Technological advances in small scale devices are hindered by the need for more efficient heat exchanging mechanisms. The design, characterization and control operation of potentially ultra-efficient, particle-driven micro-convection devices, the objective of this study, will have strong economic impact in several industries, e.g. electronics, aerospace, automotive, and energy. Recent technological advances for building small flow channels and particles, which are explored in this project, points toward the potential scalability of the proposed approach from macro- down to micro- and nano-scale applications, making this study relevant to heat and mass transfer equipment not only in mature but also in many emerging industries, such as fuel-cells, micro-engines, micro-chemical reactors, and bio- and space-sensors. Analytical, numerical and experimental efforts will be combined to provide insight and knowledge of this new approach, critical in determining its suitability for diverse applications. This is an essential study for gaining fundamental insight of new thermo-hydraulic effects resulting from the proposed use of small particles in convection. This project will also boost the awareness of young under-represented and under-served girls, many of Latino origin, about STEM careers. The development of a new Micro-Thermal Devices course with a collaborative, research-driven international study abroad program is planned, as well as a new web portal for disseminating the work on micro-thermo-fluidics.
The standard modern approach to using small (micro- and nano-scale) solid particles in convection equipment begins by mixing the particles with a base fluid to form fluid-solid (slurry) mixtures. The present project aims at transforming this standard approach by investigating the use of these mixtures in channels with flow passage similar to the particle size. This new approach has been bio-inspired by the study of gas transfer in alveolar capillaries, where red blood cell particles (RBCs) flow through capillaries having flow passage similar to the RBC size. In this case, each particle becomes a discrete component of the mixture, possibly sweeping the convection boundary layers as they flow through a channel. The proposed work on parallel-plates and capillary channels, with particles of different sizes (different particle-channel gaps), provides a drawing board for developing a fundamental design tool for microdevices, where high heat transfer coefficient must be weighed against potential pressure-drop penalty. Another advantageous effect of the new approach is the possibility of controlling the particle's thermo-hydraulic effects by simply varying the number of particles flowing through the channel, which can be done easily on-the-fly. This aspect, which would be fundamental for devices with time-varying thermo-hydraulic loads, will also be investigated in this study. Analytical, numerical and experimental efforts will be combined to provide insight and knowledge of the convection and rheological behaviors of this new approach, critical in determining its suitability for diverse applications. This is a foundational study, essential also for building experimental and numerical data-banks for validating and optimizing predictive analytical models.