Nanoparticles submerged in confined flow fields occur in several technological applications involving heat and mass transfer in nanoscale systems. Describing the transport with nanoparticles in confined flows poses additional challenges due to the coupling between the thermal effects and fluid forces. Here, we focus on the relevant literature related to Brownian motion, hydrodynamic interactions and transport associated with nanoparticles in confined flows. We review the literature on the several techniques that are based on the principles of non-equilibrium statistical mechanics and computational fluid dynamics in order to simultaneously preserve the fluctuation-dissipation relationship and the prevailing hydrodynamic correlations. Through a review of select examples, we discuss the treatments of the temporal dynamics from the colloidal scales to the molecular scales pertaining to nanoscale fluid dynamics and heat transfer. As evident from this review, there, indeed has been little progress made in regard to the accurate modeling of heat transport in nanofluids flowing in confined geometries such as tubes. Therefore the associated mechanisms with such processes remain unexplained. This review has revealed that the information available in open literature on the transport properties of nanofluids is often contradictory and confusing. It has been very difficult to draw definitive conclusions. The quality of work reported on this topic is non-uniform. A significant portion of this review pertains to the treatment of the fluid dynamic aspects of the nanoparticle transport problem. By simultaneously treating the energy transport in ways discussed in this review as related to momentum transport, the ultimate goal of understanding nanoscale heat transport in confined flows may be achieved.

This work provides an overview of the use of nanomaterials in solar energy and desalination sectors. Nanotechnology has received considerable attention in the past few years due to availability of new structures at nanoscales with potential applications in various industrial applications especially in the energy field. This work offers the most recent advances of nanotechnology in thermal storage systems, photovoltaic systems, and solar desalination. With the application of nanomaterials, photovoltaic solar cells are increasing their efficiency while reducing the production costs of electricity and manufacturing. According to the US Department of Energy, few power-generating technologies have as little environmental impact as photovoltaic solar panels. Photovoltaic systems generate considerably smaller amount of harmful air emissions (at least 89%) per kilowatt hour than conventional fossil fuel-fired technologies.

Computational fluid dynamics and its counterpart computational heat transfer are subjects that inspire alarm in precomputer-trained professors and awe in young would-be researchers. One aim of this chapter is to diminish these reactions by clarifying both the laudable and the debatable natures of the subjects. A second aim is to make clear, to those who are not overanxious to follow fashion, that there remains much scope for valuable innovations. The chapter reviews items selected from approximately half a century of three-steps-forward-two-steps-back actions, and it contains such adumbrations of detail and expressions of personal opinion as its author judges to be conducive to its aim.

Abstract This is a critical review of the application of infrared (IR) techniques in micro-scale boiling phenomena. Investigations performed within the last decade were used to analyze the specific features of micro-scale IR measurements. The method is illustrated by various examples of heat transfer determination using image analysis of the heater surface temperature. The good results obtained in the last decade by widespread use of IR technique in experimental studies of convective problems have proved the IR technique to be an effective tool in overcoming several limitations of the standard sensors.

Abstract Owing to their high reliability, simplicity of manufacture, passive operation, and effective heat transport, flat heat pipes and vapor chambers are used extensively in the thermal management of electronic devices. The need for concurrent size, weight, and performance improvements in high-performance electronics systems, without resort to active liquid-cooling strategies, demands passive heat-spreading technologies that can dissipate extremely high heat fluxes from small hot spots. In response to these daunting application-driven trends, a number of recent investigations have focused on the design, characterization, and fabrication of ultrathin vapor chambers for proximate heat spreading away from these hot spots. The predominant transport mechanisms and operational limits have been found to be different under these conditions relative to conventional low-power heat pipes. Noteworthy advances in the fundamental understanding of evaporation and boiling from porous microstructures fed by capillary action and improvements in vapor chamber characterization, modeling, design, and fabrication techniques are reviewed. Characterization of evaporation and boiling from idealized and realistic wick structures, observation of vapor formation regimes as a function of operating conditions, assessment of fluid dryout limitations, design of novel multiscale and nanostructured wicks for enhanced transport, and incorporation of these high-heat-flux transport phenomena into device-level models are discussed. These recent developments have successfully extended the maximum operating heat flux limits of vapor chambers.

The constructal law of design evolution is the law of physics that expresses the natural tendency of all flow systems, bio and nonbio, to morph into configurations that provide greater flow access over time. River basins, animal locomotion and migratory routes, snowflakes, and turbulence structure illustrate this tendency of design occurrence and evolution over time. The movement and persistence of human life on the landscape (people, goods, construction, and mining) also evolves in accord with the constructal law. Each of us belongs to the “human and machine” species, the evolving design that is better known as technology evolution. In this chapter, I illustrate the technology evolution phenomenon by showing that larger flow components (organs) belong on larger vehicles and animals and that the time arrow of the constructal law points toward smaller sizes over time (miniaturization). This evolutionary direction is further illustrated by the evolution of cooling technology for high-density heat transfer, from natural convection to forced convection and pure conduction, Fourier and non-Fourier. Tree-shaped flow architectures emerged from the same constructal-law tendency when the flow connects one point with an infinity of points (area and volume). At bottom, all technology evolution is about facilitating the movement of the human and machine species on the world's map. This is why the more advanced groups consume proportionally more fuel and why both wealth and fuel consumption continue to rise naturally.

Abstract Although energetic chemical reactions have been known for at least 50 years to either enhance or attenuate both external and internal forced convective heat transfer strongly, this effect, let alone its explanation, does not appear to have been mentioned in any textbook on transport, heat transfer, reaction engineering, or process design. The enhancement or attenuation of internal forced convection are described and explained herein by means of a combination of essentially exact numerical solutions and of approximate, closed-form asymptotic expressions. The complexity and the additional parameters introduced by the localized generation of the heat of reaction and the exponential dependence of the reaction-rate constant on temperature appear to preclude a generalized predictive or correlative equation for the enhancement and attenuation. However, the numerical solution of a realistic model on a case-by-case basis is demonstrated to be a feasible alternative.

In the past several decades, heat transfer enhancements using extended surface (fins) has received considerable attention. A new heat transfer enhancement technique, longitudinal vortex generators (LVGs), has received significant attention since the 1990s. It is activated by a special type of extended surface that can generate vortices with axes parallel to the main flow direction. The vortices result from strong swirling secondary flow caused by flow separation and friction. The state-of-the-art on research and applications of LVG are described here. The topical coverage includes heat transfer enhancement in straight channels and in heat exchangers. Among the latter are plate and wavy fin-and-tube heat exchangers, fin-and-oval-tube heat exchangers, and fin-and-tube heat exchangers with multiple rows of tubes. The trends and future directions of heat transfer enhancement by means of LVG are discussed.