Isobaric heat capacity of potential liquid desiccant solutions containing calcium chloride and its mixtures

Abstract

Desiccant cooling and drying systems have attracted considerable attention in recent years because they can enhance the quality of dried products and reduce the use of conventional source of energy. Calcium chloride (CaCl2) aqueous solution is the cheapest and most readily available liquid desiccant that could be used in desiccant cooling and drying systems, but it has the disadvantage of being instable depending on the inlet air conditions and the concentration of the desiccant in the solution. CaCl2 + LiCl (1:1 mass) and CaCl2 + Ca(NO3)2 (5:2 mass) mixtures are thought to be the two most potential liquid desiccants with their relatively high performance and high economic efficiency. The main purpose of this research is to obtain the basic thermodynamic properties (isobaric heat capacities) of the aqueous solutions of CaCl2 and its two specially composed mixtures. The measurements were carried out at temperatures range from 308 to 348 K and different concentrations determined under consideration of the working conditions of the liquids in systems. Scanning calorimetry was applied and a specialized experimental unit for heat capacity measurements of liquids was used in this research. Based on the results, semiempirical equations as functions of temperature and solute concentration were obtained. The deviation between the equations and experiment values showed good agreements, which confirmed the capability of these equations to be used in engineering applications.