Band 28, Heft 1

The chemical looping strategy for fossil energy applications promises to achieve an efficient energy conversion system for electricity, liquid fuels, hydrogen, and/or chemical generation while economically separating CO 2 by looping reaction design in the process. Two types of chemical looping technologies have been developed based on two different reactions of chemical looping intermediates. Type I chemical looping systems utilize metal and metal oxide reduction-oxidation properties to perform the looping reactions. Type II chemical looping systems utilize metal oxide and metal carbonate carbonation-calcination properties to perform the looping reactions. The type of metal or metal oxide along with their preparation methods for applications in both types of chemical looping systems plays significant roles in the chemical looping technology performance. Understanding the reaction mechanism associated with looping intermediates in both types of reactions is important to the rate process of reactions, in turn affecting the design of the looping particles. Furthermore, as conversions of gaseous and solid reactants are closely associated with their contact modes, the intricate contact mode plays an important role in determining the reactant conversions and hence the solid reactant flux in the reactors. The purpose of this paper is thus to provide a perspective on the two key aspects of chemical looping technology, which are not well reported in the literature, namely, reaction mechanism and reactor engineering.

The global population has grown significantly over the past 50 years. Quality of life is generally increasing, along with the higher need for energy and water, alongside the proliferation of environmental issues to be resolved. High-quality drinking water is essential for day-to-day living, for food production, for better living standards, for the somehow neglected nature and for industry. The need for water is increasing rapidly and freshwater resources cannot deal with all of the requirements. Water is not accessible to all as a natural, self-renewable low-cost resource. Droughts in various regions on earth followed by “desertification” and the gravitation of populations towards this “essence of life” are calling for different considerations in terms of economic and social effects. This article summarizes the main techniques that survived and those that did not. Explanations regarding the physics and chemistry of the different processes are provided. The different modes of operation are given along with the criticisms. An analysis of new developments in the area is also presented. The different techniques, trends, economy, environmental and energy aspects, as well as other significant parameters associated with the state-of-the-art of modern desalination and other possible water resources are discussed here.

In this review, we summarize the latest studies on thermal conductivity (TC) of composite materials. TC enhancement of composite materials has been manipulated by using fillers of different properties: material type, size, geometries, and functionalization. Examples of filler size ranges are nanoparticles (1–100 nm) and microparticles (>100 nm); filler geometries could be tubes or sheets, whereas filler materials could be carbon or boron nitride, which will be the focus of this review. It has been found that hybrid composite materials, i.e., systems containing more than one type of filler, such as a blend of nanosize and microsize fillers, give better TC than any of these individual fillers. Besides the filler intrinsic properties, its concentration, dispersion quality, and the preparation method of the composite affects the composite properties as well. The challenge is to optimize these parameters with the desired final performances.

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