Microfluidic Heat Engines for Recovery of Distributed Waste Heat

在我们地球上消耗的15 TW的电力中，大部分最终作为热量被排放到环境中。因此，当今最大的可再生能源来源之一是废热。然而，这些能源分布在我们的家庭、工厂和汽车中，很难回收和再利用。此外，温度通常相对较低，这降低了热到有用功或电的转换效率。我们建议开发由废热驱动的微型热机，可以使用批量制造方法（例如基于MEMS的微制造技术）在大型平面阵列中制造。微型热力发动机将以片材的形式出现，可以直接集成到热源，例如热的汽车发动机排气，工业过程烤箱的墙壁，以及排出热气体或液体的排水管或烟囱。我们最近在微观尺度上发现了导致不寻常热力学循环的独特行为。然而，需要更好地理解主导物理学及其对微加工器件的影响。该范围由三个主要研究目标组成：1）了解受限微通道和腔室中爆炸蒸发的物理学; 2）控制传热，流体动力学和机电学之间的动态耦合; 3）设计微制造方法，以低成本和高容量批量制造微流体热机。该方法包括一个组合的实验研究，使用的变体的微型原型和测试结构，探索和理解的主导物理，沿着与分析和数值建模。还将开发微加工工艺和原型，用于实验验证和演示。结果将是新的热力学循环的解释，建立知识基础的设计微型热力发动机运行在这些周期，并在热流体科学，机电，复杂系统的设计和微技术的多学科领域的HQP的培训。

Out of the 15 TW of power consumed on our planet, a majority is eventually rejected as heat to the ambient. One of the largest sources of renewable energy available today is therefore waste heat. This energy is however distributed in our homes, factories and cars, making it difficult to recuperate and reuse. Furthermore, temperatures are typically relatively low, which reduces the conversion efficiency of heat into useful work or electricity. We propose to develop micro heat engines driven by waste heat that can be fabricated in large planar arrays using batch fabrication approaches, such as MEMS-based microfabrication technologies. The micro heat engines will come in the form of sheets that can be directly integrated to the heat sources, such as hot automobile engine exhausts, walls of industrial process ovens, and drain pipes or chimneys rejecting hot gases or liquids. We have recently discovered unique behavior at the microscale that leads to uncommon thermodynamic cycles. Much better understanding of the dominant physics and their impact on the microfabricated device is however needed. The scope is composed of three main research objectives: 1) Understand the physics of explosive evaporation in confined microchannels and chambers; 2) Control the dynamic coupling between the heat transfer, fluid dynamics, and electromechanics; 3) Devise microfabrication approaches to batch fabricate microfluidic heat engines at low-cost and high volume. The methodology consists of a combination of experimental investigations using variants of miniature prototypes and test structures to explore and understand the dominant physics, along with analytical and numerical modeling. Microfabrication processes and prototypes will also be developed for experimental validation and demonstration. The outcomes will be the explanation of the novel thermodynamic cycles, an established knowledge base for the design of micro heat engines operating on these cycles, and training of HQP in the multidisciplinary fields of thermofluid sciences, electromechanics, design of complex systems, and microtechnologies.