Thermal Diffusion in Binary Liquid Hydrocarbon Mixtures

Trevoy, D. J.; Drickamer, H. G.

doi:10.1063/1.1747125

Cited by 38 publications

(19 citation statements)

References 4 publications

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“…Since then the apparatus has been improved in design by various investigators. Specifically, one can find the concentric cylindrical version [83], a Low-Temperature Thermodiffusion Column made of glass [84] and more recently, a parallel plate version [80]. Urtaega et al [85] have also demonstrated a high pressure TGC.…”

Section: Thermogravitational Column (Tgc)mentioning

confidence: 99%

Experimental approaches to study thermodiffusion – A review

Srinivasan

Saghir

2011

International Journal of Thermal Sciences

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Section: Thermogravitational Column (Tgc)mentioning

confidence: 99%

Experimental approaches to study thermodiffusion – A review

Srinivasan

Saghir

2011

International Journal of Thermal Sciences

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“…Different experimental techniques were applied to investigate the thermal diffusion behavior of toluene/hexane, 12-14 alkane/alkane, 15,16 cyclohexane/benzene, 10 and n-alkane/benzene 13,[17][18][19][20][21] mixtures. The three binary mixtures of dodecane, isobutylbenzene and 1,2,3,4 tetrahydronaphthalene 22 were the subject of a benchmark study to provide reliable values for the Soret, diffusion and thermal diffusion coefficients of these mixtures.…”

Section: 9mentioning

confidence: 99%

Study of the Thermal Diffusion Behavior of Alkane/Benzene Mixtures by Thermal Diffusion Forced Rayleigh Scattering Experiments and Lattice Model Calculations

2006

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In this work the thermal diffusion behavior of binary mixtures of linear alkanes (heptane, nonane, undecane, tridecane, pentadecane, heptadecane) in benzene has been investigated by thermal diffusion forced Rayleigh scattering (TDFRS) for a range of concentrations and temperatures. The Soret coefficient S T of the alkane was found to be negative for these n-alkane/benzene mixtures indicating that the alkanes are enriched in the warmer regions of the liquid mixtures. For the compositions investigated in this work, the magnitude of the Soret coefficient decreases with increasing chain length and increasing alkane content of the mixtures. The temperature dependence of the Soret coefficient depends on mixture composition and alkane chain length; the slope of S T versus temperature changes from positive to negative with increasing chain length at intermediate compositions. To study the influence of molecular architecture on the Soret effect, mixtures of branched alkanes (2-methylhexane, 3-methylhexane, 2,3-dimethylpentane, 2,4-dimethylpentane, 2,2,3-trimethylbutane and 2,2,4-trimethylpentane) in benzene were also investigated. Our results for the Soret coefficients show that the tendency for the alkanes to move to the warmer regions of the fluid decreases with increasing degree of branching. The branching effect is so strong that for 2,2,4-trimethylpentane/benzene mixtures the Soret coefficient changes sign at high alkane content and that equimolar 2,2,3-trimethylbutane/benzene mixtures have positive Soret coefficients in the investigated temperature range. In order to investigate the effect of molecular interactions on thermal diffusion, we adapted a recently developed two-chamber lattice model to n-alkane/benzene mixtures. The model includes the effects of chain-length, compressibility, and orientation dependence of benzene-benzene interactions and yields good qualitative predictions for the Soret effect in n-alkane/benzene mixtures. For the branched isomers, we find some correlations between the moments of inertia of the molecules and the Soret coefficients.

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“…Several researchers have separated mixtures of different isotopes and several binary organic mixtures using this effect 7–9. Parallel‐plate or concentric‐cylinder types of apparatus are exclusively used in separating the liquids by thermal diffusion.…”

Section: Introductionmentioning

confidence: 99%

Experimental identification of design parameters for novel reactor–separator

Shah

Suppes

2005

AIChE Journal

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IntroductionExpansion of the world's biodiesel industry is significantly limited by high capital costs of the biodiesel refineries. The process of biodiesel production is referred to as alcoholysis (a type of transesterification), in which methanol reacts with oils and fats to give methyl esters and glycerin. Separation of the glycerin from biodiesel is achieved by decanting the glycerin phase because the two components are substantially immiscible. Methanol is soluble in both biodiesel and glycerin, presenting the need for additional flash or distillation separation processes.The present work evaluates the feasibility of removing methanol from both glycerin and biodiesel by flowing these products through a temperature gradient in such a manner that the methanol is flashed from the products and sent back into the reactor before discharge. Figure 1 compares the reactor-separator to a conventional configuration. The conventional configuration uses a flash column to remove methanol from glycerin and biodiesel. The reactor-separator has a lateral discharge extension that uses a temperature gradient to drive methanol out of the glycerin phase and into the reactor. The extension is referred to as auto-recycle discharge and replaces the flash separator and condenser, thus alleviating the need for storing crude glycerin containing Ͼ20% methanol.As a result of this relatively simple design:(1) A substantially methanol-free glycerin phase is discharged from the reactor.(2) Methanol is inherently forced back into the biodiesel phase where it can be used to drive high conversions to the biodiesel product (reaction is equilibrium limited).(3) Biodiesel is discharged substantially methanol-free and the methanol is forced back (recycled) into the reactor and any enthalpy of condensation is effectively used to heat influent reagents. This approach can be used in either a semibatch or continuous mode. In a semibatch mode, up to 10% of the biodiesel and Correspondence concerning this article should be addressed to G. J. Suppes at suppesg@missouri.edu. glycerin may be kept in the reactor from one batch to the next with only a corresponding 10% reduction in reactor capacity. This glycerin and biodiesel help solvate the methanol. By the end of a batch, a mixture of about 50% methanol, 25% glycerin, and 25% biodiesel may be at about 120°C (being at 90°C at the start of glycerin discharge from that batch). This 120°C liquid and respective methanol vapors (under pressure) are mixed with oils/fats and methanol from the new batch and, in so mixing, the energy used for driving the methanol out of the products of the previous batches is recovered in the reagents of the new batch. The net impact is that more energy is recovered by this method than is typical with conventional batch processes. © 2005 American Institute of Chemical Engineers REACTORS, KINETICS, AND CATALYSIS AIChEPotential advantages of this design and mode of operation are:(1) Reduced energy costs associated with removing and recycling methanol (2) Eliminated equipment costs ...

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Thermal Diffusion in Binary Liquid Hydrocarbon Mixtures

Cited by 38 publications

References 4 publications

Experimental approaches to study thermodiffusion – A review

Experimental approaches to study thermodiffusion – A review

Study of the Thermal Diffusion Behavior of Alkane/Benzene Mixtures by Thermal Diffusion Forced Rayleigh Scattering Experiments and Lattice Model Calculations

Experimental identification of design parameters for novel reactor–separator

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