Contemporary Challenges for Thermal and Mass Transport Technologies: A Perspective on Twenty-First Century Opportunities for the Field

Abstract

The development of thermal and mass transport as a subject of scientific study holds a central place in the origin and advancement of the Industrial Revolution by enabling the steam engine, which in turn provided unprecedented levels of power and speed for transportation, material processing, and eventually the distribution of electricity. Even earlier, elementary understanding of heat and mass transfer were crucial elements in providing for human safety and comfort, as well as food preservation via cooking and drying. Given this rich and diverse history, a logical question is: how much more of this subject remains to be discovered and explored? One answer would point to nuances of how heat and mass flow occurs at different scales through various material solid and fluid hosts, new forms of which are constantly being discovered and developed (Bergman et al., 2008). However, such a perspective seems relatively narrow in comparison to the outsize history of impact in the field, yet at the same time global grand challenge problems, such as clean energy and water, food security, or eradication of disease are too general to have useful meaning for the present purpose. Instead, we consider here how improved understanding of the details of thermal and mass transport might rekindle a new set of discoveries and technologies with broad global impact. tranSient and nOn-eQUiliBriUM prOceSSeSA useful starting point for imagining the possibilities of transformative discoveries in the area of transport processes is the semiconductor industry. Borne of a seemingly simple yet profound combination of materials built into a unique device, the solid-state transistor has served as the genesis of multiple industries, ranging from personal computing to telecommunications (Brinkman et al., 1997). One of the crucial insights to the development of integrated circuits (ICs) was that individual devices could be operated away from thermodynamic equilibrium in a repeated and coordinated manner to produce a greater overall effect than the "sum of their parts. " With such developments arose other specialized circuit elements such as micro-capacitors and dynamic memory devices that, along with a set of community-driven and shared design tools (Dutton and Yu, 2012), have enabled the simple transistor to form the basis of ICs that now touch nearly every technology-based device and product.In comparison, the study of transport phenomena has focused strongly on near-equilibrium and steady-or quasi-steady-state processes. This emphasis is apparent in virtually any textbook on heat, mass, and/or fluid transport, largely because of the myriad complexities produced by nonequilibrium thermodynamics and transient dynamics (Groot and Mazur, 1962). One important example of non-equilibrium behavior involves the fast collection of "hot carriers" as proposed