FEATURE
INCORPORATING COLD CHAIN
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in the systems. HFCs are costly and
the refrigerant used on sites every
year is truly alarming.
Minimising downtime that would result
in stock losses. Refrigeration systems
normally give you warning signals
prior to a failure. If you do planned
servicing, you can hopefully pick this
up and take corrective actions.
Keeping records. R717 systems have
very strict safety precautions that
need to be complied with at all
times. Records need to be kept on
site of components that require re-
certification every 36 months.
ENERGY EFFICIENCY
Ammonia plants (such as this one at Go Chill) are a popular choice for cold storage refrigeration solutions.
Moodley. “The biggest headache is
ensuring that everyone gets out safely
during an emergency evacuation,”
he says. “But if the services are done
monthly, there are no major issues with
the plant besides a few minor trips
that are identified and resolved by our
temperature team.”
LOOKING AT MAINTENANCE
A refrigeration system (usually) works 24
hours a day. If you drove a car at 100km/h
for 24 hours a day, then you would cover
± 70 000km per month. This gives an
indication of how hard a compressor works
and the need to maintain it before it breaks
down, Van der Merwe explains. “Planned
maintenance is critical to ensure the plant
operates reliably and at peak efficiency.”
According to Ford, it’s key that service
contacts are put in place to maintain
the system, ensuring maximum efficiency
and preventing any chance of major
breakdowns that could cause stock or
product loss. “It is important to note that
operation costs can increase due to
unmaintained systems.”
Maintenance is an ongoing process
and aims to prolong plant life and reduce
down-time resulting from breakdowns,”
explains Smith. The maintenance
programme should, among other duties,
include leak checking, oil changes, filter
changes, and condenser/evaporator
cleaning, he advises. Mechanical and
electrical checks must also be conducted
so that worn parts can be replaced.
“In doing regular maintenance,
you can prevent major problems in
the plant in the future,” says Ford.
Other than regular maintenance, a
more comprehensive service and
maintenance plan will be needed
to keep the plant running optimally
after it reaches a certain age. “A plan
should be put in place for the life span
expected of the plant, to keep it running
at its best capacity throughout its cycle.”
If you consider the value of product
that is being stored in a freezer store,
the potential loss of product, and the
implications of finding alternative storage
costs at short notice, then it is a better bet
to carry out the scheduled maintenance,
Van der Merwe says. “Scheduled
maintenance is generally a predictable
cost with reliable operation at expected
temperatures as opposed to running until
the equipment fails and then scrambling
to sort out the problems and potentially
dumping spoiled product.”
Moodley explains that at their cold
store, maintenance is done monthly.
Condensers, drip trays and plant rooms
are cleaned. Oil is drained from the
system. The system is checked for leaks,
rust and corrosion. Water is tested for pH
value. “All of this is done to ensure that the
plant is kept healthy at all times and we
don’t encounter problems during our steri-
cooling cycles.”
“Planned maintenance would offer
the facility owners a more predictable
operational life,” agrees La Grange. Here
are some tips he considers important:
• Having qualified technicians with the
required South African Qualification
and Certification Committee for Gas
(SAQCC Gas) licence attending
to any installation containing a
refrigerant. Should you have a R717
installation, additional training and
testing is required as part of the
maintenance staff’s SAQCC gas
licence. This requires additional
training and re-testing every three
years to remain current.
• Having extensive commissioning
information to refer to. Commissioning
a system is important to confirm that
the design was done correctly and
accurately. It’s also for defining
the system’s correct operating
conditions. It’s very important
that the system’s refrigerant is
recorded for future reference. The
commissioning data would also
contain crucial details regarding
operational settings to achieve
optimal operational efficiency.
• Minimising leakage rates and doing
regular checks to keep the refrigerant
COLD LINK AFRICA • July/August 2019
“Energy saving has become very important
for all users of refrigeration of late,” says
Smith. Energy saving comes at a cost and
the more energy saving devices or systems
added, the greater the CAPEX cost.
“Energy saving comes from efficient design
and the use of energy efficient alternatives
when selecting your equipment.”
First cost is generally a once-off cost
if the correct equipment is supplied and
installed, explains Van der Merwe. “It
is accepted that it costs more to install
a system with a higher efficiency but it
is money well spent and it will pay for
itself.” Running costs are incurred on a
continuous basis for the entire life of the
plant and this quickly outweighs any
capital cost savings if you install a low cost
system with high running costs. Electrical
costs will increase annually so this cost
portion will only get worse.
“Energy efficiency is a very big, if
not the biggest, deciding factor of big
installations,” says La Grange. If one
reviews the TEWI formula (the indirect
global warming factors), the weighting of
energy consumed is especially heavy in
South Africa, due to the widespread use
of coal to generate the overwhelming
majority of the country’s energy needs.
Adding a renewable source like solar has
been applied very successfully to reduce
the load from the national grid and in doing
so, installations’ TEWI index is dramatically
reduced, says La Grange. “Using green
alternatives as refrigerants reduced the
warming impact but the biggest impact
is still the pollution resulting from energy
required to operate the facility.”
In South Africa, our electrical energy is
for the greater part generated by burning
coal. The weighting of energy generated
from coal has a dramatic effect on the
calculations. At an average of around
1 075gCO 2 /kWh of electricity generated
by burning coal, it compares very poorly
with an average of 155gCO/kWh from
www.coldlinkafrica.co.za
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