Stulz CyberCool 2, Оригинальное руководство пользователя

Страница: 21 / 102

21
© STULZ GmbH – all rights reserved EN/09.2019/G41
cybercool 2 screw original insTrUcTions
Oil transport is carried out by means of differential pressure without a mechanical
oil pump. The compressor contains a fine-mesh suction gas filter, a three-stage oil
separator and an oil heating.
Depending on the compressor type, a part-winding control or star/delta commu-
tation provides for a limitation of peak current. The integrated motor protection
Air outlet grille
Air inlet grille
Compressor
In every unit there are two screw compressors, the cooling capacity of which can be controlled continuously
for each compressor from 25 - 100% by means of an internal capacity control. In combination with the pos-
sibility, to individually operate the refrigerant circuits the total range of capacity control extends from 12,5
- 100%.
The continuous capacity control system shifts the entry point of the refrigerant along the axis of the screw,
which varies the compression section and thus the compression itself. The shorter the compression section,
the lower is the compression and the smaller is the produced cooling capacity.
Condenser
The necessary air for cooling is drawn in across the condenser coils placed on the long side and blown verti-
cally upward through speed-controlled axial fans (EC technology). The W-shaped arrangement of the micro-
channel coils completely made of aluminium increases the heat exchange surface which gets in contact with
intake air and improves the energy efficiency.
device features the following functions:
- Monitoring of motor coil temperature (PTC)
- Monitoring of rotating direction
- Monitoring of oil temperature (PTC)
- Restart interlock in case of malfunction
The compressor cabinet is cooled by air intake grilles in the
base and air outlet grilles to the condenser fan intake area
on both sides. The temperature in the compressor cabinet is
measured by a sensor in the ceiling area.
Evaporator
The tube evaporator is equipped with an anti freeze heater, which is switched in dependance of the chilled
water outlet temperature by the anti freeze thermostat and by the outside air temperature. In the C7000 con-
troller an anti freeze control can be adjusted which in addition to the anti freeze heater also affects the pump
control.
Economizer
The units of the capacity sizes 3302, 4002, 4602, 5102, 6602, 7102, 8002, 9602, 9802, 11102, 12602,
14102 feature an economizer.
The economizer refrigerant line is only opened via a solenoid valve when the compressor is running on 100%.
By this, an arrangement of heat exchanger, solenoid valve and thermostatic expansion valve located between
condenser and electronic expansion valve is designated, by which it is possible to extend the capacity range
upwards.
Downstream the condenser, a plate heat exchanger is installed in which the liquid refrigerant is subcooled, by
letting expand a part of the refrigerant mass flow through a thermostatic expansion valve and by introducing
it in the plate heat exchanger against the main mass flow. The evaporated partial mass flow is drawn in by the
compressor and added at an intermediate pressure level. The additional subcooling upstream the electronic
expansion valve provides a higher exploitation of cooling capacity in the evaporator.