Share

Risk assessment of residential heat pump systems using 2L flammable refrigerants.

Number: pap. 11

Author(s) : LEWANDOWSKI T., REYNOLDS REID K.

Summary

R410A is currently the primary refrigerant used in residential AC systems and heat pumps. It is a greenhouse gas, and possible replacements include ASHRAE Class 2L refrigerants, which have reduced global warming potential but are mildly flammable. Accidental releases due to equipment faults or fatigue could potentially result in refrigerant ignition if a sufficient ignition source is present. A risk assessment of R32, R1234yf, and R1234ze(E) in residential split heat pump systems was conducted. The work included CFD modeling, experimental measurements, and fault tree analysis (FTA) to quantify ignition risks. The assessment indicated that large releases of R32, R1234yf and R1234ze(E) (i.e., on the order of 170 g/s for R-32, 78 g/s for R1234yf and R1234ze(E)) from units installed in basements, garages or attics would not reach flammable concentrations in areas where a sufficient ignition source might be present. Large releases of all three refrigerants from a unit located in a utility closet can generate flammable concentrations in the closet, although the time the refrigerant concentration was flammable was brief (70 s for R32 and R1234yf and 45 s for R1234ze(E)). Flammable concentrations did not occur with smaller leaks of R1234ze(E) and R1234yf (i.e., 1.5 g/s or less) in utility closets. The FTA estimated that the risks of refrigerant ignition due to an accidental leak of R32, R1234yf and R1234ze(E) were 9 x 10-5, 2 x 10-5 and 2 x 10-5 ignition events per unit per year, respectively. For comparison, the risk of a significant home fire in the US is 1 x 10-3 per home per year. The FTA in this study considered refrigerant ignition and did not determine whether a fire would ensue due to the ignition of surrounding materials. The analysis also did not include potential mitigation factors that would further reduce the probability of refrigerant ignition.

Available documents

Format PDF

Pages: 14 p.

Available

  • Public price

    20 €

  • Member price*

    15 €

* Best rate depending on membership category (see the detailed benefits of individual and corporate memberships).

Details

  • Original title: Risk assessment of residential heat pump systems using 2L flammable refrigerants.
  • Record ID : 30007987
  • Languages: English
  • Source: ASHRAE/NIST Refrigerants Conference: moving towards sustainability.
  • Publication date: 2012/10/29

Links


See other articles from the proceedings (20)
See the conference proceedings

Indexing