Energy efficiency in refrigeration and global warming impact 12–14 May 1993, Ghent, Belgium

Conference review Revue de la r union Energy Efficiency in Refrigeration and Global Warming Impact 12-14 May 1993, Ghent, Belgium The international conference on Energy Efficiency in Refrigeration and Global Warming Impact that took place from 12 to 14 May 1993 in Ghent (Belgium) was organized by the Belgian Association of Refrigeration (ABF/BVK) in cooperation with the Faculty of Applied Sciences of the University of Ghent for commissions B1 and B2 of the International Institute of Refrigeration. The conference was attended by 102 delegates from 15 countries to listen to a selection of 30 papers as well as three keynote speeches. However, this summary does not go into details of all the papers presented at the conference but points out the trends of the research. The review paper of D. Frimout, Belgian astronaut of the European Space Agency, and C. Muller, of the Belgian Institute for Space Aeronomy, set the scene for much that followed. From measurements in the stratosphere and in the troposphere, Dr Muller has clearly shown the effects of greenhouse gases, which include CFCs, on global warming and the relationship of chlorine chemistry to ozone concentration in the stratosphere. In the field of refrigeration, global warming will be affected not only in the case of emission of refrigerants into the atmosphere, the so-called direct effect, but also by the indirect effect due to emission of CO2 resulting from their use in machines. This indirect effect is therefore related to the energy efficiency of the refrigeration cycle. The usual refrigerants containing chlorine, CFCs and HCFCs, which are commonly used today, are to be abandoned in order to respect international, national or regional regulations. The consumption of our everyday refrigerants must decrease according to a given scenario. In the near future, most refrigerating equipment will continue to rely on vapour compression cycles using acceptable substitutes but technologies such as absorption and adsorption-desorption processes or evaporative cooling will take a small part of the existing CFC market. The search for substitutes having low ozone depletion potential (ODP) and low global warming potential (GWP) values and which lead to a better energy efficiency is the task of researchers in this field. Two ways of reducing the direct effect on global warming are possible: 1. Search and develop substitutes derived from hydrocarbons (but without chlorine atoms) and that have lower GWPs than the fluids they are supposed to replace; HFCs are candidates for this.

2. Turn to 'natural refrigerants' such as CO2, H20, NH3, C a l l 8 and C4Hlo. HFCs received a great share of interest during the three days of the conference. Experimental measurements of their physical properties, such as critical parameters, sound velocity, specific heat, p, v and T properties, etc., equations of state and prediction methods to calculate the properties of pure fluids and of their mixtures were presented. Their behaviour with lubricating oil, mainly solubility, were also studied. A few papers dealt with transport properties: viscosity and heat transfer coefficients. From the important scientific and technical activities on refrigerant substitutes, it was noted that 'natural refrigerants' could very rapidly play a major role in refrigeration. Work performed in Norway and in Germany on the use of CO 2 was presented. Colleagues from Denmark and Germany described equipment specially designed to use H20 as a refrigerant. Mechanical water vapour compression is used for cooling of water, production of ice, and waste heat recovery. Mixtures of propane and iso-butane in conventional domestic refrigerators lead to a decrease in energy consumption for an equivalent useful effect; the use of flammables in this application does not introduce risks if some minor changes are made to the equipment. A review of the various risks encountered in using conventional or 'new' refrigerants was presented. To reduce the indirect effect, modification or improvement of equipment to increase the efficiency of the cycle have been proposed by several authors. The changes involve expansion valves, heat exchangers and compressors, etc. The use of binary or ternary mixtures to match the temperature profile of the external fluid in heat exchangers is among the solutions to improve energy efficiency leading to a lower indirect effect. Summaries of all the papers in French and English were available at the conference desk and the proceedings will be published soon. An attractive scientific and technical programme combined with an excellent social programme as well as perfect organization were the keys to the success of the Ghent conference. Professor A. Pilatte

Facult~ Polytechnique de Mons, Belgium

Rev. Int. Froid 1994 Volume 17 Num6ro 3

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