<p>This study evaluated the effectiveness of an aluminum (Al) electrode and its ability to enhance nonthermal drying using an electrohydrodynamic <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$(\text{EHD})$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <mtext>EHD</mtext> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> drying mechanism. Conventional drying techniques consume significant energy and generate byproducts and greenhouse gases, compromising both process sustainability and product quality. In contrast, EHD drying leverages corona discharge or ionic wind to induce moisture removal with reduced energy consumption and minimal impact on product attributes. In the present investigation, a point-to-plane electrode configuration was employed, featuring a 10 cm-long Al needle with a tip diameter of 0.085 cm, positioned 2.54 cm above a test container. The container, packed with water-saturated soda lime glass beads, was placed inside a 120 cm long square-channel test section fabricated from an 0.8 cm thick acrylic sheet. Experiments were performed under two conditions: natural drying (ambient environment) and forced convection with crossflow velocities of 0.8 m/s and 1.9 m/s. The experimental design allowed for direct comparisons of moisture loss between the test container subjected to corona discharge and a reference container undergoing natural drying under controlled ambient temperature <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$(T)$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <mi>T</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> and relative humidity <InlineEquation ID="IEq3"> <EquationSource Format="TEX">$(\%RH)$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <mo>%</mo> <mi>R</mi> <mi>H</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation>. Drying enhancement was quantified using dimensionless numbers: the Sherwood number (<InlineEquation ID="IEq4"> <EquationSource Format="TEX">$Sh$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="italic">Sh</mi> </mrow> </math></EquationSource> </InlineEquation>), EHD Reynolds number (<InlineEquation ID="IEq5"> <EquationSource Format="TEX">${Re}_{EHD}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mrow> <mi mathvariant="italic">Re</mi> </mrow> <mrow> <mi mathvariant="italic">EHD</mi> </mrow> </msub> </math></EquationSource> </InlineEquation>), and EHD number (<InlineEquation ID="IEq6"> <EquationSource Format="TEX">${N}_{EHD}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>N</mi> <mrow> <mi mathvariant="italic">EHD</mi> </mrow> </msub> </math></EquationSource> </InlineEquation>). Under static conditions (without crossflow), a regression correlation was established, demonstrating a nearly two-fold increase in the drying rate compared to natural drying. Under forced convection, the interplay between the ionic wind and crossflow was evident. At a moderate crossflow velocity (0.8 m/s), the drying enhancement indicated that the ionic wind effectively augmented convective mass transfer. However, at a higher crossflow velocity (1.9 m/s), the trend reversed, suggesting that excessive crossflow may suppress the corona discharge effect by reducing the ion density and the resultant momentum transfer. These results highlight that while an aluminum electrode can reliably sustain the high-voltage conditions necessary for effective corona discharge, its drying enhancement capability is highly dependent on crossflow velocity (<InlineEquation ID="IEq7"> <EquationSource Format="TEX">$u$</EquationSource> <EquationSource Format="MATHML"><math> <mi>u</mi> </math></EquationSource> </InlineEquation>). This study underscores the potential of EHD drying as an energy-efficient, sustainable alternative to conventional methods and suggests further research to optimize the electrode geometry, electrode gap, and operational parameters for industrial-scale applications. This study advances EHD drying by demonstrating the feasibility of aluminum electrodes for energy-efficient and sustainable industrial applications.</p>

Experimental investigation to evaluate the effectiveness of Aluminum (Al) as a feasible material for electrodes in an Electrohydrodynamic (EHD) enhanced drying process

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发表日期：

2026年2月2日

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Mohammad Saifullah Khan,
Minhaj Ahemad,
Vimal Chand Sontake

摘要

This study evaluated the effectiveness of an aluminum (Al) electrode and its ability to enhance nonthermal drying using an electrohydrodynamic $(\text{EHD})$ $(EHD)$ drying mechanism. Conventional drying techniques consume significant energy and generate byproducts and greenhouse gases, compromising both process sustainability and product quality. In contrast, EHD drying leverages corona discharge or ionic wind to induce moisture removal with reduced energy consumption and minimal impact on product attributes. In the present investigation, a point-to-plane electrode configuration was employed, featuring a 10 cm-long Al needle with a tip diameter of 0.085 cm, positioned 2.54 cm above a test container. The container, packed with water-saturated soda lime glass beads, was placed inside a 120 cm long square-channel test section fabricated from an 0.8 cm thick acrylic sheet. Experiments were performed under two conditions: natural drying (ambient environment) and forced convection with crossflow velocities of 0.8 m/s and 1.9 m/s. The experimental design allowed for direct comparisons of moisture loss between the test container subjected to corona discharge and a reference container undergoing natural drying under controlled ambient temperature $(T)$ $(T)$ and relative humidity $(\%RH)$ $(% R H)$ . Drying enhancement was quantified using dimensionless numbers: the Sherwood number ( $Sh$ $Sh$ ), EHD Reynolds number ( ${Re}_{EHD}$ ${Re}_{EHD}$ ), and EHD number ( ${N}_{EHD}$ $N_{EHD}$ ). Under static conditions (without crossflow), a regression correlation was established, demonstrating a nearly two-fold increase in the drying rate compared to natural drying. Under forced convection, the interplay between the ionic wind and crossflow was evident. At a moderate crossflow velocity (0.8 m/s), the drying enhancement indicated that the ionic wind effectively augmented convective mass transfer. However, at a higher crossflow velocity (1.9 m/s), the trend reversed, suggesting that excessive crossflow may suppress the corona discharge effect by reducing the ion density and the resultant momentum transfer. These results highlight that while an aluminum electrode can reliably sustain the high-voltage conditions necessary for effective corona discharge, its drying enhancement capability is highly dependent on crossflow velocity ( $u$ $u$ ). This study underscores the potential of EHD drying as an energy-efficient, sustainable alternative to conventional methods and suggests further research to optimize the electrode geometry, electrode gap, and operational parameters for industrial-scale applications. This study advances EHD drying by demonstrating the feasibility of aluminum electrodes for energy-efficient and sustainable industrial applications.