Airedale TurboChill FreeCool 200kW - 1830kW - Manual (Page 9)

9 Chiller Technical Manual 7525355 V1.1.0_04_2013
Introduction
Chillers TurboChill™ Air Cooled and FreeCool
Free Cooling Operation
The TurboChill Free Cool chiller has been designed to provide the cooling load required whilst optimising energy
efficiency at all times and as such will take advantage of free cooling whenever available. If the free cooling available
cannot satisfy the required full cooling load, direct expansion cooling is used to supplement the output.
In high ambients where free cooling is not available the fan speed modulates in the conventional manner to maintain
an optimised head pressure. Free cooling is initiated wherever the outdoor ambient is 2°C less than the return water
temperature.
During concurent cooling mode condensing temperature is constantly monitored and intelligently kept within the
compressor envelope to allow the fans to run as fast as possible and therefore achieve the most free-cooling without
having a negative impact on compressor integrity.
In ambients where the free cooling coil is capable of satisfying the full cooling demand, the condenser fans are
modulated to provide the desired duty. The condenser fans are capable of being modulated between 15-100% (EC) or
40% - 100% (AC) of airflow to maintain the supply water temperature.
During periods where the condenser fan speed has been reduced to a minimum, the supply water temperature will then
be controlled by the 3 way valve.
Free - cooling vs Mechanical cooling
System operated on 100% Free
Cooling (77% of Year)
System operated on
mechanical cooling only (33%
of Year)
Cooling
Load
Mechanical (Compressor) cooling
Free - Cooling
-7°C
0.5°C
12.5°C
Ambient Temp
Refrigerants
The range has been designed and optimised for operation with ozone benign R134a refrigerant.
Construction
The base shall be fabricated from galvanised steel to ensure a rigid, durable, weatherproof construction.
Unit panels shall be manufactured from galvanised sheet steel coated with epoxy baked powder paint to provide a
durable and weatherproof finish.
Standard unit colour shall be Light Grey (RAL 7035).