Conceptual design of a novel hybrid fuel cell/desalination system

A novel concept for integrating fuel cells with desalination systems is proposed and investigated in this work. Two unique case studies are discussed — the first involving a hybrid system with a reverse osmosis (RO) unit and the second — integrating with a thermal desalination process such as multi-stage flash (MSF). The underlying motivation for this system integration is that the exhaust gas from a hybrid power plant (fuel cell/turbine system) contains considerable amount of thermal energy, which may be utilized for desalination units. This exhaust heat can be suitably used for preheating the feed in desalination processes such as reverse osmosis which not only increases the potable water production, but also decreases the relative energy consumption by approximately 8% when there is an increase of just 8°C rise in temperature. Additionally, an attractive hybrid system application which combines power generation at 70%+ system efficiency with efficient waste heat utilization is thermal desalination. In this work, it is shown that the system efficiency can be raised appreciably when a high-temperature fuel cell co-generates DC power in-situ with waste heat suitable for MSF. Results indicate that such hybrid system could show a 5.6% increase in global efficiency. Such combined hybrid systems have overall system efficiencies (second-law base) exceeding those of either fuel-cell power plants or traditional desalination plants.     

Effect of irrigation and nitrogen fertilizer on yield,oil content,nitrogen accumulation and water use of canola (Brassica napus L.)

Effects of N application and water supply on yield, oil content and N accumulation by canola, cultivar Marnoo, grown on a heavy clay soil in the Goulburn Murray Irrigation Region were investigated. Treatments were rainfed (R_f) or watered at a deficit of 50 mm (40–60 mm, I₅₀) beginning in the spring. N treatments were 0, 50, 100 or 200 kg N ha^–1 at sowing or as split applications of 20/80, and 50/50 kg N ha^–1 at sowing and rosette, respectively.Yield (Y_g) ranged from 170 to 520 g m^–2. Irrigation and N increased yield in both years. Grain yields were increased by N application on the irrigated treatments when 100 or 200 kg N ha^–1 was applied. Oil concentrations ranged from a maximum of 46.4% in treatment N₀ to a minimum of 40.6% in treatment N₂₀₀ and was inversely related to seed N concentration. Although fertilizer N decreased oil concentration, it increased the yield of oil.Nitrogen accumulation (N_b) limited yield of all treatments and was described by the equation, Y_g = 806[1-EXP(–0.039*N_b)]. This implied a decrease in yield per unit of N_b at the higher rates of fertilizer addition with consequent increases in grain N concentration.The efficiency of water use in the production of grain (WUE_g) and biomass (WUE_b) were 7.5 and 23 kg ha^–1 mm^–1 respectively. Nitrogen additions increased WUE_g and WUE_b in both seasons. Maximum values of 8.9 (WUE_g 1986) and 26.8 (WUE_b 1987) were measured from treatment N₂₀₀. These data suggest that the crops made efficient use of the applied water.     

Effect of vermicomposting on the transformation of some trace elements in fly ash

One major constraint of the agricultural uses of fly ash (FA) is the low availability of different plant nutrients despite their high occurrence in the total amount. However, degrading FA through increased microbial activity can improve the availability of these nutrients substantially. It has been found that intestines of epigeic earthworms contain a high concentration of different microorganisms. Therefore, in the present study we addressed the effects of vermicomposting technology on the solubility of some micronutrient cations (Fe, Mn, Cu, and Zn) and some heavy metals (Pb, Cd, and Cr) in different combinations of fly ash and organic matter, applied in the form of cow dung (CD). Various combinations of FA and CD were treated with and without an epigeic earthworm (Eisenia fetida) and the solubility of different trace elements in the treatments were estimated periodically. The results revealed that the inclusion of epigeic earthworm Eisenia fetida in different combinations of fly ash and cow dung converted a considerable amount of the micronutrients into bio-available forms. On the other hand, the solubility of heavy metals tended to be reduced by the microorganisms, presumably by formation of some organo-metallic complex. Application of these vermicomposted FA and CD combinations to a red lateritic soil was found to improve the soluble Fe, Mn, Cu, and Zn status of the soil. Furthermore, the use of vermicomposted FA and CD (1:1) in potato cultivation demonstrated that use of this mixture at 10 ton per hectare (t ha⁻¹; fresh weight) was able to compensate 80% of the recommended NPK fertiliser, along with farm yard manure application, without compromising the crop yield.     

Efficient usage of highly dispersed Pt on carbon nanotubes for electrode catalysts of polymer electrolyte fuel cells

A Pt-deposited carbon nanotube (CNT) shows higher performance than a commercial Pt-deposited carbon black (CB) with reducing 60% Pt load per electrode area in polymer electrolyte fuel cells (PEFCs) below 500 mA/cm². K₂PtCl₄ and H₂PtCl₆·6(H₂O) are used for the Pt deposition onto multi-walled CNTs (MWCNTs), which are produced by the catalytic decomposition of hydrocarbons. The electric power densities produced using the Pt/CNT electrodes are greater than that of the Pt/CB by a factor of two to four on the basis of the Pt load per power. CNTs are thus found to be a good support of Pt particles for PEFC electrodes. TEM images show 2–4-nm Pt nanoparticles dispersed on the CNT surfaces. These high performances are considered to be due to the efficient formation of the triple-phase boundaries of gas–electrode–electrolyte. The mechanisms of Pt deposition are discussed for these Pt-deposited CNTs.     

低压开车法在CO2气提法尿素装置的应用

介绍了低压开车法在改进型CO2气提法尿素装置中的实际应用，总结了低压开车法的优点，论述了低压投料的技术要点和措施，给出了开车过程曲线及技术数据。     

水土流失遥感调查中植被覆盖度因子提取研究

植被覆盖度是水土流失的主要影响因子,而利用遥感影像判读可以快速有效地获得大范围的植被覆盖度。简要介绍了水土流失遥感调查中植被覆盖度因子提取的方法。基于遥感与实地野外调查数据,采用MODIS时序数据融合高分遥感数据的方法,以湖南省蓝山县为试验区,对植被覆盖度因子进行了提取。结果表明,该方法提取植被覆盖度因子的结果较理想。提出的植被覆盖度因子提取方法对今后的水土流失动态监测研究具有重要的理论意义和实践意义。     

Effect of granule size and the placement geometry on the efficiency of urea supergranules for wetland rice grown on a permeable soil

In a laboratory experiment 5 cm depth of water was allowed to percolate daily down through a 15 cm thick soil (Typic Ustipsamment) layer. It was observed that leaching losses of urea supergranules (USG)-N could be decreased by about 20% by the placement of four 0.25 g granules at four points instead of one 1 g granule at one point. In field microplots, the placement of approximately 30 granules of 0.30 g size instead of 9 granules of 1.00 g size resulted in reduced leaching of USG-N and, in turn, increased rice yield. In a follow-up field study, the advantage of more frequently placed USG was confirmed. As compared with 1 g USG placed in the usual manner in the center of four rice hills, increasing the density of placement in soil produced 15% more rice grain. Further increase in rice yield could be obtained by increasing the number of USG placed in the soil and decreasing the size of the granule from 1.00 g to 0.70 or 0.35 g. With USG of 0.35 and 0.70 g yields were equal or sometimes even slightly higher than with split application of prilled urea on a heavily percolating, low-CEC, light-textured soil.     

Increase of N2O Fluxes in Agricultural Peat and Sandy Soil under Elevated CO2 Concentration: Concomitant Changes in Soil Moisture, Groundwater Table and Biomass Production of Phleum pratense

The effects of elevated atmospheric CO₂ concentration on soil moisture, N₂O fluxes, and biomass production of Phleum pratense were studied in the laboratory. Farmed peat and sandy soil mesocosms sown with P. pratense were fertilized with a commercial fertilizer. In peat soil 10 g N m⁻² of commercial fertilizer were added and in sandy soil 15 g N m⁻². In both experiments, soil moisture was regulated with deionized water; 18 mesocosms were tended to keep equally moist, and the other 18 were watered with equal amounts of water. Nine mesocosms from both watering treatments were grown under ambient (360 μmol mol⁻¹) CO₂ concentration and the remaining nine under doubled (720 μmol mol⁻¹) CO₂. N₂O efflux was monitored using a closed chamber technique and a gas chromatograph. The elevated supply of CO₂ increased production of above- and belowground biomass, soil moisture and N₂O fluxes, but decreased the total N content in the aboveground biomass, especially for the sandy soil. In similar water levels, N₂O efflux from the sandy soil was the same magnitude as that from the peat soil. In addition to moisture, N availability was the main limiting factor for N₂O production, but C availability also seemed to regulate the denitrification activity. In addition to an increase in C availability the increase in the N₂O efflux under the raised CO₂ concentration also required a simultaneous increase in soil moisture.     

The roles of nitrogen,phosphorus and Potassium in the production of sugarcane in South Africa

The amounts of N and K fertilizers used in the South African sugar industry have increased dramatically in the past four decades, due partly to an increase in the area under sugarcane but also to large increases in the amounts of N and K fertilizers applied per hectare. There has also been an increase in the amount of P fertilizer used but this has been more gradual. The main fertilizer carriers for cane and their relative efficiency are discussed. During this period there has been considerable research into the nutrient requirements of sugarcane. Correlations established between soil and leaf analysis and crop responses to N, P and K fertilizers, and their effects on cane quality, are reviewed. While fertilizer recommendations based on soil and leaf analysis have provided a useful guide for determining the nutrient requirements of cane, they are continually being modified in the light of current research.     

A study of PtRuO2 catalysts thermally formed on titanium mesh for methanol oxidation

Platinum-based catalysts, for the electro-oxidation of methanol, have been made by thermal decomposition of chloride precursors onto titanium mesh. The catalysed electrodes were successfully operated in acidic methanol electrolytes. Electrochemical characterisation has been carried out using cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic polarisations. A complete analysis of the electrochemical results showed that the preliminary performance of the catalysed titanium mesh was comparable to that achieved with carbon-supported PtRu catalysts. The catalysts formed on titanium mesh by thermal decomposition also exhibited dimensional stability. Catalysed titanium mesh therefore appears to be a promising alternative to carbon-supported catalysts for certain fuel cell applications.