Experimental studies on the effect of inert gases on diffusion distillation of ethanol–water mixtures

Singh, Neetu; Прасад, Рам

doi:10.1002/jctb.2659

Cited by 8 publications

(6 citation statements)

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“…al. [61] excluding the diffusion coefficient which for air in pure water and in pure ethanol was taken from Singh and Prasad [62] and mixture values were assumed to depend linearly on mole fraction [63]. The resulting images allow for accurate determination of the planar major and minor axes of bubbles, as shown in Fig.…”

Section: Modulation Of Interfacial Surface Tensionmentioning

confidence: 99%

Experimental investigation of the effect of ethyl alcohol surfactant on oxygen mass transfer and bubble size distribution in an air-water multiphase Taylor-Couette vortex bioreactor

Ramezani

Legg

Haghighat

et al. 2017

Chemical Engineering Journal

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Volumetric liquid side mass transfer, bubble size distribution, and bubble shape was measured in a vertically oriented semi-batch gas-liquid Taylor-Couette vortex reactor with an aspect ratio of Γ=h/(r o -r i )=40 and radius ratio of η=r i /r o =0.75. Azimuthal Reynolds number, Axial Reynolds number and Capillary number were varied between 0 to 3.8×10 4 , 7 to 99, and 6.1×10 -6 to 76.0×10 -6 , respectively. Power-law correlations based on these data were presented for dimensionless Sauter mean diameter and Sherwood number in terms of the dimensionless parameters. Presence of ethanol as surfactant in the liquid was shown to inhibit bubble coalescence, which in addition to lowering interfacial surface tension causes a generally smaller bubble size at higher concentrations of surfactant. It was also shown that the mass transfer coefficient generally increases with higher concentrations of surfactant. Both the bubble diameter and mass transfer are influenced more at lower concentrations of surfactant, and the introduction of higher amount of ethanol causes a decrease in both parameters. Keywords Gas-liquid mass transfer, Surfactant, Sherwood number, Taylor-Couette vortex bioreactor.  The addition of surfactant decreases bubble size Nomenclature Roman a Specific gas-liquid interfacial surface area [m 2 /m 3 ] C Concentration [mg/L] d Bubble diameter [mm] D Diffusion coefficient [m 2 /s] E Ellipticity of spheroid g Gravitational acceleration [m/s 2 ] h Axial distance from the bottom of reactor [m] k Volumetric mass transfer coefficient [m/s] l Spheroid major diameter [m] m Spheroid minor diameter [m] N Impeller (inner cylinder) rotational speed [rev/s] Q Volumetric flow rate [L/min] r i Outer radius of the inner cylinder [m] r o Inner radius of the outer cylinder [m] u Superficial velocity [m/s] Greek Γ Reactor aspect ratio (Γ=h/(r o -r i )) ε G Gas holdup η Reactor radius ratio (η=r i /r o ) ω Rotational speed of the inner cylinder [rad/s]

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Section: Modulation Of Interfacial Surface Tensionmentioning

confidence: 99%

Experimental investigation of the effect of ethyl alcohol surfactant on oxygen mass transfer and bubble size distribution in an air-water multiphase Taylor-Couette vortex bioreactor

Ramezani

Legg

Haghighat

et al. 2017

Chemical Engineering Journal

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“…where H vi is the heat of vaporization of component i in J mol -1 . Equations (18) and (19) provide the following equation for condensing interface temperatureT c I :…”

Section: Energy Balancementioning

confidence: 99%

“…The simulated column length and annular gap are considered to be 720 mm and 6.5 mm (which are the effective length and annular gap of the diffusion distillation column used for experiments by Singh and Prasad) to facilitate comparison with the experimental data. The column is divided into 72 sections to integrate the differential equations.…”

Section: Modelingmentioning

confidence: 99%

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Performance of diffusion distillation column for production of fuel grade ethanol

Singh

Прасад

2014

J of Chemical Tech & Biotech

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BACKGROUND Diffusion distillation process was used for separation of ethanol–water mixtures of azeotropic composition. Experimental results were compared with a Stefan–Maxwell equations based mathematical model by assuming point behavior of the process. RESULTS The performance of a diffusion distillation column for anhydrous ethanol production has been investigated by extending the point behavior to an integral column under process relevant operating conditions. New modeling results are in better agreement with the experimental data than old modeling results. The maximum variation in selectivity is obtained at lowest flow rate (0.05 mol m‐1 s‐1). CONCLUSIONS The diffusion distillation column should be operated at the lowest possible feed rate and the highest possible vaporization temperature to minimize the column length requirement for anhydrous ethanol production. The effect of selectivity on enrichment of ethanol is negligible in long diffusion distillation columns and flux to flow ratio is more important for determination of enrichment. © 2014 Society of Chemical Industry

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“…(Battino et al, 1983). The diffusion coefficient of air in pure water and in pure ethanol was taken from Singh and Prasad (Singh and Prasad, 2011), and mixture values were assumed to depend linearly on mole fraction (Wong and Himmelblau, 1964). The detailed procedure for measuring bubbles and equations used in calculation of the bubble Sauter diameter are explained in length by Ramezani et al (Ramezani et al, 2015) and similarly, the bubbles are assumed to take on a prolate shape for all cases with a rotating inner cylinder and an oblate shape for cases without rotation of the inner cylinder (annular bubble column).…”

Section: Modulation Of Interfacial Surface Tensionmentioning

confidence: 99%

Experimental investigation of multiphase flow: Mass transfer and fluid flow in Taylor-Couette reactor and velocity field of train of particles in a square duct

Ramezani

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Experimental studies on the effect of inert gases on diffusion distillation of ethanol–water mixtures

Cited by 8 publications

References 4 publications

Experimental investigation of the effect of ethyl alcohol surfactant on oxygen mass transfer and bubble size distribution in an air-water multiphase Taylor-Couette vortex bioreactor

Experimental investigation of the effect of ethyl alcohol surfactant on oxygen mass transfer and bubble size distribution in an air-water multiphase Taylor-Couette vortex bioreactor

Performance of diffusion distillation column for production of fuel grade ethanol

Experimental investigation of multiphase flow: Mass transfer and fluid flow in Taylor-Couette reactor and velocity field of train of particles in a square duct

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