Finally, a replacement for R123?

USA: While much has been made of the new HFO refrigerants 1234yf and 1234ze, another lesser known HFO could provide a much needed alternative to R123 in chiller applications.

Introduced in the early 90s during the CFC phase-out, R123 was seen as an ideal alternative to R11 in centrifugal chiller applications. Hugely efficient, it had a very low ODP and, although not deemed significant at the time, a GWP of around 77. Although widely adopted in the US and elsewhere, it was, however, largely shunned in Europe due to its B1 toxicity after long-term inhalation was found to cause an increased incidence of benign tumours in the liver, pancreas, and testis of rats. 

Being an HCFC, R123 is destined for phase-out around the world despite US attempts to save it from extinction based on its negligible ODP, low GWP and high efficiency. R123’s removal from circulation will, however, also finally end arguments as to which centrifugal chillers are more efficient – R134a or R123? 

But now a new refrigerant said to offer even better efficiencies than R123 is being fast-tracked for adoption. Like 1234ze, which was initially promoted as a foam propellant but found applications as an alternative to R134a in chillers, foam blowing agent HFO-1233zd(E) could be similarly attractive to those dedicated to finding an alternative to R123. 

HCFO-1233zd(E) is a single component refrigerant with a GWP of just 6. It has been submitted for designation and classification to ASHRAE 34, and is likely to be A1 (low toxicity, non-flammable) under that standard as well as ISO 817. 

Strangely, 1233zd(E) is itself an HCFC, as such contains ozone-depleting chlorine but falls outside the Montreal Protocol phase-out of these gases. This is because its ODP is measured as being between 0.00024 to 0.00034 (R22 is 0.055). Even with worst case estimates of emissions which assume that this compound would substitute for all compounds it could replace, the impact on global atmospheric ozone abundance is considered statistically insignificant.

The latest UNEP TEAP report on alternatives says efficiency levels are slightly better than HCFC-123 when used in centrifugal chillers. 

Already being produced in commercial quantities as a solvent and foam blowing agent, the cost would be moderate and will have a reasonable payback period due to its high energy efficiency.