ALTERNATIVE REFRIGERANTS
Desperately seeking the ‘perfect’ range
John Poole of Refrigerant Solutions looks at the development of refrigerants in relation to current requirements.
T
he ‘perfect’ refrigerant range should be able to cover duties from low temperature refrigeration to air conditioning; low hazard – low toxicity and non-
fl ammability – both at point of use and in bulk storage; low global warming potential to minimise the direct environmental impact from adventitious leaks; and energy effi cient to reduce carbon emissions since fossil fueled stations will continue for the foreseeable future to be a major power source globally.
Unfortunately, the perfect refrigerant range does not exist. HFCs provide non-fl ammability and low toxicity, but have high GWPs. HFOs have low GWPs, but are marginally fl ammable and cannot provide low temperature refrigeration. The so-called ‘natural’ ammonia and hydrocarbons are technically good refrigerants covering most cooling duties, but many fatal accidents have been regularly reported. Carbon dioxide certainly combines low toxicity, non-
fl ammability and low GWP, and appears to be suffi ciently energy effi cient for low temperature as technology improves. But despite the vociferous protestation of environmental activists and the German Government CO2
has not proven,
so far, to be suffi ciently energy effi ciency for mobile air conditioning (MAC). The auto industry has, consequently, selected marginally fl ammable, low GWP R1234yf to replace non-fl ammable, high GWP R134a and thus meet EU existing regulations, but does not preclude CO2
based MAC being introduced later. 34 December 2016
Perhaps the HVAC and refrigeration industries, and their customers, can learn from this compromise and choose refrigerant solutions that will reduce global warming now. Application of the F-Gas Regulation and the Directive on Mobile Air Conditioning in Europe has caused uncertainty concerning the long term future of hydrofl uorocarbons (HFCs) owing to their high direct Global Warming Potential in comparison to carbon dioxide.
Substantial taxes in Spain and Scandinavia have been imposed on HFCs, while Denmark, Austria, the USA and other countries have imposed more rigorous controls. HFCs are included in the Kyoto Protocol and the British government has stated publicly that HFCs are not sustainable technology in the long term.
There is an air of déjà vu about all of this for the refrigeration and air conditioning industry which, having switched away from CFCs to HCFCs, is now in the process of completing the change to HFCs.
Understandably, there is considerable concern arising from the mixed messages about the viability of HFCs as replacements for ozone depleting substances. The result has been to accelerate the search for alternatives which have similar properties but without the high GWP of HFCs. Some well known major companies such as Coca Cola, Uniliver, McDonalds, Marks & Spencer and Tesco have announced that they are looking towards the use of natural refrigerants as the long term solution to this problem.
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