Cold Link Africa January / February 2020 | Page 36

CONTRIBUTORS
INCORPORATING COLD CHAIN
The importance of measuring
your refrigeration plant
By Kevin Schlemmer, director, CoolCheck
In this article, I hope to draw attention to the ‘hidden’ opportunity of improving efficiency in cooling
systems and explore some of the challenges and barriers to increase efficiency and reliability of all types
of cooling systems from air-conditioning to refrigeration and even heat-pumps.
‘
Cold’ touches our lives every single
day, be it the food you eat or the air
conditioning in your office. With rising
temperatures, air conditioning has
become more than a luxury.
According to the International Energy
Agency, the number of air conditioners
in use globally will increase from 1.5 billion
to 5.5 billion units by 2050. Ironically, this
in-and-of-itself will add to the global
warming crisis. By definition, we have
created a spiralling feedback loop or
‘Catch 22’.
Right now, cooling systems consume
a massive 20% of all power generated
globally with that percentage likely to
increase as the world population increases.
The demand for more refrigerated foods
will drive the growth in refrigerated cold
stores and household fridges.
The good news is that the efficiency
of the majority of cooling systems can
be improved by 10% to 30% by means of
low-cost interventions. At an international
workshop in 2018, the United Nations
(UNIDO) identified this aspect as the most
effective and quickest way to reduce
carbon emissions.
The bad news is that correctly measuring
cooling efficiency is not easy and therefore,
not commonly found in the market. To
address this ‘problem’, a Swedish company
developed a system that is quick and easy
to use (and is non-invasive).
Measuring efficiency is common sense,
but not commonplace, unfortunately,
therefore many opportunities go
undetected and energy is wasted as
a result.
WHAT IS ‘COP’?
For those unfamiliar with the term,
‘COP’ or ‘Co-efficient of Performance’,
it is simply a ratio between what you got
versus what you paid. A good analogy
would be the amount of fuel used by your
car to drive 100km. If a cooling system
generates say three units of cooling and
uses one unit of electricity, then the COP is
three. (three divided by one equals three,
that simple).
We all know that electricity is
measured in kilowatts and cooling is
also measured similarly. Usually, the
letter ‘R’ or ‘r’ is added to the end of
the ‘kW’ (kWr) to differentiate it, but
in energy terms they are the same.
Let’s take a different example; a chiller
generates/produces 45kWr of cooling
but consumes 20kW of electricity, then
the COP is 45/20 which is a ratio of 1 to
2.25 or just simply 2.25.
In precisely the same way you want
to get the most amount of groceries for
every rand at the supermarket, COP
is the same – the more cooling kWr
you get for every 1kW of electricity the
better. The higher the COP, the better!
The performance tool that measures efficiency.
Chiller performance improved by 20% at Karsten Boerdery in the Northern Cape.
THE COP MYTH
Kevin Schlemmer in front of a refrigeration plant measuring its performance.
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On face value, this statement contradicts
the previous paragraph but let me
explain. This is one of the most common
misconceptions both within and outside
the industry (those that own and
operate the systems, and the end-
users). The chiller (or refrigeration system)
is manufactured in a factory where
the actual efficiency must conform to
recognised standards. These ‘design’
COP values are then used in the technical
manuals and marketing material.
People seem to fixate on the quoted
COP and assume that because they
bought (or sold) a chiller with a ‘high’
COP that they are guaranteed efficient
and reliable operation for the life of the
plant. This is a misconception, as the
stated value of COP is not a static number
because when the system is running it
changes all the time – every minute of
every day! All cooling systems operate
in a highly dynamic fashion, meaning
that many different things affect the
performance and efficiency such as
warm (or cold) weather, high cooling
load, compressor control (loading and
unloading) – the list is long.
Between the time that the shiny new
cooling system leaves the factory, until it
is running on that specific site, with those
specific ambient conditions, with those
particular installation and maintenance
procedures, and so on, a lot of COP can
and usually does evaporate.
COLD LINK AFRICA •
January/February 2020