ACR Journal

CMYK / .ai CMYK / .ai CMYK / .ai 23 ADVERTORIAL acrjournal.uk countries have taken independent actions, and the United States ratified the agreement in September 2022. Overall, the trend in refrigerant technology and approach over the past 40+ years has been the continued movement toward systems with a reduced GWP and overall lower environmental impact. Breaking Down Environmental Impact of Refrigerants The environmental impact of refrigerants – and why the A2L category is coming into focus – comes back to the holistic impact those chemicals have on the environment. In this context, chemicals are generally classified in terms of both flammability and toxicity according to ISO 817. Chemicals in category A3 are considered less toxic, but highly flammable – such as propane. While chemicals at B1 may not be flammable, they are toxic. A2L chemicals are slightly flammable but are less toxic. The third factor to consider is how efficient and effective a chemical is for a given purpose. After all – most of the environmental impact of HVAC equipment – about 70 percent – is in their power consumption (and the energy generation processes used to provide it). Holistically, the goal is to find the balance between a chemical’s global warming potential (GWP) and its efficiency in use in an HVAC environment while also considering flammability, toxicity, or other issues. While legacy hydrofluorocarbons did provide strong efficiency in HVAC systems for their time, they carried extremely high GWP rates, in addition to the ozone depletion issues discussed prior. Many A2L refrigerants developed in the years since deliver stronger HVAC performance without those ozone- depleting or greenhouse gas side effects. Other chemicals – such as propane, CO2, or ammonia - have also been used in this application, but each of them has issues which stand as barriers to truly widespread use. CO2 systems operate at 5 to 10 times higher pressure than other systems and may not be permitted in some context, propane is extremely flammable, and ammonia has the potential to be highly toxic. That concept of finding the right balance between GWP, safety, and cooling efficiency is the genesis behind the A2L category, and its use within the HVAC context. Codifying A2L HVAC Systems in Buildings A2Ls have been used in the European Union, Japan, India, Australia, and the auto industry for some time. But as the advantages of using A2L systems became more clear, regulatory bodies made adjustments to account for their use in commercial and residential HVAC systems, such as ASHRAE 15-2019 and UL 60335-2-40. In order to burn, A2L gases would need to leak, reaching concentrations above the chemical’s lower flammability limit, and then be exposed to an open flame or other ignition source. To prevent this, much of the regulatory focus has been on the preventing and detection of leaks within a given system. Systems designed to operate with A2L refrigerants must be designed so they cannot operate if leak detection systems are bypassed. Those same leak detection systems must withstand very challenging environmental conditions – high in condensation with significant temperature extremes - without needing additional maintenance or calibration over a planned 15-year equipment life. In addition, many chemicals used in servicing HVAC equipment may use oils or other chemicals which may foul some detection systems. Those factors put the pressure on HVAC OEMs and their partners to develop solutions for this next generation of equipment. Looking Forward with Refrigerant Technology Stretching back more than 40 years, the continuing arc of HVAC technologies has been the continued push toward more environmentally friendly technologies and refrigerants – a trend which will likely continue to take shape in the coming decades. Actions taken under the Kigali Amendment to reduce and eliminate the use of HFCs is expected to prevent more than 100 million tons of carbon dioxide equivalent of greenhouse gases from the atmosphere. By 2100, that effort will have hopefully helped to avoid up to 0.5 degree Celsius of global temperature rise. Looking ahead, further enhancements in HVAC system design throughout the coming years and decades will continue to take shape, governed by that ongoing focus on safety, environmental impact, and energy efficiency worldwide. R12 Freon (Banned CFC) HFC-134a HFC-152a CO2 (R-744) Propane (R290) Ammonia Ozone Depletion Potential (ODP) 1 0 0 0 0 0 Global Warming Potential (GWP) 10,200 1,430 124 1 3 0 Flammability/Toxicity A1 A2L A2L A1 A3 B2L Operating Pressure Range 2.1 - 11.7 bar 0.6 - 6.7 bar 0.6 - 6.7 bar 10 -150 bar 10 - 50 bar 2.9 -13.5 bar