EAGER: Uncovering the Physical Mechanism behind Flow Boiling Critical Heat Flux

Case Western Reserve University, Cleveland OH

Investigators

Abstract

Many industries including those in energy, aerospace, defense, and consumer electronics sectors are seeing a significant increase in energy utilization. Current cooling systems that use air or water flows are often incapable of extracting the heat effectively and maintaining reasonable operating temperatures. Boiling of liquids is a very effective cooling mechanism, but there is a limit on how much boiling systems can extract, defined by the critical heat flux. Exceeding the critical heat flux can cause a failure of the heat-generating system or device. The overarching goal of this project is the understand the physics behind the critical heat flux. This understanding can then be used to to avoid failure in boiling systems. The educational and outreach goal for the project is to complement the research activity by developing a module for Case Western Reserve University’s “Introduction to Innovation” program, the centerpiece of a new campus-wide broader impact strategy, to give middle school educators experience in applying core scientific concepts to understanding simple cooling systems. A lab demonstration of the pool boiling phenomena has been planned to supplement the teaching section of the module to focus on phase-transformation due to boiling in natural systems. It has been shown that flow boiling critical heat flux can be triggered by hydrodynamic liquid-vapor instabilities occurring in the flow. However, to date, no thorough validation of the phenomena has been performed to ascertain the mechanism behind it. In this project, the investigators plan to develop a fundamental understanding of the mechanism behind critical heat flux by exploring interfacial flow dynamics during flow boiling by using a combination of high-speed imaging and particle image velocimetry measurements. Using the data obtained, a mechanistic model will be developed to predict critical heat flux. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.