This paper explores the developments that have been achieved in the last 20 years and assesses the progress that has been made. It challenges some traditional beliefs about the refrigeration and air-conditioning industry, using some recent reports and research papers to develop an alternative view of the situation. It looks to the future and outlines a possible development scenario.
In the refrigeration and air-conditioning industry the pace of development has been faster in the last twenty years than at any time in the preceding century. Great progress has been made in dealing with significant issues of global concern and in some ways the industry has been transformed. So why do we need to innovate?
Closer analysis of the majority of the major innovations that have appeared in the last twenty years show that many of these changes have been forced upon the industry by environmental concerns and legislative changes. While it is true that vast resources have been poured into research in the refrigeration and air-conditioning industries much of the development has been reactive, prompted by some regulatory imperative, which means that other areas, perhaps more significant in the long term, have been neglected. In some cases technology has stood still; in other respects, particularly with respect to similar market segments we seem to be moving backwards. The need to respond to the twin threats of ozone depletion and global warming have drawn huge funds into the refrigeration industry, but they have also distracted the development effort away from areas that would be more positive, more useful and ultimately more beneficial to mankind. It is in one sense difficult to argue that anything is more beneficial than protecting the ozone layer or mitigating the effects of climate change, but there is a need for proactive development which looks for ways to improve the situation rather than just delivering preventative measures which aim to stop it from getting any worse.
When we consider development in this light it is easy to see that there are many areas which have been neglected particularly in comparison with progress in other sectors. In the domestic appliances market for example washing machines, dishwashers and cookers have all been repackaged to include tangible benefits of sophisticated microprocessor control to deliver user-friendly flexibility of use and energy efficiency. The refrigerator however does not seem to have kept pace with these changes. The significant developments which have taken place have been in the change from R-12 to R-134a and then to isobutane. This is undeniably beneficial but it is invisible to the consumer. Worse than that, the visible developments, for example the inclusion of automatic ice dispensers in the fridge have added convenience and sophistication, but at the expense of energy efficiency and reliability. This is not to suggest that the move away from ozone depleting substances was trivial or easy, just that it is not evident to the user of the fridge. In the commercial market there has also been a substantial development effort to move away from R-22 and R-502. This has not however delivered systems that are significantly different for the consumer; the benefits of the change are invisible. The same is true for industrial refrigeration, although the development path has been very different.
2. HISTORICAL CONTEXT
The principle of mechanical refrigeration was demonstrated by Prof William Cullen in 1755 when he cooled volatile liquids by creating low pressure above them, but it took almost 100 years for the concept to be industrialised and a further 25 years for the systems to be commercialised. Once the refrigeration industry was established there were a further two periods of about 50 years each. The first saw the refinement of various competing technologies generally using working fluids that were readily available and the second was the transfer from those original fluids to synthesised chemicals that offered easier, safer, more reliable systems. By the mid 1970s CFCs and HCFCs were widely used in the full range of refrigeration systems and air conditioning had been added to the scope of their application. However the use of chlorinated compounds presented a threat to the layer of ozone in the stratosphere which protects life forms from ultraviolet radiation. Within 15 years of the publication of first concerns an international accord, known as the Montreal Protocol had been drafted, distributed and almost universally accepted by the international community. This unprecedented action, which will ultimately result in the almost complete elimination of CFCs and halons from the atmosphere seems to have been successful in reversing the trend of ozone depletion. At the same time increased understanding of climate effects have resulted in similar concern about the effects of industrial gases on the atmosphere. Although this is commonly called “global warming” the climate change effects of increased amounts of “greenhouse gases” in the atmosphere might be localised cooling, increased rainfall, more frequent tropical storms and even localised stratospheric ozone depletion.
Within the same timeframe as the development of legislation about ozone depleting substances and climate change we have also seen an increase in the regulation of other aspects of the industry. Safety laws are perhaps the most obvious example of this, including a group of European directives such as the Machinery Directive, the Pressure Equipment Directive and the ATEX directives. There are also many national laws for example in the UK the Construction (Design and Management) Regulations and the Pressure Systems Safety Regulations which govern the ways in which we conduct or daily business. Coping with this wide range of new rules has been a challenge, and companies who have taken all this on board successfully should be congratulated but we should also remember two things. Firstly we are partway through the process, not at the end of it and secondly the challenges are set to get more difficult in the next five to ten years. This can be characterised by the simple saying “The questions asked of us are getting harder and the time given to answer them is getting shorter.” The development trail is shown diagrammatically in Figure 1.
Figure 1 – The progression of refrigerant development
3. CURRENT CHALLENGES
It is likely that in the next five to ten year period the refrigeration and air-conditioning industry in the developed world will have to face and overcome several unrelated but concurrent challenges. Energy efficiency is becoming more important in all areas, driven by the twin imperatives of increased fuel costs and the need to reduce carbon emissions in order to limit the extent of anthropogenic climate change. Increased use of heat pumps is one response to the energy challenge, ranging from small domestic water heaters to industrial heating systems serving whole cities (Hoffmann and Pearson, 2011). At the same time refrigeration systems must become more effective, since there is ever-growing pressure on all sections of the food chain and the current high levels of food waste are not sustainable. In his plenary address to the International Congress of Refrigeration in 1999 Billiard wrote “It has to be stressed and reiterated ad infinitum, that it is economically sounder to implement better preservation of foodstuffs that have been produced thanks to considerable efforts in terms of growers’/farmers’ time and costly irrigation, fertilizers and pesticides , etc., rather than to accept losses as inevitable.” Unfortunately it seems that not much has changed in the subsequent decade, except for the world population. It reached 6 billion people in that year, and it is predicted to pass 7 billion later this year, apparently on 31 October. However the fundamental problem is not simply the number of people in the world, it is the rapid increase in consumption that accompanies industrialisation of developing countries. This includes improved nutrition and dietary changes from subsistence crops such as cereals and pulses to meat, fish, fruit and vegetables. From a health perspective this shift is to be welcomed, but it raises the stakes, since the production of beef, pork, lamb and poultry are so energy intensive. It is estimated that it takes 6kg of plant protein to produce 1kg of animal protein, and on average (in energy terms) 28kJ of plant protein to obtain 1kJ of animal protein (Pimentel, 2004). Beef and lamb are significantly more energy intensive than average, requiring about 50kJ of plant protein to produce 1kJ of animal protein. Recently the increased use of corn to produce fuel ethanol has put further pressure on the meat industry. It is clear that a transformation of our production and consumption practices is required, as indicated in the United Kingdom Government’s report “The Future of Food and Farming, published in January 2011 (Foresight, 2011). Refrigeration technology can play a part in this. Pressure on the food chain is also increasing due to the expected shortage of fresh water. Anything that can be done to improve the effectiveness of the cold chain at all stages from harvest to consumption will relieve the stress on these key resources of energy, food and water.
A further challenge was highlighted by the Institution of Mechanical Engineers in the United Kingdom. In their report “Population: One planet, too many people?” (IMechE, 2011) they indicated that all of the problems listed above are exacerbated by the continued trend of population shift from rural to urban environments. The IMechE report suggests that by 2050 about 75% of the world’s population will live in cities. In other words, the population of large cities in 2050 will be the same as the total global population now. This stretches the food chain even further, and emphasises how important it will be to have it functioning as effectively, efficiently and reliably as possible.
In this context it is rather sobering to note that the majority of major developments in refrigeration, air-conditioning and heat pumps have been focussed on the switch away from ozone depleting substances and greenhouse gases. In other areas of technology huge progress has been made, for example in materials, communications, nanoparticles and controls leading to huge improvements in performance, efficiency and reliability. It is wrong to say that no progress has been made in refrigeration, but there is not the same step change in freezer plant from the 1970s and 80s as there has been in, for example, the car industry or in the construction of buildings.
4. FUTURE POSSIBILITIES
Refrigeration and air-conditioning systems need to become more effective and efficient. They need to deliver more reliable performance while requiring less maintenance and they need to deliver this improvement while costing less to install and using less raw materials. In order to achieve these advances we would need to address several “sacred cows” in the refrigeration world. We need to move on from traditional compressor technology, eliminating lubricating oil and frictional losses and we need drive systems that maintain their efficiency across a wide range of speeds and loads. We need to move away from brazed copper and welded steel and to achieve heat transfer without relying on wasteful parasitic loads in fans and pumps. We need control systems with the sensory sophistication of an automotive engine management system and the ability to manage the whole system, not just small parts of it. We need a holistic approach to system design which eliminates heating and cooling loads where they are not required and combines them as much as possible when they are really necessary.
Most of these technologies are not science-fiction. They are already being applied in other fields but have not yet made it to the leafy backwater that is the refrigeration industry. However in application to the refrigeration industry we find a dilemma. On the one hand our systems are too expensive and cannot be sold for widespread use in the third world because the producers and suppliers there cannot afford them. We can therefore ill afford to make them even more expensive to purchase by adding “unnecessary gimmicks”. On the other hand we persist in selling our expertise too cheaply in an area which is clearly technically sophisticated and deeply misunderstood by the majority of laymen.
The development focus on transition from chlorinated fluorocarbons has done our industry a lot of good, but has also created a lot of potential difficulty. It has attracted a huge pool of innovative talent into universities and commercial enterprise, hand-in hand with substantial funding for the necessary development. These people have become well-versed in the complexities of the Perkins cycle but in many cases are ready to move on to new challenges. If we are to make progress in addressing the challenges outlined in section 3 we need to persuade the skilled and experienced researchers in our industry to stay on and turn their attention to these more pressing issues.
The refrigeration industry has been too focussed on the up-front challenges presented by the termination of CFC and HCFC use. This has caused some neglect of other development opportunities and as a result the refrigeration sector has fallen behind other industries in the adoption of new technology. The transition from saturated fluorochemicals is not yet complete and there are many research problems to overcome. We need to complete that task – in my opinion we will see the phase down of HFCs starting in the next five years, and possibly turning (as did the original Montreal Protocol “phase-down” of CFCs) into an outright ban. During this process we also need to strengthen the technical ability of technicians and craftsmen in our industry. This can be done through increased regulation of entry qualifications and the registration of skilled operators, as is now being introduced under the f-gas regulations. At the same time we need to start addressing a wider range of development opportunities. We need to consider how the refrigeration industry can contribute to food security, how we can address water shortages and energy conservation, and how we can make our technology more cost effective. In short, we need to innovate.
Billiard, F., “New developments in the food cold chain worldwide”, International Congress of Refrigeration, Sydney, 1999
Foresight. “The Future of Food and Farming (2011) Final Project Report”, The Government Office for Science, London, 2011
Hoffmann, K. and Pearson, D., “Ammonia Heat Pumps for District Heating in Norway – a case study”, Proc Inst Ref, London, 2011
Institution of Mechanical Engineers, “Population: One planet, too many people?”, London, 2011
Pimentel, D. 2004. Livestock production and energy use. In, Encyclopedia of Energy. R. Matsumura (ed.) San Diego, CA: Elsevier. pp. 671-676