Truck & Off-Highway Engineering - April 2022 - 34

CHEMOURS
Q&
A
Commercial vehicles begin shift to HFO refrigerant
R-1234yf refrigerants for mobile air-conditioning systems have
been widely used in passenger vehicles the past several years,
but they are just now gaining traction in medium- and heavyduty
commercial vehicles. Environmental policies are driving
the shift to R-1234yf, which has a Global Warming Potential
(GWP) of <1 compared to R-134a's GWP of 1,300.
" The significant difference is due to R-1234yf being a hydrofluoroolefin
(HFO), a molecule that has a very short-lived
atmospheric life, " said Christina Spalding, account manager
for The Chemours Company, which makes Opteon YF
(R-1234yf) refrigerant. " Where hydrofluorocarbon (HFC)
R-134a remains in the atmosphere an average
of 12 years, R-1234yf's atmospheric lifetime
averages a mere 11 days. "
As of November 2021, R-1234yf has been
listed as a proposed alternative under the EPA
SNAP (Significant New Alternatives Policy)
Program. " In anticipation of the publication of
the final ruling, many OEMs are now actively
developing systems using R-1234yf, " she said.
Also driving this shift is the mandated HFC
phasedown defined by AIM (American
Innovation and Manufacturing), which began
January 1, 2022. Spalding shares additional
insights with TOHE:
off-highway segment has not been widespread across other regions.
However, the recent SNAP ruling, in combination with the
AIM Act in the U.S., positions R-1234yf as the preferred replacement
for R-134a for global manufacturers.
Any specific challenges to applying R-1234yf to commercial/
off-highway vehicles?
The thermal performance, non-toxic chemistry and stability
are nearly the same between R-1234yf and R-134a. The primary
difference between the two is R-1234yf being slightly
more flammable. ASHRAE classifies R-1234yf as a " mildlyflammability "
fluid (A2L); R-134a carries an
A1 safety classification due to its lower flame
propagation.
The risk characteristics of the increased
flammability of R-1234yf were evaluated in
the SNAP ruling, but this difference prevents
the refrigerant from being a direct drop-in
replacement. In addition, the system components
need to be rated for R-1234yf before
the refrigerant can be used. The SNAP ruling
recommends SAE safety standards J639,
J1739 and J2844 for the applicable use cases.
Why has there been such a delay between
passenger and commercial vehicles employing
the new refrigerant?
R-1234yf was listed as an EPA-approved mobile
refrigerant for new vehicles under SNAP
in 2012. R-1234yf usage was accelerated with
signature of the Kigali Amendment to the
Montreal Protocol in 2016. This multinational
agreement pledged the phasedown of certain
HFCs like 134a. Though the U.S. has not signed
it, adoption of Kigali in the EU compelled automakers
to develop R-1234yf-based systems.
The final driver in the U.S. for the passengervehicle
transition to R-1234yf was the 2015
EPA SNAP rule 20 prohibiting 134a in new
light-duty cars and trucks as of model year 2021.
OEMs prioritized the SNAP listing [rule 24] for R-1234yf in
Christina Spalding,
account manager for
The Chemours Company.
" The properties
and regulatory
fit of HFO-1234yf
make it an ideal
base molecule for
electrified heavyduty
vehicles. "
new off-highway heavy-duty vehicles due to the desire to
manufacture vehicles in the U.S. and ship them to Europe.
There has not been similar motivation in the on-highway medium-
and heavy-duty truck vehicle classes until the passage
of the AIM Act, which defines the timeline by which the OEMs
will need to reduce R-134a usage.
Have any regions adopted R-1234yf faster than others?
Although R-1234yf is being used globally by a majority of key
OEMs in light-duty automotive, the transition to the commercial/
34 April 2022
Are there any differences in the refrigerant
system itself?
There aren't any specific new types of components
required. However, it is critical to
ensure that system components are rated
for R-1234yf and that the appropriate safety
standards are followed. In addition, it is
strongly encouraged that users include an
internal heat exchanger (IHX). Following this
best practice will help to ensure cooling capacity
of the evaporator can be met at all
desired operating conditions given the slight
differences in properties between the two
refrigerants.
Any other benefits beyond environmental?
R-1234yf has a higher vapor density than
R-134a. Higher vapor density enables the use of a smaller
compressor, reducing the system's energy consumption.
Does electrification impact the outlook for refrigerants
moving forward?
The properties and regulatory fit of HFO-1234yf make it an
ideal base molecule for electrified heavy-duty vehicles.
Because EVs present unique challenges in cabin heating and
battery cooling, innovators such as Chemours are constantly
evaluating options to tailor the benefits of R-1234yf for electrified
applications.
Ryan Gehm
TRUCK & OFF-HIGHWAY ENGINEERING
Truck & Off-Highway Engineering - April 2022

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