Continuous flow solar thermal pasteurization of drinking water: Methods,devices, microbiology,and analysis

The ability to simply and robustly pasteurize drinking water would present tremendous worldwide human health benefits. Ingestion of unsafe drinking water is a leading cause of sickness and death in the developing world. A simple method to use concentrated solar power is presented here with two complimentary numerical models. The first model allows a prediction of water temperatures within the concentrator and enables a user to vary operating parameters to assess the impact on the temperatures. The second model relates the temperatures to pathogen inactivation kinetics so that predictions of pathogen populations can be made. It is found that with a modest size system that includes a parabolic trough concentrator, a thermally activated valve, and a fluid-to-fluid heat exchanger, near complete pathogen inactivation can be achieved. Comparisons are made between simulated and experimentally determined temperatures. The comparison demonstrates the veracity of the model.     

Simulation of anomalous transport in tokamaks using the FACETS code

The development of a new parallel framework for integrated modeling of tokamak plasmas is a primary objective of the SciDAC Framework Architecture for Core-Edge Transport Simulations (FACETS) project. The FACETS code will be used to predict the performance of tokamak discharges and to optimize tokamak discharge scenarios. Novel parallel numerical algorithms and solvers have been developed in the FACETS project in order to simulate the multi-scale dynamics of tokamak plasmas. The status of development of modules for anomalous transport in the FACETS code is described in this paper. Mechanisms that are used for coupling 1D anomalous transport in the plasma core together with 2D transport in the plasma edge (in near separatrix and scrape-off-layer regions) are considered. Results of the first verification studies based on predictive modeling of several analytical and experimental equilibria are presented.     

Modeling of heat recovery from a steam‐gas mixture in a high‐temperature sorption process

A high pressure condenser is considered to remove water vapor as well as recover heat from the desorbed steam—CO₂ gas mixture in a novel sorption enhanced reaction process. It is possible to have water condensation at the gas side as well as water evaporation at the coolant water side because of large temperature difference between the hot and cold side. A model of heat and mass transfer and phase change was developed to understand the complex phenomena associated with the simultaneous condensation and evaporation taking place in the unit. A finite difference method was used to solve the boundary value problem. Additional insight was obtained by describing the operating lines and equilibrium condition in an enthalpy diagram. The model was used to explore the performance in terms of the heat recovery. The heat recovery was best at the beginning of the process when the superheated steam was generated. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Mesoporous nanostructured Ni/MgAl2O4 catalysts: Highly active and stable catalysts for syngas production in combined dry reforming and partial oxidation

In this paper, the combination of dry reforming and partial oxidation of methane on nickel catalysts supported on mesoporous MgAl₂O₄ was investigated. The support was prepared by a facile sol-gel route using propylene oxide as a gelation agent. The characterizations of the catalysts were performed by BET, XRD, TPR, TPO, TPH, UV–vis, CO-dispersion, SEM and TEM techniques. In addition, the effects of nickel content, reaction and reduction temperatures, feed ratio and the GHSV value on the physicochemical and catalytic properties were studied. The results revealed that the nickel content had an optimum value of 7.5 wt% and the catalyst with this content of nickel exhibited the highest activity. Furthermore, the results demonstrated that the increase in reaction temperature enhanced the rate of the dry reforming reaction and led to obtain a H₂/CO ratio around unity. The 7.5 wt% nickel catalyst showed a 5% decline in activity within 15 h in combined reforming. The TPO analysis showed that there was no deposited carbon on the catalyst surface in combined reforming and the SEM analysis confirmed the results of TPO analysis.     

A first-principles study on the hydrogenation of acetone on HxMoO3 surface

Hydrogenation of acetone on the (010) surface of hydrogen molybdenum bronzes was investigated by density functional theory (DFT) calculations with periodic slab models. The formation of H-bond between the carbonyl oxygen of acetone and the terminal OH group of the surface leads to a stable adsorption of acetone. The effect of hydrogen concentration in the bronzes on the hydrogenation of acetone was systematically investigated, indicating the hydrogenation reaction is a one-step concerted and exothermic process regardless of the hydrogen contents in the bronzes surface. The 8H surface with increased H-content shows a significantly exothermic reaction process and exhibits the smallest kinetic barrier compared with 4H or 6H surfaces. Additionally, the selectivity for hydrogenation acetone could increase owing the absence of CC bond activation. The findings in this study can help with designing of high-efficient and low-cost metal oxide catalysts for hydrogenation of unsaturated substances.     

Pricing in non-convex markets with quadratic deliverability costs

This article studies the problem of obtaining equilibrium clearing prices for markets with non-convexities when it is relevant to account for convex quadratic deliverability costs and constraints. In a general market, such a situation arises when quadratic commodity or transactions costs are relevant. In the particular case of electricity markets, there is a mix of resources including dispatchable and renewable energy sources, leading to the presence of integer variables and quadratic costs reflecting ramping needs. To illustrate our results, we compute and analyze the equilibrium clearing prices of the Scarf's classical market problem with the addition of ramping costs.     

Fast Diffeomorphic Image Registration via Fourier-Approximated Lie Algebras

International Journal of Computer Vision - This paper introduces Fourier-approximated Lie algebras for shooting (FLASH), a fast geodesic shooting algorithm for diffeomorphic image registration. We...     

Review of grain boundary complexion engineering: Know your boundaries

Grain boundary structure-property relationships influence bulk performance and, therefore, are an important criterion in materials design. Materials scientists can generate different grain boundary structures by changes in temperature, pressure, and chemical potential because interfaces attain their own equilibrium states, known as complexions. Complexions undergo first-order transitions by changes in thermodynamic variables, which results in discontinuous changes in properties. Grain boundary complexion engineering is introduced in this paper as a method for controlling complexion transitions to improve material performance. This International Conference on Sintering 2017 lecture describes the tools for grain boundary complexion engineering: complexion equilibrium and time-temperature-transformation (TTT) diagrams. These tools can be implemented in processing design to tailor grain boundary properties, including grain boundary mobility. While impactful, these diagrams are often limited in scope because they are currently empirically derived. This article discusses how measurement techniques can be combined with data analytical methods to build mechanistically derived complexion equilibrium and TTT diagrams.