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Overview of New and Alternative Refrigerants

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Overview of New and Alternative Refrigerants BNCR35: Overview of New and Alternative Refrigerants Version 1.2 This Briefing Note and referenced information is a public consultation document and will be used to inform Government decisions. The information and analysis form part of the Evidence Base created by Defra’s Market Transformation Programme. 1 Summary This Briefing note is an overview of existing and alternative refrigerants and includes summary of main legislations and regulations. It also illustrates main characteristics of these refrigerants and their application and usage. All existing and new/alternative refrigerants and their corresponding designation and composition are listed in Appendix 1. 2 Introduction With the discovery of the link between chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) and the depletion of the ozone layer, the United Nations Environment Programme (UNEP) formulated the Montreal Protocol in 1987 to phase-out the use and production of these substances. In response to the Montreal Protocol, alternative refrigerants were sought, and this search produced a number of potential substances for applications where only CFCs and HCFCs were previously used: hydrofluorocarbons (HFCs), hydrocarbons (HCs), ammonia and carbon dioxide (CO 2). Simultaneously, attention focussed on the issue of climate change. Subsequently, the Kyoto Protocol was developed under the UN in 1997, which prescribes the limitation and reduction of emissions of a group of anthropogenic “greenhouse gases” (GHGs): CO 2, nitrous oxide (N 2O), methane (CH 4), HFCs, perfluorocarbons (PFCs) and sulphur hexafluoride (SF 6). Numerous governments, including the European Union, have since published legislation to help meet the Kyoto targets for emissions reduction. In order to quantify the contribution of these gases to climate change, the discussions on climate change in 1990 adopted the use of Global Warming Potential (GWP) of the gas (IPCC, 1990). GWP is a measure of the insulating properties that a gas has on the heat radiating away from the surface of the earth, and is relative to the effect of one kilogram of CO 2. Ultimately, these political actions have resulted in a drive by the refrigeration and air- conditioning (RAC) industry to reduce the environmental impact of systems, manifest Version: 1.2 First created: 20/12/2006 Updated: 28/11/07 www.mtprog.com Last reviewed: 07/01/08 1 of 12 0845 600 8951 as development of new refrigerants and cooling technologies. This document addresses the following related issues: • Refrigerant options • Characteristics of alternative refrigerants • Environmental impact • Efficiency and applications of alternative refrigerants • Refrigerant leakage • Recent developments and technical barriers The number of available refrigerants is vast. Appendix 1 lists those with an “R- number”, as defined in EN 378: 2000 (and ISO 817 and ASHRAE standard 34). Out of about 110 designated refrigerants (excluding CFCs) only about ten are being used extensively in industry. In addition there are several hundred commercially available fluids that have not been allocated an R- number to date. In order to maintain focus, only refrigerants with an R- number and those significant to future use will be discussed henceforth. 3 Summary of refrigerant options 3.1 Legislative requirements The possible choice of refrigerant for new systems varies globally as a result of national and regional legislation, but is largely dictated by the requirements of the Montreal Protocol (and subsequent amendments). In general, CFCs have already been prohibited in developed countries (from 2001 in the EU), and phase-out of HCFCs is occurring at present. However, a large number of countries have produced national legislation that accelerates these phase-out schedules; within the EU as from 2004 HCFCs were prohibited in all new systems and their use for servicing (including recycled HCFCs) will also cease in 2015. Similarly, national and regional legislation originating from the Kyoto Protocol will also impact on refrigerant choice. For example, in Denmark, Norway, Austria and Switzerland the use of high-GWP refrigerants is being prohibited in a number of different applications and/or a GWP- tax is applied to the purchase of such refrigerants. To date the UK Government has not produced any specific legislation, although in their Climate Change Programme they provide a general policy on HFCs. This states that “HFCs should only be used where other safe, technically feasible, cost effective and more environmentally acceptable alternatives do not exist”, and that “HFCs are not sustainable in the long term – the Government believes that continued technological developments will mean that HFCs may eventually be able to be replaced in the applications where they are used” (DEFRA, 2006). New European legislation (which was agreed in January 2006) has imposed some controls on the use of HFCs (the “F-gas” regulation and directive). The main provisions in the regulation (Regulation EC No 842/2006 on certain fluorinated greenhouse gases) cover: Version: 1.2 First created: 20/12/2006 Updated: 28/11/07 www.mtprog.com Last reviewed: 07/01/08 2 of 12 0845 600 8951 • containment through responsible handling during use; • recycling and end-of-life recovery; • training and certification for personnel involved in the containment and recovery of f-gases; • reporting on quantities produced, supplied, used and emitted; • labelling of products and equipment; • certain application specific controls on use; • certain placing on the market prohibitions. The directive (Directive 2006/40/EC relating to emissions from air-conditioning systems in motor vehicles) will place restrictions on the types of Mobile Air Conditioning (MAC) systems fitted to vehicles before vehicles are approved for sale, and specifically: • a two-step phase out of MACs that use f-gases with a GWP greater than 150: 1 January 2011 for new types of vehicle, and 1 January 2007 the sunset date for all new vehicles; • maximum annual leakage limits within the interim period before the phase out; • controls on refilling and retrofitting for these systems. Both the Regulation and Directive will enter into force in 2006 with the main body of the provisions in the set to apply from one or two years after that date. 3.2 Characteristics of common refrigerant types This section provides a summary of the various types of refrigerants that are broadly applicable to domestic and commercial RAC equipment. Important characteristics such as chemistry and compatibility, pressure-temperature and thermophysical properties, safety (toxicity and flammability) and direct environmental impact are mentioned. A comprehensive list of refrigerants is provided in Appendix 1, including basic information on composition, normal boiling point (NBP), safety and environmental data. Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) CFCs and HCFCs were the standard refrigerants for most new RAC applications, and R12 and more so R22 are the reference fluids for the development of new refrigerants. In general, CFCs and HCFCs have broad compatibility with many materials, adequate solubility with most types of refrigeration oils (although most often used with mineral oils) and are relatively tolerant of contaminants in the system. Amongst the various fluids in these groups, a wide range of pressure/temperature characteristics are available and their favourable thermophysical properties result in good cycle/system efficiency. Version: 1.2 First created: 20/12/2006 Updated: 28/11/07 www.mtprog.com Last reviewed: 07/01/08 3 of 12 0845 600 8951 Hydrofluorocarbons (HFCs) HFCs such as R134a, R404A 1 and R407C have dominated the replacement of CFCs and HCFCs, mainly because they broadly possess similar chemical, thermodynamic and flammability/toxicity characteristics as well as having been extensively marketed by manufactures. However HFCs are more difficult to apply because of poor compatibility with construction materials and in particular mineral oils, which has meant that certain synthetic lubricants, typically polyolesters (POEs) and polyalkylglycols (PAGs) have to be used instead. Moreover, they are less tolerant to contaminants within the system. Most HFCs are used in binary or tertiary mixtures, partially to suit certain desired operating characteristics such as replicating R22. HFCs tend to have low toxicity and are largely non-flammable, although a couple of fluids, such as R32 and R152a that are used in several blends are flammable. In terms of environmental impacts, although HFCs have a negligible ODP they do retain the high GWP characteristic of most fluorinated refrigerants, hence the introduction of afore mentioned legislation. Of lesser importance are some other environmental impacts associated with HFC production and emissions, including the release of ozone depleting substances during their manufacture (Banks and Sharratt, 1996) and the production of trifluoroacetic acid as a decomposition product which is highly persistent and bio-accumulative may be harmful to aquatic life (IPCC/TEAP, 2005). Hydrocarbons (HCs) HC refrigerants include a broad range of substances (e.g., R600a and R290) that cover the range of pressure-temperature characteristics of the conventional CFC and HCFC fluids, and they have been used since the evolution of mechanical refrigeration. Also their good material compatibility and solubility with lubricants is comparable to that of the CFCs. Certain thermophysical properties do differ from the fluorinated fluids, particularly
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