Session: Government Agency Student Posters

Paper Number: 173612

Ionic Liquid and Hydrofluorocarbons Ternary Systems Equilibria 

The majority of current hydrofluorocarbon (HFC) based refrigerants are azeotropic and have high global warming potential (GWP). Azeotropic refrigerants cannot be separated through conventional distillation. However, some of the HFCs in the mixture have low enough GWP to be used in future refrigerant blends. Therefore, it is imperative that new technologies are developed to effectively separate azeotropic refrigerants to support refrigerant recovery and potentially reduce high GWP. Emerging technology, such as extractive distillation using an ionic liquid (EDIL), has been used to separate azeotropic HFC-based refrigerants. To optimize this technology, HFC’s solubilities in ionic liquids (ILs) are needed. Most of the experimental solubility data found in the literature are for ideal binary systems. However, EDIL systems operate in an actual ternary system. In this work, solubilities from a ternary HFC(1)/HFC(2)/IL(3) system are experimentally measured using a high-pressure and high-temperature variable volume cell (VVC). The VVC system is composed of a high-pressure high-temperature cell (in house built), an oven (MK 56, Binder), a densitometer (2 DMA HPM Wide Range, Anton Paar), and a gas chromatograph (GC) (8610C, SRI Instruments) in line. The VVC’s moving piston finely regulates volume and pressure. The variable volume cell (VVC) temperature is regulated by an internal resistance-based heating source.  The recirculation pump (5979 Optos 2HM, ¼’’ head, SS, Eldex Laboratories, Inc) and the magnetic stirrer allows the system to reach equilibrium faster. A digital video camera allows the visualization of phase behavior changes through the cell's sapphire window during the experiment. LabVIEW data acquisition software is used to record experimental pressure, temperature, and phase behavior changes. Vapor and liquid equilibrium (VLE) composition of the ternary mixture of two reference HFC solutes, pentafluoroethane (HFC-125) and difluoromethane (HFC-32), and ionic liquid solvent 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C2C1im][Tf2N] are measured at different pressures (0.1, 0.2, 0.3, 0.4 and 0.5 MPa) and temperatures (25, 30, 40, and 50°C). Gas Chromatography is used to analyze HFC-125 and HFC-32 vapor and liquid compositions from the ternary system equilibria. Available binary system experimental data show that HFC-32 solubilities in ionic liquids are higher than HFC-125. Therefore, we expect similar results for ternary system equilibria. A comparative analysis will confirm our hypothesis. This study will contribute to the optimization of the EDIL system to aid in azeotropic refrigerant separation. Recycling and reclaiming refrigerants are essential strategies for reducing the global warming impact of the heating, ventilation, and air conditioning (HVAC) industry and create a circular economic practice.

Presenting Author: Kirshaun Mcghee Delaware State University

Presenting Author Biography: Kirshaun McGhee is a senior Chemistry major attending Delaware State University. She has completed two Chemical engineering internships at notable research institutions such as Purdue University and the University of Kansas. She hopes to expand her scientific knowledge to become a well-rounded scientist and work in academia in the near future.

Authors:

Kirshaun Mcghee Delaware State University
Julia Espinoza Mejia Univeristy of Kansas
Mark Shiflett University of Kansas
Aaron Scurto University of Kansas