Technical
blends only. An essential barrier for the application as a pure
substance so far is the flammability. This requires adequate
charge limitations and/or additional safety measures,
especially with installations inside buildings.
In addition, there are very high-pressure levels and
discharge gas temperatures (compression exponent higher
than with R22 and R410A). On the other hand, R32 has
favourable thermodynamic properties, for example very
high evaporating enthalpy and volumetric refrigerating
capacity, low vapour density (low-pressure drop-in
pipelines), low mass flow, and favourable power input for
compression.
The global warming potential is relatively low (GWP =
675). Looking at these favourable properties and taking into
account the additional effort for emission reductions, R32
will increasingly be used as a refrigerant in factory produced
systems (air conditioning units and heat pumps) with low
refrigerant charges.
It was proven in flammability tests that the necessary
ignition energy is very high and Figure 23, R32/R410A –
comparison of performance and operating data of a scroll
compressor the flame speed is low. Therefore, R32 (like
R1234yf and R1234ze) has been placed in the new safety
group A2L according to ISO 817. The resulting safety
requirements are specified in the revised EN 378 (amended
version 2016).
R32 is also considered an alternative for systems with
larger refrigerant charge, for example liquid chillers for
air conditioning and process applications and heat pumps
previously operated with R410A. However, depending on
the installation site of the system, appropriate refrigerant
charge limits must be observed. On the other hand, there
are no such restrictions when installed outdoors (without
access to unauthorised persons) and in machine rooms (for
example, according to EN 378-3:2016). It should be noted,
however, that R32 pre-charged chillers may be subject
to special conditions during transport (according to the
Pressure Equipment Directive, R32 is classified under Fluid
Group 1).
For refrigerant properties, application ranges and
lubricant specifications, see future issues of RACA Journal.
For reasons of clarity the less or only regionally known
products are not specified in this issue, which is not intended
to imply any inferiority.
*Previous trade names are not used any more.
** All figures depicted are numbered as they appear in the
report – for ease of reference. RACA
52
RACA Journal I August 2020
www.hvacronline.co.za