Proceedings of COBEM 2005 18th International Congress of Mechanical Engineering Copyright © 2005 by ABCM November 6-11, 2005, Ouro Preto, MG THE USE OF HYDROCARBONS PROPANE AND ISOBUTANE IN REFRIGERATION SYSTEMS Jacqueline Biancon Copetti Universidade do Vale do Rio dos Sinos Av. Unisinos, 950 – São Leopoldo - RS jcopetti@euler.unisinos.br Mario Henrique Macagnan Universidade do Vale do Rio dos Sinos Av. Unisinos, 950 – São Leopoldo - RS mhmac@unisinos.br Mariana Geyer Universidade do Vale do Rio dos Sinos Av. Unisinos, 950 – São Leopoldo - RS Rejane De Césaro Oliveski Universidade do Vale do Rio dos Sinos Av. Unisinos, 950 – São Leopoldo - RS decesaro@euler.unisinos.br Abstract. The object of this work meets the increasing world-wide concern with the environmental problems caused by the use of hydrochlorofluorocarbons refrigerants in refrigeration systems and the viability to substitute them for natural refrigerants. The results of the theoretical study are presented to characterize the hydrocarbons propane (R290) and isobutane (R600a) to be used in refrigeration systems in substitution for the R22. The performances of these refrigerants in refrigeration cycles are compared by using a standart refrigeration cycle, with evaporation temperatures between -20°C to 10°C and condenser temperature of 40°C. This study was carried out with the aid of the Cycle_D simulation program. The refrigerants thermodynamic properties were obtained from REFPROP (NIST). The results showed that both R290 and R600a can be R22 substitutes in this range of application. The hydrocarbon R600a presented a better thermodynamics behavior than the R22 in the majority of the analyzed performance parameters, mainly for evaporation temperatures higher than -10°C. The hydrocarbon R290, showed similar results to the R134a. Keywords: Refrigeration systems, refrigerants, hydrocarbons, R22 drop-in 1. Introduction Since their introduction in 1930, chlorofluorocarbons (CFC) and hydrochlorofluorocarbons (HCFC) composites have been the preferred refrigerants for the majority of the applications in the refrigeration industry because of their unquestionable advantages (Bhatti, 1999), mainly high efficiency and security. However, nowadays they are being gradually eliminated because of their implication in the destruction of the ozone layer and in the increase of greenhouse effect. The great refrigeration industry dependence on these composites has delayed the elimination of their production and consumption. To promote and manage a gradual process of elimination and substitution for the CFCs, some countries were congregated in 1985 in the Convention of Vienna and started an agreement that was firmed up in 1987 in Canada, the Protocol of Montreal. This protocol determined the elimination of the CFCs until 1996 and the HCFCs until 2030 in the developed countries, and a lack of 10 years in the developing countries (GTO-Interminesterial Ozone Working Group, 1994). Besides chlorine in their constitution, these composites are characterized by the great stability, what makes them persist in the terrestrial atmosphere for many years. From the commercial point of view, the CFCs R-11 and R-12 and the HCFCs R-22 and R-502 substitution became the most important. Table 1 shows the environmental impacts of refrigerants R12 and R22 through the Global Warming Potential (GWP) and the Ozone Depleting Potential (ODP). These indexes characterize the action level of these chemical composites on the ozone layer and the greenhouse effect, besides the atmosphere lifetime.