Airedale OptiChill FreeCool 500kW - 1365kW - Manual (Page 17)

Chillers OPTICHILL
™
Chillers
17
Technical Manual : 6530166 V1.6.0 02_2013
Design Features & Information
ECONOMISER
ES
The addition of an economiser circuit provides increased cooling and enhances EER,
in full and part load operation.
Sub-cooled liquid is expanded using a dedicated EEV to a medium pressure and is
passed through one side of a plate heat exchanger and liquid at the normal pressure
flows through the opposite side of the plate heat exchanger. Consequently, the sub-
cooling of the liquid entering the system EEV is increased as is the evaporator
performance. Additionally, the suction pressure within the compressor body is lifted,
improving compressor efficiency.
ELECTRONICALLY
COMMUTATED (EC)
FAN MOTOR
ES
EC motors are DC motors with integrated ac to DC conversion; this gives the flexibility
of connecting to ac mains with the efficiency and simple speed control of a DC motor.
The EC fan offers significant power reduction in comparison with equivalent ac fan at
both full and modulated fan speeds. The inbuilt EC fan control module allows for fan
speed modulation from 15-100%, a standard ac fans modulating range is typically 40-
100% of full fan speed.
The EC fan presents superior energy efficiency at part load fan speeds compared to
the equivalent ac fan motor, offering typical efficiency savings up to 70%.
Fan speeds are factory set to either 900 rpm or 750 rpm depending on sound level
variant, refer to
General Specification , on page 40.
Standard voltage regulated (VR) fan speed controllers offer a linear response. By
comparison the EC fan is adjusted on demand via the unit microprocessor with
precision, offering substantial energy savings. The following illustration shows a
comparison of the typical power input required by each method.
In
pu
t Po
w
e
r %
0
20
40
60
80
100
120
0 20 40 60 80 100 120
Key
EC (Electronically
Commutated) Fan
Speed Control
Voltage Regulated
(VR) Fan Speed
Control
Fan Speed %
Example: Fan speed of 60%
VR input power required 60%
EC input power required 18%