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02-27-2005, 03:32 AM
hi friends ,
how can calculate quantity of chilled water required for 102 ton cooling coil capacity ?rules of thumb ,articles and equations will be appressiate.
thanks for all.

icemeister
02-27-2005, 08:29 AM
Btu/hr = 500 x GPM x DT

DT = Delta T or T(out) - T(in)
1 Ton = 12000 Btu/hr

triton99
02-27-2005, 08:53 AM
Make sure that you install either a circuit setter or an autoflow control valve to balance the chilled water flow through the coil.

rupert
02-27-2005, 01:24 PM
one method you can use assuming a 10 degree temp drop through the chiller is 2.4gallons per min per ton of cooling and 3.0 gallons per min per ton through your condenser if it is water cooled.

ceng
02-28-2005, 11:55 AM
if you are asking the volumn of the system, the rule of thumb of controlling the chiller is 3gallon/ton. McQuay has very detailed formular you can use.

triton99
02-28-2005, 01:06 PM
Normally the 3 GPM/ton is for the condenser water. The formula above by icemeister is correct. Q=500 x GPM x DT

03-03-2005, 08:56 AM
hi friends
thank u very much for your help.

ceng
03-03-2005, 09:49 PM
triton99: if gladstone is asking the flow rate, it is 3 gpm/ton,what I said 3 gallon/ton is for column. YOu have to have enough volumn in a chilled water system for the chiller control function properly.

03-03-2005, 10:41 PM
hi friends
i need more clarification 2 gpm/ton for what :cooling coil capacity in the A.H.U or for chiller evaporator i am sorry i am new in hvac
thanks for all

triton99
03-03-2005, 11:50 PM
Ceng, my bad. I should have read closer. I agree that you have to have enough volume in the system. I had a design years ago when I was starting out and the air-cooled chiller kept short cycling. I contacted Trane and they pointed out to me in their catalog under applications, they have a section that talks about it. Their technical support said with the new microprocessors they need at least a one minute loop time for the system to stabilize or it would short cycle. They preferred more, but that was the minimum.

Gladstone: The 3 gpm/ton rule of thumb is for sizing the flowrates through the condensers of water cooled chillers. The calculation for chilled water flow is Q=500 x GPM x DT.

triton99
03-03-2005, 11:53 PM
Gladstone: The formula Q=500 x GPM x DT is for chilled water through chillers or coils.

EXAMPLE:
Size chilled water flowrate for 40ton chiller

Q=500 x GPM x DT

(40 ton)(12,000 BTU/Hr)=500 x GPM x (54 - 44 Deg. F)
GPM = 96

Hope this helps!!

03-04-2005, 12:07 AM
thank u triton for your help now it is clear so am i correct for this sequence to size chiller?
calculating calculating load in ton for given space -size A.H.U in ton of cooling capacity using psychmetric chart-calculate flow rate for cooling coil as equation u give me.
now how size chiller -flow rate and circulating pumps?
thanks for every one help

thor7000
03-04-2005, 08:35 AM
Gladstone, if you are having so many problems sizing the system, wouldn't it be to your customers benefit to have it properly designed by an engineer???

thor7000
03-04-2005, 08:41 AM
I thought you should design based on 6 GPM per ton for water volume within the system??

If it is an open circuit with a cooling tower I would think 3 GPM would be a little low due to evaporation ect.

Please correct me if I am wrong!!

rupert
03-05-2005, 10:26 AM
3 galls per min per ton would be enough due to a makeup water supply keeping the volume of water constant in the cooling tower sump, as it is being evaporated in cooling the condenser water.

triton99
03-05-2005, 07:59 PM
I know Trane has always used 3 GPM/ton for condenser water. I think I read a post on this site a while back where manufacturers and engineers are starting to look at other flowrates for the condenser water. I remember not long ago when they wanted constant flow for the evaporator and now variable chilled water flow is common with all manufacturers.

rupert
03-06-2005, 04:01 PM
the trane website engineers newsletter archive has some very interesting articles on variable flow rates in chilled water systems.

coviepresb1647
05-15-2008, 12:05 PM
Normally the 3 GPM/ton is for the condenser water. The formula above by icemeister is correct. Q=500 x GPM x DT

What is the reference/citation for that formula?