E360 Outlook: Weighing up natural refrigerant alternatives
In the previous Climate Conversions post, we discussed several business drivers that are encouraging a shift toward natural refrigerant systems, including CO2. Here are several other viable natural refrigerants, along with important considerations relating to their use.
Propane is classified as A3 by ASHRAE: a non-toxic and flammable refrigerant, with ozone depletion potential (ODP) of zero and a GWP of 3. Hydrocarbons are environmentally benign refrigerants and have low discharge temperatures compared to HCFCs and HFCs, thus improving system reliability. Hydrocarbons offer an approximately 40 percent reduction in charge compared to R22 and R134a. Pressures are similar to R22; however, a system must be specifically designed to use hydrocarbon refrigerants.
Propane applications are likely to grow, especially in smaller sizes, as safety in service will be important for adoption.
Isobutane is used in 95 percent of domestic refrigerators and freezers in Europe today, and countries like Argentina, Brazil and China are following. Millions of pieces of light commercial equipment use R290 and R600a (as well as CO2) worldwide. Early adopters of the technology include The Coca-Cola Company, Unilever, Red Bull and PepsiCo.
Ammonia is an abundant and affordable refrigerant, which has been used for years in large capacity industrial systems. It is lighter than air, breaks down rapidly in the environment, and has zero ODP and zero GWP. R717 is up to 25 percent more efficient than HFCs, has excellent heat recovery and low leakage. Because of its toxicity, it is identified and addressed rapidly in case of leakage.
Applications for R717 include: food and beverage; cold storage; recreational ice; ground freezing in mining; district heating and cooling; and heat pumps.
Although hydrocarbons and ammonia have their application challenges, their uses continue to increase in specialized applications.
Director of CO2 Business Development
Emerson Climate Technologies