Oscillating Water Column Wave Energy Converter by Means of Straight-bladed Darrieus Turbine☆

Abstract The present paper deals with a preliminary study on an Oscillating Water Column Wave Energy Converter (OWCWEC). The energy conversion is based on a straight-bladed Darrieus type wind turbine. The design of the turbine for maximum power coefficient is discussed. A physical laboratory scale OWC wave energy converter model was built to measure velocity field in the column. The air column was built using transparent materials to allow Particle Image Velocimetry measurements. Velocity field around air turbine rotor was measured by means of PIV. The measured velocities with and without the air turbine are used as inputs in the design procedure and to calibrate and test mathematical models. Moreover, design criteria were obtained using experimental and mathematical results

Supported Au---Pt catalysts : Characterization and hydrogen transfer activity between benzene and cyclohexane

Two series of Au---Pt catalysts supported on SiO2 were prepared by the incipient wetness method. In one series the total amount of metal (Au + Pt) was kept constant at about 0.7 wt% (Series A), while in a second series the amount of Pt was kept constant at about 0.7 wt% (Series B). In the latter the total amount of metal ranged between 1.03 to 6.13 wt%. The two series were characterized by H2 and O2 chemisorption, wide-angle X-ray scattering, and electron spectroscopy for chemical analysis. There was indication of the presence of mixed Au---Pt particles as well as of particles containing Au only. In depth compositional profile of Series B showed homogeneous composition extending to at least about 12 A below the surface, while in Series A compositional inhomogeneities were found. The rate of the carbon-14 equilibration between benzene and cychohexane and the rate of equilibration between H2 and D2 were measured on both catalyst series in a flow system at a total pressure of 1 atm. For the carbon-14 equilibration reaction the temperature was 205 [deg]C, contact time in the range of 10 to 30 sec. The influence of the ratio cyclohexane to benzene on the reaction rate was recorded. For the deuterium equilibration the temperature was -78 [deg]C and a ratio of pD2/pH2 = 1 was employed. The rate of the carbon-14 equilibration was found to be independent of surface composition of the Au---Pt particles for Series A, while for Series B the rate increased upon addition of Au to Pt. Differences in rate up to about one order of magnitude were observed between catalysts from Series A and B possessing a similar overall Au/Pt ratio. No difference in the rate of deuterium equilibration was found between Series A and Series B catalysts. The kinetic behavior of Series B is discussed, and suggestions of the nature of the Au---Pt interaction, responsible for the enhancement of the reactivity of Pt, are advanced. The concept of reaction sensitivity to surface structure is viewed as a dynamic factor which includes the position of the reaction steady state and the corresponding degree of reaction conversion. Consequently, a reaction may be sensitive or insensitive to the surface structure depending upon its conversion.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23599/1/0000561.pd

energy performance of chp system integrated with citrus peel air steam gasification a comparative study

Abstract The aim of this work is to exploit the potential of residual biomass, different from the traditional wood feedstock, by thermochemical gasification process. In particular, citrus peels waste of the juice extraction process, was selected since it is a typical local Sicilian residue. The citrus peel conversion performances in air-steam gasification process were evaluated and compared with those obtained with pinewood as feedstock. Experimental activities of air-steam gasification were carried out in a bench-scale fluidized bed reactor at 1023 K, for both citrus peel and pinewood, varying the steam to biomass ratio (S/B). A simulation model of the experimental facility was developed in order to find a useful tool to realize the virtual scale-up of the system with downstream syngas utilization. The cold gas efficiency (CGE) and the net cold gas efficiency (CGE net ) were calculated to define the best gasification conditions. Results showed that using pinewood a very low reactivity can be observed, showing a very low net CGE. The highest net CGE for citrus peel was observed at S/B = 0.5, while for pinewood the addition of water did not improve the net CGE. Finally, an integration of the citrus peel gasification system with a commercial CHP unit was proposed and the efficiencies were evaluated

Statistical optimization of a culture medium for biomass and poly(3-hydroxybutyrate) production by a recombinant Escherichia coli strain using agroindustrial byproducts

A statistically based Plackett-Burman screening design identified milk whey and corn steep liquor concentrations as well as ionic strength (based on phosphate buffer concentration) as the three main independent components of the culture medium that significantly (p < 0.05) influenced biomass and poly(3-hydroxybutyrate) (PHB) production in recombinant cells of Escherichia coli. This strain carries a plasmid encoding phb genes from a natural isolate of Azotobacte sp. Response surface methodology, using a central composite rotatable design, demonstrated that the optimal concentrations of the three components, defined as those yielding maximal biomass and PHB production in shaken flasks, were 37.96 g deproteinated milk whey powder/l, 29.39 g corn steep liquor/l, and 23.76 g phosphates/l (r2 = 0.957). The model was validated by culturing the recombinant cells in medium containing these optimal concentrations, which yielded 9.41 g biomass/l and 6.12 g PHB/l in the culture broth. Similar amounts of PHB were obtained following batch fermentations in a bioreactor. These results show that PHB can be produced efficiently by culturing the recombinant strain in medium containing cheap carbon and nitrogen sources. [Int Microbiol 2005; 8(4):243-250

Oxygen chemisorption on supported gold

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23605/1/0000567.pd

Analysis of Reforming Gas Combustion in Internal Combustion Engine

Abstract The present paper deals with the study of the combustion of reforming gas in a small size Internal Combustion Engine. Therefore, mathematical models of both reforming process and internal combustion engine were implemented. In particular, steams reforming of glycerol to produce synthesis gas and spark ignition four strokes ICE were studied. The reforming process mathematical model was verified using experimental data. Synthesis gas was used to feed the ICE with different syngas and engine configuration. On the basis of the comparison with the experimental results, it is possible to state that the mathematical model is validated. Engine performance and pollutant emission evaluation was carried out using the integrated mathematical models with reference to the engine running on standard commercial fuel. The results highlight a reduction in engine performance and, at the same time a reduction of pollutant emissions in terms of CO and CO 2

Cyclopropane hydrogenation on Ru and Ru---Au catalysts

The rate of reaction between cyclopropane and hydrogen was measured in a flow system on unsupported Ru, Ru/SiO2, andRu/MgO. The effect of the addition of Au to Ru/MgO was also investigated. The temperature was in the range 30-170 [deg]C; partial pressures were 0.01 cp PH2 3H6 + H2 --&gt; C3H8, (1) cyclo-C3H6 + 2H2 --&gt; CH4 + C2H6, (2) cyclo-C3H6 + 3H2 --&gt; 3CH4. (3)At low temperatures (110 [deg]C), reaction (3) was also detected. Ruthenium particle size and presence of Au on the surface were found to have a strong influence on reaction (3), while reactions (1) and (2) were unaffected. It is suggested that, on Ru, reactions (1) and (2) have the same intermediate or they require a surface site having the same geometry.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23388/1/0000333.pd

Isotopic oxygen exchange on supported Ru and Au catalysts

The isotopic exchange reaction of molecular oxygen is applied to supported ruthenium and gold catalysts. The results on supported ruthenium are similar to those on RuO2. The exchange reaction seems to be unaffected by differences in particle size or nature of the support (MgO or SiO2, respectively). The heterogeneous exchange kinetics deviate from an exponential law. This indicates the presence of nonuniformities on the catalyst surface and/or a contribution of oxygen diffusion. On supported gold, high exchange activity and massive uptake of labeled oxygen by the solid phase are observed. Au/MgO is one order of magnitude more active than Au/SiO2. The activation of support oxygen for the isotopic exchange reaction is related to an interaction between gold and support.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23234/1/0000167.pd

The microstructure of bimetallic Ru---Cu/SiO2 catalysts: A chemisorption and analytical electron microscopy study

Supported bimetallic Ru---Cu/SiO2 catalysts are characterized by transmission electron microscopy, energy dispersive X-ray spectroscopy, electron microdiffraction, and chemisorption. Metal particles up to 4 nm in diameter are bimetallic, while particles larger than 4 nm contain only Cu. Considerable compositional nonuniformity is observed from one individual metal particle to the next. Microdiffraction patterns obtained from individual particles can be attributed to either Ru or Cu suggesting no significant modification in crystallographic structure of either metal component. Addition of Cu to Ru results in a drastic suppression of H2 chemisorption while the extent of O2 chemisorption is not as strongly affected. The suppressed H2 chemisorption capability of Ru in the bimetallic catalysts is an indication of atomic interdispersion of Ru and Cu on the surface of the bimetallic clusters, leading to the break-up of the Ru ensembles which would be necessary for dissociation of molecular hydrogen. The influence of catalyst preparation techniques on the relative interdispersion of Ru and Cu and consequent discrepancies in the Ru---Cu literature are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26092/1/0000168.pd

TPR Investigation of bimetallic Ru-Cu samples supported on SiO 2 , Al 2 O 3 and MgO

Bimetallic Ru-Cu samples supported on SiO 2 , Al 2 O 3 and MgO were studied by the temperature-programmed reduction (TPR) technique. Experiments were carried out both on unreduced impregnated salts and after oxidation of already reduced samples. The TPR profiles reveal a simultaneous reduction of ruthenium and copper precursors, even though the Ru and Cu in the monometallic catalysts exhibit reduction peaks which differ by up to 150 °C. It is suggested that the two metal salts interact during the stages of preparation and drying, and after reduction form bimetallic aggregates which are not stable and tend to separate. The stability of the bimetallic particles was found to be strongly dependent on the support used, being higher on SiO 2 than on Al 2 O 3 and MgO. It is suggested that the chemical nature of the support determines the different degree of interaction and/or agglomeration of the bimetallic particles. Auf SiO 2 , Al 2 O 3 und MgO aufgebrachte bimetallische Ru-Cu-Proben wurden mittels temperaturprogrammierter Reduktion (TPR) untersucht. Experimente wurden sowohl mit unreduzierten, durch Impregnation aufgebrachten Salzen als auch mit nach vorangegangener Reduktion reoxydierten Proben ausgeführt. Die TPR-Profile lassen eine gleichzeitige Reduktion der Ruthenium- und Kupfervorstufen erkennen, obwohl Ru und Cu in monometallischen Katalysatoren Reduktionspeaks zeigen, die um bis zu 150 °C voneinander entfernt liegen. Es wird angenommen, daß die zwei Metallsalze während des Darstellungs- und Trocknungsstadiums miteinander in Wechselwirkung treten und nach der Reduktion nicht stabile, zum Zerfall tendierende bimetallische Aggregate bilden. Die Stabilität der bimetallischen Partikel ist stark vom Träger abhängig, sie ist an SiO 2 höher als an Al 2 O 3 und MgO. Es wird angenommen, daß die chemische Natur des Trägers den Grad der Wechselwirkung und/oder Agglomeration der bimetallischen Partikel bestimmt. Методом температурн о-программного восстановления (ТПВ) и зучены биметаллические обр азцы рутений — медь на подложках из двуокиси кремния, о киси алюминия и окиси магния. Экспер именты были проведен ы как с невосстановленными пропитанными солями, так и с вновь ок исленными ранее восстановленными об разцами. Профили крив ых показывают одноврем енное восстановлени е рутения и меди, тогда как в случа е монометаллов пики восстановления рутения и меди отлича ются на 150 °C, Это свидетельствует о том, что соли обоих металлов взаим одействуют между соб ой на стадии получения и высушива ния, а после восстановления обра зуют биметаллически е агрегаты, которые неустойчивы и имеют тенденцию к разделению. Установ лено, что стабильност ь биметаллических час тиц сильно зависит от характера подложки, я вляясь более высокой на двуокиси кремния по сравнению с тем, что на окиси алюминия и окис и магния. Предположен о, что химическая природа п одложки определяет различную степень вз аимодействия или агл омерации биметаллических час тиц.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43142/1/10973_2005_Article_BF01912699.pd