Chiller capacity:
C= Q/12000
C= Chiller capacity in Ton
12000= one Ton of refrigeration in Btuh
Q= building block load for cooling at the time of building peak hour (Sensible +Latent) in Btuh
In some instances, the chiller’s capacity is indicated in Kilowatts (kw), (1 ton=3.5kw).
Chilled Water Flow:
F= Q/(500 ∆T)
F= water flow through chiller in gpm
500= conversion facto for lb to gpm for water, 8.34lb/gal X 60 min/hr=500.4
∆T=Temperature difference of chilled water supply and return ℉ (can be 10, 12, 14, 16, 18, 20).
If 50% water and 50% glycol is being used instead of 100% water, the mixture of water and glycol will have a lower density versus using 100% water. Therefore, the flow formula will be:
F= Q/(450 ∆T)
The chilled water flow in chiller varies at different temperature (∆T):
|
∆T (℉)
|
gpm/ton
|
|
10
|
2.4
|
|
12
|
2
|
|
14
|
1.7
|
|
16
|
1.5
|
|
18
|
1.33
|
|
20
|
1.2
|
Using higher ∆T makes the pipe sizes smaller.
