Ammonia, CO₂ and hydrocarbons aren't new — but with current refrigerants being phased out over the next decade, they matter more than ever for existing sites and new designs.
Natural refrigerants. We hear this phrase a lot, and many people may not know what it even means. Natural refrigerants are fluids like ammonia (R717), carbon dioxide (R744) or a variety of hydrocarbons (R290, R600a). These fluids aren’t especially new — they have been in use since vapour-compression systems were invented.
So, you may ask, “Why do we need these refrigerants when our current refrigerants work completely fine?” I’m glad you asked. Many refrigerants in use today can have a terrible impact on our environment when they are not handled properly, or in the event of a refrigerant leak. Every refrigerant has what is called a GWP (Global Warming Potential) and an ODP (Ozone Depleting Potential).
GWP and ODP
GWP measures the amount of heat trapped in the upper atmosphere relative to CO₂. For example, if a refrigerant had a GWP of 1,250, over 100 years 1,250 times more heat would be trapped than by the same amount of CO₂.
ODP is the ratio of ozone destroyed by a certain mass of refrigerant relative to the same mass of R11, which has a reference value of 1. For example, if a refrigerant had an ODP of 10, it would destroy 10 times more of the ozone layer per unit of mass.
The phase-out
Luckily for us, refrigerant manufacturers are constantly looking at ways to improve these figures. For decades, most countries involved in the Montreal Protocol have had a duty to reduce harmful refrigerant imports every year. In Australia, current refrigerants will be almost entirely phased out within the next decade. This means retrofitting older sites needs to be a serious consideration, and when designing a new system, the equipment selected should be future-proofed for this phase-out.
Where natural refrigerants come in
This is where natural refrigerants come into play. Apart from their lower environmental numbers, they also rival current refrigerants in performance. For example, ammonia has a fantastic volumetric cooling effect, resulting in a lower mass flow requirement — less compressor work to achieve the same cooling result. R744 has a nominal density four to five times greater than previous refrigerants (R134a, R404A and so on), resulting in smaller pipework across your site and saving you money.
The drawbacks
The aforementioned performance points are great, but I should mention some of the drawbacks. Ammonia is toxic and requires automatic leak detection with stringent safety requirements. R744 is an inert, odourless, non-flammable gas which can be deadly without the right protection methods: leak detection, automatic system shutdown and isolation. Like anything, nothing is perfect — but we can control the risks of these natural refrigerants.
Consumers and refrigeration companies alike should be mindful of this push to alternative refrigerants over the next decade. Replacing existing systems sooner will provide a safer, smarter and cleaner way forward for your business and equipment.