Central air conditioning based on adsorption and solar energy Antonio Pralon Ferreira Leite a , Francisco Antonio Belo b , Moacir Machado Martins c , Douglas Bressan Riffel d, * a Federal University of ABC, Brazil b Solar Energy Laboratory, Federal University of Paraiba, 58051-900, João Pessoa, PB, Brazil c Federal Institute of Pernambuco, Av. Professor Luis Freire, 500, Cidade Universitária, 50.740-540, Recife-PE, Brazil d Department of Mechanical Engineering, Federal University of Sergipe e UFS, Av. Marechal Rondon S/N, 49100-000 Aracaju-SE, Brazil article info Article history: Received 18 February 2010 Accepted 10 August 2010 Available online 21 August 2010 Keywords: Adsorption chiller Activated carbonemethanol Thermal storage Solar energy abstract This paper presents the characterization and the pre-dimensioning of an adsorption chiller as part of a 20 kW air conditioning central unit for cooling a set of rooms that comprises an area of 110 m 2 . The system is basically made up of a cold water storage tank supplied by an activated carbonemethanol adsorption chiller, a hot water storage tank, fed by solar energy and natural gas, and a fan-coil. During an acclimatization of 8 h (9e17 h), the following parameters were obtained for dimensioning the cooling system: 504 kg of activated carbon, 180 L of methanol, 7000 L of hot water, 10,300 L of cold water with its temperature varying in the fan-coil from 1  C to 14  C. Considering the mean value of the total daily irradiation in João Pessoa (7  8 0 S, 34  50 0 WG), and a cover of regenerating heat supplied by solar energy equivalent to 70%, the adsorption chiller’s expected coefficient of performance (COP) was found to be around 0.6. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Solar cooling is an interesting application of solar energy because, the stranger the insolation, the greater needs for cooling. As a rule, the systems requiring thermal energy as their main power input for the production of frigorific effect are most dependable on sorption processes. The use of solar energy for cooling applications e a device based on the liquid sorption cycle e was reported more than forty years ago by Chinnappa [1]. The energy needed for a sorption cooling system is essentially thermal, and may come from different sources, such as: process heat, residual vapor or solar energy. One of the main advantages of such a system in relation to the conventional vapor compression system lies on its minimum use of electric energy and on its low cost of maintenance. Because of its functioning simplicity, the adsorption technology applicable to refrigerating systems differs significantly from that of absorption. In adsorption there occurs an interaction between a solid and a fluid e the transportation of the latter being a dependable thermal gradient, for it does not require the use of pumps. In the case of absorption, a solution interacts with a refrigerating fluid, calling for a number of electromechanical devices so as to move both the solution and the fluid. Moreover, the adsorption cycle depends on fewer electrome- chanical components (heat exchangers, valves). Conversely, adsorption refrigeration has exhibited performance coefficients lower than those obtained by liquid absorption. In the field of solar refrigeration by adsorption, various kinds of solid pairs have been considered; zeoliteewater [2,3] and silica gelewater [4,5] are used for cold storage, whereas activated carbonemethanol [6,7] and activated carboneammonia [8,9] are used for ice production. A comparative study between the liquid, chemical reaction and adsorption cooling systems was published by Meunier [10]. In all these systems, the mechanical energy consumption is kept to a minimum or null. This represents a great advantage over the conventional vapor compression systems, especially in countries like Brazil whose energy consumption depends heavily on hydro- electric power. Solar energy is abundant over large areas in Northeastern Brazil (annual average being over 6 kW/m 2 day), securing, as a result, a great potential supply for use in helio-thermal conversion systems applicable for both heating and cooling purposes. Many farm and fishing products are lost in this region, mainly because of unsatisfactory refrigeration, or otherwise, these products have their final value decreased for lack of economical frigorific preservation. In the last two decades, absorption chillers, running on natural gas, have been introduced in markets all over the developed world * Corresponding author. E-mail address: dougbr@ufs.br (D.B. Riffel). Contents lists available at ScienceDirect Applied Thermal Engineering journal homepage: www.elsevier.com/locate/apthermeng 1359-4311/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.applthermaleng.2010.08.010 Applied Thermal Engineering 31 (2011) 50e58