40 likes | 148 Views
Report of the Scientific Assessment Panel. Cl. OEWG, 33 rd meeting, Bangkok , 24–28 June 2013. ODP and GWP of 1,2-dichlorohexafluoro-cyclobutane (c-C 4 F 6 Cl 2 , RC-316c). Cl. Commercial R-316c is as a mixture of 52% ( E )- and 48% ( Z )- isomers. ( Z )-R-316c. ( E )-R-316c.
E N D
Report of the Scientific Assessment Panel Cl OEWG, 33rdmeeting, Bangkok, 24–28 June 2013 ODP and GWP of 1,2-dichlorohexafluoro-cyclobutane (c-C4F6Cl2, RC-316c) Cl • Commercial R-316c is as a mixture of 52% (E)- and 48% (Z)- isomers (Z)-R-316c (E)-R-316c • lifetime primarily determined by photolysis in the stratosphere • Isomers have different atmospheric photolysis rates and, hence, different atmospheric lifetimes, ODP, and GWP • Both isomers are long-lived; have high ODP and GWP Cl Cl OEWG Bangkok June 2013 R316c
UV absorption cross sections of RC-316c Burkholder et al., 2013 (recent work) Temperature (K) 296 233 • Absorption cross sections of the individual isomers have been measured. • Absorption cross sections were measured as a function of temperature • The E-isomer absorbs UV more than the Z-isomer 273 213 253 (Z)-R-316c Cl Cl (E)-R-316c Cl Cl Atmos. l Range OEWG Bangkok June 2013 R316c
Infrared cross section of RC-316c Burkholder et al., 2013 (recent work) Calculated Radiative Efficiency(W m-2 ppb-1) (Z)-R-316c 0.282 Cl Cl (E)-R-316c 0.310 Cl • Measured IR cross sections are slightly different • Calculated radiative efficiency differ by ~10% Cl OEWG Bangkok June 2013 R316c
ODP and GWP of RC-316c Cl Cl (E)-R-316c (Z)-R-316c Atmospheric Lifetime (2-D model) Fleming et al., 2013 114 years 75 years ODP (semi-empirical) ~0.6-0.7 ~0.5 GWP-20 4885 5615 Cl GWP-100 4360 5800 Cl Bottom Line: ODP and GWP of R-316c is similar to, and slightly smaller than, CFC-11 and CFC-12 OEWG Bangkok June 2013 R316c