Natural Refrigerants CASE STUDIES
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Information and case studies for Australian Businesses Natural Refrigerants CASE STUDIES PREPARED BY THE AUSTRALIAN INSTITUTE OF REFRIGERATION, AIR CONDITIONING AND HEATING, with funding from the Department of Environment and Water Resources Natural refrigerants case studies Contents Technology overviews Ammonia 4 Carbon dioxide 6 Hydrocarbons 8 Cascade / secondary loop systems 10 Case studies Hydrocarbon refrigeration 12 Coles Gisborne 16 CRF Colac 20 Other resources 24 Writers: Claire Heaney, Rick Swinard, Andrew Pang and Stuart West Editor: Stuart West Technical committee: Ray Clarke, Andrew Pang, Tony Kimpton, Ben Adamson, Klaas Visser and Rick Ives The views and opinions expressed in this publication are those of the authors and do not necessarily reflect those of the Australian Government or the Minister for the Environment and Water Resources. While reasonable efforts have been made to ensure that the contents of this publication are factually correct, the Commonwealth does not accept responsibility for the accuracy or completeness of the contents, and shall not be liable for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the contents of this publication. Foreword Natural Much of the refrigeration and air conditioning equipment in Australia uses fluorocarbon refrigerants to facilitate the heat transfer process. Fluorocarbon Rerigerants refrigerants are synthetic chemicals which usually have a high global warming potential, and some still have the potential to cause damage to the ozone layer as well if released to the atmosphere. Alternatives to these chemicals exist that can help to mitigate some of the environmental risks. Often referred to as ‘natural’ refrigerants because the substances also occur in nature, these alternatives include ammonia, carbon dioxide and hydrocarbons. These substances have been used as refrigerants for many years, however, they are now finding their way into applications where previously fluorocarbons were the preferred option. This document has been put together to provide industry decision makers with more information on the potential of ‘natural’ refrigerants. It includes an overview of each of the alternatives, case studies on how they’ve been put to use in Australia, and pointers to some sources of further information. The case studies are written in plain English, and attempt to give a realistic picture of how alternatives to fluorocarbon refrigerants were used in each case — the advantages they provided, the challenges that needed to be overcome, and the drivers behind each project. Hopefully you will find them and the other resources provided herein useful, and will consider alternatives to fluorocarbon refrigerants next time you have to make a decision regarding air conditioning or refrigeration equipment. Natural Refrigerants Guide Ammonia GEA Grasso ammonia chiller Plant room of an ammonia being installed on a building refrigeration plant room at a roof in Sydney cold storage facility in Victoria Ammonia is a naturally-occuring substance that can be used as an Potential applications alternative to fluorocarbon refrigerants in refrigeration systems. As mentioned above, for many years ammonia has been the Indeed, ammonia has been in use as a refrigerant since long before refrigerant of choice in large industrial refrigeration applications the invention of fluorocarbons – it was one of the refrigerants (process cooling, cold storage, mining, etc). Australian inventor, James Harrison specified for his ground In recent years, the focus has broadened to look at other breaking refrigeration machine patented in 1856 [1]. applications that ammonia may be suitable for. Unlike carbon dioxide and hydrocarbons, ammonia has been used Chillers for building air conditioning, using ammonia as a as a refrigerant consistently since the invention of fluorocarbons, refrigerant, have been released to the market in recent years, however, its use has largely been restricted to large industrial though only a relatively small number of installations in Europe had applications. been reported at the time of writing [3] [4]. One possible reason for the small number of installations to date Basic properties could be the price of the equipment – estimated to be almost 250% of equivalent standard fluorocarbon refrigerant units [4]. Ammonia (chemical symbol NH , refrigerant designation R717) is a 3 It has also been suggested, however, that ammonia chillers could colourless gas at atmospheric pressure, and has what many would operate more efficiently and result in cost savings over the whole view to be the ideal environmental properties for a refrigerant – it life of the equipment [3] [4]. has both a zero ozone depletion potential (ODP) and a zero global warming potential (GWP) [2]. While using ammonia in populated areas can bring about some safety concerns (see section on safety below), ammonia chillers In isolation, these properties obviously make ammonia an attractive designed for use in building air conditioning systems in Europe prospect as a refrigerant, given that fluorocarbon refrigerants can have addressed these concerns with the introduction of systems have global warming potentials as high as 3900 [2]. such as containment casings (erecting a structure around the chiller to contain any leaks and ‘scrub’ the air inside before it is exhausted), Many readers will be familiar with ammonia as an ingredient in ammonia absorption systems and flameproof electrical panels [4]. household cleaners, fertilizers and other products, and also be The additional safety equipment required will obviously increase familiar with its characteristic odour. Ammonia carries a B2 safety costs, however, manufacturers claim that operational energy and classification, meaning that it has a high toxicity, and also carries a maintenance savings will potentially outweigh the increased initial medium flammability risk [2]. outlay in the long run [4]. Ammonia is compatible with some, but not all, commonly used Ammonia’s traditional usage in industrial applications is also refrigeration system lubricants. In particular, it is not suited for evolving. Around the world, large ammonia systems are being use with polyol ester (POE) and poly vinyl ether (PVE) lubricants, subjected to increasingly stringent safety regulations and pressure and it has only limited applications with poly alkylene glycol (PAG) is being placed on companies to reduce the size of ammonia lubricants [2]. refrigerant charges [5]. Natural Refrigerants Guide One solution that is being embraced by a number of owners of Conclusions large industrial plants is to use ammonia in conjunction with a secondary refrigerant such as carbon dioxide in a ‘cascade’ system, Ammonia has been in consistent use as a refrigerant since the meaning that less ammonia is required to do the same job, and that 1800s. It can be a very efficient alternative to fluorocarbon the ammonia charge can be contained in a plant room or other refrigerants in a number of applications, and has been the safe environment. This solution is already in use in Australia, as refrigerant of choice in areas such as industrial refrigeration demonstrated by the case study on CRF Colac presented herein. for many years. As with hydrocarbons, if ammonia is to be used in a system Its environmental properties (zero ODP and zero GWP) are also designed for a different refrigerant (such as a fluorocarbon), it highly favourable. should be noted that some modifications will probably be required to ensure compatibility and address the issues associated with Concerns do exist regarding the safe use of ammonia as a result ammonia’s flammability, toxicity and the standards applying to its of its toxicity and flammability. Many advances have been made usage (see below). The system manufacturer should be consulted in recent years to minimise these risks, however, including using before ammonia is substituted in an existing piece of equipment [6]. ammonia in conjunction with other refrigerants in order to reduce and isolate the ammonia charge, and using advanced safety equipment. Safety issues While ammonia is a toxic substance, it is also found in small amounts in a number of substances we come in contact with on a regular basis. A glass of drinking water can contain as much as References 1mg of ammonia, a 200g steak as much as 13mg, and some food 1 Lang, W.R.; James Harrison – pioneering genius; additives can contain as much as 18mg [7]. Cigarette smoke and IMAG Digital Media, Melbourne, 2003 even the air we breathe also contains ammonia in small amounts. 2 Lommers, C A; AIRAH Air Conditioning and Refrigeration This demonstrates that the human body can deal with ammonia in Industry Refrigerant Selection Guide; AIRAH, Melbourne, small quantities. Generally, any amount in the atmosphere below 20 2003 (also available online from www.airah.org.au) parts per million (ppm) is regarded as not dangerous. At amounts of up to 53 ppm, ammonia’s characteristic odour will be noticeable [8]. 3 Rolfsman, L.; Reviewing current state-of-the-art systems using ammonia; Alternative Cooling Technologies conference In amounts of 300-400ppm, prolonged exposure will become presentation, London, February 1, 2005 unpleasant, and in amounts over 700ppm it can cause burns 4 Mundie, I.; Exploring the extent to which ammonia is viable and serious damage to eyes. In amounts of 5000ppm or above, as a widespread commercial alternative to HFCs; Alternative exposure can be lethal to humans within five minutes