Airedale Ultima Compact FreeCool 30kW - 450kW - Manual (Page 10)

ULTIMA COMPACT Chillers
10
Chillers
Technical Manual : Part No 6259543 TM E_1.3.0 04/2013
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 UCC250DQ-8/2 with a permanent load of 95 kW
Vm =
250 x 60
x 2 x
60 x 1.2
= 1085 Litres
4.19 x 5 95
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 UCC250DQ-8/2 permanent load unknown
Vm =
250 x 3600
x
60
x 1.2 x
1
= 1031 Litres
4.19 x 5 250 12
Method 1 is always preferred.