Microscale Heat Transfer in Digital Microfluidics

热是电子设备正常工作时不可避免的副产品，是电路活动过程中电能转化为热能而产生的。电子系统速度的提高通常是通过降低由于较高的电路封装密度而导致的电路延迟来实现的。不幸的是，这伴随着每个电路的功耗增加。随着对快速电子设备需求的增加，对有效和高效地去除热流的能力的需求也越来越大。为此，从非常小的区域安全地散发大量热量的能力是当今许多尖端技术的关键。目前，在高性能超级计算机、电力电子设备、电动汽车、先进军用航空电子设备、雷达和激光器等领域，都遇到了将热流降低100-1000 W/cm2以上的问题。该研究将探索液滴的主动和按需微驱动和传输，这一过程被称为数字化传热（DHT），用于高功率紧凑型系统的有效热管理。DHT技术有两个主要优点。首先，与连续的液体冷却流和空气冷却系统相比，单个液滴的使用和液滴内部随后引入的再循环区域允许增加的热量排出率。其次，液滴可以被离散地操纵，使其成为流体处理的单个、基于指令的编程，其中液滴在不需要移动机械部件的情况下以包的形式运输、混合、反应、存储和分析。DHT的这种能力非常适合于瞬态热管理和功率峰值耗散期间温度超调的抑制。除了上述热科学、流体动力学和计算技术方面的技术进步外，本科生和研究生将在这些主题上接受培训。本科研究助理将通过REU的补充支持寻求，并且可能来自上述领域。PI打算在佛罗里达大学开设一门微尺度传输课程，并通过增加制造和计算组件来扩展他目前的微纳米热流体课程。PI现有的多学科课程将因这项工作的结果而丰富，扩大学生接触微流体学的不同方面。

CBET-1403828MohseniHeat is an unavoidable byproduct of the normal operation of an electronic device, generated as a result of electrical energy being converted to thermal energy during circuit activities. An increase in speed of an electronic system is often achieved by reduction in circuit delay due to higher circuit packaging densities. Unfortunately, this is accompanied by increased power dissipation per circuit. As the need for fast electronic devices increases, the ability to remove heat flux effectively and efficiently is in greater demand. To this end, the ability to safely dissipate large amounts of heat from very small areas is key to many of today's cutting edge technologies. Reducing heat fluxes by an order of 100-1000 W/cm2 and beyond is currently encountered in high performance supercomputers, power electronic devices, electric vehicles, advanced military avionics, radars, and lasers. The proposed investigation will explore the active and on-demand micro actuation and transport of liquid droplets, a process termed Digitized Heat Transfer (DHT), for effective thermal management of high-power compact systems. The DHT technique has two main advantages. First, the use of individual droplets and the subsequent introduction of recirculation zones inside the droplets allows for an increased heat removal rate as compared to continuous liquid-cooling flows as well as air-cooling systems. Second, the droplets may be discretely manipulated, enabling it individual, instruction-based programming of fluid processing, where droplets are transported, mixed, reacted, stored, and analyzed in packets without the need for moving mechanical parts. This capability of DHT is aptly-suited for transient thermal management and the suppression of temperature overshoots during the dissipation of power spikes.In addition to the technical advances in thermal sciences, fluid dynamics, and computational techniques anticipated above, undergraduate and graduate students will be trained in these topics. Undergraduate research assistants will be sought via supplementary REU support, and can be expected to come from the previously mentioned fields. The PI intends to develop a course in micro-scale transport at the University of Florida and expand his current course on micro and nano thermofluidics with the addition of both a fabrication and a computational component. The PI's existing multidisciplinary courses will be enriched with results from this work, expanding student exposure to different aspects of micro fluidics.