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GRANT LAIDLAW
Grant Laidlaw is currently the owner of the Air Conditioning and Refrigeration Academy (ACRA) in Edenvale.
He holds a Bachelor of Business Administration and an associate degree in educational administration. He
has a National Technical Diploma and completed an apprenticeship with Transnet. He has dual-trades status:
refrigeration and electrical. He has been involved with SAIRAC for 17 years and has been a Johannesburg
committee member for the past eight (chairman in 2011 and 2012). Currently he is the treasurer (Johannesburg
council) as well as president (national council).
LOOKING AT HFO R1234YF
By Grant Laidlaw
Many people ask for assistance in the understanding of theoretical and
practical aspects of the industry. I will endeavour to enlighten.
Stewart asks: Grant, in our sector we are moving away
from R134a and see the usage of HFOs on the increase, in
particular R1234yf. Any advice on the usage would be most
helpful, and do we need a safe handling license for R1234yf?
Is R1234yf compatible with existing R134a systems?
Hi Stewart, yes, I am aware of Hydrofluoroolefins, or in short
HFOs, being used in the market. This is an acronym that
is familiar to many of us. R1234yf, R1234ze(E) are few examples
of HFOs. They are used in a number of applications today,
predominantly in the automotive sector. These are relatively new
in the air conditioning sector, appearing around a decade ago.
WHAT ARE THE HFOS?
Having said that, HFOs are nothing new to the chemistry
industry. Much like traditional hydrofluorocarbons (HFCs), they
are composed from hydrogen, fluorine and carbon. The only
difference is that they are unsaturated, meaning that they have
at least one double bond. Such molecules are named olefins or
alkenes. The HFO label has become the most used name to refer
to refrigerants with carbon-carbon double bonds.
The presence of the carbon-carbon double bond is not unique
for HFOs as there are other unsaturated compounds to be found,
as for example unsaturated hydrocarbons (for example propene). In
fact, HFO-1234yf is a propene molecule that has been halogenated.
STRUCTURAL FORMULA OF HFO-1234YF
HFOs are relatively stable compounds but are more reactive
than HFCs due to the reactivity of the carbon-carbon bond. This
also reduces their global warming potential (GWP) and thus they
became favourable refrigerants in the light of increasing concerns
on climate change.
Environmental effect
The interest in HFOs as potential refrigerants arose with the
adoption of European directives on mobile air-conditioning
systems that focussed on reducing emissions of the fluorinated
greenhouse gases (GHG). The fluorinated propene isomer
R1234yf has thus become the alternative to R134a.
Having said that there are automotive manufacturers who
have begun including R744 (CO 2
) systems to their product
line-up. Looking at R1234yf, we find that unlike R134a,
R1234yf refrigerant has a very low effect on global warming.
This feature is common for HFOs. This is mainly due to HFOs
relatively short lifespan in the atmosphere which is only a few
weeks for many HFOs. The latest figures suggest the R1234yfs
GWP is less than 1.
Safety
The benefits of HFOs on the environmental side are partly
outweighed by the concerns on their safety.
There are two main safety issues that are related to HFO’s:
flammability and their potential to form dangerous acids:
• A number of HFOs, including HFO-1234yf, HFO-1234ze, are
flammable.
• HFOs are easily decomposable at high temperatures and
form hydrogen fluoride - a gas that is highly soluble in water
and that easily forms acid that can cause skin, eye and throat
irritation and could lead to death. This becomes an issue
should a vehicle be involved in an accident. R1234yf then
poses an additional danger to both the vehicles occupants
and rescue personnel.
It is obvious that flammable refrigerants have greater probability
to be affected by high temperatures and therefore pose greater
risk of formation of dangerous substances.
40
RACA Journal I August 2020
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