ACR Journal

October 2022 | November 2022 REFRIGERANTS 18 By Edoardo de Pantz, managing director, Acquaria Propane R290 as a refrigerant for the HVAC industry Volume 8 No.6 In August 2021, the Intergovernmental Panel on Climate Change ( IPCC ), released the first version of the AR6 report Climate Change 2021 – The Physical Science Basis - which contains the new official GWP (Global Warming Potential) values for hydrocarbons. This report, using the 6th assessment, shows that propane R290 has a 100-year GWP of 0.02 , much lower than the traditional value of 3 using the 4th assessment (because of its three atoms of carbon (C3H8). Although 3 is a very low value if compared with most popular HFCs, it is still many times higher than the new value. This news, together with the increased R32 GWP value from 675 to 771, could be a game-changer in the HVAC industry, especially if the 6th assessment is implemented by DEFRA as the reference point for F-GAS use enforcement, as most likely it would be no longer possible to use R32 in new equipment from January 1st 2025 (for new single-split units, with a charge under 3kg at least). The change to the 6th assessment has added weight to the fact that propane has become a valid alternative as refrigerant gas, on top of its effectiveness and energy-efficiency as a refrigerant. Why natural? Propane is mainly obtained as a by-product of natural gas extraction and oil cracking. Before being used in refrigeration systems, it is optimised through a specialist cleaning process. Environmental impact To demonstrate the environmental impact of a refrigerant it is sometimes clearer to use a CO2 equivalent reference rather than using GWP figures, that is the refrigerant carbon footprint of the HVAC appliance that we put into the market. A simple example can be worth a thousand words. A typical 50kW air source heat pump (ASHP) using a 10kg charge of R410A has the carbon impact equivalent of 21 tonnes of CO 2 . The same system with R290 has 15kg of CO 2 equivalent, and now using the new AR6 classification the carbon impact can be as low as 90 grammes! The majority of HVAC manufacturers are late in re-designing chillers and their heat pump ranges to use R290 as a refrigerant. However, a few of them started decades ago and now have significant case studies, practical experience and evidence of its successful use. It’s fair to say a large number of manufacturers are now playing catch-up and in the next few years we will see many new products entering the market. ASHP will be the focus, but water to water (W2W) appliances will also be of significant interest, especially when thinking of HP cascade systems and the system efficiency calculations now advised in CIBSE AM17:2022. In designing for the first time or re-designing a new heat pump, manufacturers will follow the detailed and specific Standard & Regulations (EN 378, ISO 5149), and will make sure to implement all the relevant safety measures required. But the real challenge will come from the thermodynamic performances of R290 compared with conventional refrigerants, and the advantages / opportunities that thermodynamics will give with R290 - as state of the art and as future developments – in perspective. Benefits of R290 Interestingly, when we analyse R290 thermodynamic performances as 50kW ASHP • R410A • GWP=2088 • Refrigerant charge: 10kg • CO 2 Equivalent: 2088 * 10/1000 = 20.88 Tonnes Example of Carbon Footprint : 50kW Heat Pump 50kW ASHP • R290 • GWP=3.3 • Refrigerant charge: 4.5kg • CO 2 Equivalent: 3.3 * 4.5/1000 = 14.9 kg 20.88 T 14.9 kg 90 grams * *with IPCC report AR6 new value (GWP=0.02) Edoardo de Pantz