NEWS
INCORPORATING COLD CHAIN
Life-size plant for
training skills in CO 2
The plant is a subcritical cascade system
with CO 2 in the low stage and R134a on the
high stage.
“The use of CO 2 refrigeration, especially in
the commercial and supermarket sector, is
gaining momentum and it is our philosophy
to provide training that will keep our students
abreast of the latest trends,” was proudly
told by Isolde Döbelin, director of OTTC.
Peter Döbelin, the founder of the Open
Trade Training Centre (OTTC), had a deep
affection for ammonia refrigeration and built
the first life-size ammonia training plant in
South Africa. As an extension to its training
in ammonia, OTTC has always planned to
have a CO 2 plant and thanks to Christian
Richter of Germany, their first state-of-the-
art CO 2 plant is now operational. OTTC
can now offer training in all the skills in the
most commonly used natural refrigerants,
ammonia and CO 2 .
Richter, a gold winner in the 2009
Apprentice of the Year competition in
Germany, has made many visits to OTTC
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and also completed his OTTC Practical
Diploma course. In 2014, after being at OTTC
to train South Africa’s contestant, Dylan le
Matre, for the 2013 World Skills competition
in Leipzig, Richter started to design and
build a CO 2 training plant. The frame of the
packaged unit was built by Gideon Jansen
van Vuuren at OTTC, and the compressors
and vessels were sponsored by Bitzer.
Multistage Cooling provided the electrical
control box, enclosure, and mounting of the
outdoor R134a condenser and much of the
required cabling, wiring, some piping, and
hardware.
On his return to the family business and to
join his father at Dreshner Kuhlanlagenbau
T
he newest addition to the OTTC college
in Springs, a life-size CO 2 plant, will
provide instruction in the fundamentals
of CO 2 refrigeration as well as training in
safety skills. Construction of the plant started
in 2014 and ended with the commissioning
of the display cabinets in March 2018.
By John Ackermann
(DKV) GmbH, a refrigeration contractor,
Richter started to canvas sponsorships of the
material for the CO 2 plant at OTTC.
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Since 2014, Richter has made many
visits to OTTC, totalling about nine weeks,
and was on occasion accompanied by his
father, to do further work on the CO 2 plant.
The plant, commissioned in March 2018,
has four Bitzer Octagen semi-hermetic
compressors: two on the low stage (CO 2 )
and two on the high stage (R134a). Each
of the compressors are fitted with a Danfoss
variable frequency drive(VFD) to control
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the cooling capacity. To provide training in piping layouts allow parts of the circuit to
the operation of different capacity controls, be insulated, when needing to do repairs
the R134a circuit has a Siemens electronic or maintenance and for such to be done
expansion valve, a Danfoss TEV, and a safely, have been incorporated.
Danfoss AKV electronic expansion valve An oversized vertical vessel allows the
mounted in parallel with shut-off valves to CO 2 charge to expand without the release
bring into circuit as required.
To provide extra cooling load, the R134a
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becomes warm. High-pressure copper
cabinet with glass doors. piping, similar to what is used for R410A
The CO 2 circuit has Danfoss AKV
electronic expansion valves in circuit with
a DX evaporator, supplied by Thermofin,
3. The CO 2 plant has four Bitzer Octagen semi-hermetic compressors: two on R134a and two on
the CO 2 circuit.
4. The refrigerated display units connected to the CO 2 plant.
5. Signage has been added to the plant to recognise the support of all the suppliers who made
this project possible.
charged systems, has been used throughout.
Safety, because of the high pressures,
when working on CO 2 systems is of
utmost importance. The level of CO 2 in
Germany. The second heat load is a 2.4m the surrounding environment is of equal
upright frozen food vending cabinet with importance, and the required gas detection
glass doors and the third a CO 2 /glycol plate has been fitted to the plant to provide
heat exchanger. The glycol at -18°C is pump
2. The plant has additional pressure gauges and sensors to illustrate operating parameters.
and when the surrounding air temperature
circuit also has an upright chill vending
three heat loads, a 2 × 2 × 3m cold store with
1. During one of his visits to OTTC in Springs, from left: Isolde Döbelin, Christian and his father,
Wolfgang Richter.
to the atmosphere when the plant is idle
circulated through a model of a small frost-
protection and the required training of students.
“The workmanship and layout of the
covered polar bear, which is the mascot training plant is of a high level and in itself
of DKV. serves as a good form of training for our
The training plant has many pressure and
students. I extend my congratulations to
temperature sensing points to demonstrate and admiration of Christian Richter on such
the operating parameters of the plant an outstanding installation and design,”
under different loads and with different said Martin McEneaney, full-time OTTC
components in circuit. Three different lecturer.
COLD LINK AFRICA • June 2018
CLA
www.coldlinkafrica.co.za
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