Airedale Ultima Water Cooled 75kW - 450kW - Manual (Page 12)

ULTIMA WATER COOLED Chillers
12
Chillers
Technical Manual : Part No 6259477 V1.4.0_07_2014
Design Features & Information
MINIMUM SYSTEM WATER VOLUME CALCULATIONS
METHOD 1 Where the system permanent heat load is known:
Vm = Water Flow Rate (litres/minute) x Minimum Compressor Run Time
(mins) x Chiller Loading Factor
Where Vm is the minimum water volume in litres
Minimum Compressor Run Time is 2 minutes
Chiller Loading Factor = Minimum Turndown (kW) x 1.2
Permanent Heat Load
The Chiller Loading Factor limits:
Max
1.00
Min 0.25
Example 250 kW Chiller, 7/12°C Water, Model UWC250DQ with a permanent load of 95 kW
litres 1085
95
1.2 60
2
5 4.19
60 250
Vm 

 



METHOD 2 Where the system permanent heat load is unknown:
Vm = Water Flow Rate (litres/hour) x Minimum Turndown Ratio x 1.2
Maximum Compressor Starts Per Hour
Where Minimum Turndown Ratio = Minimum Stage Capacity (kW)
Chiller Full Capacity (kW)
Example 250 kW Chiller, 7/12°C Water, Model UWC250DQ permanent load unknown.
litres 1031
12
1
x 1.2 x
250
60
x
5 x 4.19
3600 x 250
Vm
 






Method 1 is always preferred.