Journal of Porous Media, 20(9):859–863 (2017) SPECIFIC HEAT CAPACITY OF WATER-SILICA GEL ADSORBED PHASE J.A. Amorim, 1,* I.C.A. Brito, 2 H.M. Vieira, 1 P.J. Vodianitskaia, 3 & J.M. Gurgel 1 1 Federal University of Paraiba, Campus Universitário, João Pessoa PB, Brazil 2 Federal Institute of Education, Science, and Technology of Ceará, Campus Cedro, Mechatronics Department, Ceará, Brazil 3 Graduate Program in Mechanical Engineering, Federal University of Paraiba, PPGEM/CT/UFPB, Campus Universitário, João Pessoa PB, Brazil *Address all correspondence to: J.A. Amorim, Department of Food Engineering, Federal University of Paraiba, João Pessoa, Paraíba, Brazil, E-mail: joselmaaraujo@yahoo.com.br Original Manuscript Submitted: 3/30/2016; Final Draft Received: 10/31/16 The importance of adsorption refrigeration and air conditioning technology is growing, as a response to the demand for more sustainable, low–carbon intensity technologies. These versatile systems work with heat from flat-plate solar collectors or waste heat at temperatures as low as 65 ◦ C. However, the market share of adsorption chillers is still a niche. Power density is one of the key factors to improve market penetration of such systems, allowing for smaller equipment at lower cost. Specific heat capacity is one of the determining factors of performance, affecting cycle dynamics and thermal performance, being related to the couple adsorbent-adsorbate. However, few experiments in the literature have considered real-size adsorptive beds and combined heat capacity of the adsorbed phase, as presented here. A scanning calorimetry technique is used to validate a representative mathematical model. The intensity of endothermal peaks is directly related to the ones related to the specific heat capacity of the adsorbed phase. The c p values for the range considered were lower than the c p values for the liquid phase but were closer to the liquid phase than to the vapor phase. KEY WORDS: adsorption, adsorbed phase, specific heat capacity, silica gel, calorimetry 1. INTRODUCTION In a recent report issued by the United Nations Environmental Program (2015), refrigeration and air conditioning are recognized as vital means to addressing fundamental human needs, whereas some negative environmental impacts are pointed out. In general, refrigeration and air conditioning equipment potentially produces impacts associated with the choice of refrigerants, both direct, owing to chemical composition, and indirect, such as use of energy and materials, and the emission of greenhouse gases (GHG) along the life cycle, among other impacts. Recent climate negotiations under the United Nations Framework Convention on Climate Change (2015) led to the Paris Declaration, in which the 197 parties expressed the “aim . . . to achieve a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century” (UNFCCC, 2015). This balance means that global net GHG emissions should fall to zero by 2100 to avoid the most catastrophic consequences of anthropogenic climate change. Among many important applications of physical adsorption, refrigeration and air conditioning systems addition- ally bring the particular attractiveness of suitable refrigerants—also called adsorbates—from renewable sources, such as water, ethanol, and methanol, presenting low global warming potential. They also can be designed to work at temperature levels compatible with the use of solar energy from low-cost flat-plate collectors. 1091–028X/17/$35.00 © 2017 by Begell House, Inc. www.begellhouse.com 859