1 Copyright ' 2004 by ASME Proceedings of ISEC 2004 A Solar Harvest: Growing Opportunities July 11–14, 2004, Portland, Oregon USA ISEC2004-65097 DESIGN AND CONSTRUCTION OF A COMPACT AIR-COOLED ABSORPTION MACHINE FOR SOLAR ENERGY APPLICATIONS Rafael A. Perez Reisler University of Puerto Rico – Mayaguez PO Box 9045, Mayagüez PR 00681 E-mail: piculinortiz@yahoo.com Jorge E. González Santa Clara University, Department of Mechanical Engineering, Santa Clara, CA. 95051 E-mail: jgonzalezcruz@scu.edu Hector M. Sanchez HS Mechanical Works Corp., Mayaguez, P.R. 00680 Luis H. Alva Caribbean Thermal Technologies 177 Balboa St., Mayagüez, Puerto Rico 00680 ABSTRACT This paper presents a methodical procedure for the design and sizing of a compact, water fired, air- cooled absorption chiller. The proposed compact machine uses Lithium-Bromide/Water as absorbent/refrigerant fluid pair. The machine was designed using a detailed heat transfer analysis for each individual component (i.e. desorber, condenser, absorber and evaporator). The condenser uses conventional fin-tube heat transfer surfaces while the evaporator uses an inner corrugated surface to increase the heat transfer area. The generator has a concentric tube arrangement in which the dilute solution is in the inner section and the heating water flows in the outside section. This arrangement results in a regeneration effect at temperatures close to 75”C which can be easily provided with solar collectors. The absorber and evaporator work together as a single unit. The vapor exiting the evaporator comes into thermal contact with the concentrated LiBr solution that enters the absorber from the top and falls inside the vertical tubes, creating the absorption effect. Moreover, air is cooling the outside surface of the tubes removing the heat released during the absorption process. The evaporator was designed to be a falling film evaporator such that when applying the cooling load, condensed water falling on the evaporator tubes evaporates and rises through the vertical tubes of the absorber. A set of highly efficient fans are used to bring outside air to remove the necessary heat in both the absorber and condenser, respectively. Furthermore, all system components have been constructed and assembled into a working prototype of variable cooling capacity between 10.5 to 17.5 kW having final dimensions equivalent to a volume of 5 m 3 . The preliminary characterization of the thermal performance of this prototype is presented in the paper with the objective of validating the design methodology. Keywords: absorption, air cooled, thermal performance. INTRODUCTION In the Caribbean one of major areas of energy consumption is room comfort for commercial, industrial and residential applications. Due to the hot and humid conditions that are characteristics of the region, room comfort has become a need instead of a commodity. In a study conducted in Florida it showed that for hot and humid climates about 40% of household energy consumption is used in room space conditioning [1]. Statistics from planning board in Puerto Rico shows about 27,000 new units households were constructed in the year 2000 alone [2]. The demand of energy for residential purposes is high and increasing and therefore there exists a very high priority to attend this need. The use of solar driven absorption machines has been suggested during the last few years to offset the energy consumption in the Caribbean for air conditioning applications [3-4]. The experimental results for a 35 kW closed absorption system installed in the city of Cabo Rojo, Puerto Rico, showed that