HFC-245fa as a Blowing Agent for Water Heater Foam Insulation

Abstract

The North American water heater market has eliminated the use of the chlorofluorocarbon blowing agent CFC-11 in polyurethane insulation systems. Today the water heater market primarily uses the hydrochlorofluorocarbon blowing agent HCFC-141b. However, as a result ofthe Montreal Protocol, HCFC-141b is a transitional blowing agent, and must be replaced with third generation blowing agents by 2003. The next generation of blowing agents must have zero ozone depletion potential (ODP) and low global warming potential (GWP). Additionally for the water heater market, the blowing agent must produce foams with low thermal conductivity. Water heaters must conform to energy requirements established by the Department of Energy. Future legislation is expected to impose stricter requirements on the energy efficiency of water heaters. In addition to low thermal conductivity, there are other desirable features of a blowing agent for water heater insulation systems. The blowing agent should be a liquid at room temperature, with a boiling point similar to those of CFC-11 and HCFC-141b. The blowing agent should be miscible with many different polyols and processable in existing foam equipment. It should be non-flammable and non-toxic. It should be reasonably priced and readily available. HFC-245fa has been identified as a primary candidate for a liquid, zero ODP blowing agent. The objective of this work was an evaluation of HFC-245fa in water heater insulation systems. Water heater foam systems using HFC-245fa were evaluated for stability processability physical properties, and energy performance. Results of these studies were compared to HFC-141b water heater foam systems.