Advanced insulations for refrigerator/freezers: the potential for new shell designs incorporating polymer barrier construction

The impending phase-out of chlorofluorocarbons (CFCs) used to expand foam insulation, combined with requirements for increased energy efficiency, make the use of non-CFC-based high performance insulation technologies increasingly attractive. The majority of current efforts are directed at using advanced insulations in the form of thin, flat, rectangular, low-conductivity gas-filled or evacuated panels, which we refer to as advanced insulation panels (AIPs). Allʹs can be used in conjunction with blown polymer foams to improve insulation performance in refrigerator/freezers (R/Fs) of conventional design and manufacture. This AIP/foam composite approach is appealing because it appears to be a feasible, near-term method for incorporating advanced insulations into R/Fs without substantial redesign or retooling. However, the requirements for adequate flow of foam during the foam-in-place operation limit the allowable thickness and coverage area of AIPs. This restriction, combined with the thermal bridging effects of elements such as steel outer shells and surrounding foam, allow only relatively small improvements in overall thermal resistance with AIP/foam composite insulation.