In the current research, the binary solution containing ionic liquid (IL), 1-ethyl-1-methylmorpholinium dimethyl phosphate ([C1C2MOR][DMP]), 1-ethyl-1-methylpiperidinium dimethyl phosphate ([C1C2PIP][DMP]), or N,N,N-triethyl-N-methylammonium dimethyl phosphate ([N1,2,2,2][DMP]) with ethanol are investigated as new working fluids for absorption refrigeration technology. The IL was mixed with ethanol, which was considered as a refrigerant. Experimental (vapor + liquid) phase equilibria (VLE) of these binary systems were measured by an ebulliometric method within a temperature range from T = (328.15 to 348.15) K with an increment of 10 K and pressures up to 90 kPa. Experimental VLE data were correlated using non-random two-liquid (NRTL) within the maximum average relative deviation of 0.45%, which confirms the effectiveness of using such a model for calculations. Each of the proposed binary systems exhibit a negative deviation from Raoult’s law, which is a very important characteristic for working pairs used in absorption heat pumps or absorption refrigerators. From a technological point of view, measurements of physicochemical properties play an important role. In this research, liquid density and dynamic viscosity were determined at temperatures from T = (293.15 to 338.15) K at ambient pressure over the whole concentration range. These properties were correlated using empirical equations. From experimental density data, the excess molar volumes were determined and correlated using the Redlich–Kister type equation. Ionic liquid: [C1C2MOR][DMP] and [C1C2PIP][DMP] were synthesized and characterized using NMR analysis. The thermophysical characterization of pure ILs, including glass transition temperature (Tg) and heat capacity at the glass transition temperature (ΔgCp), was determined using the differential scanning calorimetry technique (DSC) at atmospheric pressure. In this work, the combination of basic studies on the effect of the cation structure of an ionic liquid on the properties of their solutions with ethanol and the possibility of future application of the tested systems in a viable refrigeration system are presented.
In recent years, many compounds have been proposed as additives to conventional working fluids to improve the performance of the absorption refrigeration system. The main aim of this research is to show the influence of ionic liquid based additives on thermodynamic and physicochemical properties of {LiBr + water} solutions. The following additives: 3-(1-methyl-morpholinium)propane-1-sulfonate, N,N-di(2-hydroxyethyl)-N,N-dimethylammonium bromide, and N,N,N-tri(2-hydroxy-ethyl)-N-methylammonium bromide have been added to aqueous lithium bromide solutions (IL to LiBr mass fraction, w2 = 0.3). The physicochemical and thermodynamic properties of {LiBr (1) + additive (2) + water (3)} and {LiBr + water} systems including (vapor + liquid) phase equilibria (VLE), density (ρ) and dynamic viscosity (η) were determined over wide temperature and composition ranges. The conductor-like screening model for real solvents (COSMO-RS) was used for the VLE data prediction. For the density and dynamic viscosity correlations, empirical equations were applied. A comparison of experimental data for {LiBr + additive + water} with those for {LiBr + water} systems shows the influence of using the additives proposed in this work. The data presented are complementary to the current state of knowledge in this area and provide directions for future research.
In this work, three
solutions consisting of ionic liquid and ethanol
were considered for forward-looking use in absorption refrigeration
technology. It is proposed to use the following ionic liquids as absorbents:
1-ethyl-3-methylimidazolium diethyl phosphate (abbreviated as [EMIM][DEP]),
4-ethyl-4-methylmorpholinium diethyl phosphate ([EMMOR][DEP]), and
1-ethyl-1-methyl-pyrrolidinium diethyl phosphate ([EMPYR][DEP]). Since
the thermodynamic and physicochemical properties of working fluids
determine the efficiency of the refrigerator while looking for alternative
operating fluids, it is crucial to perform their extensive characteristics.
Therefore, in this work, (vapor + liquid) phase equilibria (VLE),
liquid density (ρ), and dynamic viscosity (η) were determined
for the ethanolic solution of the three mentioned diethyl phosphate-based
ionic liquids. The isothermal VLE was measured by an ebulliometric
method within a temperature range from T = (328.15
to 348.15) K with an increment of 10 K and pressures up to 90 kPa.
Non-random two-liquid (NRTL) equation with temperature-dependence
parameters was used to correlate experimental data. Physicochemical
properties including liquid density and dynamic viscosity were determined
at temperatures from (293.15 to 338.15) K at ambient pressure over
the whole concentration range. These properties were correlated using
empirical equations. From experimental density and viscosity data,
the excess molar volumes and the deviations from additivity were determined
and correlated using the Redlich–Kister-type equation. Two
of the tested ILs, [EMMOR][DEP] and [EMPYR][DEP], were synthesized
and characterized using NMR analysis. The thermophysical characterizations
of pure compounds, including glass transition temperature (T
g) and heat capacity at the glass transition
temperature (Δg
C
p), have
been determined using a differential scanning calorimetry technique
(DSC) at atmospheric pressure. The work presented
is a combination of basic studies on the effect of the cation structure
of an ionic liquid on the properties of their solutions with ethanol,
with the possibility of future application of the tested systems in
a viable refrigeration system.
In this work, new
experimental data on thermodynamic properties
of ionic liquid (IL) aqueous solutions are presented. The (vapor +
liquid) phase equilibria, liquid density, and dynamic viscosity of
binary mixtures composed of N,N-diethyl-N-methylammonium bromide ([NH,1,2,2][Br]), or N,N-diethyl-N-methylammonium
methanesulfonate ([NH,1,2,2][CH3SO3]) and water are presented as functions of temperature and composition.
Both ILs were synthesized and specific basic characterization including
the NMR spectra and the water content determination was done. The
basic thermal properties of the pure IL, including the glass-transition
temperature, heat capacity at glass transition, and temperature and
enthalpy of (solid + solid) phase transition as well as the temperature
and enthalpy of melting were determined using the differential scanning
calorimetry (DSC) technique. The isothermal (vapor + liquid) equilibrium
(VLE) was measured by the ebulliometric method within a temperature
range from T = 338.15 to 368.15 K and pressures up
to 85 kPa. Experimental VLE data were successfully correlated using
the NRTL equation. The experimental VLE data were tested for thermodynamic
consistency using the Van Ness test. The liquid density and the dynamic
viscosity were determined as a function of IL’s mole fraction
over a wide temperature range. For the correlation of physicochemical
properties, empirical equations were applied. From the experimental
density data, the excess molar volumes were determined and correlated
using the Redlich–Kister-type equation.
New experimental data on the thermodynamic properties of imidazolium-based ionic liquids (ILs) and {IL + water} solutions are presented. The isothermal (vapor + liquid) phase equilibrium (VLE) and the density of binary mixtures composed of 1-ethyl-3-methylimidazolium formate, [EMIM]-[HCOO], or 1-ethyl-3-methylimidazolium acetate, [EMIM]-[CH 3 COO], and water are demonstrated. The experimental data were measured at temperatures from 298.15 to 348.15 K over a wide IL mole fraction under ambient pressure. Both ILs were delivered by IoLiTec, and the water content was determined by the Karl−Fischer titration technique. The thermophysical properties of the pure ILs, that is, glass-transition temperature, heat capacity at glass-transition change, and the temperature and enthalpy of melting, were determined by differential scanning calorimetry technique. The VLE has been measured by an ebulliometric method at temperatures from 338.15 to 368.15 K and pressures up to 85 kPa. The experimental VLE data were tested for thermodynamic consistency using the Van Ness test. The nonrandom two-liquid model equation was used to correlate the experimental VLE data. The density of the tested aqueous solution has been measured as a function of IL's mole fraction over a wide temperature range. The empirical equations were applied for density data correlation. From the experimental density data for the {[EMIM][CH 3 COO] (1) + water (2)} system, the excess molar volumes were determined and correlated using the Redlich−Kister equation.
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