High efficiency series
This new series of units combines elevated efficiency rates (EER) with
the use of R134a refrigerant.
The excellent level of performance was achieved thanks to the
accurate sizing of all internal components in order to fully exploit the
characteristics of the ecological refrigerant used. Special attention was
paid to all the heat exchange surfaces, compressors and new
asymmetrical evaporators with improved and more efficient refrigerant
distribution both in the liquid and steam phases.
The new screw compressors are specially designed for R134a
refrigerant. The continual adjustment feature constantly modulates the
capacity of each compressor between 100% and 50% of its potential.
This adjustment mode also allows the exact power required by the
system to be instantaneously delivered and precisely adapted to load
variations. This in turn reduces the number of start-ups and
consequently improves reliability.
The accompanying unit adjustment
feature, based on evaporator outlet water temperature control with
Quick Mind adjustment logic, guarantees extremely small variations
compared with the set point (+/- 0.5 ˇăC, probe precision limit) as well as
considerably reducing the time required for the system to become fully
operative.
The advantages of the continual adjustment of individual compressors
are enhanced with the use of electronic thermostat valves.
Their precision and rapidity of response optimise load variations and
allow stable conditions to be achieved in a very short time, even when
operating in the part load mode.
The accurate sizing of the system combined with this series of units
offers considerable energy saving and consequently significant
reductions in running costs.
Water-to-water chillers
Water-to-water chillers. The unit is supplied with anti-freeze oil and refrigerant and has been factory tested. On-site installation therefore just involves making connections to the mains power and water supplies.
Unit charged with R134a refrigerant.
STANDARD UNIT COMPOSITION
Frame comprising supporting elements in polyester-painted thick
hot-galvanised sheet steel. The self-supporting frame containing the
main components is designed to ensure maximum ease of access
during servicing and maintenance operations. The various components
have been arranged to reduce the overall dimensions of the unit to a
minimum.
Screw compressors
Semi-hermetic screw-compressors with 2 five and six-lobe rotors. The
five-lobe rotor is directly splined onto the 2-pole motor (2,950 rpm)
without the use of overgears. Compression occurs five times every
motor turn and the gas therefore discharges continuously without the
typical throbbing common to reciprocating compressors. Leading-edge
numerical control machines were used to make the rotors and machine
the bearing seats. Compressor cooling power is continuously
modulated from 100 to 50%. In addition to the standard no-load starting
feature, the motors are fitted with electric starting devices which limit
the power absorbed during the compressor starting phase. A check
valve on the coolant delivery line prevents the rotor from reversing after
stopping. Special maintenance-free bearings allow very long work
cycles. Lubrication is forced, without the use of an oil pump. The high
efficiency built-in oil separator ensures the constant presence of oil in
the compressor. The rotors are dynamically balanced to ensure that the
vibrations common to reciprocating compressors do not occur. The lack
of vibrations and the absence of delicate intake and delivery valves, in
addition to very fine manufacturing tolerances, sophisticated quality
controls during the production process and a limited number of moving
parts, guarantee quiet and highly reliable operation. Each compressor
is fitted with manual-reset motor thermal protection, delivery gas
temperature control, an oil level float, an oil level sight-glass and an
electric resistance for heating the oil when the compressor is stopped.
Water-refrigerant heat exchanger
Direct expansion shell and tube exchanger with asymmetric refrigerant
circuits for keeping the refrigerant at the correct speed inside the tubes
during the change from the liquid to the gaseous phase. The steel shell
is insulated with a closed-cell condensation proof lining in foamed
elastomer. The copper pipes are internally grooved to improve heat
exchange and are mechanically expanded onto the tube plate ends.
Refrigerant-water heat exchanger
Finned coil exchanger with steel shell and finned coil made from
copper tubes with external fins, mechanically expanded onto the tube
plate ends. The heads can be removed to inspect the tubes. Water
connections are fitted standard for water from towers; connectors for
water from wells can be supplied on request.
Refrigerant circuit
Main components of the refrigerant circuit:
- compressor discharge check valve,
- compressor discharge shut-off valve,
- liquid line shut-off valve,
- liquid line solenoid valve,
- dryer filter with replaceable cartridge,
- refrigerant line sight glass with humidity indicator,
- externally equalised thermostatic valve,
- high pressure safety valve,
- low pressure safety valve,
- high and low pressure transducers
- high pressure switches,
- differential pressure switch for water
Electric power and control panel
Electric power and control panel, built to EN 60204-1/EC 204-1 standards, complete with:
- control circuit transformer,
- general door lock isolator,
- power circuit with bar distribution system,
- fuses and contactors for compressors,
- terminals for cumulative alarm block (BCA),
- remote ON/OFF terminals,
- spring-type control circuit terminal board,
- electronic controller.
- phase sequence relay
Basic model
Unit without heat recovery.
Model with partial heat recovery (D)
Water cooled chiller with partial heat recovery. Compared with the
basic configuration, this version features an additional refrigerant/water
heat exchanger on the gas delivery line. This heat exchanger, fitted in
series before the traditional cooling circuit condenser, is large enough
to recover heat for the production of medium-to-high temperature water
for domestic hot water and the like. The heating capacity of the heat
recovery circuit is approximately equal to the power input of the
compressor.
Model with total heat recovery (R)
Water cooled chiller with total heat recovery. This version features an
oversized water/freon heat exchanger with a dual water circuit
comprising a dual shell and tube exchanger for heat condensation and
total recovery, all enclosed in a single steel shell with removable heads
and externally lagged in closed-cell neoprene. This exchanger is large
enough to recover condensation heat and produce hot water
(secondary or recovery circuit). Hot water can be produced in the
recovery circuit for domestic hot water and the like. The heating
capacity of this circuit is approximately equal to the cooling power plus
the power input of the compressor.
Accessories
Acoustic box
Rubber isolators
Compressor suction valve
Increased evaporator insulation.
Cu/Ni condensers
Flanges on evaporator (if not standard)
Evaporator water flow switch (supplied separately)
Pressure valve for water from wells (14/30ˇăC)
Automatic circuit breaker for compressors
Free voltage contacts for compr. operation signalling
Remote keyboard
Sequencer (supplied separately)
Pump relay
Numbered wires
Electronic expansion valves (if not standard)
|
