Primary and Secondary Chilled Water Pumps

If I understand Primary/Secondary pumping systems correctly, the flow rates do not necesarily need to be equal. Primary and secondary loops areoccasionally set up to operate over different temperature ranges and can operate at different flow rates at certain times of the season.

Dear Daim,

It seems that chilled water delta t in your system is 10 c, I do not know what is your ambient design temp, if it is more than 45 c ( 115 F) it will not easy to get 461 TR as one chiller capacity, however Primary pumps should match chiller capacity, but because there will be always diversity factor so the building will not request full load,By other minimum rpm is not less than 30% of rated rpm.then selection of secondary pump should match pump discharge at 30% of rpm and could be less than primary pump in same rate of the cooling load diversity factor.please I think you have to prepare strategy like the following one ( it is applicable to sec. p. capacity equal to double of P.P.):

Sr. no chillerQty. ---P.P Qty ---------water flow -----------sec.p Qty

1- one------------ one pump-------- 65 l/ sec -------------one part load

2- two------------ two -------------130 ------------------two part load

3- three----------- three -----------195 ------------------two part load

4- four------------- four ------------260------------------ three part load

5- five------------- five------------ 325 ------------------three high load

6- six --------------six --------------390 -----------------four part load

7- seven -----------seven -----------465 ------------------four high load

from above note that sec. p will not run in full load which mean it will have long live but not efficient in power consumption.

yes you are correct..it is impossible to get 461Tr in single chiller. our ambient is 46 C

we may need to revised our design. back to this Secondary Pump, I dont have to use equation usgpm = TR x 24 / delta T to get the flowrate?

Dear daim,

I know ther is know 416 ton, It seam your project is a Mall. please contact me and I will help you allot. firstly you have to think for water cooled chillers instead of air cooled chiller, if your client/ management do not like this option then select 10 chillers of 300 ton each,in future you will need more chillers due to revised load because of end user requirement. please ask me if you need any help in this regards.

You can take 2.4USGPM per Ton

and i can be same for primary and secondary pump

Where do you work