This work explores the production of biohydrogen from brewery wastewater using as inoculum a culture produced by natural fermentation of synthetic wastewater and Klebsiella pneumoniae isolated from the environment. Klebsiella pneumoniae showed good performance as inoculum, as evaluated using assays of between 9 and 16 cycles, with durations of 12 and 24 h, carbohydrate concentrations from 2.79 to 7.22 g L−1, and applied volumetric organic loads from 2.6 to 12.6 g carbohydrate L−1 day−1. The best results were achieved with applied volumetric organic loads of 12.6 g carbohydrate L−1 day−1 and cycle length of 12 h, resulting in mean volumetric productivity of 0.88 L H2 L−1 day−1, maximum molar flow of 10.80 mmol H2 h−1, and mean yield of 0.70 mol H2 mol−1 glucose consumed. The biogas H2 content was between 18 and 42%, while the mean organic compounds removal and carbohydrate conversion efficiencies were 23 and 81%, respectively. The inoculum produced by natural fermentation was not viable. 相似文献
The present work mainly deals with the testing and modeling of a commercially-available copper indium diselenide (CIS) ST40 module from the former Siemens Solar Industries (SSI). For this purpose, a large quantity of current/voltage characteristics were measured in the Paul Scherrer Institute (PSI)’s photovoltaic test-facility under different cell temperatures, solar irradiation and air mass, AM, conditions. They were used to develop a semi-empirical efficiency model to correlate all measured data sets. The goal was to make available a model, allowing quick and accurate calculation of the performance of the CIS module under all relevant operating conditions.
For the undegraded state of the module, the efficiency model allowed us to deduce the efficiency at Standard Test Conditions, STC, and its temperature coefficient at STC, which were 11.58% and minus 0.050%/°C, respectively. The output of the undegraded module under STC was found to be 42.4 W, i.e., 6% higher than specified by the manufacturer (40 W). Furthermore, the efficiency does not decrease with increasing air mass. At a cell temperature of 25 °C and a relative air mass of 1.5, the module has a maximum in efficiency of 12.0% at an irradiance of about 650 W/m2. This indicates that the series-resistance losses become significant at higher irradiances. Hence, improving the transparent conducting oxide (TCO) electrode on the front side of the cells might lead to a higher output at high irradiances.
Identical testing and modeling were repeated after having exposed the module to real weather conditions for one year. We found that the STC efficiency was reduced by 9.0%, from 11.58 down to 10.54%. The temperature coefficient of the efficiency had changed from minus 0.050 %/°C to minus 0.039%/°C. These results indicate possible chemical changes in the semiconductor film. The output of the module at STC was reduced by 9.0% from 42.4 W down to 38.6 W.
Using meteorological data from a sunny site in the South of Jordan (Al Qauwairah) and the efficiency model presented here allows us to predict the yearly electricity yield of the CIS module in that area. Prior to degradation, the yield was found to be 362 kWh/m2 for the Sun-tracked module; and 265 kWh/m2 for the fix-installed module (South-oriented, at an inclination angle of 30°). After degradation the corresponding yields were found to be 334 and 241 kWh/m2; meaning losses of 8.4% and 9.5%, respectively. (Note: all units of energy, kWh, are referred to the active cell area.) Having available efficiency models for other module types, similar predictions of the yield can be made, facilitating the comparisons of the yearly yields of different module types at the same site. This in turn allows selecting the best module type for a particular site. 相似文献
Switchgrass (Panicum virgatum L.) has been identified as a potential biomass crop in North America. A two-year study was conducted to characterize leaf area development and estimate radiation-use efficiency (RUE) of switchgrass in eastern Canada. Three cultivars, Cave-in-Rock (CIR), Pathfinder (PF) and Sunburst (SB) were grown in solid stands in a randomized complete block design. Dry matter (DM) yield, leaf area development and light interception were monitored bi-weekly throughout the growing season. Herbage subsamples were hand separated into leaf and sheath-stem fractions. Mean seasonal maximum leaf area indices (LAI) were 6.1, 5.3 and 5.1 for CIR, PF and SB, respectively. By early July of each season the canopies were intercepting about 90% of the incoming light. End of season DM yields were 12.2, 11.5 and 10.6 Mg ha−1 for CIR, PF and SB, respectively. The stem plus leaf sheaths constituted the major component of DM and its accumulation trend parallelled that of total DM. End of season stem-sheath components averaged 764, 714 and 691 of the total g kg−1 DM for CIR, PF and SB, respectively. Energy contents of the switchgrasses averaged 17.4 MJ g−1 DM and did not vary among cultivars or during the season. This translated into total energy yields ha−1 of 216 GJ for CIR, 197 for PF and 186 for SB. Radiation-use efficiencies computed using total incoming solar radiation, for the near linear growth phases, averaged 1.07 g DM MJ−1 for CIR, 0.90 for PF and 0.89 for SB. The respective values based on photosynthetically active radiation were 2.20, 2.00 and 1.96 g DM MJ−1. Changes in LAI, relationships between LAI and light interception and DM yield could all be described by predictive regression equations. These results indicate the potential of switchgrass as a biomass crop in short season areas. 相似文献
The catalytic steam reforming of acetic acid over both Ni/ and Co/Ce0·75Zr0·25O2 (CZO) catalysts in the temperature range of 450–650 °C and steam-to-carbon molar ratios of 3–9 was studied. It was found that the complete acetic acid conversion was achieved for all the conditions investigated. Nevertheless, the C–C bond cleavage conversion was attained less than the acetic acid conversion at a given condition due to carbon deposition on the catalyst. However, hydrogen yield was obtained in the same trend as C–C bond cleavage conversion as well. The results revealed that the CZO as an active support prefers to promote the ketonization reaction to the C-C bond cleavage reaction at a lower temperature, and vice versa at a higher temperature. The Ni/CZO catalyst exhibits higher C–C bond cleavage conversion than the Co/CZO catalyst particularly at 650 °C whereas the Co/CZO catalyst is more active for ketonization reaction at low temperatures. However, as an increase in reaction temperature, the Co/CZO catalyst promotes ketonization reaction more pronouncedly toward aldol-condensation reaction thus giving rise to the carbon deposition. The results deduced from the effect of space velocity on the activity and product distribution suggested that the steam reforming of acetic acid over Ni/CZO catalyst is dominated by decomposition of acetic acid, while that of Co/CZO catalyst by ketonization reaction. 相似文献
Investigations of Ce3+-doped Cs2LiLaBr6 (CLLB) crystals show a systematic trend in their scintillation properties with varying Ce concentrations. The concentration studies provide input in the optimization of growth of the CLLB crystals. Scintillation properties viz. radioluminescence, energy resolution, light yield, decay times, and non-proportionality are discussed for samples from 0% to 20% Ce concentration. 相似文献
Aqueous synthesis of CdS quantum dots (QDs) using thiolactic acid (TLA) as a capping agent was reported. These QDs exhibited excellent colloidal and photostability over a span of 2 years and showed intense broadband and almost white photoluminescence suitable for solid state lighting devices. The photoluminescence (PL) property of the aqueous CdS QDs is optimized by adjusting various processing parameters. The highest quantum yield (QY) achieved for TLA capped CdS QDs of average size 3.5 nm was ∼50%. Luminescence lifetime measurements of CdS-TLA QDs indicated longer lifetimes and a larger contribution of the surface-related emission, indicating removal of quenching defects. 相似文献