BCWC
Water-Cooled Water Chiller
with “oil-free” centrifugal compressors
R134a (320-1250kW)
1
Overview
BCWC0320A – 320kW, 90 ton
BCWC0630A – 630kW, 190 ton
2
Overview
BCWC0950A – 950kW, 270 ton
BCWC1250A – 1250kW, 360 ton
3
Overview
4
Overview
5
MAIN COMPONENTS
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Main Components - Framework
The framework is produced in galvanized sheet steel, with panels painted with epoxy powder
paints (color RAL7037) conforming to the ASTM B117 standard. Furthermore, all external
screws, nuts, etc are in stainless steel.
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Main Components – Electrical Panel
The panel is built to conform to the 73/23/EEC directive and to its relevant standards.
The panel has a general door interlock switch and is housed in an appropriate compartment
protected by a panel fastened with ¼ turn screws.
The maximum internal temperature of the electrical panel is controlled by a thermostat,
and is maintained within parameters which ensure that the panel is protected by the ventilation
of external air.
Main features:
• Conforms to EC standards
• General shut off switch
• IP42 protection class
• 24V auxiliary circuit for the mainboard
• 230 V auxiliary circuit for compressor contactors
• Fuse protection for each compressor against shortcircuits
• Contactors provided for compressors
• 1 voltage-free contact for remote signalling of general alarms
• Contact for external pump group start-up
• EMC filter with harmonic protection
• Maximum internal termperature control
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Main Components – R134a
The units are equipped with one to four centrifugal compressors with magnetic bearings on a
single refrigerant circuit. Since it is, and always has been, an environmentally conscious
company, UNIFLAIR has designed these units for use with R134a.
It is “ecological” in the sense that it does not harm the ozone layer
and contributes minimally to global warming.
The TEWI (Total Equivalent Warming Impact) index value is very low,
less than 10% with respect to R407C.
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Main Components – R134a
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Main Components - Compressor
The units in the BCWC range are equipped with the new generation of “oil-free” centrifugal
compressors. The “oil-free” technology of the centrifugal compressors is based on the use of
magnetic bearings which are integrated with a frequency control (inverter) which enables
extremely high rotation speeds to be reached (up to 40000 cycles/min) and to guarantee, at
the same time, efficient control at different loads.
The integrated soft starter allows progressive start up with low inrush currents and the
absence of oil allows more than one compressor to be installed in parallel on each circuit,
maximizing efficiency at partial loads (“Tandem” logic).
The high efficiency of the compressor is supported
by the high efficiency of the flooded evaporator,
without the problems associated with the return of
oil, given that the system is completely oil-free.
The Uniflair UpCO3m control system, by
communicating with the internal control of the
compressor, results in optimum operation of the
chiller.
The use of this type of compressor creates a
substantial reduction in operating costs and
environmental impact as well as guaranteeing high
reliability.
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Main Components - Compressor
The impellers operate within a magnetic toroidal
field, avoiding mechanical friction.
BCWC units are the ideal choice for:
• Optimum efficiency at all load conditions
• Maximum reliability
• Minimum maintenance
• Reduced dimensions and weights
• Ultra silent operation
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Main Components - Compressor
Speed Control
with inverter
DC/DC brushless
synchronised motor
2 stages of centrifugal
compression
Temperature and
pressure sensors
IGV
Control of the motor and
magnetic bearings
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Main Components - Compressor
Refrigerant flow
The refrigerant enters form the suction slow pressure and low temperature side and is heated.
It passes therefore through a valve which has adjustable fins (IGVs) which is usually used in
centrifugal compressors to regulate the capacity.
The gas is subjected to the first compression by the first stage impeller.
The centrifugal forces produced by the rotation of the first impeller increases speed and
pressure.
The gas is directed at high
speed by means of a de-swirl
vane to the impeller of the
second compression stage and
is discharged through the volute.
(The speed decreases in the
volute
and
the
pressure
increases).
From here the high pressure gas
at a high temperature exits from
the discharge exhaust
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Main Components - Compressor
Gas compression
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Main Components - Compressor
The rotor shaft is held in position with ten
separately controlled electro magnetic
cushions which continually changes in
strength to keep the shaft centrally
positioned.
The shaft’s position is monitored with ten
sensor coils who’s signal is fed back to a
digital controller.
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Main Components - Compressor
The
compressor’s
speed
adjusts
automatically to match the load and
current operating conditions so that
optimum efficiency is gained
The slower the compressor, the greater
the efficiency; as speed is reduced,
energy consumption is reduced by the
cube.
The
compressor’s
speed
varies
dependent on the conditions. Its
operating speeds ranges from 18,000 to
40,000 rpm
The inverter is built into the compressor
as is the rest of the control system
Another advantage of this system is its
low starting current, the compressor
draws 2 A to start compared to 500 A on
a conventional compressor
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Main Components - Compressor
Mechanical components
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Main Components - Compressor
Electric and Electronic devices
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Main Components - Compressor
Control management
A closed loop control is used.
A closed loop is constantly adjusting the controlled device, sensing the change and making a
decision about how much to make the next adjustment.
The sensor provides information to the controller (shaft position). Based on the controller’s
program, the controller would send a signal to the PWM power module to strengthen the
magnetic fields of the magnetic bearings.
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Main Components - Compressor
Cooling circuits
The stator does produce heat. The
Turbocor compressor case has been
designed with internal cooling circuits to
remove heat from the stator windings
(maintaining
it
to
an
average
temperature of 55°C).
The heat from the stator becomes part
of the overall cooling load that the
compressor must pump.
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Main Components - Compressor
Operating field
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Main Components - Compressor
Top level performance.
An “Oil-free centrifugal compressor is an inverter-driven compressor which only uses the IGV
in extreme conditions.
BCWC units are able to adapt the cooling capacity to the load with extreme precision.
Delta T
The T at the set-point is ±0,2°C
(with load higher that min load)
BCWC
BRWC
Traditional
Time
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Main Components - Compressor
Top level performance.
BCWC units are able to adapt the cooling capacity of the compressor to the load extremely
efficiently.
The IPLV and ESEER show that the BCWC efficiency is optimized in all operating conditions.
12
10
EER
8
6
4
2
0
25%
50%
75%
BCWC - 630kW
BRWC - 630kW
100%
Load [%]
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Main Components - Compressor
Running cost [€/year]
Top level performance.
100.000,0
-100%
90.000,0
-90%
80.000,0
-80%
70.000,0
-70%
60.000,0
50.000,0
-60%
-48%
-50%
40.000,0
30.000,0
-40%
-38%
-38%
-39%
-30%
20.000,0
-20%
10.000,0
-10%
0,0
320
650
''oil-free'' compressor chillers
Screw compressor chillers
% Energy saving
0%
950
1250
Cooling capacity [kW]
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Main Components - Compressor
BCWC units have an integrated soft start.
Current [A]
Top level performance.
• 320 kW

< 2A
• 650 kW

< 75A
• 950 kW

<140A
• 1250 kW

< 205A
Current [A]
This means a very low starting current:
Time
SCR Switch-on
Time
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Main Components - Compressor
“Oil-free”
"Oil-free" means less cost!
• Reduced energy losses in the heat exchangers
• Compressors in parallel: optimum performance at partial loads
• Flooded evaporator: higher energy efficiency
• No oil changes or filter replacements: low maintenance costs
• No maintenance of the bearings: low maintenance costs
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Main Components - Compressor
Reduced dimensions.
The BCWC unit is lighter and more compact than any other compressor with the same
capacity featuring traditional technology.
6000
Weight [Kg]
5000
4000
3000
2000
1000
330
BCWC
BRWC
630
950
1250
Models [kW]
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Main Components - Compressor
Low noise.
• Extremely low noise levels
• Extremely flat spectrum
• Absence of vibrations
Noise power level
100
90
80
70
60
50
40
330
BCWC
BRWC
630
BRWC - LN
950
1250
Frequency [Hz]
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Main Components - Compressor
Low noise.
Noise power level
100
90
80
70
60
50
40
63Hz
125Hz
250Hz
500Hz
1000Hz
2000Hz
4000Hz
8000Hz
Frequency [Hz]
BCWC - 630kW
BRWC - 630kW
BRWC - LN - 630kW
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Main Components - EEV
An electronic expansion valve consists of two main parts: the valve itself and the step by step
motor. The motor is situated in the upper part of the valve and is connected directly to the
body of the valve. The body of the valve, including the valve and the motor, is hermetic and
welded in order to eliminate the risk of refrigerant leaks. As is the case for the compressors,
the valve motor is in contact with the refrigerant.
The electronic expansion valve is equipped
with a bipolar, 2-phase motor which has the
operating characteristics typical of any step by
step motor. It is kept in position until the pulses
of current from the driver command it to rotate
in one of the two directions. Each impulse
commands the rotation of the rotor for one
step, and it is rotated for a set degree, while a
series of pulses produce continuous rotation of
the rotor. The number of steps or levels is
extremely high in order to offer a wide and
refined regulation field. A mechanical device
transforms the rotation movement of the shaft
in a linear movement which enables the
running of the regulation element of the valve.
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Main Components -EEV
The valve is designed to control the flow of
refrigerant which has linear characteristics, in such
a way as to allow a wide range of variation in
capacity with a linear relationship between the flow
and the position of the valve itself.
Ordinary thermostatic expansion valves are selfactivating, that is, they are activated by the
pressure under which they are subjected to with the
help of an internal retaining spring.
Instead, electronic expansion valves are not selfactivating and the step by step motor requires
external elements and functions in order to be able
to carry out its own action.
Two things are essentially necessary: an external
driver and an algorithm which establishes the
operation of the valve itself. Both of these function
are included in the Turbocor compressor’s features.
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Main Components - Condenser
The units are equipped with one shell & tube condenser with one water-side and one
refrigerant-side passage.
Made from copper tubing and built in such a way as to ensure high efficiency for the entire life
of the exchanger: in fact, the tube is equipped with a special spiral which stops incrustation
forming.
The units can also be supplied on request with special condensers which are suitable for
operation with sea water (Cu/Ni tubes).
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Main Components - Evaporator
The units are equipped with a flooded evaporator.
All of the advantages of an “oil-free” centrifugal
compressor are optimized with a flooded evaporator.
The total efficiency compared to that of a traditional
evaporator (dry expansion) is higher due to the
following three factors:
1) Increased energy efficiency:
 exchange coefficient
 ΔT (water/refrigerant)
2) Reduced energy losses
NO superheating
 decreased pressure drops
3) Precise water temperature control
“accumulation” effect of refrigerant
inside the evaporator
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Main Components - Supports
To reduce vibration, BCWC units can be supplied with neoprene anti-vibration supports.
Each anti-vibration support is composed of:
• Height-adjustable steel bell with level screw
• Vulcanized steel plate with rubber base
• Hardness: 70°shA
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REFRIGERANT
AND ELECTRICAL
LAYOUTS
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Refrigerant Drawing
37
Electrical Connections
38
Electrical Connections
COMPRESSOR
I/O BOARD
FILTER DRYER
CONDENSER
TURBOCOR
COMPRESSOR
FLOODED EVAPORATOR
ELECTRONIC
EXPANSION VALVE
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Electrical Connections
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Electrical Drawing
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Electrical Drawing
TYPE A
ALARM
PUMP
TYPE B
ALARM
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Electrical Drawing
43
Electrical Drawing
44
Electrical Drawing
45
Electrical Drawing
46
Electrical Drawing
47
Electrical Drawing
48
Electrical Drawing
49
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