EHD-Enhanced Water Evaporation

Lai, F. C.; Huang, Mei‐Rong; Wong, David Shan Hill

doi:10.1081/drt-120030003

Cited by 42 publications

(18 citation statements)

References 16 publications

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“…In addition, the applied electric field also accelerates the solvent evaporation rate as has been reported in the literature. [21] As a result, the polymer chains are quickly frozen and the QDs are confined to their place before they reach their lowest Gibbs free energy. This speculation was confirmed by the following two experiments.…”

Section: Resultsmentioning

confidence: 99%

Electrospinning: A Facile Method to Disperse Fluorescent Quantum Dots in Nanofibers without Förster Resonance Energy Transfer

Zhang

et al. 2007

Adv Funct Materials

163

103

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Fluorescent CdTe quantum dots (QDs) can be dispersed into poly(vinyl alcohol) (PVA) solid nanofibers by electrospinning of a QD–PVA blend solution. Although solution blending methods usually cause phase separation as the solvent evaporates; here, attractively, the QDs do not aggregate, on the contrary, they attain a separation and distribution in the PVA matrix that is as good and uniform as that in solution. Consequently, Förster resonance energy transfer (FRET) between QDs is efficiently avoided, leading to the good preservation of the original fluorescence properties of QDs even when multi‐color QDs are incorporated. Thus, the emission color of the solid nanofibers can be well predicted from the electrospinning solution. Further investigation reveals that the fast evaporation rate of the solvent in the electrospinning process lies at the basis of the uniform distribution of the QDs. Because of the quick “freezing” of the polymer chains, the CdTe QDs are confined to their places with no time to aggregate.

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Section: Resultsmentioning

confidence: 99%

Electrospinning: A Facile Method to Disperse Fluorescent Quantum Dots in Nanofibers without Förster Resonance Energy Transfer

Zhang

et al. 2007

Adv Funct Materials

163

103

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“…For a laminar tangential flow over a surface, the combined effect of inertia and electrical force could lead to a fourfold increase of the Nusselt and Sherwood numbers (Sadek et al 1972). Nevertheless, in the specific case of evaporation by a flow over a surface, the enhancement was not observed (Lai and Sharma 2005;Lai et al 2004). Experiments showed that the inertial effects were more predominant than the electrical effects.…”

mentioning

confidence: 83%

Assessment of the Electrohydrodynamic Drying Process

Ahmedou

Rouaud

Havet

2008

Food Bioprocess Technol

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Industries using energy-intensive processes are being forced to explore ways for reducing their energy consumption. In the food industry, air drying is one of the more energy-consuming processes. To reduce the energy consumption during this operation, alternative processes should be investigated. One promising alternative consists in the electrohydrodynamic (EHD) enhancement of heat and mass transfer. This paper analyses the literature and describes the great potential of this innovative process based on the generation of an electric wind by a corona discharge. The main aspects of this technique are discussed and special emphasis is given on its benefit for food processes. The main part of this paper concerns experimental investigations carried out to assess the EHD enhancement on the drying process. An experimental setup was designed to measure the weight losses on a food product submitted to an electrostatic field and to a cross air flow. Present results confirm that, for a low cross air velocity, the ionic wind leads to an enhancement of the drying rate. The best results are obtained for the smaller distance between the food surface and the corona electrode. Nevertheless, the process is less efficient for a high air velocity. The last part deals with a numerical model that was developed to evaluate the electric parameters and the flow field in turbulent regime. This model provides useful information on the coupled phenomena and permits to explain the experimental observations and to help in designing EHD drying processes. Nomenclature a surface (m 2 ) b ionic mobility (m 2 V −1 s −1 ) d food surface-electrode gap (m) e edge of the wind tunnel (m) E electric field (V m −1 ) F e electric body force (C m −2 s −1 ) g gravity (m s −2 ) I electric current (A) J current density (A m −2 ) k turbulent kinetic energy (m 2 s −2 ) L length of the wind tunnel (m) p pressure (Pa) U velocity vector (m s −1 ) v i ionic wind velocity (m s −1 ) V voltage (V) x distance along surface (m) y height above surface (m) φ diameter (m) ɛ turbulent dissipation rate (m 2 s −3 ) ɛ 0 permittivity of free space (C m −1 V −1 ) Ρ density of air (kg m −3 ) ρ c space charge density (C m −3 ) μ dynamic viscosity of air (Pa s −1 ) μ t turbulent viscosity (Pa s −1 )

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“…Thus, production of turbulence by positive corona is more usable. Also, the effect of corona wind for a wire electrode with negative discharge is weaker than that of a wire electrode with positive discharge in the presence of large cross-flow [15]. In this paper, there are cross-flow with the Reynolds number of 8478 and 18,652.…”

Section: Computational Geometrymentioning

confidence: 88%

“…For the current numerical analysis, a 3D computational domain has been considered based on the experimental study reported by Lai et al [15], which consists of a rectangular channel and a Water container which is mounted on the base of the rectangular channel ( Fig. 1).…”

Section: Computational Geometrymentioning

confidence: 99%

“…They also showed the corona wind in low Reynolds number is more effective to enhance heat transfer. Lai et al [15] presented an experimental study on enhancement of evaporation from a water surface using corona wind in a rectangular wind tunnel. According to their results, corona wind has a great enhancement effect on the water evaporation rate, but its effectiveness diminishes by increasing air flow velocity.…”

Section: Introductionmentioning

confidence: 99%

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