Flow Prediction and Fluctuation-sensitivity Investigations for Quasi-steady Shear Driven Condensing Flows in Milli-meter to Micro-meter Scale Two-Phase Systems

这项研究将有助于开发涉及液-汽相变的微型热力系统。为了达到所需的系统性能，通常情况下，剪切驱动的准稳态冷凝流动必须以可预测和可维护的方式运行。因此，毫米到微米级的冷凝器需要可靠的流量预测能力。智能优点：这项研究试图量化进出冷凝流的波动能量传递机制，这些机制可能会在微尺度冷凝器内外引起显著的暂态行为。实验涉及三个不同的测试部分(特征尺寸从200微米到2毫米的水平间隙或管子)，将导致测量的定量信息，即小规模冷凝器如何动态和热学地响应通过其进出口传递的波动能量。要测量的量包括换热系数、压降和其他对成功的设计和操作至关重要的重要标准。实验研究将用模拟来加强，以产生适用于各种几何形状和各种冷凝表面温度条件的预测能力。辐射影响：流动沸腾和冷凝具有在许多应用中满足高热流需求的前景。这项研究将使更定量地预测小型冷凝器内的流动和换热。这项研究将涉及从代表性不足的群体中招募的研究生和本科生。

1033591NarainThis research will aid the development of microscale thermal systems that involve liquid-vapor phase change. To achieve desired system performance, it is often the case that shear-driven quasi-steady condensing flows must be made to behave in a predictable and maintainable fashion. Reliable flow prediction capability is therefore needed for millimeter-to-micrometer scale condensers. Intellectual Merit: This research seeks to quantify the fluctuation energy transfer mechanisms to and from a condensing flow that might cause significant transient behavior within and outside of a microscale condenser. Experiments involving three different test sections (horizontal gaps or tubes with characteristic dimensions of 200 micrometers to 2 millimeters) in an instrumented flow-loop facility will lead to measured quantitative information on how a small-scale condenser responds - dynamically and thermally - to fluctuation energy transferred through its inlet and outlet. Quantities to be measured include heat transfer coefficients, pressure drops, and other important criteria that are crucial for successful design and operation. The experimental study will be augmented with simulations to generate a predictive capability applicable to a wide array of geometries and various condensing surface temperature conditions.Broader Impacts: Flow boiling and condensation has promising potential to meet high heat flux needs in many applications. This research will enable a more quantitative prediction of flow and heat transfer in small scale condensers. The research will involve graduate students and undergraduate students recruited from underrepresented groups.