ASHRAE Journal - August 2021 - 40

TECHNICAL FEATURE
these knowledge gaps. For example, early adoption
of R-1234yf (Class 2L) in automotive applications in
the 2010s provided some research on possible risks,
but the amount of refrigerant used is quite small. So,
events have been unlikely. There were other relevant
studies related to using fluorocarbons as fire suppressants,
and a few studied thermal degradation in fire
situations.
The project is nearly complete with the review of the
draft final report underway and an expected completion
in third quarter of 2021.
Key knowledge gaps include a lack of information
on when ignition of 2L refrigerants will form a flame
and how much will burn, as well as how long the
fluorinated combustion or decomposition products
persist after their creation in various HVAC&R sector
scenarios. Basic outlines of possible studies to address
some of these data gaps are still being discussed with
the project monitoring subcommittee. The results from
RP-1806 will be particularly useful since the modeling
outputs can be used to understand how much and
what types of fluorinated by-products will form as a
result of a combustion event.
TRP-1879: Foamability Properties of LGWP Refrigerant
And Oil Mixtures
By Ivan Rydkin, Associate Member ASHRAE
Foaming of lubricants in HVAC&R systems is a phenomenon
that needs to be understood for optimal system
design. Anti-foaming and pro-foaming additives
are added to lubricant in HVAC&R design to optimize
the foaming properties of lubricants. ASHRAE has
sponsored research over the years studying foaming
with chlorofluorocarbons (CFCs), hydrochlorofluorocarbons
(HCFCs) and hydrofluorocarbons (HFCs) for
the industry, but evaluating lubricants' foaming qualities
with refrigerants has not been reviewed by ASHRAE
since 1998. This tentative research project, TRP-1879:
Foamability Properties of LGWP Refrigerant and Oil
Mixtures, would investigate how foaming characteristics
of various low GWP hydrofluoro-olefins (HFO) refrigerants
and their preferred lubricants.
Lubricant foaming can happen during compressor
start-up, shutdown or as the refrigerant goes through
an expansion device. When the refrigerant/oil mixture
foams, the oil gets displaced and pumped into the system,
which has the potential to starve the bearing and
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ASHRAE JOURNAL ashrae.org A U G UST 2021
wear surfaces from oil. Lubricant loss from the compressor
can lead to compressor failure.
Developing a new test method, aligning it with existing
research and evaluating the slate of HFO/ HFOblend
refrigerants could help oil development and oil
selection.
HFO/HFO-blends have different solubility and miscibility
properties in modern polyolester oil, polyalkylene
glycol, polyether and polyvinyl ether lubricants.
Certain refrigerants can have too much solubility with
traditional lubricants. This can thin the oil enough for
the refrigerant velocity to carry the oil away from the
compressor. A method to test for these properties and a
method to test for foam formation would be critical in
equipment qualification.
The goal of the research project is to create and validate
a test method that lubricant companies and original
equipment manufacturers (OEMs) could use to test
various lubricants and lubricant additive packages by
simulating realistic lubricant foaming conditions of new
HFO based refrigerants. Engineers could then look at
the method or at the set of refrigerants/lubricants evaluated,
which can help guide their selection with low GWP
refrigerants.
The research project is out for bid and is cosponsored
by ASHRAE Technical Committee 3.4, Lubrication.
Closing Knowledge Gaps
ASHRAE-sponsored research continues to help close
knowledge gaps and enable the use of new lower GWP
refrigerants in preparation for expected phasedown
regulations in North American in this decade.
RP-1806 has shown that it is possible to correlate
experimental ignition events to modeled ignition
events. These comparisons have created the ability
to predict risks from the severity of potential ignition
events.
RP-1855 has identified key knowledge gaps, including
a lack of information on when ignition of 2L refrigerants
will form a flame and how much will burn.
TRP-1879 will close knowledge gaps in foamability of
these new low GWP F-gases with their lubricants and
determine if there are differences from refrigerants and
lubricant used today in HVAC&R systems.
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ASHRAE Journal - August 2021

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