Circulation pump head calculation in a pressurized closed loop

[vij36]

Dear Sirs,

Calculating a circulation pump head in a pressurized closed loop for the below scenario.

Attached a simple schematic.

A booster having more head (up to 6 bar) and low volume flow, pressurizes a tank and maintains the pressure in the closed loop, supply and return.
Circulation pump supplies chilled water to a building utilities like FCU, AHU etc.,
One of the Air handling unit is located at 30 meter height, which is the highest point in the building.
The total flow in the supply and return closed loop is around 50,000 LPH.

To calculate the circulation pump head, do we consider only friction loss in the supply and return line OR the entire head of 30 meter ?
Isn't the friction loss head is enough for the circulation pump, since the booster pump is maintaining the required pressure in the line .... Taking into the consideration of gravity of the building adds to the return line.

Also, as per the Pascal fluid theory pressure in a closed pressurized tank is same throughout the tank.

Kindly guide.

 

[vij36]

sorry, i did see this is already discussed in below thread in september

Link

So the static head is zero in a closed system. And only friction losses and coil losses to be considered.

We are storing the chilled water in tanks which are about 15 meters lower level than chiller.
What would be the ideal location of the circulation pump, at the chiller or at the tanks ?

Thanks,

 

[Geo Lu]

Multiple Pumps into a common Header:

The most important part in evaluating is to do a dynamic drawing of the process: (i.e.) our situation were 4 pumps into a common header Draw the main header and underneath it draw 4 vertical pipes connecting into the main header.
Assign various PSI values you know exist with your system in the vertical pipes. Assign the PSI value in the Header. Now examine the pump with the highest PSI value of the 4 and extend this value above the other 3 vertical pipes joining to the header. Which value is the highest? Do you think that lower PSI values will be able to inject their fluid into the header while existing higher PSI value is above it? The answer is a resounding NO.

Solution: Match each pumps output PSI to each other. They will all contribute their flow to the header equally. To do this the pump's motor (diesel or electric) will need to have the ability to regulate the RPMs individually to
reach the desired uniform PSI into the Header.

https://www.pumps.org/2022/06/15/five-keys-to-understanding-parallel-pump-optimization/