New HCFO Refrigerants

We might be seeing refrigerants containing chlorine again sometime in the near future. Some of the new olefin based refrigerants contain chlorine but still manage to have almost no ozone depletion potential. These chemicals are hydrochlorofluoro-olefins, or HCFOs. Why are chemical manufacturers taking a new look at chemicals containing chlorine? In short, to produce chemicals that have a low global warming potential, are non-flammable, and work at pressures common to “normal” refrigeration systems. Hold on - what about ozone depletion? Turns out, eliminating chlorine is not the only way to make a refrigerant that will not deplete the ozone. Another way it to make a compound with a very short atmospheric life. The atmospheric life of HCFOs is measured in days instead of years. HCFO refrigerants break apart quickly in the atmosphere, before they are able to reach the stratosphere. This same characteristic also helps reduce the global warming potential of HCFO refrigerants. For example, HCFO-1224yd(Z) has an atmospheric life of 21 days and HCFO 1233zd(E) has an atmospheric life of 26 days. They also have nearly 0 ozone depletion potential; for example HCFO 1233zd(E) has an ODP of 0.00012, which is commonly reported as 0.  Both a GWP less than 1. In addition, both have an A1 safety rating and can be used with both POE or napthenic mineral oil. HCFO 1233zd(E) from Honeywell and HCFO 1224yd(Z) from AGC Asahi Glass are currently the only two HCFO refrigerants I know about. They are both for low pressure centrifugal chillers. One more characteristic of these new HCFO refrigerants - they are very expensive. Like, if you have to ask how much you can't afford it expensive.