Chilled water distributaion header designing

[mfk87]

Hi,
i m designing chilled water distribution to AHU. now i m looking to design pipe header which supply chilled water to 7 AHU, each having flow 1.26 m3/hr also have inlet outlet pipe dia 3/4". AHU placed three different rooms. AHU unit 1 placed room 1, AHU unit 2~4 fitted in room 2 and remaining AHU unit 5~7 in room 3.
i want to design a pipe header which supply chilled water to all rooms, although 2" GI pipe having flow 15.2 m3/hr feed chilled water to the header. how many branches i have taken and size of branches from header. please help

 

[chemEcaleb]

If you're wondering if your pipe size is good, I would refer you to the Crane Fluid Flow manual which has some good rules of thumb for maximum flow rates through different pipe diameters. Just glancing at your flows I'd say 2" pipe for the header and 3/4" pipe for the branches is fine. You'll want to look at your pump curve to verify that you can supply enough pressure/flow. Toss in some valves and rotameters to set the flow rates and isolate the line, and you're good to go!

 

[GameJudge]

In addition to Crane's, Cameron Hydraulic Data can also be useful in these instances.

 

[srfish]

There is a chapter in the Handbook of Heat Exchnager Design that is about headers, nozzles and turnarounds. There are charts for momentum coefficients and branch loss coefficients for divided flows.

 

[chemEcaleb]

It's not rocket science though. You could probably do without calculations to design this header, and it would turn out fine. It all depends on your pump's capacity. Get the isometric designed, calculate the TDH, then look at the pump curve and make sure you're under the curve. Then you just use manual valves to set each flow rate.