© RACA Journal www . refrigerationandaircon . co . za RACA Journal I March 2025 5
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THE JOURNEY TO A BETTER WORLD :
A REFRIGERATION PERSPECTIVE ( PART 3 )
By Andy Pearson , Star Refrigeration
RACA Journal is presenting the entire presentation in four sections . This is Part 3 of a four-part series .
… continued from Part 2 .
The sector that has had the most difficulty up to now in adapting to the changes in refrigerant acceptability is the market for split and multi-split air-conditioners . These devices were originally developed in Japan in the 1960s and have become very common all over the world , particularly in the addition of air-conditioning to older buildings that are not suitable for the installation of air ducts or large water pipes . Originally designed for R-12 and R-22 , they transitioned to R-407C in the 1990s , then R-410A and more recently R-32 . The move to R-32 has required a substantial rethink on system safety and flammability as well as a significant increase in design pressure .
It also required significant technical development to achieve acceptable efficiency levels as the critical temperature of R-32 , at 78 ° C , is much lower than R-12 or R-22 , which are 112 ° C and 96 ° C respectively . Significant effort has also been invested in the development of air conditioners using hydrocarbons as refrigerants but their widespread adoption is hampered by legitimate safety concerns over their higher flammability .
Heat pumps come in a wide range of sizes and need to be considered sector by sector . The district heating market for water-source heat pumps has seen strong competition between systems using ammonia in screw or reciprocating compressors and systems using HFO-1234ze ( E ) in centrifugal compressors . More recently large systems have been engineered using carbon dioxide in a combined compressor-expander but these are not yet widely available and their efficiency has not been proven . There has been some limited use of air-source heat pumps with HFCs , even up to several megawatt capacity , but these are also not common . In smaller commercial and domestic heat pumps the trend tends to follow the split air-conditioning market ,
even where the heat pump is only for hot water heating in central heating systems . At present HFC-410A and HFC32 are the most common refrigerants with some limited use of hydrocarbons in smaller systems . Carbon dioxide has
( Left to right ) SAIRAC president Robert Fox , Dr Andy Pearson and Johannesburg Centre chairman , Chad Vercuiel .
been widely used in heat pump water heaters used to heat mains water to above 60 ° C . It is difficult to make those systems efficient for heating recirculated water for central heating because the return water temperature is usually not low enough .
Over the last 30 years some significant advances have been made in efficiency terms , but there is still room for improvement . For example , in the US a law entered into force in 1992 that required residential air-conditioners to have a seasonal energy efficiency ratio ( SEER ) of at least 9 . SEER is the ratio of the annual cooling effect achieved ( measured in BTU ) to the electrical energy used over the year ( measured in Wh ). By 2015 the legal minimum SEER had increased to 14 in hot climates and 13 in the rest of the US , meaning that on a like for like basis the baseline efficiency has improved by 30 %. However , there are models on the market with SEER in the 20s or even 30s which would reduce energy use to about 30 % of the 1992 minimum standard . In other sectors there have been similar improvements in efficiency , for example in water chillers , but it is evident across many sectors that operating efficiency often falls far short of the design ideal . In a survey of European cold storage conducted about ten years ago it was noted that the average energy consumption across several hundred locations was about ten
© RACA Journal www . refrigerationandaircon . co . za RACA Journal I March 2025 5