Driven by functionality and purity demand for applications of inorganic nanoparticle colloids in optics, biology, and energy, their surface chemistry has become a topic of intensive research interest. Consequently, ligand-free colloids are ideal reference materials for evaluating the effects of surface adsorbates from the initial state for application-oriented nanointegration purposes. After two decades of development, laser synthesis and processing of colloids (LSPC) has emerged as a convenient and scalable technique for the synthesis of ligand-free nanomaterials in sealed environments. In addition to the high-purity surface of LSPC-generated nanoparticles, other strengths of LSPC include its high throughput, convenience for preparing alloys or series of doped nanomaterials, and its continuous operation mode, suitable for downstream processing. Unscreened surface charge of LSPC-synthesized colloids is the key to achieving colloidal stability and high affinity to biomolecules as well as support materials,...

Laser Synthesis and Processing of Colloids: Fundamentals and Applications

A review of thermoelectric cooling: Materials, modeling and applications

Thermoelectric (TE) technology is regarded as alternative and environmentally friendly technology for harvesting and recovering heat which is directly converted into electrical energy using thermoelectric generators (TEG). Conversely, Peltier coolers and heaters are utilized to convert electrical energy into heat energy for cooling and heating purposes The main challenge lying behind the TE technology is the low efficiency of these devices mainly due to low figure of merit (ZT) of the materials used in making them as well as improper setting of the TE systems. The objective of this work is to carry out a comprehensive review of TE technology encompassing the materials, applications, modelling techniques and performance improvement. The paper has covered a wide range of topics related to TE technology subject area including the output power conditioning techniques. The review reveals some important critical aspects regarding TE device application and performance improvement. It is observed that the intensified research into TE technology has led to an outstanding increase in ZT, rendering the use TE devices in diversified application a reality. Not only does the TE material research and TE device geometrical adjustment contributed to TE device performance improvement, but also the use of advanced TE mathematical models which have facilitated appropriate segmentation TE modules using different materials and design of integrated TE devices. TE devices are observed to have booming applications in cooling, heating, electric power generation as well as hybrid applications. With the generation of electric energy using TEG, not only does the waste heat provide heat source but also other energy sources like solar, geothermal, biomass, infra-red radiation have gained increased utilization in TE based systems. However, the main challenge remains in striking the balance between the conflicting parameters; ZT and power factor, when designing and optimizing advanced TE materials. Hence more research is necessary to overcome this and other challenge so that the performance TE device can be improved further.

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A comprehensive review of thermoelectric technology: materials, applications, modelling and performance improvement

The constructal law and the evolution of design in nature.

This is a review of the theoretical and applied progress made based on the Constructal law of design and evolution in nature, with emphasis on the last decade. The Constructal law is the law of physics that accounts for the natural tendency of all flow systems (animate and inanimate) to change into configurations that offer progressively greater flow access over time. The progress made with the Constructal law covers the broadest range of science, from heat and fluid flow and geophysics, to animal design, technology evolution, and social organization (economics, government). This review presents the state of this fast growing field, and draws attention to newly opened directions for original research. The Constructal law places the concepts of life, design, and evolution in physics.

Constructal law of design and evolution: Physics, biology, technology, and society

Mathematical modeling and numerical characterization of composite thermoelectric devices

Geometric optimization of thermoelectric elements for maximum efficiency and power output

Thermoelectric elements, made of semiconductor slices laminated onto highly conductive interconnector materials, are termed composite thermoelectric device (TED). An integrated TED is a composite TED with the interconnector designed as an internal heat exchanger with flow channels directing the working fluid between the source and element legs. In this work, novel composite and integrated TEDs are proposed as an alternative to conventional TEDs, and their performance in terms of power output P 0 , heat input Q h , conversion efficiency η, and the produced electrical current I is studied using analytical solutions. The top and bottom surfaces of the TED are subjected to a temperature differential while the side surfaces are exposed to either ambient or adiabatic conditions. An increment in temperature differential results in enhanced device performance. For a fixed temperature differential, the integrated TED shows nearly an eight-fold increase in both P o and Q h and a four-fold increase in I, whereas the composite TED shows approximately a two-fold increase in P 0 , Q h , and I when compared to the conventional TED values. Both novel TED designs have a minimal impact on efficiency predictions. However, an increase in semiconductor slice thickness resulted in an exponential decrease in P 0 , Q h , and I, and an exponential increase in η values and reaches a limit of conventional TED values. The effect of semiconductor slice thickness on η in the novel TEDs is remarkable when it is less than 1 mm. The change in ambient conditions via convective heat transfer coefficient has negligible effects on P 0 ; however, a substantial change in η occurs when it is less than 100 Wm ―2 K ―1 .

Thermoelectric Performance of Novel Composite and Integrated Devices Applied to Waste Heat Recovery

Laminar forced convection in a heat generating bi-disperse porous medium channel

Thermoelectric elements made of semiconductor plates laminated onto a highly electrical and thermally conductive inter-connector with a flow channel configuration can be treated as an integrated thermoelectric device (iTED). An element constructed with bulk crystalline n- and p-type (Bismuth-Telluride) semiconducting materials and copper as a conducting material is considered. In this study, the thermoelectric performance of such an element using fluid-thermoelectric coupled field numerical methods has been investigated. The iTED is subjected to constant cold temperature at the bottom and top surfaces, while the inter-connector channel walls are exposed to hot fluid flow; the remaining surfaces are kept adiabatic. The performance of the iTED element is studied in terms of heat input Q h , power output P 0, conversion efficiency η, produced electric current and Ohmic and Seebeck voltages for different load resistances, inlet hot fluid temperatures T in , semiconductor material heights d, and flow rates Re....

B. V. K. Reddy

Papers

Mathematical modeling and numerical characterization of composite thermoelectric devices

Geometric optimization of thermoelectric elements for maximum efficiency and power output

Thermoelectric Performance of Novel Composite and Integrated Devices Applied to Waste Heat Recovery

Laminar forced convection in a heat generating bi-disperse porous medium channel

Three-Dimensional Multiphysics Coupled Field Analysis of an Integrated Thermoelectric Device