Zero Ozone Depletion Potential Chemical andEquipment Technology for the CommercialRefrigeration Market

摘要

Historically, the rigid polyurethane insulation industry utilized relatively few blowing agents. The industry’swork-horse blowing agents started with CFC-11 and CFC-12, which were later eliminated due to their severe ozonedepletion potential (ODP). After the elimination of these materials in many geographies, HCFC-141b and HCFC-22became the blowing agents of choice. With the elimination of HCFC-141b and the current phase out of HCFC-22 inmany geographies, including North America, the list of available zero ODP blowing agents becomes more diverse.Common zero ODP blowing agents include the chemical blowing agents water and formic acid and physicalblowing agents like HFC-245fa, HFC-134a and hydrocarbons like pentane. Combinations of these blowing agentsare an option as well. It should be noted that each of these zero ODP blowing agents also has some degree of globalwarming potential (GWP). The variation in GWP between blowing agents is likely to become a more significantconcern as the focus on global warming increases. Each of these blowing agents also has its own unique handling,processing and physical property characteristics which must be considered when developing a solution for aparticular application.This paper discusses each of the blowing agent’s unique processing and property characteristics in rigidpolyurethane foams for the commercial appliance market. Emphasis is placed on the special handling requirementsnecessary for the increased vapor pressure and flammability of some of the blowing agent options. Due to the everincreasing demand for energy efficiency, a comparison of the thermal conductivity of the various blowing agents isalso presented.Equipment options available to the commercial appliance market are also discussed. Low pressure dispensingequipment, high pressure dispensing equipment and The Dow Chemical Company’s proprietary Eliminator andLinks dispensing systems are presented. Again, vapor pressure and flammability concerns need to be taken intoconsideration when choosing an equipment option.Finally, we will present the chemical technologies available from The Dow Chemical Company as solutions forthe market’s new zero ODP environment. We will focus on the North American market which has just completedthe full phase out of HCFC’s this year.