Influence of the management strategy and operating conditions on the performance of an adsorption chiller Alessio Sapienza * , Salvatore Santamaria, Andrea Frazzica, Angelo Freni Consiglio Nazionale delle Ricerche (CNR), Istituto di Tecnologie Avanzate per l’Energia “Nicola Giordano” (ITAE), S. Lucia Sopra Contesse 5, 98126 Messina, Italy article info Article history: Received 16 March 2011 Received in revised form 4 July 2011 Accepted 13 July 2011 Available online 9 August 2011 Keywords: Adsorption cooling system Performance evaluation Management strategy Operating conditions abstract The aim of this experimental work was to study the influence of the operation mode (i.e. cycle time and relative duration of ads-/desorption phases, R) as well as of the operating conditions on the performance of an adsorption chiller. The testing campaign demonstrated that the management optimization strongly improves the performance of such kind of machines. The Coefficient of Performance (COP) and the Specific/Volumetric Cooling Power (SCP, VCP) vary, respectively, in a range of 133% and 43% when the cycle time (s cycle ) increases from 5 to 20 min at fixed boundary conditions (T e ¼ 15  C, T c ¼ 35  C, T h ¼ 90  C) while a further increasing in performance (up to 15%) is reached, at fixed cycle time, by protracting the duration of the adsorption phase at the expense of the desorption one. The complete set of results allowed to draw a map of performance suitable for the optimization of the management mode taking into account the specific application. At T e ¼ 15  C, T c ¼ 35  C, T h ¼ 90  C, if high SCP is required (e.g. automotive air conditioning), the optimal choice is s cycle ¼ 7 min and R ¼ 2.5 (SCP ¼ 394 W/kg, COP ¼ 0.60, VCP ¼ 223 W/m 3 ) while to assure a good efficiency (e.g. solar cooling) the proper management is s cycle ¼ 20 min and R ¼ 1 (SCP ¼ 204 W/kg, COP ¼ 0.69, VCP ¼ 116 W/m 3 ). Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction In recent years, the adsorption cooling systems have attracted much attention as alternative to the traditional electric vapor compression machines due to their ability to use environmentally friendly refrigerant fluids (i.e. water, methanol, ammonia) [1] and because these systems can be driven by the low grade thermal energy (<100  C) coming from waste heat sources [2,3], cogene- ration, solar thermal energy [4e6], etc. In addition to these features, other relevant advantages are: the absence of moving parts, the simple control and low operation costs. The current state of art of this technology is reported in [7]. Nowadays, adsorption heat pumps/chillers both for domestic and commercial applications are still in an early market stage and their widespread diffusion and commercialization requires considerable efforts in order to enhance their performance and to make this technology competitive with traditional electric units or with absorption systems [8]. In particular, the research activity on adsorptive machines is mainly focused to increase the overall efficiency in terms of Coefficient Of Performance (COP) as well as to obtain a strong reduction in weight and dimensions by the improvement of the cooling power density. Novel zeolitic sorbents have been specifically studying for adsorptive cooling applications where a low grade thermal energy source is available [9e11] while new families of composed mate- rials [12] allow to fit the design of the adsorbent on the specific cooling applications in accordance with the boundary tempera- tures and the employed refrigerant [13e15]. The integration of the sorbent material into thermally efficient heat exchangers as well as the direct synthesis of the adsorbent material on conductive substrates are being also optimized in order to guarantee both high heat and mass transfer efficiency [16,17]. Furthermore, a recent study [18] demonstrated the possibility to reach a remarkable growth of the overall performance by the identification of optimal management strategies taking into account both the thermody- namic and kinetic properties of the adsorbent. In fact, experimental measurements carried out on several working pairs demonstrated that the adsorption and desorption phases of the thermodynamic cycle require different times due to the difference in kinetics of ads-/desorption of vapor at different temperature/pressure levels [19]. Agreed to the above, this paper presents the experimental evaluation of the influence of the testing conditions and of the management strategy on the performance of an adsorption machine for cooling applications. The study was performed using * Corresponding author. Tel.: þ39 90 624243; fax: þ39 90 624247. E-mail address: alessio.sapienza@itae.cnr.it (A. Sapienza). Contents lists available at ScienceDirect Energy journal homepage: www.elsevier.com/locate/energy 0360-5442/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.energy.2011.07.020 Energy 36 (2011) 5532e5538