FEATURE
INCORPORATING COLD CHAIN
42
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Working with small companies that do
not have a track record and may not
stand by their design and installation.
Working with companies that are not
compliant with our current legislation.
right, you can get a synthetic refrigeration
plant pretty close to the COP of an
ammonia system even.
CO 2 is also now starting to play in the
synthetic refrigerant domain; that is where
the future of energy efficiency seems
to be going, according to Walter. CO 2
hasn’t really taken off in the packaging
and processing arena yet, though.
But, because with CO 2 you need high,
medium, and low temp, it is perfect for
processing facilities, as you generally
have chillers, freezers, and drop temp
areas with different facilities. CO 2 is
not suited for big, single-temperature
requirements.
Electronic expansion valves have also
improved efficiencies. Also, if you need
According to Kriel, another issue is assuming
that catalogue climate control systems
will be suitable for a specialist job. Often,
humidity control is underestimated (either
high or low requirements).
ENERGY EFFICIENCY
Processing facilities generally use massive
amounts of energy — how do you
improve energy efficiencies?
Kriel’s advice is to use life cycle cost
analysis as a key decision-making tool;
not capital cost. While Amschwand
advises using energy-efficient refrigerants,
good designs, and keeping the plant well
maintained, to ensure optimal energy
efficiency.
Walter advises keeping up with
technology. Technology has advanced
to improve efficiencies, especially energy
efficiency. This includes variable speed
drives (VSDs) for compressors and soft
starters to bring down your peak power
draw. If it’s a freezer, it’s always more
efficient to water-cool it. Water cooling
improves your coefficient of performance
(COP) by running your compressors at
lower discharge pressures. If you do it
heating, a desuperheater can heat the
water from the waste heat on a cooling
plant. This is basically free heating
that can be retrofitted to most air-
conditioning and refrigeration systems.
On existing installations, Van der
Merwe suggests carrying out an audit
on the equipment operating conditions
and assessing where the plant can be
improved. “There will be costs to improve
the efficiencies, but the payback can be
calculated to see if it is viable.”
“Spending on upgrading certain
elements of the system can make a
notable difference to plant reliability,
potentially reducing the maintenance
costs as well as the running costs,” says
Van der Merwe.
“Although the installers of industrial
refrigeration systems generally follow
the regulations regarding safety, the
methods of installing many commercial
refrigerating systems are poor,” he says.
Particularly piping. Poorly bracketed
piping leads to vibration and pipe
fractures. “I am told the average
refrigeration system having distributed
users and synthetic refrigerants loses
50% of its charge every year.” These
are refrigerants with ozone depletion
potentials (R22) or high GWPs. Even in
Europe, leakage rates are 10% a year.
Another issue comes in during the
design phase already. “Our industry is
very cost conscious and as such, the
lowest price is always attractive to the
end user,” explains Van der Merwe.
“The lower price is often achieved by
offering reduced equipment capacities,
which results in either higher running
costs or cold rooms that do not operate
at the desired temperatures.” Improved
efficiency is available at a premium, so
efficiently designed plants will result in
lower running costs, but few end users
appreciate the value in spending more
upfront to upgrade the equipment.
According to Van der Merwe, other
common errors are:
• Underestimating the room heat load.
• Undersizing the evaporators and
condensers.
Modern packaging can preserve product freshness through the combined effect of modified
atmosphere (MA), modified humidity (MH), and condensation control, extending shelf life and
reducing waste in the fresh produce supply chain.
www.coldlinkafrica.co.za
COLD LINK AFRICA • May 2019