HEAT EXCHANGERS


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Moving towards a greener industry


James Trant, internal sales engineer at Marstair talks about the impact of F-Gas on the development of heat exchangers.


18 W


ith the first phase-down targets in place and only stricter targets to


come, there is a bigger push than ever towards more economically viable and environmentally friendly alternatives to current high global warming potential (GWP) refrigerants. The F-Gas phase-down has brought an increase in innovation across industry, with the aim to make better use of existing refrigerants until a solution is made, found, or legislation changes. In 2018, the F-Gas Regulations


have enforced legislation leading to a reduction in the refrigerant GWP quota of 37% when compared to 2015 and by 80% by 2030. This is turning suppliers and contractors towards distributing and purchasing alternative refrigerants with low GWPs as refrigerant prices inflate exponentially as a result. A solution that many


manufacturers and installers are heading towards is the use of A1 refrigerants with lower GWPs. These include refrigerants R448A, R449A and R452A, which result in reduced carbon emissions compared with the equivalent volume of R404A. Whilst greener refrigerants do offer reduced


environmental impact, they only work as a temporary measure. Further phase-down will later restrict their use, making this a questionable long-term strategy. Newer A2L refrigerants such as R454C have a much lower GWP than HFC equivalents, but have refrigerant charge restrictions placed on them which limit the amount of refrigerant that can be used in a system, dependent on the room size in which the product is situated. This restriction is designed ensure that, in the event of a leak, the volume of refrigerant will never be able to reach the lower flammability concentration limit at which combustion can occur.


This makes them unsuitable


for many split refrigeration applications as the refrigerant charge requirement is unknown prior to the installation. This is also made more difficult when the indoor evaporator and outdoor condensing units are supplied by different manufacturers requiring systems to be charged to a sight glass. Health and safety standards are not yet fully in place for the manufacture of refrigeration products for use with A2L refrigerants, further limiting use.


is an effective and widely used alternative, but it is cost prohibitive for smaller systems. The investment costs for


CO2


manufacturers to develop products for new refrigerants are high. There is also a risk regarding return on investment as new refrigerants are being developed on a regular basis, resulting in the development becoming obsolete in a matter of years. This may lead to reluctance of manufacturers to innovate.


One development which


is certain to give a return on investment, as well as cost reduction for the customer, is directly reducing the amount of refrigerant required per system. This solution will give savings no matter which refrigerant is used and can provide additional benefits by ensuring levels remain below the lower flammability limits of A2Ls. This refrigerant reduction can be achieved by reducing the tube diameter inside the heat exchangers. This, teamed with rifled tubing, increases efficiency and gives a better kW yield per kg of refrigerant required. Also, there is a significant reduction in the copper and aluminium required to manufacture these coils. Taking


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