Proceedings of COBEM 2009 20th International Congress of Mechanical Engineering Copyright © 2009 by ABCM November 15-20, 2009, Gramado, RS, Brazil EXPERIMENTAL ANALYSIS OF THE UNSTEADY BEHAVIOR OF AN ABSORPTION REFRIGERATION SYSTEM André Aleixo Manzela, manzela@petrobras.com.br PETROBRAS, Exploration and Production, Av. Rui Barbosa, 1940 – 3º andar, Zip code 27915-012 – Macaé – RJ, Brazil. Sérgio de Morais Hanriot, hanriot@pucminas.br Luben Cabezaas-Gómez, luben@pucminas.br Cristiana Brasil Maia, cristiana@pucminas.br José Ricardo Sodré, ricardo@pucminas.br Pontifical Catholic University of Minas Gerais - Dom José Gaspar Avenue, 500, Coração Eucarístico - Zip code 30535-610, Belo Horizonte, Minas Gerais, Brazil. Abstract. This paper presents an experimental analysis of an absorption refrigeration system. The experiments were performed in a domestic refrigerator. Two different energy sources were analyzed: the original energy source (combustion gases of Liquefied Petroleum Gases – LPG) and exhaust gases from an internal combustion engine (ICE). Temperature and humidity were evaluated during experimental tests. The energy requested, the cooling capacity and the coefficient of performance (COP) were determined for the energy sources and the results were compared. Keywords: absorption refrigeration, experimental analysis, unsteady behavior 1. INTRODUCTION Technical, economical, strategic and environmental considerations brought a new interest for the refrigeration systems feed by thermal sources, sometimes characterized as residual of processes (Falconi Filho, 2002; Zukowski Júnior, 1999; Lima et al., 2002; Pereira et al., 1998). A considerable research effort has been invested in the study of this kind of refrigeration system in the last years (Aphornratana and Eames, 1995; Cheung et al., 1996; Mcquiston and Parker, 1994; Meunier et al., 1996; Moran and Shapiro, 1999; Pereira et al., 1998; Reis and Silveira, 2002; Santos et al., 2001; Srikhirin et al., 2001; Wylen et al., 1998). The interest is mainly because of the inferior cost and quality of the energy requested (Aphornratana and Eames, 1995; Horuz and Callander, 2004; Meunier et al., 1996; Pereira et al., 1998; Reis and Silveira, 2002; Santos et al., 2001; Stoecker and Jones, 1985; Varani, 2001). An important factor to be mentioned while discussing the research development dedicated to the use of absorption refrigeration systems is the necessity of substitution for alternative refrigerants to chlorofluorocarbons (CFC’s) used in the compression refrigeration systems, which were convicted, in 1974, as the majors responsible for the ozone layer damage, and that are becoming gradually substituted in response to the Montreal Protocol signed in 1987 by 46 countries that assumed the compromise to reduce the consume of these refrigerants. This Protocol was revised in 1990 when were approved more restrictive measures that anticipated the total elimination to 2000. However, the fast elimination of CFC’s would bring a substantial growth in the production costs due to the necessity of new technologies and the abandoning of investments done in technologies for the production of them (Aphornratana and Eames, 1995; Ashrae, 1997; Atwood and Hughes, 1990; Braswell, 1988; Garimella, 2003; Kern and Wallner, 1988; Lorentzen and Pettersen, 1993; Meunier et al., 1996; Moran and Shapiro, 1999; Pereira et al., 1998; Reis and Silveira, 2002; Riffat et al., 1997; Santos et al., 2001; Varani, 2001; Wylen et al., 1998). It’s proper to note that ammonia appears as one of the most potential refrigerants to be used in large scale (Braswell, 1988; Moran and Shapiro, 1999; Pereira et al., 1998; Reis and Silveira, 2002; Wylen et al., 1998). Recently, many advanced cycles for absorption systems have been investigated. Then, the potential fields of application of absorption systems are growing (Aphornratana and Eames, 1995; Braswell, 1988; Meunier et al., 1996; Reis and Silveira, 2002; Varani, 2001; Ziegler and Riesch, 1993). Among the several works from literature, some resents works can be commented. Jiangzhou et al. (2003) presented an adsorption air conditioning system used in internal combustion engine locomotive driver cabin. The system consists of an adsorber and a cold storage evaporator driven by the engine exhaust gas waste heat, and employs zeolite-water as working pair. The mean refrigeration power obtained from the prototype system was 5 kW, and the chilled air temperature was 18 °C. The authors described the system as simple in structure, reliable in operation, and convenient to control, meeting the demands for air conditioning of the locomotive driver cabin. Quin et al. (2006) developed an exhaust gas-driven automotive air conditioning working on a new hydride pair. The results showed that cooling power and system coefficient of performance increase while the minimum refrigeration temperature decreases with growth of the heat source temperature. System heat transfer properties still needed to be improved for better performance. Finally, Huangfu et al. (2007) designed and developed an experimental prototype of an integrated thermal management controller (ITMC) for internal-combustion-engine-based cogeneration system. Based