Airedale Ultima Compact FreeCool 30kW - 450kW - Manual (Page 15)

Chillers ULTIMA COMPACT FREECOOL
Chillers
15
Technical Manual : 6259576 V1.2.0_02__2013
Design Features & Information
MINIMUM SYSTEM WATER VOLUME CALCULATIONS
(DX Mechanical Cooling Mode Requirements)
GENERAL Based on 20% Ethylene Glycol Concentration
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 150 kW Chiller, 7/12°C Water, Model UCFC150D-3/1 with a permanent load of 60 kW
Vm =
150 x 60
x 2 x
40 x 1.2
= 738 Litres
3.9 x 5 60
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 150 kW Chiller, 7/12°C Water, Model UCFC150D-3/1 permanent load unknown.
Vm =
150 x 3600
x
1
x 1.2 x
1
= 692 Litres
3.9 x 5 4 12
Method 1 is always preferred.