PROJECT
INCORPORATING COLD CHAIN
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1. Evaporative condensers.
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2. Robotic racking.
The refrigeration plant is designed as a
dual-stage plant, with the freezer store
and the ACF on the -37.5°C (low-stage)
circuit and the chiller store and airlock
on the -10°C (high-stage) circuit.
The installed refrigeration duty is
1 122kW on the low stage and 1 776kW
on the high stage.
Both the freezer
and chiller stores are
equipped with fully
automatic robotic
racking systems that
require no human
intervention within
the stores.
ABOUT THE PLANT
in coefficient of performance (COP), The freezer and chiller stores are fitted
The plant had to be sized for:
• 150 tons per day automatic carton
freezer (ACF) of 380m²
• Freezer store of 2 000m² / 40 000m 3
• Chiller store of 1 000m² / 20 000m 3 resulting in an electrical consumption with an oxygen suppression system used
reduction over the -40°C that this system for fire prevention. This eliminates the
was originally designed to use. need for any sprinkler system within the
• racking systems that require no human Kingspan QuadCore insulated panels
intervention within the stores. and is the first store to be built with this
Airlock store of 3 100m².
The ACF is the first of its size built within
the country. The carton freezer design
was refined in consultation with WSP
to operate at -35°C at the evaporator
coils and still achieves the design’s
throughput. This gives a 23% increase
Both the freezer and chiller stores are
equipped with fully automatic robotic
The freezer and chiller stores are both
close to 20m in internal height, each with
facility.
The facility has been built with
type of panelling in the country.
Dehumidification is achieved in the
a total volume of 40 000m 3 and 20 000m 3 , airlock with ammonia hot gas reheat
respectively. Given these dimensions, it is coils. This method was selected due to
said to be one of the highest freezer and its efficiency in terms of power and also
chiller stores within South Africa. its effectiveness.
One low-stage and one high-stage
compressor are each fitted with
insulated motor bearings and oil
coolers suitable for 60Hz operation
in future. This will allow for improved
energy efficiency.
CHALLENGES
Careful thought and design went into
selecting the most suitable compressors
for the application, as the load turndown
on this facility is quite substantial. The
ACF accounts for about 80% of the low-
stage refrigeration load, and with this
load offline, it is important to ensure the
low-stage compressors do not cycle on
and off continuously, as this is inefficient
COLD LINK AFRICA • November/December 2018
www.coldlinkafrica.co.za
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