FEATURE
INCORPORATING COLD CHAIN
processes with different life cycle costs and
environmental impacts can quite possibly
result in the same Eco-Efficiency.
SUBSTITUTES FOR R22/R502 IN
REFRIGERATION SYSTEMS: R404A
AND R507A
These blends are chlorine free substitutes
(ODP = 0) for R22 as well as for R502 in
medium and low temperature ranges. A
composition which was already launched
at the beginning of 1992 is known under
the trade name Suva® HP62 (DuPont).
Long term use has shown good results.
Further blends were traded as Forane®
FX70 (Arkema) and Genetron® AZ50
(Allied Signal/ Honeywell) or Solkane®
507 (Solvay). HP62 and FX70 have been
listed in the ASHRAE nomenclature as
R404A and AZ50 as R507A. The basic
components belong to the HFC group,
where R143a belongs to the flammable
category.
Due to the combination with a
and the resulting environmental impact.
With this evaluation approach, the entire life
cycle of a system is taken into account in
terms of:
• ecological performance in
accordance with the concept of Life
Cycle Assessment as per ISO 14040; and
• economic performance by means of a
Life Cycle Cost Analysis.
This means that the overall environmental
impact (including direct and indirect
emissions), as well as the investment costs,
operating and disposal costs, and capital
costs are taken into account. The studies
also confirm that an increase of Eco-
Efficiency can be achieved by investing
in optimised plant equipment (minimised
operating costs).
Hereby, the choice of refrigerant and
the associated system technology play
an important role. Eco-Efficiency can be
illustrated in graphic representation (see
Figure 3). The results of the Eco-Efficiency
evaluation are shown on the x-axis in the
system of coordinates, whilst the results of
the life cycle cost analysis are shown on
the y-axis.
This shows clearly: A system that is
situated higher in the top right quadrant
exhibits an increasingly better Eco-
Efficiency – and conversely, it becomes
less efficient in the bottom left sector.
The diagonals plotted into the system
of coordinates represent lines of equal
EcoEfficiency. This means that systems or
relatively high proportion of R125 the
flammability is effectively counteracted,
even in the case of leakage. A feature
of all three ingredients is the very low
isenropic compression exponent which
results in a similar, with even a tendency
to be lower, discharge gas temperature to
R502 (Figure 5).
The efficient application of single
stage compressors with low evaporating
temperatures is therefore guaranteed.
Due to the similar boiling points for
30
www.coldlinkafrica.co.za COLD LINK AFRICA • September 2020