ASHRAE Journal - February 2020 - 34

FEATURE
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Research Update on
Lower GWP Flammable
Refrigerants
Ten years ago, ANSI/ASHRAE Standard 34-2010, Designation and Safety Classification of
Refrigerants, added a new optional flammability sub-classification, A2L, specifically
for low-toxicity refrigerants with low burning velocity. In 2016, ASHRAE, DOE and
AHRI began collaborating on a research program to provide the technical knowledge
needed to facilitate and accelerate the safe use of these refrigerants (see sidebar,
"How It Began"). ASHRAE committed to fund three initial research projects and as of
December 2019, two of the projects have published their final reports. What follows is
an update of the program.
RP-1806: Flammable Refrigerants Post-Ignition Simulation and Risk
Assessment Update
Contractor: Gexcon, US; Principal Investigator: Scott Davis
The project's results will allow for the assessment of the
overall risks of using flammable refrigerants in HVAC&R
products, considering both ignition event probability and
severity.
Prior research focused on the probability of an ignition
event when using a flammable refrigerant in various
types of air-conditioning and refrigeration equipment.
After those results were published, discussion focused on
the need to understand the severity or consequences of
an event to fully understand the risks.
This project used a computer-based simulation to
understand events' severity sides. It is a computational
fluid dynamic software that incorporates advanced
combustion models. The second objective is to update
risk assessments and roll in the total risk, including both
probability and severity.
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A S H R A E J O U R N A L ashrae.org FEBRUARY 2020

The project's first phase was to take and validate an
existing CFD-based simulation code against existing
experimental combustion data, and as needed, modify
or improve the CFD models to accurately represent
ignition and combustion events involving Class 2L and
Class 3 refrigerants. Second, run a series of scenarios
or cases to simulate ignition and combustion events
for several applications and types of equipment. Some

How This Research Began
In June 2016, the U.S. Department of Energy (DOE)
invited ASHRAE and the Air-Conditioning, Heating, and
Refrigeration Institute (AHRI) into a research collaboration to establish a more robust fact base about the properties and the use of mildly flammable refrigerants. This
$5.2 million research program, with financial contributions from DOE ($3 million), ASHRAE ($1.2 million), and
AHRI ($1 million), is part of an ongoing global effort to
phase down the use of high-GWP refrigerants and identify
appropriate climate-friendly alternatives.

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ASHRAE Journal - February 2020

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