A Method for Evaluating the Effect of Blowing Agent Condensation on Sprayed Polyurethane Foams

Abstract

/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. ABSTRACTAn experimental procedure for the determination of temperature dependence of thermal conductivity of foam insulations blown with condensable gases is presented. The procedure is used to investigate the effect of the blowing agent on thermal conductivity of a polyurethane system blown with CFC-11 or HCFC-123, at various stages of its aging. A method to calculate the partial pressure of the blowing agent in the cell gas mixture of the test specimens, from the data on thermal conductivity, is also presented.

Effect of Time and Temperature on R-Value of Rigid Polyurethane Foam Insulation Manufactured with Alternative Blowing Agents

“…Only the Base 88 was, therefore, analyzed with help of the model. These findings were further verifted with a technique [1] based on the Clausius-Clapeyron equation, called the beginning of condensation (BC) method. All the experimental results gave evidence to the fact that during the prolonged storage period a significant reduction in the blowing agent pressure took place within the encapsulated specimens.…”

“…This point, called the beginning of condensation (BC) point may be observed at about 16.5°C on the theoretical curve. Any further reduction in temperature successively decreases the amount of the blowing agent in the cell gas mixture until the whole blowing agent has been liquified out of the cell gas mixture [1].…”

“…Uniform distribution of pressure across the specimen allows application of the BC method [1] to find if any change in the blowing agent pressure occurred during the torage period. Figure 8 compared model cal ul, tions with the experimental results shown in Figurt· 3(a) [typical of the rc ult presented in Figures 3(a) through 3(d)] .…”

“…One such experimental technique was recently developed and reported by the authors [1]. In this technique, the exchange of gases between specimen and its environment is prevented by means of specimen encapsulation.…”

High-Performance Vacuum Insulation Panel: Development of Alternative Core Materials

“…The thermal conductivity of most of the commonly used blowing agents is lower than half of the thermal conductivity of air. The researchers at the National Research Council (NRC) Canada, Institute for Research in Construction (IRC) have been working on the performance of closed-cell foam insulation for more than 15 years now (Kumaran et al 1989;Bomberg and Kumaran, 1991;Mukhopadhyaya et al 2004). This research effort has so far culminated to the development of a standard test method for determination of long-term thermal resistance (LTTR) of closed-cell thermal insulating foams (CAN/ULC-S770).…”