Background
Due to the potential environmental impact, there has been a shift to consider the use of natural refrigerants, which have a lower Global Warming Potential (GWP) than traditional fluorocarbon-based refrigerants. One type of natural refrigerant are hydrocarbons (e.g. propane), which are classified as Class A3 refrigerants per ASHRAE Standard 34. The Environmental Protection Agency (EPA) has a charge limit of 150g of hydrocarbon per appliance, which is defined as a closed-loop refrigeration circuit. Previous work has been completed on Class A2L refrigerants, but Class A3 refrigerants need more study to provide a technical basis for any changes to the current limits for use in refrigerator units. There is a need to assess the fire hazard of Class A3 refrigerants, and specifically propane, in larger volumes to evaluate their viability as alternatives to traditional refrigerants in more applications.
Research goal
Evaluate the fire hazard of R-290 propane in refrigeration appliances used in commercial retail and kitchen settings.
Project tasks
Task 1
Conduct a literature review of any previous work that relates to the use of flammable refrigerants in quantities over the current EPA limit and background information related to the environments and sources of ignition within the spatial confines in which refrigerated display cases are located. Perform a gap analysis.
Task 2
Perform an analysis that includes both multiple hazard analysis (MHA) and Failure Mode Effects Analysis (FMEA) to develop characteristic accidental release scenarios in commercial retail and kitchen settings including the failure modes, the potential leak rates, and ignition sources. This should include the evaluation of different types of refrigerated display cases being used in commercial retail and kitchen settings (e.g. open vs closed cases) and specifying which should be considered for the Task 4 testing. As part of this task, develop a detailed list of potential failures. Also, consider the impact of pressure rise and rate of pressure rise as part of the analysis.
Task 3
Based on the findings from Task 2, develop and implement a plan for Computational Fluid Dynamics (CFD) modelling to assess the fire hazard of accidental releases of R-290 propane from appliances used in commercial retail and kitchen settings. The CFD analysis should consider various charge sizes from the EPA limit of 150g to a maximum charge size that is appropriate for commercial retail and kitchen settings. This maximum charge size considered should not be less than 1000g. Analysis should include consideration of the environmental aspects as well as internal design aspects. Based on the findings from the CFD analysis, develop an experimental test plan that will be implemented in Task 4.
Task 4
After considering the feedback from the Technical Panel on the test plan, implement the test plan and collect relevant data to present in a report. This task should include ignition testing to assess the severity of events at various charge amounts.
Task 5
Using the findings from the previous tasks, perform a risk assessment of refrigerant ignition considering the results of the testing related to the severity of the events along with the likelihood of an event occurring and document the results in a final report. This assessment should provide conclusions on the risk of various charge sizes. Develop recommendations on how to mitigate the risks posed by R290 propane used as a refrigerant in commercial retail appliances. In addition, assess the specific risk of reclaiming propane during maintenance operations compared to venting propane during these activities.
Sponsors
Principal sponsors
- AHT
- Bitzer
- Carter
- Delhaize
- Emerson
- Heatcraft
- Hillphoenix
- Hussmann
- Target
Participating sponsors
- Chemours
- Energy Squared Consulting Engineers
- CTA Architects Engineers
Research team members (Gexcon)
- Scott G. Davis, Ph.D., P.E., CFEI
- John Pagliaro, Ph.D., P.E., CFEI
- Derek Engel, P.E., CFEI
- Drew Botwinick
- Kees van Wingerden
- Matthijs van Wingerden
- Morten Holme
