Circulating piping system

[semantha]

hi,

I am designing a ground source heat pump system. I need to design a circulating piping system to disipate heat to the soil.my system is using the a very long U tube. the fluid will circulating from the surface of the ground to the underground (very deep, bout 50m). my question is it correct i am using bernoulli equation to calculate the overall system head to size the circulating pump? i ignore the minor losses since the pipeline is relatively long and i am using the HDPE pipe.

thank you very much!!

 

[JStephen]

You should be able to use some form of Bernouli's equation.

You need to include pipe friction losses, which you don't mention. You need to include effects of density variation due to temperature variation. Pumping cold water down and hot water up, you may not need a pump at all, and will require additional pumping to go the other way.

 

[hbw]

Contact HDPE pipe manufacturer and request water pressure loss table.

Otherwise refer to Crane Technical Paper No 410, "Flow of Fluids though Valves, Fittings and Pipe" published by Crane Company, 104 N. Chicago Street, Joliet, IL 60434

 

[gimini21]

Semantha,
If you are sizing your pump as a close-loop system, whether your distribution is higher than or lower than your pump level, the only method I know and is theoritically appropriate is the Bernouli's theorem. Surely you can ignore minor losses and I believe you understand these type of losses. In my case unless the data are practically hard to find, I normally make it a habit to plug every losses I encountered. So I gues what you are planning is to make an energy balance from pump inlet to pump outlet, right? Your elevation head on this is just a few inches difference between your pump inlet and outlet nozzle. I would strongly suggest use the temperature of water when cold to be safe that is as you know the colder the higher is the density. And I believe you you are aware of cavitation too when handling hot fluids. Just a reminder.

Gimini21