Development of intelligent micro cooling system utilizing ER effects

利用ER效应开发智能微冷却系统

• 批准号: 17560138
• 负责人: NARUMI Takatsune
• 金额: $ 2.24万
• 依托单位: Niigata University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2005
• 资助国家: 日本
• 起止时间: 2005 至 2006
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17560138/
• 关键词: Liquid crystal; ER effect; Yield pronerty; Functional fluid; Flow rate control; Smectic liquid crystal; Phase change; 降伏応力; 流体工学; 先端機能デバイス; 冷却

We have tried to develop a new cooling system utilizing liquid crystal which shows ER (electro-rheological) effect under electric fields applied and phase change by the temperature control. In the early stage of this project, it was found that flow rate of liquid crystal was controllable with applying electric fields. But, it was also clarified that it was difficult to obtain higher cooling efficiency than the water system because of higher viscosity and similar heat transfer property of liquid crystal. Hence we have examined the applicability of smectic liquid crystal as a functional fluid to stop the flow utilizing its yield property controlled with the electric field strength and the temperature.In the second stage, ER characteristic in smectic phase of the liquid crystal have been investigated utilizing a parallel-plate type rheometer. The strength of the alignment structure in the Smectic phase is experimentally examined from the change in yield stress under various conditions. When the electric field strength was low, the yield stress was almost the same as that obtained under no electric field. Above a threshold of DC electric field, the yield stress increased and then became constant. Moreover, photographs were taken in yield process, and it is found that the collapse of the structure under the DC electric field is generated not uniformity but like spots.In the final stage, the yield properties with two dimensional channels in the pressure flow have been measured with the same smectic liquid crystal. The growth of smectic phase structure at the entrance of the channel increased the stop valve effect of the system.From these results, it is considered that the flow control with the liquid crystal is helpful to develop intelligent cooling systems.

我们试图开发一种新的冷却系统，利用液晶显示ER（电流变）的效果下施加的电场和相变的温度控制。在本项目的早期阶段，人们发现液晶的流速可以通过施加电场来控制。但是，也明确了由于液晶的较高粘度和类似的传热性质，难以获得比水系统更高的冷却效率。因此，我们已经检查了近晶液晶作为功能流体的适用性，以停止利用其屈服性能控制的电场强度和温度的流动。在第二阶段，ER特性在近晶相的液晶已经研究利用平行板型流变仪。在近晶相的对齐结构的强度进行实验检查从屈服应力在各种条件下的变化。当电场强度较低时，屈服应力几乎与无电场时相同。在直流电场阈值以上，屈服应力先增大后趋于恒定。在屈服过程中拍摄了照片，发现结构在直流电场作用下的崩塌不是均匀的，而是点状的。最后，用同样的近晶相液晶测量了压力流中二维通道的屈服特性。近晶相结构在通道入口处的生长增强了系统的截止阀效应，由此认为，利用液晶进行流量控制有助于开发智能冷却系统。

项目成果

Hasegawa, Transient Response of Liquid Crystal in Folw Reversal under Electric Fields

长谷川，电场下液晶的瞬态响应

• 发表时间: 2006
• 期刊: Proc. 2006 Annual Meeting, JSFM, CD
• 作者: T. Narumi;T. Ito;T.
• 通讯作者: T.

電場下の液晶の流動反転時の過渡応答

电场作用下液晶反向流动的瞬态响应

• 发表时间: 2006
• 期刊: 日本流体力学会年会2006講演要旨集
• 作者: H. Uematsu;T. Narumi;T. Hasegawa;鳴海 敬倫
• 通讯作者: 鳴海 敬倫

スメクティック液晶の降伏応力に対する諸条件の及ぼす影響

各种条件对近晶液晶屈服应力的影响

• 发表时间: 2006
• 期刊: 日本機械学会流体工学部門講演会講演論文集 06-21
• 作者: H. Uematsu;T. Narumi;T. Hasegawa;鳴海 敬倫;鳴海 敬倫;渡部 光太郎
• 通讯作者: 渡部 光太郎

Influence of Electric Fields on Yield Property of Smectic Liquid Crystal

电场对层列液晶成品率的影响

• 发表时间: 2007
• 期刊: Proc. JSME Fluid Engineering Conference 2007, 07-16, CD
• 作者: H. Uematsu;T. Narumi;T. Hasegawa
• 通讯作者: T. Hasegawa

液晶のスメックティック相形成時の条件による降伏特性の変化

液晶中近晶相形成时的条件导致的产率特性的变化

• 发表时间: 2006
• 期刊: 第54回レオロジー討論会講演要旨集
• 作者: H. Uematsu;T. Narumi;T. Hasegawa;鳴海 敬倫;鳴海 敬倫;渡部 光太郎;渡部 光太郎
• 通讯作者: 渡部 光太郎