Combined Dielectrophoretic and Electrohydrodynamic Conduction Pumping for Enhancement of Liquid Film Flow Boiling

Abstract

This paper extends previous liquid film flow boiling studies by including the effect of an additional electrohydrodynamic (EHD) force, namely, the dielectrophoretic (DEP) force. Rather than using only EHD conduction pumping of the liquid film to electro-wet the heater surface, a localized nonuniform electric field above the heater surface is established to generate a DEP force for improved vapor bubble extraction during the nucleate boiling regime. The effects of liquid film height and applied potential are studied as a function of heater superheat and heat flux. A brief analytical study is also used to estimate the expected DEP force magnitude to explain the results. All of the above studies are also used to quantify the enhancement in heat transfer that can be achieved when heat transport systems are driven or augmented by these two EHD mechanisms. The results show remarkable enhancement of up to 1217% in boiling heat transfer coefficient at a given superheat when both mechanisms are used simultaneously. The experimental data are important for applications in thermal management in terrestrial and space conditions.

Bubble Control, Levitation, and Manipulation Using Dielectrophoresis

“…Hence the ability described in this work to electrostatically detach, i.e., to dislodge and control bubbles at will in dielectric and conducting liquids has potential applications in; improving efficiency by rapidly removing nucleated bubbles in immersion heat transfer, [ 48–50 ] as an active “debubbler” in conventional microfluidics, for controlling bubbles in microgravity environments, [ 7 ] as well as opening up new avenues to achieving “wall‐less” surface driven bubble‐microfluidics with the intervening liquid layer avoiding the issues associated with moving contact lines. [ 51 ]…”

Overview of electrohydrodynamic conduction pumping

“…Yazdani 和 Seyed-Yagoobi [28,[135][136][137][138][139] 利用传导机制，产 生高速射流冷却加热表面、进行球型储液器的热均匀 化处理以及增强流速通道来流的强迫对流，提高系 统的散热能力。 Nourdanesh 与 Esmaeilzadeh [140] 采用平 嵌电极泵送煤油，进行传导强化对流散热与自然对 流散热对比实验研究。Nourdanesh 等 [141] 在文献 [140] [142,143] 构建了一种新型的 EHD 传导强化双管换热器， 在冷却管中布置平嵌电极，增强液体对流换热。 图 25 嵌入纺织手套中，用于调节体温的可伸缩泵 [33] Fig 25 Stretchable pump embedded in a textile glove for on-body thermal regulation [33] Cacucciolo 等 [33] 将柔性泵嵌入在纺织手套内，进 行体温热调节，如图 腾时，性能几乎不受重力的影响 [146] 。实验结果有力 地证实了电导泵长期应用于航空散热系统的应用前 景。传导机制还可应用于提高池沸腾临界热流密度、 强化沸腾传热 [147][148][149][150] 。Pearson 和 Seyed-Yagoobi [151] 创 新设计了同心环形的结合电极布置，使容器周围液 体从不同方向流向中心加热蒸发区。在给定热通量的 条件下，传导机制产生可观的循环速度湿润中心液 体沸腾区与液膜几乎停滞无传导机制的状态相比， 蒸发器表面液体过热温度显著降低。 图 26 液体薄膜沸腾实验系统 [152] Fig 26 Experimental system of liquid film boiling [152] 为 [21,[153][154][155] 基于 MEMS 加工技术制作的微注入泵、华南理工 大学万珍平等 [58] 基于微加工制作的一种微电导泵。山 东大学李斯盟等 [156]…”

In-depth description of electrohydrodynamic conduction pumping of dielectric liquids: Physical model and regime analysis

“…When used in heat transfer applications, it is better to consider the efficiency of EHD conduction pumps in terms of heat transfer enhancement versus their input electric power. Past experiments have shown that a single watt of input power can generate two or three order of magnitudes enhancements in the resultant heat transport capacity 11,27 . Therefore, EHD conduction pumping efficiency in heat transport systems is defined as the ratio of the maximum additional heat removed from the system due to the presence of the EHD conduction pump and the input electric power to the pump.…”