Thermal Transport in Micro- and Nanoscale Systems

Abstract

Small scale (micro/nanoscale) heat transfer has broad and exciting range of applications. Heat transfer at small scale quite naturally is influenced-sometimes dramatically-with high surface area to volume ratios. This in effect means that heat transfer in small scale devices and systems is influenced by surface treatment and surface morphology. Importantly, interfacial dynamic effects are at least non-negligible and there is a strong potential to engineer the performance of such devices using the progress in micro and nanomanufacturing technologies. With this motivation, the emphasis here is on heat conduction and convection. The chapter starts with a broad introduction to Boltzmann Transport equation which can capture the physics of small scale heat transport and outlining the reasons why small scale transport distinct from classical micro scale heat transport. Among applications, examples are thermoelectric and thermal interface materials where micro and nanofabrication has led to impressive figure of merits and thermal management performance. Basic of phonon transport and its manipulation through nanostructuring materials are discussed in detail. Small scale single phase convection and the crucial role it has played in developing the thermal management solutions for next generation of electronics and energy harvesting devices are discussed as next topic. Features of micro cooling platforms and physics of optimized thermal transport using micro channel manifold heat sinks are discussed in detail along with a discussion of how such systems also facilitate use of low grade, waste heat from data centres and photovoltaic modules. Phase changes process and their control using surface micro/nanostructure are discussed next. Among the feature considered, the first are microscale heat pipes where capillary effects play an important role. Next the role of nanostructures in controlling nucleation and mobility in boiling, condensation and icing are discussed great detail. Special emphasis is placed on the limitations of current surface and device manufacture technologies while also

A Review of Nano and Microscale Heat Transfer: An Experimental and Molecular Dynamics Perspective

“…Energy transfer in micro/nano heat exchangers is primarily governed by two mechanisms, i.e., conduction and convection [173]. However energy transport at these scales is usually associated with multiple nonequilibrium processes due to the similarity in the system length scales with the molecular mean free path and process time scales being lower than the relaxation time [174].…”

“…Changes in the interfacial area between the fluid and the solid caused by bubble entrainment can also affect the transport across surfaces. Chemical reactions and adsorption are impacted by an increase in the interfacial area [174,190].…”

Hybrid Approach in Microscale Transport Phenomena: Application to Biodiesel Synthesis in Micro-reactors

“…The research reported here originated through a UK-Brazil Newton Fund-FAPERJ collaborative development project, offering a holistic approach to address the complex nexus challenges from the societal demand for food, water, energy and need for environmental care. The motivation involved a combined system, harnessing electrical energy from high efficiency water cooled HCPVs and using the resulting waste heat for water desalination and continuous biodiesel production, making use of nano and micro-scale transport phenomena analysis tools recently employed in different thermal engineering applications [8][9][10][11]. The original aspects of the present research includes problem formulation and simplification strategies, modern analytical-numerical solution methods for differential equations, parametric and functional identification through inverse analysis, symbolic computation tools, nano and micro-fabrication, non-intrusive optical techniques in micro-scale heat and fluid flow, employed individually or jointly, as needed to answer the basic questions raised by the applications to be advanced.…”