R. Dohrn et al., Vapor-phase thermal conductivity of 1,1,1,2,2-pentafluoropropane, 1,1,1,3,3-pentafluoropropane, 1,1,2,2,3-pentafluoropropane and carbon dioxide, FLU PH EQUI, 160, 1999, pp. 1021-1028
The insulation efficiency of polyurethane foam is mainly (60 to 65%) determ
ined by the thermal conductivity of the cell gas, which is a mixture of car
bon dioxide (CO2) and a blowing agent. Until recently CFC-11 (trichlorofluo
romethane) was the most widely used blowing agent. To find adequate substit
utes for CFC-11, the vapor-phase thermal conductivity of several potential
blowing agents has been measured. The experimental procedure is based on th
e transient hot-wire method. The apparatus was designed in cooperation with
the University of Stuttgart (Prof. K. Stephan). The measuring cell (stainl
ess steel, 1.4571) with a length of 270 mm and a diameter of 48 mm consists
of two parallel chambers with platinum wires of different lengths. In this
paper experimental results for the vapor-phase thermal conductivity of car
bon dioxide(CO2), 1,1,1,2,2-pentafluoropropane (HFC-245cb), 1,1,1,3,3-penta
fluoropropane (HFC-245fa), and 1,1,2,2,3-pentafluoropropane (HFC245ca) are
given. Experiments have been performed at pressures between 0.2 h MPa and 1
.5 MPa and temperatures between 298 K and 419.91 K. (C) 1999 Elsevier Scien
ce B.V. All rights reserved.