Reduced Global Warming Potential (GWP) is one of the main criteria for the next generation of refrigerants, but it is not completely straight forward.
China has been the largest producer and consumer of HCFC refrigerant gases. They are the most ozone depleting substances in mass production and consumption in the world and are classified as the first class controlled substances in Annex C of the Montreal protocol. On the other hand, middle class population in China is growing with a result of higher demand on the living standards; therefore, the need for domestic air-conditioning systems is higher than ever.
Several Chinese manufacturers have launched HFC products in the domestic and overseas markets. Compared with HCFCs, HFC refrigerant gases have zero Ozon Depleting Potential (ODP) and significantly lower Global Warming Potential (GWP). However, HFCs weren’t a drop in replacement for HCFCs since they are not miscible with mineral based oils used in traditional refrigeration systems. A new refrigerant required a new system and other materials to complement it, and the development of those materials were urgently needed. Among those materials, the development of suitable refrigeration compressor lubricant was of greatest importance in ensuring a good performance.
Polyol esters (POEs) are well known in the lubricant industry for displacement type refrigeration systems. POEs are derived from the reaction of a polyol with monofunctional carboxylic acids. Such polyol esters are especially suited for use in HFC refrigeration systems. POEs polar nature provides improved miscibility with the HFC refrigerant in comparison to other lubricants such as mineral oils, poly-alpha-olefins, or alkylated aromatics.
Regulations, both in national and international level, have been of the most important drivers for urging investment in new technology. The F-gas regulation was implemented at January 1, 2015. The regulation put in place a HFC phase-down from 2015 to 2030 by means of a quota system and sectorial bans on high GWP refrigerants [ref: Danfoss]. Low GWP (Hydrofluoroolefins (HFOs)) and natural refrigerants are going to be the ultimate replacement for HFCs. However, concerns in safety, energy efficiency and environmental acceptance have clouded the direction of future refrigerant development, including challenges with lubricant-refrigerant optimization. Lots of studies showing that POEs can be tailored to the requirements for many new low GWP refrigerants.