A-Gas Managing Director John Ormerod with an overview of how mildly inflammable refrigerants are taking centre stage.
In our industry an ideal refrigerant would be non-toxic, non-flammable, energy efficient, have low installation and maintenance costs and have the right environmental credentials. But gone are the days when one class of refrigerant ticks all of these boxes.
HFCs meet four out of five of these demands but, as I am sure you are aware, they are under scrutiny for their impact on the environment. With few alternatives, we will have to start making compromises when it comes to selecting a refrigerant of choice.
Energy Efficiency at a Relatively Low Cost
Ammonia is an excellent energy efficient, natural refrigerant that ticks the cost effective box but on the downside it is highly toxic. Ammonia installations require external plant rooms and secondary systems are needed to make the refrigerant a practical alternative. That said, secondary Heat Transfer fluids, such as MEG and MPG, are readily available making this a viable option.
The Grey Area
HFOs are definitely starting to make their mark. They have a short atmospheric life and don’t contribute to global warming like HFCs. However, HFOs do take us into a grey area because they are mildly flammable.
With regard to working practices we will have to wait and see what comes out of the redrafting of the European Standard EN378 which I think will provide the certainty the industry is looking for on how to deal with mild flammability issues. Once that is completed engineers should fully understand the areas that HFOs can be used in.
"HFOs do take us into a grey area because they are mildly flammable."
R1234ze won’t be suitable as a drop-in for systems because of the volumetric capacity but for new systems it is a good energy efficient option.
The Boiling Point Issue
As a result HFOs blends are emerging which do offer a practical alternative to high GWP refrigerants. The Solstice L40X (R455A) refrigerant from Honeywell is an ultra low GWP R404A replacement scheduled to be commercially available later in the year. This hybrid mixture contains R32 and CO2 and is classified as a mildly flammable gas. R455A matches the capacity of R404a and has the same or better efficiency. Solstice L40X is a refrigerant to keep an eye on.
Some supermarkets are already testing HFOs to gain an understanding of the mixtures involved and how they perform. A number of chiller manufacturers have incorporated R1234ze as a standard refrigerant in some of their equipment and there have been good reviews on this application. This could be an another area where HFOs will make their mark in the industry.