NEW TECHNOLOGIES IN REFRIGERATION
AND AIR CONDITIONING

Louis LUCAS
Président Association Française du Froid

These annual conferences in the Centro Studi Galileo update practitioners on what is changing in the area of refrigeration and air conditioning.
At this turn of the century, several issues converge and call for quite important changes, including:
· the recent phase out of CFCs and upcoming phase out of HCFCs,
· concern over global warming with consequences of the use of HFCs and the need for better energy efficiency,
· requirements from end users for a better quality of refrigeration services: relative humidity, air quality, constant temperature, cooling rate, etc.,
· new possibilities for control.

This paper suggests some of the main changes related to:
1. - refrigerants,
2. - systems,
3. - the use of refrigeration.
and gives a few hints about what is going to happen.

Every practitioner should be aware of what is happening. In addition to national journals and events, practitioners may find it very valuable to:
· readily obtain news from all around the world: for that purpose, the International Institute of Refrigeration publishes every second month abstracts in English of most documents published anywhere in the world in any of some 30 different languages. All you need to do is to look at the pages you are most interested in. Reading it requires effort but is very rewarding.
· take part in international events: I invite all of you who are able to attend the XXth International Congress of Refrigeration in Sydney, Australia, on September 19-24, 1999, to do so.

I - Refrigerants

Þ R12, R11, R502 and other CFCs and mixtures containing CFCs have been phased out in Europe even a bit earlier than requested by the Montreal Protocol. They are being phased out in developing countries with a deadline of 2010. Systems using them are likely to have to be retrofitted or no longer manufactured in Europe starting very soon.
Þ R22, R123 and other HCFCs and mixtures containing HCFCs have been used as transitional fluids to accelerate the phase out of CFCs. They are in turn being phased out.
Þ R134a and mixtures of HFCs such as R404A, R407C, R410 and many others, can be useful substitutes. Their Global Warming Potential (GWP) has led environmentalists to ask for limitations in their use. It is indeed important to take into account not only their GWP but also the total effect of using a given refrigerant on global warming. In particular, the energy efficiency of systems and containment are important factors that should influence decisions (1).
Þ Natural fluids, i.e. fluids present in nature, are examined as interesting alternatives: NH3, hydrocarbons, water, air, CO2, etc. Some of them are flammable and/or toxic. Special precautions are then required. Others need large volumes or high pressures. Nevertheless, practitioners will have to get used to using them (2).
Þ The use of secondary refrigerants is a way of overcoming some of these drawbacks (3).
II - Systems

Some of the main changes concern:

Þ Indirect systems: their use makes it possible to employ flammable or toxic refrigerants in smaller quantitites and in separate machine rooms. Special design can allow use of the flexibility of such systems so as to almost counterbalance the energy losses caused by the additional heat exchange between primary and secondary circuits. Secondary refrigerants include:
· liquid secondary refrigerants: either aqueous solutions or organic fluids (3),
· two-phase secondary refrigerants, in particular ice slurry, a very promising technology, for which the IIR has set up a new working party that IIR associate members will be able to follow more closely (4),
· CO2 is particularly valuable in some applications.
Þ Absorption: this type of machine competed with compression machines at the end of the XIXth century. It is gaining impetus again thanks to more efficient machines and more interest in energy recovery and in gas as an energy source.
Þ Heat pumps: energy savings and more efficient systems make heat pumps more and more reliable and profitable first in industry, second in large public buildings, third in some kinds of housing.
Þ Control systems: these systems offer increasingly broad perspectives and make it possible to better meet the needs of consumers, as illustrated in the following section.
Þ Heat exchangers: more efficient heat exchangers have been developed and may allow new system design.

III - Users' needs

Refrigerants and refrigeration systems have to be modified in order to address environmental requirements related to technical progress.
These changes provide equipment manufacturers and practitioners with opportunities to better meet the needs of their customers. These needs have also been changing quite a lot, in particular in terms of:
· Humidity control: it is difficult to control both temperature and humidity. Nevertheless, there is increasing demand in this field. This is the case of the following in particular:
* food preservation, namely chilled food, flowers and in display cabinets,
* plant and processing rooms,
* all air conditioning systems, where humidity control has led to choosing temperatures that are far too low in many cases, with discomfort and high energy consumption as consequences.
· Hygiene: requirements related to hygiene have become increasingly stringent in the food sector as well as in air conditioning.
· Reliable cold chain: in particular during transport, at interfaces, etc., with the need for monitoring, recorders and/or integrators.
· Energy savings: in relation to economic efficiency as well as with regulatory requirements about global warming. a lot of progress can be achieved in air conditioning design for example. The IIR Congress in Sydney will focus on this point in particular.

CONCLUSION

With all these changes taking place, practitioners need to update their knowledge. National journals such as " Industria e Formazione " and conferences such as this one, are very necessary.
For those who are courageous enough to try, being members of the International Institute of Refrigeration is a very valuable and worthwhile small investment, so as to be aware of all new trends from the very beginning, and to become ware of the approaches of various people to these trends.

Bibliography
(1) 12th IIR Informatory Note on Fluorocarbons and Global Warming.
(2) Ammonia as a Refrigerant, IIF/IIR, 120 p., 1999.
(3) Thermophysical Properties of Liquid Secondary Refrigerants, IIF/IIR, 122 p., 1997.
(4) IIR note on associate membership.