Aqueous solution of [EMIM][OAc]: Property formulations for use in air conditioning equipment design

Liquid desiccant air conditioning (LDAC) is a promising alternative to vapor compression refrigeration based space cooling and dehumidification for the reduction of energy consumption and the improvement of indoor air quality. However, its use in the air conditioning market is still very limited due to its high installation cost, intensive carryover, and high cost of operation and maintenance associated to the corrosion of the current desiccant liquids. Substitutes for the traditional desiccant liquids with better properties and no corrosion are highly needed. Ionic liquids, which are salts comprised of organic cations and inorganic anions or organic anions, have high thermal stability, negligible or no vapor pressure, varied solubility in water, low or no corrosion to metals, and low driving temperatures to achieve dew point temperatures. All of those characteristics make them as perfect substitutes for traditional desiccant liquids. Up to date, a very few research groups investigated ILs as potential alternatives to traditional desiccant liquids for LDAC. The study in the paper aimed to identify the ionic liquids as ideal desiccant liquids to achieve better cost-effectiveness and higher system performance of LDAC. There were 13 different ionic liquids (IL) identified and screened for the most promising candidate. 1-Ethyl-3-methylimidazolium acetate, [EMIM][OAc], was selected as an ideal candidate for the capable of the most adsorption and desorption. The paper was mainly focused on the development of calculation models for the thermo-physical properties of the aqueous solution of [EMIM][OAc] to represent the property data needed for use as the desiccant liquid in sorption-based air conditioning equipment. It aims to provide convenient methods for use in the design and model of the sorption-based air conditioning. The calculation models for the following thermo-physical properties of the aqueous solution of [EMIM][OAc] were proposed and presented in the paper: the vapor pressures, specific heat capacity, density, and dynamic viscosity at various temperatures and concentrations.