Filters
Results 1 - 10 of 31649
Results 1 - 10 of 31649.
Search took: 0.043 seconds
| Sort by: date | relevance |
[en] One of the important compounds that were used in the structural ceramic is aluminum. During the last years, a variety of synthesis methods have been developed to obtain raw materials with suitable characteristics in terms of the particle composition, size and shape. The controlled precipitation method (CPM) allows reaching these demands and with this method it is possible to control the synthesis one so as to guarantee characteristics of ceramic powder. One stage of the CPM is the formation of the intermediate complexes of cation whose oxide is necessary. In this work the effect of the concentration and the solvent of wash during this process are indicated. For this study we used potentiometric titration to follow the advancement of the process. We utilized XRD and tem to characterize the solid phase present in the system
Journal
Revista de la Academia Colombiana de Ciencias Exactas, Fisicas y Naturales; ISSN 0370-3908; 
; v. 29(113); p. 571-580
; v. 29(113); p. 571-580
[en] In this work, an active micro direct methanol fuel cell (μDMFC) system employing the catalytic combustor as the heating device is developed in order to maintain the optimum cell temperature and achieve the best cell performance. A passive feed method, combining both the saturator and the wick, is adopted to supply sufficient methanol into the micro combustor. The feasibility and the superiorities of the active μDMFC system are validated experimentally. The experimental results show that the combustor can start spontaneously and quickly at the ambient temperature of 298 K and the control unit can efficiently keep the cell temperature around the optimum value. The proposed active μDMFC system also performs much better than the conventional one at the ambient temperature of 298 K. Moreover, the performance and stability of the active μDMFC system at 298 K and the conventional one at 338 K are compared and analyzed respectively. The results verify that the active μDMFC system can real-time control the cell temperature and prevent overtemperature. Therefore, the active μDMFC system greatly increases the cell performance and stability. The active μDMFC system presented in this research also has great potential for portable applications. - Highlights: • A novel active μDMFC system is developed to solve the heat manage problem. • The micro catalytic combustor is employed as the heating device. • An electronic control unit is programmed to maintain the optimum cell temperature. • The presented active μDMFC system shows better performance and great stability.
Journal
[en] In this report, the mass and energy balance along with a land-to-wheel Life Cycle Assessment (LCA) is described for a corn stover-to-ethanol industrial process assumed to consist of the main technologies being researched at ENEA TRISAIA: pretreatment by steam explosion and enzymatic hydrolysis. The modelled plant has a processing capacity of 60kt/y (dimensioned on realistic supplying basins of residues in Italy); biomass is pre-treated by acid catalyzed-steam explosion; cellulose and hemicelluloses are hydrolyzed and separately fermented; enzymes are on-site produced. The main target was to minimize the consumption of fresh water, enzymes and energy. The results indicate that the production of 1kg bio ethanol (95.4 wt%) requires 3.5 kg biomass dry matter and produces an energy surplus up to 740 Wh. The main purpose of the LCA analysis was to assess the environmental impact of the entire life cycle from the bio ethanol production up to its end-use as E10 blended gasoline. Boustead Model was used as tool to compile the life cycle inventory. The results obtained and discussed in this reports suffer of some limitations deriving from the following main points: some process yields have been extrapolated according to optimistic development scenarios; the energy and steam recovery could be lower than that projected because of lacks in the real systems; water recycle could be limited by the yeast tolerance toward the potential accumulation of toxic compounds. Nevertheless, the detailed process analysis here provided has its usefulness in: showing the challenging targets (even if they are ambitious) to bet on to make the integrated process feasible; driving the choice of the most suitable technologies to bypass some process bottlenecks
[it]
Questo rapporto illustra il bilancio di massa e di energia insieme alla valutazione del Ciclo di vita (LCA) per un processo industriale di produzione di bioetanolo da residui di mais costituito dalle principali tecnologie studiate nel centro ENEA di Trisaia: il pretrattamento a base di steam explosion e l'idrolisi enzimatica. L'impianto modellato ha una capacita di 60kt/a (dimensionato su bacini di approvvigionamento realistici in Italia); la biomassa e pretrattata con processo di steam explosion acido-catalizzato; la cellulosa e l'emicellulosa sono idrolizzate e fermentate separatamente; gli enzimi sono prodotti in situ. L'obiettivo principale e stato la minimizzazione del consumo di acqua di rete, di enzimi e di energia. I risultati indicano che la produzione di 1 kg di etanolo (95.4% in peso) richiede 3.5 kg di biomassa su base secca e produce un surplus di energia fino a 740 Wh. L'obiettivo principale dell'analisi LCA e stata la valutazione di impatto ambientale dell'intero ciclo di vita dalla produzione del bioetanolo fino al suo utilizzo in miscele E10. Il Boustead Model e stato utilizzato per compilare l'inventario di ciclo di vita. I risultati ottenuti e discussi in questo rapporto risentono di alcune limitazioni dovute principalmente ai seguenti punti: alcune rese di processo sono state estrapolate sulla base di previsioni di sviluppo ottimistiche; il recupero di energia e vapore potrebbe essere inferiore a quello calcolato per le perdite nei sistemi reali; il riciclo di acqua potrebbe essere limitato dalla tolleranza del lievito all'accumulo di potenziali sostanze tossiche. Ciononostante, la dettagliata analisi di processo sviluppata nel rapporto ha la sua importanza: nel quantificare gli obiettivi critici (ancorche ambiziosi) ai quali puntare per rendere fattibile il processo integrato; nel guidare la scelta delle tecnologie piu appropriate per superare alcuni colli di bottiglia del processoSource
2008; 127 p; ISSN 0393-3016;
[en] This paper investigates a question sometimes overlooked by policymakers and regulators, namely the need of a robust value proposition for green technologies to successfully enter the market. In particular, results from consumer choice models are used to develop measures of consumer acceptance of ethanol blends and flex-fuel vehicles is studied, a fuel-vehicle system that has received attention in a variety of federal and state policies. The analysis suggests that, under projected fuel prices and given the characteristics of the competing vehicle-fuel systems, consumers are unlikely to substitute ethanol blends for gasoline. The analysis also highlights the need for further research in this area. (author)
Journal
[en] We successfully characterized the effect of methanol treatment on the nanoscopic structures of a nafion film, which is widely used in direct methanol fuel cells (DMFCs). Atomic force microscopy (AFM) was used to repetitively image a particular region of a nafion sample before and after methanol solutions were dropped onto the nafion film and dried in air. When the surface was treated with 20% methanol for 5 min, many nanopores appeared on the surface. The number of nanopores increased when the sample was treated twice or thrice. By repetitive AFM imaging of a particular region of the same sample, we found that the shapes of the nanopores were deformed by the repeated methanol treatment, although the size of the nanopores had not significantly changed. The creation of the nanopores was affected by the concentration of methanol. Our results directly visualized the effects of methanol treatment on the surface structures of a nafion film at nanoscale levels for the first time
Journal
[en] With growth prospects in the oxygenated fuel-driven market strong but current demand sluggish, a number of methanol holdings have come on the market. Cash-strapped Quantum Chemical has placed a for sale sign on its Deer Park, TX plant, Hoechst Celanese Chemical (Dallas) is seeking a new joint venture partner for its Clear Lake, TX plant and Morgan Stanley Leveraged Equity Fund II (New York) is seeking to reduce its stake in Beaumont Methanol (Beaumont, TX). Industry sources also say that Novacor Chemicals (Calgary) is receptive to offers for its Medicine Hat, AB plant
Journal
| 1 | 2 | 3 | Next |