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GRANT LAIDLAW
Grant Laidlaw is currently the owner of the Air Conditioning and Refrigeration Academy ( ACRA ) in Edenvale . He holds a Bachelor of Business Administration and an associate degree in educational administration . He has a National Technical Diploma and completed an apprenticeship with Transnet . He has dual-trades status : refrigeration and electrical . He has been involved with SAIRAC for over two decades and served on the Johannesburg committee as chairman and was also president between 2015 and 2018 . Currently he is the SAIRAC national treasurer .
WELCOME TO THE SOLUTIONS PAGE
By Grant Laidlaw
Many people ask for assistance in the understanding of theoretical and practical aspects of the industry . We are going back to basics as I have questions coming in that indicate that the basic understanding necessary to work in the industry is not in place .
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Gordon asks : Hi Grant , looking at refrigerants , we all see the trends towards naturals . I have seen hydrocarbons being featured but what of carbon dioxide ? It seems that we only have large chiller type and retail refrigeration systems utilising carbon dioxide . Will the refrigerant enter the light commercial market ? I know that beverage cooler companies were introducing carbon dioxide transcritical systems but have ultimately gone with R290 . Why are we looking at carbon dioxide , and what are some of the safety concerns ?
Hi Gordon , transcritical carbon dioxide ( CO
2
) R744 refrigeration systems have gained acceptance in the supermarket refrigeration industry and there is some movement in the light commercial and other sectors of the industry . National and international refrigerant phase down policies are being expanded to include HFCs .
In South Africa , HFCs for example , are about to enter the start of the phase down process . This will have a massive impact on our industry and in particular the air-conditioning sector . Both R32 and R410a are HFCs and are to be phased down in accordance with the Kigali amendment of the Montreal Protocol . Although R32 has a GWP 32 % lower than R410a , the fact remains that R32 ’ s GWP of 675 is above the cut off GWP of 500 .
Given that CFCs are long gone , HCFCs are being phased out and HFCs are about to begin being phased down , so where do we go ? Naturals are the future , and the selection revolves around ammonia , hydrocarbons , some hydrofluoroolefin ( HFO ) refrigerants and carbon dioxide . I am aware of some research around using water ( H
2
O ) as a refrigerant – but we have yet to see commercially viable results .
RACA Journal I June 2024
Technology advancements in CO
2 systems are making these systems more economically viable , in terms of both equipment and installation cost but also energy and operating costs .
Gordon , looking at some background information , we find that
CO
2 is a naturally occurring compound in Earth ’ s atmosphere and it is the fourth most common atmospheric compound , behind nitrogen , oxygen and argon . As we all know carbon dioxide is an integral part of the life cycle of plant and animals , as the primary product of respiration in animals and humans . In turn the carbon dioxide is absorbed by trees and converted back to oxygen .
Through the process of photosynthesis , leaves draw in carbon dioxide and water and use sunlight to convert this into chemical compounds such as sugars that feed the tree . As a byproduct of that chemical reaction oxygen is produced and released by the tree . It has been calculated that one large tree can provide oxygen for up to four people .
Trees also store carbon dioxide in their fibres helping to clean the air and reduce the negative effects that this CO 2 could have had on our environment . According to the Arbor Day Foundation , in one year a mature tree will absorb more than 48 pounds of carbon dioxide from the atmosphere and release oxygen in exchange .
“ The CO₂ system pressure becomes a safety concern when liquid becomes trapped in a portion of the system that is not rated for the full pressure at higher temperature .”
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