PROJECT
INCORPORATING COLD CHAIN
CLIENT BRIEF
The client insisted on a trans-critical CO 2
system instead of the more traditional sub-
critical CO 2 /R134a refrigeration system.
Absolutely no delays were permitted,
the cost had to be no more than 10%
higher than the quoted sub-critical system,
and no municipal water was to be used to
assist cooling.
SYSTEM DESCRIPTION
The refrigeration plant room is located on
the rooftop of the new Centre Point Mall
and the trading floor is two storeys below at
the opposite end of the mall.
To take care of its refrigeration needs,
Sphere locally manufactured a booster
system with parallel compression. The pack
is fitted with 10 Bitzer compressors, four of
which run the medium-temperature side,
two doing parallel compression, three
running the low temperature, and one
satellite low-temperature compressor.
The compressors are piped to four
circuits: −36°C to the fish island freezer;
−28°C to freezer cabinets and freezer store;
and −8°C to the medium-temperature
cabinets. Two compressors are piped
to provide parallel compression of flash
gas. Included in the rack is a plate heat
exchanger to reclaim heat for heating of
hot water to 55°C, which is used for washing
and cleaning in the bakery, butchery, food
preparation areas, and for staff ablution.
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1. In the receiving bay, staff are made aware of food safety and the importance of the
proper handling of perishables for customer satisfaction.
2. The HC gas cooler has four 800mm-diameter ebm-papst fans with EC motors.
3. Water is pumped from the storage tanks to the gas cooler when ambient temperatures
become extreme.
4. The complete rack with control panel was trucked to Cape Town from Sphere in
Johannesburg.
5. The 10 Bitzer semi-hermetic compressors are piped to three circuits and the two (on
bottom left) piped for parallel cooling.
6. The roof space has two Climaveneta water chillers, each with two Bitzer screw
compressors. The R134a charge is minimised by the aluminium micro channel air-cooled
condenser coil with E-coating anti-corrosion protection.
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www.coldlinkafrica.co.za
COLD LINK AFRICA • March/April 2019