PROJECT
INCORPORATING COLD CHAIN
The Lutz Refrigeration team proudly posing with the large multiplex they have built for the project.
Continued from page 29
up to the evaporators. The multiplex
consists of four 70hp GEA reciprocating
compressors, which, due to the extremely
low condensing temperatures of 30°C, can
produce a coefficient of performance
(COP) of above 2 for a -25°C cold room.
Compared with COPs of 1.4 for an
industry-standard condensing temperature
of around 45°C, this represents a 40%
better conversion of electricity into cooling
and subsequently a 40% reduction in
energy bills.
The multiplex can be run at a lower
cooling capacity during winter months
if required, thus presenting flexibility to
optimise energy usage according to the
varying cooling requirements.
The temperature is measured daily and
mailed to Lutz and the client, so they
always know what is going on. Walter
receives an alarm if something goes
wrong and, since Lutz still handles the
maintenance, he is on site regularly. This
dramatically reduces the amount of on-
site inspections needed.
The electrician also checks the
generator monthly.
ENERGY EFFICIENCY
Additionally, the following other energy-
saving features were employed on this
project:
• The cooling tower fans are variable
speed driven.
• Expansion valves are of the stepper
Under construction – the cold store was built in 2015.
type to better control suction pressures
and prevent liquid flood over under
dangerous conditions.
• The airlock leading to the freezer
is dehumidified down to as low as
20% humidity via a Bry-Air chemical
dehumidifier.
• All compressors are equipped with ABB
soft starters to reduce peak kVA draw
under start-up.
Greenwave installed a grid-tied 123kWh
solar system, which makes use of 380
Canadian-supplied solar panels feeding
into a Schneider inverter system. The solar
system does not make use of battery
storage and as such, the power that is
created must be used or else it is fed back
into the grid with no financial reward.
Therefore, careful collaboration
between Greenwave and Lutz
Refrigeration was required to optimise the
efficiency of the plant, energy usage, and
correct temperatures.
The payback period on the solar
installation is about four to five years.
Going the battery route would have
doubled this period.
The final electrical innovation that has
been incorporated into this facility is a
power factor correction system supplied
by Schneider, which increases the power
factor on site from the standard 0.85 up
to 0.97. This relatively unknown innovation
is translating into a direct saving of more
than 5% in electricity.
The entire project took less than nine months to complete.
COLD LINK AFRICA • July | August 2017
www.coldlinkafrica.co.za
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