ACR Journal

CMYK / .ai CMYK / .ai CMYK / .ai 33 REFRIGERANTS The use of flammable refrigerants is rapidly growing, and many users have already found. Although however, the thought of using a flammable refrigerant is initially very daunting, the requirements for using flammable refrigerants are not the barriers many envisaged at the start of the project. From this, it is evident, for the RACHP industry to fulfil its obligations towards the reduction of climate-changing emissions, we need to be choosing refrigerants that have a low GWP, equivalent or better energy efficiency than what was used before, and can be used safely in the application being considered. How low is low GWP? This is one of those questions where if you ask different people, you will get different answers, but the F-Gas legislation does help us quantify where we need to be heading. Thanks to the reporting requirement across Europe, we have a reasonably good estimate of the quantity of fluids covered by F-Gas used in various industries. With a few assumptions, the F-Gas phasedown can be expressed as an approximate average GWP of approximately 400 by 2030. We can take this a step further as the Kigali amendment to the Montreal Protocol proposes further reductions up to 2035, which would give an approximate average GWP of 300. This provides a firm basis to gauge what constitutes a low GWP option, anything lower than 300 GWP is sustainable under these agreements, and since there are many options below this 300 figure, then there will be room for some refrigerants with GWPs higher than 300, provided they are not used in very high volume applications. With a GWP of less than ten, carbon dioxide (R-744) and hydrocarbons are easily within this range, as are many of the A2L refrigerants that are already readily available. Equivalent or better energy efficiency Energy efficiency can be a difficult comparison to make as systems can be radically different in design. As a simple example, let’s consider a condensing unit using scroll compressors operating at 10°C evaporating temperature, delivering approximately 9 kW of cooling at a design condition of 32°C ambient. Then, using selection software from a well-known manufacturer, a comparison can be made between a unit operating on a typical low GWP A2L refrigerant (R-454C, GWP=148) and R-744 operating at a 20°C ambient. The result of this comparison shows that the C.O.P. of R-454C at this condition is 28 per cent higher than for the equivalent R-744 unit and 4 per cent higher C.O.P. than an equivalent R-404A unit. This is, of course, a ‘snapshot’ comparison, but several studies published over the last couple of years have shown that over a year, in several locations representing different climatic conditions, total emissions from systems operating with A2L refrigerants are significantly lower than those from equivalent systems using R-744. This is mainly due to the difference in energy efficiency. Direct expansion (DX) systems using A3 refrigerants (e.g. propane) are, of course, even more energy efficient. Still, charge size limitations often mean these can only be used for larger systems using a secondary fluid which can also compromise the energy efficiency. Energy efficiency also translates into cost savings and has led to the term Eco- Efficiency being introduced to combine the dual benefits of emissions and cost reductions that can be made. For any retail customers interested in estimating the impact of different technologies, Climalife have access to an Eco-Efficiency Calculator which can be customised for a customer’s particular system requirements. Flammability charge size limitations There are various product-specific standards (e.g. EN60335-2-40, EN60335- 2-89) that cover flammable refrigerants, but EN378 will be the most applicable standard for most general applications. Previous articles have covered the details of EN378, and several tools are available online (e.g. Climalife Charge Size Calculator Tool), but for many typical non-hermetic applications, the compliant charge sizes for A3 refrigerants are limited to below what would be required. In contrast, for A2L refrigerants, charge sizes up to 84kg can be achieved. In addition to all this, over the coming years, the F-Gas phase down steps reduce the quantity of F-Gas (in TCO 2 e) placed on the market by more than 50 per cent of the 2021 figure. To meet this, the industry must continue to move to refrigerants with a much lower GWP and avoid any market disruption due to the availability of higher GWP refrigerants. The move to low GWP refrigerants needs to be planned well before the shortages occur. That means now! So finally, back to the original question, why use A2Ls? A2Ls are definitely not the answer to everything. There will be situations where ammonia, R-744 or hydrocarbons are the best options; however, with a sustainable GWP, equivalent or better energy efficiency than current high GWP or other low GWP options and EN378 compliant charge sizes up to 84kg, the use of A2L refrigerants has got to be high on the list of options for your next project. 2000 1800 1600 1400 1200 1000 800 600 400 200 0 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 F-GAS PHASEDOWN AS APPROXIMATE AVERAGE GWP AVERAGE GWP

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