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of fresh air and humidification to minimise the risk of spreading any
infectious agents.
“Munters has also released a white paper, specifically related to
Covid-19, which states that creating a cool and humid environment
at specific parameters, makes viruses such as the coronavirus much
less effective and even to the point it becomes inert,” says Munters
South Africa managing director Phillip Dickinson.
The scope is there now for people generally to make some type
of change in regard to building health and air quality especially
considering the long wait until a vaccine is eventually delivered to
this country.
“For many offices, factories or shops, the indoor air quality is
going to become very important, because no one wants a breakout
at their business as this would mean negotiating persistent
shutdowns which cost money,” Karovsky adds.
Continual air changes and humidity in any building or space
is proven to be significantly healthier than the re-circulated, dry
air from conventional air conditioning. Physiologically, various
medical studies have shown that occupants exposed to fresh air
and relative humidity are healthier, more alert and show higher
levels of general wellbeing.
FILTRATION
“The pads in an evaporative cooler have a filtration property
when the pads are wet, not when dry or the system is not
running, and when wet can be effective in particle reduction,”
Dickinson notes further.
Even though there is speculation that evaporative cooling ‘filters
the air’ because of the process with water, there is in fact no factual
proof of this to-date – there is some natural filtration of the air but
the process doesn’t include cleaning all particles completely from the
air. You are generally not looking for filtration at a micro-particle level
of the air because you have got high refresh rates.
“Filtration would come into the equation if the quality of the
air that you are taking from outside is bad – for example if you are
in a very polluted industrial area, or an area where the outside air
quality is poor at the installation level or instances in high pollen
areas – evaporative coolers do play a role with some natural
filtration due the high ratio of surface area of air to water in the
cooling process,” adds Karovsky.
COOLING PAD MEDIA
Typically, two media types are produced – these being cellulosebased
and glass-fibre based which are utilised in different
applications. The cellulose material is used in general applications
including agriculture, horticulture, commercially and in retail –
where the glass-based material is suitable for applications where
there is fire risk or pre-heating required – the glass-based media
being flame retardant.
“Munters was the original designer of the evaporative cooling
pad (through the Swedish founding member, inventor and
entrepreneur Carl Munters) and also held an exclusive worldwide
patent for many years. As an evaporative cooling pad supplier being
our primary function, we manufacture CELdek in South Africa, as well
as other countries around the world, which is our cellulose product,
and our GLASdek product is produced in Italy. Both of these products
hold registered trademarks. These products have corrugated
material where different flute-dimensions serve different outcomes
based on saturation efficiency and pressure drop. These pads are
produced in varying dimensions and can also be custom-produced
for clients with particular needs,” says Dickinson.
Pads are produced by combining the different flute-dimension
layers of the corrugated material that meet at different angles – for
example 45˚ and 15˚ to make a 60˚ angle when joined, and 30˚ and
60˚ to make a 90˚ angle when joined. The layering creates larger
blocks whereafter they are cured at approximately 100˚C and then
cut to the required profiles.
Pad replacement is highly dependent on water quality as a
major contributor because when you evaporate the water, salts and
minerals remain behind so pump flow rate is important in terms of
design. Pollution also plays a significant role when in a heavy polluted
area – the pads may become sticky if your pump selection is not
correct and then you will run the risk of clogging up the pads and
reducing the cooling and natural filtration effects.
“If you are in a very aggressive area where water PH or
chemicals are intense you do get a quicker degradation of the
pads (they don’t last forever) but having said that, most HVAC
applications would have some sort of water treatment plant that
provides a good water source and this offers longevity of the
product. Typically, replacement cycles are 2 to 3 years in HVAC
units, and depending on particular circumstances this may be
longer,” adds Dickinson.
CONSIDERATIONS FOR THE FUTURE
With the new general awareness of germs that building occupants
have developed, as well as developments in terms of air quality
and airborne risks, designers, engineers and contractors will no
doubt be directed by market needs to adapt and adopt to different
methodologies in ensuring building health through air flows, social
distancing and ease of maintenance.
Further, the requirements in smaller offices or home offices also
poses a different slant to the industry dynamics and one would
wonder what the impact would be on peak electricity supply by
installing less energy-efficient methods in cooling. I personally
doubt the grid would be able to sustain a million more installations
of that nature when we are already on the edge of an abyss of our
electricity supply. Better alternatives must be sought out as the
industry works on overall efficiencies now including the critical
elements of health and wellbeing. RACA
SOURCES:
This article was compiled through information obtained from the
following participants:
1. Air Dale Engineering (Cool Breeze Airconditioning SA)
2. Raptor Engineering (Aolan Evaporative Cooling Systems)
3. Seeley International
4. Munters South Africa
5. Baltimore Aircoil Company
www.hvacronline.co.za RACA Journal I October 2020 25