Thermal Conductivities of Alternatives to CFC-11 for Foam Insulation

摘要

The present work examines the thermal conductivities of several dilute vapors which are potential alternatives to chlorofluorocarbons (CFCs) for cellular-plastic foams. Thermal conductivity data are reported inthe vapor phase, from 280 to 340 K, for trichlorofluoromethane (CFC-11), 1,1,1-trifluoro-2,2- dichloroethane (HCFC-123), 1-fluoro-1,1-dichlorQethane (HCFC-141b), 1,1,2-trifluoroethane (HFC-143), 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), 1,1,1,2,3,3-hexafluoropropane (HFC-236ea), 1,1,1,3,3,3- hexafluorQpropane (HFC-236fa), 1,1,2,2,3-pentafluoropropane (HFC-245ca), 2-(difluoromethoxy)-1,1,1- trifluoroethane (HFE-245fa1), 2-(trifluoromethoxy)-1,1,1-trifluoroethane (HFE-263fb1), octafluorocyclo- butane (RC318), 1,1,1-trifluoroacetone, and a 75 mol % cyclopentane + 25 mol % pentane mixture. These data were obtained with a transient hot-wire instrument andare estimated to have an uncertainty of +-2% (2a confidence) at these low densities.