465525 Molecular Dynamics Simulations of Mixtures of Refrigerants and Deep Eutectic Solvents
Molecular dynamics simulations of mixtures of refrigerants and deep eutectic solvents
Rubaiyet Abedin, John C. Flake and Francisco R. Hung
Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA 70803
Heating and cooling buildings in the U.S. consumes an enormous amount of energy (>10 quadrillion BTU), and is responsible for adding ~1 billion metric tons of CO2 in the earths atmosphere every year. Much of this energy is used as electricity in vapor-compression systems; however, this technology is mature and only evolutionary improvements are expected in the near future. Remarkably, a few studies have shown that several common ionic liquids (ILs) can be combined with standard fluorocarbon refrigerants for use in absorption refrigeration systems that use waste heat at relatively low temperatures (~100 °C). Nevertheless, there is limited understanding (and data) on the VLE behavior of these systems, and only one working example of an absorption system using this type of mixture. Furthermore, deep eutectic solvents (DESs), a relatively new class of solvents, share many of the properties of ILs while being considerable cheaper and mostly nontoxic. A fundamental understanding of how the chemical structure of the different species affects the solubility of fluorocarbons in a DES is crucial to design mixtures suitable for use in absorption refrigeration systems that use solar energy or waste heat. In this work, we performed molecular dynamics simulations of mixtures of a conventional fluorocarbon refrigerant, 1,1,1,2-tetrafluoroethane (R134a) with three deep eutectic solvents (1:2 choline chloride/urea, 1:2 choline chloride/glycerol and 1:2 choline chloride/ethylene glycol). We report and discuss a number of properties for these systems, including Henrys law constants of R134a in the three DESs as a function of temperature, radial distribution functions, and diffusion coefficients.