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

这个合作的早期概念探索性研究赠款（EAGER）研究项目的重点是一个设计概念，可以通过将热量转换为电能，从废热中收集能量。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，存在一系列蛇形布置的微型通道，其部分地填充有工作流体。在通过使用热管收集能量方面的研究如果有的话也很有限。由于蒸汽膨胀和流体流动，热管在其结构内提供显著的机械功。这项研究的目的是收获这个内部的工作，通过利用一个专门设计的能量收集系统，使电的工作，通过压电效应，即热驱动压电转换（TPT）的产生，增加OHP热传递到环境。该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，使用OHP进行能量收集。这项研究将桥接热/流体科学和发电的研究视角和方法。这些装置的潜在应用是众多的，特别是用于废热回收和/或可再生发电。衍生的技术和基础科学可以导致：用于通信设备的离网发电（例如，第三世界国家的蜂窝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。地热温度梯度也可以通过实施超大型OHP/TPT系统或串联排列的OHP/TPT来用于恒定的可再生发电。这个合作项目将支持研究生和本科生的研究人员，一直是传统上代表性不足。OHP还没有被调查作为一种手段，以不稳定的自然温度梯度，建立一个斯特林循环的目的，也没有被调查作为一种手段发电。使用TPT的一个独特机会是在平板振荡热管（OHP）的顶部-一种通过内部工作流体的循环相变有效传递热量的设备-在其表面上产生振荡温度场。该研究将调查TPT和OHP用于组合1）发电/能量收集，以及2）高效传热的使用。为了实现这一目标，将设计一种独特的能量采集器，直接连接到OHP表面，由微型散热器、封装气体和悬浮的弹簧抵抗压电材料组成。一个积极的时间表，精心设计的实验计划，以确定如何有效的TPT取决于OHP和能量采集器的设计。一个高度耦合的控制方程组将被定义和解决加入常见的OHP热/流体模型与压电材料的本构方程。将利用数值多物理场软件来模拟能量采集器中的对流气流和所提出的用于OHP集成TPT的方法所固有的发电。将评估用于TPT的各种压电材料的机械响应和疲劳。通过所提出的OHP/TPT进行热电发电是一种独特的、潜在的热电转换方法，因为OHP/TPT可以有效地将热量从一个位置传递到另一个位置（具有超高的导热性），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.