Gexcon US has entered into an agreement with the American Society of Heating, Refrigeration and Air-conditioning Engineers (ASHRAE) to quantify the flammability and explosion risks of environmentally friendly refrigerant working fluids. The project involves the validation of FLACS for use with low burning velocity fuels and application of the CFD model to quantify the severity of post-ignition events involving mildly flammable refrigerants used in residential and commercial settings.
Societal demands to reduce human-induced climate change have resulted in a transition in the Heating, Ventilating, Air-conditioning, and Refrigerating (HVAC&R) industry toward new refrigerant working fluids with lower global warming potential (GWP). Unfortunately, the properties that lower the GWP of these compounds also make them flammable, introducing new safety hazards and design constraints associated with their use.
Assessing Event Severity with CFD
Several industry-funded projects have quantified the probability of combustion events involving mildly flammable refrigerants based on leak frequency and ignition probability analysis, but very little work has been performed to quantify the post-ignition severity/consequence associated with such events.
The general approach to-date for assessing severity has been to perform physical testing. Valuable results have come from these tests, but the number of scenarios that can be tested is limited based on the time and cost requirements. CFD is currently applied in several other industries to assess the severity of fire and deflagration events. Current CFD models could, with some improvement, become well-suited to assess the severity of ignition events involving refrigerant/air and refrigerant/lubricant/air mixtures.
Scope and Objectives
- Improve and validate FLACS for use with flammable refrigerants
- With FLACS, simulate post-ignition combustion events involving flammable refrigerants leaked from Heating, Ventilation, Air-conditioning and Refrigeration (HVAC&R) equipment in residential and commercial applications.
- Combine severity predictions from FLACS with the existing risk assessment data to provide a broader and more complete assessment of risks associated with eco-friendly refrigerants that are mildly flammable.
Scott G. Davis
President and Principal Engineer, Gexcon US
Phone: +1 617-407-3300