction los calculation lines

[Peter_1]

We use for the calculation of the friction loss along the lines the formula

Dp = Re x L x rho x V(square) /d/2 where rho is the density of the refrigerant in that line, d= inner diameter, L = length of the line (and additional the equivalent length of the bends in this line) and Re the Reynolds number of the used copper.

Literarture I have gives me Re numbers from 0.015 to 0.035 (or a differencee of +/- 250% which can give me a friction loss difference of 250%)
Does anyone have more accurate numbers because you then better guess the friction loss?

Or does someone use another formula to calculate this?

[Josip]

Hi, Peter_1 :)

Is this of some help;)

Best regards, Josip :)

[Peter_1]

Thanks Josip but I think I have the same problem: what do I have to take for 'f' ??

Formula 3 inlet and outlet pressure, that's now exactly what I need to calculate.

[US Iceman]

Peter,

Here is a link to some material that may help you.

http://arash.dejkam.com/software/pressure_loss/

I think it is in IP, but it shows the process of calculation.

The "f" is the friction factor which you need to find the pressure loss. The friction factor is read from the Moody diagram once you find the Reynolds number.

I'm still looking for an SI version, so you do not have to do unit conversions.

Have patience...;)

Edit:

Perhaps this will help you Peter.
http://www.engineeringtoolbox.com/darcy-weisbach-equation-d_646.html

[Josip]

Hi, Peter_1 :)


Thanks Josip but I think I have the same problem: what do I have to take for 'f' ??

Formula 3 inlet and outlet pressure, that's now exactly what I need to calculate.

Take a look at this:

http://www.engineeringtoolbox.com/darcy-weisbach-equation-d_646.html
http://www.engineeringtoolbox.com/colebrook-equation-d_1031.html

and


Have patience...;)

Best regards, Josip :)