A Computational and Experimental Study of the Heat Transfer Properties of Nine Different Ionic Liquids

Abstract

New experimental thermal conductivity, density, viscosity, glass transition temperature, and heat capacity values were measured for nine ionic liquids (ILs): [emim]­[TFA], [emim]­[OTf], [emim]­[DEP], [emim]­[MeSO3], [emim]­[SCN], [hmim]­[Tf2N], [bDMApy]­[Tf2N], [hDMApy]­[Tf2N], and [hmDMApy]­[Tf2N]. Classical molecular mechanics force fields were developed and used to calculate thermodynamic and transport properties for these ILs using molecular dynamics. Two versions of each force field were developed: one with integer charges of ± 1 and one with all charges scaled by 0.8. The force fields with total charges of ± 0.8 generally gave better agreement with experimental results. Very good agreement was obtained for density and heat capacity. Simulated values for thermal conductivity slightly overpredicted experimental results but captured trends between different ILs very well. Experimental Prandtl numbers were determined as a function of temperature and can exceed 10 000 at low temperature. Prandtl numbers on the order of 100–1000 were observed above 330 K. These values suggest that heat transfer with ionic liquids will be dominated by convective effects.

Structural and aggregate analyses of (Li salt + glyme) mixtures: the complex nature of solvate ionic liquids

“…Li[Ntf2], Li[NO3] and Li[CF3CO2] were modeled within the framework of the CL&P atomistic force field [21][22][23] , which is an extension of the AMBER and OPLS force fields 20 specially designed to study ions that usually compose ionic liquids and other ionic compounds with low melting points. The necessity of such correction in the model is corroborated by two distinct pieces of evidence: i) it is known that the cohesive energy of pure ionic liquids modeled using full APCs and non-polarizable atomistic force-fields is in general over-predicted by as much as 50% 28,29 . Such factor is incorporated in the model in order to take into account the reduction of the electrostatic interactions between ions due to polarization effects [24][25][26][27] .…”

Densities, Viscosities, and Conductivities of the Imidazolium Ionic Liquids [Emim][Ac], [Emim][FAP], [Bmim][BETI], [Bmim][FSI], [Hmim][TFSI], and [Omim][TFSI]

“…For each of the two thermostats a set of four capillary cells 18 was calibrated with aqueous solutions of (0.01, 0.1, and 1) mol·kg −1 KCl using the reference data reported by Pratt et al 19 The so-determined cell constants, C, ranging from 6.54 to 91.40 cm −1 (U r (C) = 0.008), were used to calculate κ = C/R ∞ . Also included are the data (a) and its deviation from the present fit (b) of Kato et al, 21 Jacquemin et al, 22 Tariq et al, 23 Froba et al, 24 Kolbeck et al, 25 Tariq et al, 26 Seoane et al, 27 Gangamallaiah et al, 28 Iguchi et al, 29 and Tenney et al 30 The dash−dotted lines in (a) and (b) are the IUPAC recommendation 14 for this IL and its relative deviation from the present fit, respectively. 10,18,20 Keeping in mind all possible sources of error an expanded (k = 2) relative uncertainty of U r (κ) = 0.015 is estimated for the conductivity measurements performed in Regensburg.…”

Forced convective heat transfer and flow characteristics of ionic liquid as a new heat transfer fluid inside smooth and microfin tubes

“…Because their applications are limited by some intrinsic disadvantages such as low decomposition temperature, low density, inflammability, high vapor pressure, harmfulness, and low chemical stability [2]. Tenney et al [4] have carried out a computational and experimental study of the heat transfer properties including the thermal conductivity, density, viscosity, glass transition temperature, and heat capacity values of nine different ILs. Classical molecular mechanics force fields were developed and used to calculate thermodynamic and transport properties for these ILs using molecular dynamics.…”