Coupling of Biomass Gasification and SOFC – Gas Turbine Hybrid System for Small Scale Cogeneration Applications☆

Abstract In this study the performances of small cogeneration power plants fed by biomass and based on conventional and advanced technologies are presented. Three system configurations have been considered and analyzed. They are characterized by: a) a biomass gasification (G) unit, based on down-draft technology; b) a power unit, based on the SOFC technology or on the micro gas turbine (MGT) technology or on a hybrid configuration SOFC-MGT; c) a thermal recovery unit. The energy analysis of the proposed power plants has been conducted by using thermochemical/thermodynamic models able to study the integrated systems and each unit in terms of operating and performance parameters

VLSH: Voronoi-based Locality Sensitive Hashing

Abstract-We present a fast, yet accurate k-nearest neighbor search algorithm for high-dimensional sampling-based motion planners. Our technique is built on top of Locality Sensitive Hashing (LSH), but is extended to support arbitrary distance metrics used for motion planning problems and adapt irregular distributions of samples generated in the configuration space. To enable such novel characteristics our method embeds samples generated in the configuration space into a simple l2 norm space by using pivot points. We then implicitly define Voronoi regions and use local LSHs with varying quantization factors for those Voronoi regions. We have applied our method and other prior techniques to high-dimensional motion planning problems. Our method is able to show performance improvement by a factor of up to three times even with higher accuracy over prior, approximate nearest neighbor search techniques

Exsolved Ru on BaCexOy catalysts for thermochemical ammonia synthesis

Ammonia (NH3) is a carbon-free and hydrogen-rich (17.8 wt% H2) chemical that has the potential to revolutionize the energy sector. Compared with hydrogen (H2), NH3 can be easily liquefied, stored, and transported globally. However, the conventional thermocatalytic process to synthesize NH3 accounts for 2% of global energy consumption and 1.2% of CO2 emissions annually. To make the process further efficient, new catalysts must be developed to allow for NH3 synthesis in milder conditions with high thermal stability. To this end, we have developed ruthenium (Ru) supported on perovskite (BaCexOy) via a ball-milling-assisted exsolution method that allows for a more tunable morphology. Reactivity is compared with the catalyst prepared via the conventional impregnation technique. The as-synthesized catalysts are characterized by XRD, H2-TPR, TEM, XPS, and APT. The NH3 synthesis is carried out in a packed-bed tube reactor thermochemically. Using N2 instead of Ar as the carrier gas during exsolution can favour reactivity by increasing active sites and perhaps improving metal-support interaction. The impregnated sample shows higher reactivity than the exsolved catalyst; however, the long-term durability is slightly better using the exsolved catalyst. Finally, APT results interestingly show that the exsolved catalyst is more resistant to hydride formation and hydrogen poisoning, which is one of the main deactivation mechanisms for such metallic catalysts

Dissociating stable nitrogen molecules under mild conditions by cyclic strain engineering

All quiet on the nitrogen front. The dissociation of stable diatomic nitrogen molecules (N-2) is one of the most challenging tasks in the scientific community and currently requires both high pressure and high temperature. Here, we demonstrate that N-2 can be dissociated under mild conditions by cyclic strain engineering. The method can be performed at a critical reaction pressure of less than 1 bar, and the temperature of the reaction container is only 40 degrees C. When graphite was used as a dissociated N* receptor, the normalized loading of N to C reached as high as 16.3 at/at %. Such efficient nitrogen dissociation is induced by the cyclic loading and unloading mechanical strain, which has the effect of altering the binding energy of N, facilitating adsorption in the strain-free stage and desorption in the compressive strain stage. Our finding may lead to opportunities for the direct synthesis of N-containing compounds from N-2

Experimental and numerical study of Pd/Ta and PdCu/Ta composites for thermocatalytic hydrogen permeation

The development of stable and durable hydrogen (H2) separation technology is essential for the effective use of H2 energy. Thus, the use of H2 permeable membranes, made of palladium (Pd), has been extensively studied in the literature. However, Pd has considerable constraints in large-scale applications due to disadvantages such as very high cost and H2 embrittlement. To address these shortcomings, copper (Cu) and Pd were deposited on Ta to fabricate a composite H2 permeable membrane. To this end, first, Pd was deposited on a tantalum (Ta) support disk, yielding 7.4 × 10−8 molH2 m−1 s−1 Pa−0.5 of permeability. Second, a Cu–Pd alloy on a Ta support was synthesized via stepwise electroless plating and plasma sputtering to improve the durability of the membrane. The use of Cu is cost-effective compared with Pd, and the appropriate composition of the PdCu alloy is advantageous for long-term H2 permeation. Despite the lower H2 permeation of the PdCu/Ta membrane (than the Pd/Ta membrane), about two-fold temporal stability is achieved using the PdCu/Ta composite. The degradation process of the Ta support-based H2 permeable membrane is examined by SEM. Moreover, thermocatalytic H2 dissociation mechanisms on Pd and PdCu were investigated and are discussed numerically via a density functional theory study

Multidisciplinary approach for hepatocellular carcinoma arising from cirrhotic liver with Budd-Chiari syndrome: a case report

Budd-Chiari syndrome (BCS) is defined by the obstruction of the hepatic venous outflow between the small hepatic veins and the junction of the inferior vena cava (IVC) with the right atrium. BCS with IVC obstruction occasionally progresses to hepatocellular carcinoma (HCC). Here, we report the case of a patient with HCC arising from a cirrhotic liver with BCS, in whom the hepatic portion of the IVC was obstructed, and who had a favorable outcome with a multidisciplinary approach and IVC balloon angioplasty