Collaborative Research: EAGER: Energy Harvesting via Thermo-Piezoelectric Transduction

这个合作的早期概念探索研究奖助金(AGIRE)研究项目专注于一种设计概念，可以通过将热能转化为电能来从废热中收集能量。这项研究的愿景是使用热管，特别是所谓的振荡热管(OHP)。在OHP内部，存在一系列蛇形排列的微型通道，其中部分填充了工作液。在通过使用热管收集能源方面的研究有限，如果有的话。由于蒸汽膨胀和流体流动，热管在其结构内提供了显著的机械功。这项研究的目的是通过利用一种特殊设计的能量收集系统来增强OHP对环境的热传递，从而收获这一内部功，该系统能够通过压电效应产生电能，即热致动压电换能器(TPT)。这一研究项目将有助于更好地理解TPT的物理和应用，提高对压电材料的理解，以及利用OHPS进行能量收集。这项研究将连接热/流体科学和发电的研究视角和方法。这些设备的潜在应用很多，特别是在余热回收和/或可再生能源发电方面。衍生的技术和基础科学可以带来：通信设备的离网发电(例如，第三世界国家的移动电话充电和国防应用)、更节能的电子封装方案，以及高热通量热能收集的新机会。还可以利用地热温度梯度，通过实施超大型OHP/TPT系统或串联OHP/TPT系统，实现恒定的可再生发电。这一合作项目将支持传统上缺乏代表性的研究生和本科生研究人员。OHP尚未被作为一种破坏自然温度梯度以建立斯特林循环的手段进行研究，也没有被作为一种发电手段进行研究。使用TPT的独特机会是安装在平板振荡热管(OHP)上，该设备通过内部工质的循环相变有效地传递热量，在其表面产生振荡的温度场。这项研究将调查TPT和OHPS在1)发电/能量收集和2)高效热传输方面的联合使用。为了实现这一点，将设计一种直接连接到OHP表面的独特的能量收集器，它将由一个微型散热器、封装的气体和悬浮的、抗弹簧的压电材料组成。为了确定TPT的有效性如何取决于OHP和能源收割机的设计，计划进行一系列精心设计的积极进度表。通过将常见的OHP热/流体模型与压电材料的本构方程相结合，定义并求解了一组高度耦合的控制方程。将利用数值多物理软件来模拟能量收集器中的对流空气流动和所提出的OHP集成TPT方法所固有的发电。对不同的TPT用压电材料的机械响应和疲劳性能进行了评价。通过拟议的OHP/TPT热电发电是一种独特的、具有潜在变革性的热电转换方法，因为OHP/TPT可以有效地将热量从一个位置转移到另一个位置(具有超高的导热系数)，同时还可以发电。

This collaborative, EArly-concept Grants for Exploratory Research (EAGER), research project focuses on a design concept that may allow energy harvesting from waste heat, by converting the heat to electrical energy. The vision of the research is to use heat pipes, in particular so-called oscillating heat pipes (OHP). Inside an OHP, a series of serpentine-arranged mini-channels exist that are partially filled with a working fluid. There has been limited, if any, research in the area of energy-harvesting through the use of heat pipes. Heat pipes provide salient mechanical work within their structure due to vapor expansion and fluid flow. This research aims to harvest this internal work by augmenting the OHP heat transfer to the environment through utilization of a specially designed energy harvesting system that enables generation of electrical work through a piezoelectric effect, namely thermally-actuated piezoelectric transduction (TPT). This research project will contribute to better understanding of the physics and application of TPT, improved understanding of piezoelectric-materials, energy-harvesting using OHPs. This research will bridge research perspectives and approaches from the thermal/fluid sciences and power generation. Potential applications for these devices are numerous, especially for waste heat recovery and/or renewable power generation. The technology and basic science derived can result in: off-grid power generation for communications devices (e.g., third world country cellular phone charging and defense applications), more energy-efficient electronics packaging schemes, and new opportunities for high heat flux thermal energy harvesting. Geothermal temperature gradients may also be exploited for constant, renewable power generation via the implementation of ultra-large OHP/TPT systems or OHP/TPTs aligned in-series. This collaborative project will support both graduate and undergraduate researchers that have been traditionally underrepresented.The OHP has yet to be investigated as a means to destabilize natural temperature gradients for the purpose of establishing a Stirling cycle, nor has it been investigated as a means for power generation. A unique opportunity for using TPT is atop a flat-plate oscillating heat pipe (OHP) - a device that effectively transfers heat via cyclic phase change of an internal working fluid - giving rise to an oscillatory temperature field on its surface. The research will investigate the use of both TPT and OHPs for combined 1) power generation/energy harvesting, and 2) highly-efficient heat transfer. To accomplish this, a unique energy harvester, which is directly attached to the OHP surface, will be designed and will consist of a micro-sized heat sink, encapsulated gas and suspended, spring-resisted piezoelectric material. An aggressive schedule of well-designed experiments is planned to determine how the effectiveness of TPT depends on OHP and energy harvester design. A highly-coupled set of governing equations will be defined and solved by joining common OHP thermo/fluidic models with the constitutive equations of piezoelectric materials. Numerical multi-physics software will be utilized to simulate the convective air flow in the energy harvester and electricity generation inherent to the proposed method for OHP-integrated TPT. The mechanical response and fatigue of various piezoelectric materials for TPT will be evaluated. Thermoelectricity generation via the proposed OHP/TPT is a unique and potentially transformative approach to enthalpy-to-electricity conversion as the OHP/TPT can efficiently transfer heat from one location to another (with ultra-high thermal conductivity) while also generating power.