R407F

R407F also known by its trade name Genetron Performax® LT was developed by Honeywell as a non-flammable non-ozone depleting lower GWP replacement for R404A and older R22 systems.

R404A has been the refrigerant of choice in most supermarkets for almost 30 years. Unfortunately, although it is non ozone depleting R404A does have a very high GWP (global warming potential) 3,922 when compared to CO₂ having a GWP of just 1.

That means that just 1Kg of R404A leaking from a fridge is equivalent to almost 4 tonnes of CO₂.

With tighter controls on using high GWP refrigerants, users of R404A had to find a better solution with a lower GWP to conform to changes in legislation. R407F is a viable lower GWP option albeit only a temporary solution. R407F has a GWP of 1,824 making it less than half that of R404A, F-Gas compliant, similar cooling capacity and improved efficiency. It should be noted that R407F does have a higher discharge temperature so demand cooling may be required.

It should also be noted that since R407F began replacing R404A, new lower GWP refrigerants are now available such as R448A GWP 1,387 and R449A GWP 1,397.

Although new lower GWP refrigerants are better than R404A they are still only classed as interim replacements with a medium GWP.

One disadvantage of R407F is that it is a zeotropic blend with moderate glide.

R407F is made up from 3 different components— 23% R32 for heat capacity, 25% R125 to reduce flammability and 52% R134 to reduce overall pressure.

Glide is the difference between the boiling and condensing temperatures of the least and most volatile components. This is easily demonstrated with alcohol distillation.

The “mash” is a basic weak mixture of alcohol and water and is a great example of a zeotropic blend containing 86% water and 14% alcohol.

Water has a boiling temperature of 100^oC and alcohol boils at 78^oC so the mash has a glide of 12^oC. When placed into a still and heated, the alcohol begins to boil off first then as the temperature approaches 100^oC the water begins to boil, as this happens the alcohol content of the mash begins to drop so it is no longer its original 86% - 14% composition, the mash has fractionated into a new composition blend.