Ammonia absorption in ionic liquids-based mixtures in plate heat exchangers studied by a semi-empirical heat and mass transfer framework

Unfavorable transport properties have always been pointed out as the key factors that hinder the application of ammonia/ionic liquids (NH3/ILs) in absorption cycles, while heat and mass transfer of these new fluids in components have been rarely reported. In this study, a corrugated plate heat exchanger is selected as the geometry for exploring the absorption of NH3 in the proposed NH3/ILs working fluids. The process is studied making use of a semi-empirical framework: experimental data is needed to determine unknown information of heat and mass transfer, and a numerical model is developed making use of frequently applied theories. In addition, relevant transport properties of the NH3/ILs working fluids are modeled based on collected experimental data. The proposed model is used to study the heat and mass transfer performance during the absorption of NH3 vapor into NH3/ILs fluids. Distribution of local parameters and overall heat and mass transfer characteristics are obtained. The performance of absorption of NH3 into different working fluids is investigated as well. The overall heat transfer coefficient is found around 1.4 kW/(m(2).K) for the most promising working fluid NH3/[emim][SDI]. (C) 2019 The Authors. Published by Elsevier Ltd.