The Duvel International Trading (China) Limited relies on its 2,633 square metre cool room to store imported Belgian and American craft beers, at a controlled temperature of 10ºC.

The cool room in Northern Shanghai has 12 high level direct expansion evaporators mounted throughout the area to offer balanced cooling throughout the room.

Each evaporator has a cooling capacity of 108 kilowatts. Externally is a twin compressor rack system, incorporating two Hanbell screw compressors, liquid receiver, suction accumulator and oil separator. The system was designed and installed by Shanghai Lan'Ge Refrigeration Company Limited.

The rack system is directly connected to a three-stage (1 Fan, 2 Fans, 3 Water) hybrid evaporative condenser and the total design capacity of the system is 1280kw.

Controls are an electronic digital electric configuration which is installed within the controlled space. An isolation room was built to enclose the panels to reduce and eliminate the possibility of corrosion and or faulty connections due to condensation.

It also eliminated the very small potential of the refrigerant entering the control panel cabinet in the event of a leak. Again, to eliminate any risk should there be a refrigerant leak, 30 hydrocarbon refrigerant safety sensors were installed at low level, and wired back to the control panel.

It was wired in such a way that should one, or more sensors alarm, the liquid line solenoid closes, the unit pumps down, and isolates all the refrigerant in the external units (rack system and condenser).

While the sensors normally operate on mains electricity, they also have an inbuilt (rechargeable) battery back-up, an audible alarm and a level indicator.

Once the system was fully installed by the main contractor, the system was then triple stage vacuumed to remove any non condensables and moisture, then filled with a holding charge of dry nitrogen to a static pressure of 150psi.

During the pressure test period, one leak on the oil separator was identified, the faulty valve was isolated, the controlled area was vacuumed, and then the holding charge of dry nitrogen was returned to 150psi. All pipework was inspected and tested for leaks. No further leaks were found, and the pressure of the nitrogen charge did not drop.

The system was then charged with ENGAS M50 hydrocarbon refrigerant. As this was a 'clean' hydrocarbon refrigerant installation, there was no 'before' data for comparison.

However, the Shanghai Lan'Ge Refrigeration Company, who have vast experience in the design, build and installation of these systems, normal conditions see the running current (for two compressors) at 2 x 250 amps average. The maximum continuous running current for the system is 2 x 310 amps.

The voltage is 380/3/50 Hz. When running on Engas M50 refrigerant, all the pressures and temperatures are normal and the typical average running current is 2 x 181 amps. That represents a 27.80 per cent reduction in power consumption.


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