Yield,water use efficiency and economic analysis of energy sorghum in South Texas

Yields, water use efficiency and economic returns (net farm revenues) of biomass sorghum [Sorghum bicolor (L.) Moench] were investigated over two years (2012 and 2014) under limited water resource conditions. Energy sorghum was grown under four water supply regimes: rain-fed (or dry-land, level 1), 50% (level 2), 75% (level 3) and 100% (level 4) of crop evapotranspiration rates (% ET_c). Biomass yields ranged from 5.8 to 16.6 Mg ha⁻¹ (dry weight) after 126 days of growth. Average water use efficiencies ranged from 3.95 kg m⁻³ to 23.4 kg m⁻³. Net return was approximately 410 $ ha⁻¹ with water depths above 400 ha-mm. These results suggest that it is possible to obtain more than 60 Mg ha⁻¹ of sorghum biomass (wet basis) with at least 425 mm of water. While biomass yield under irrigation was greater than rain-fed conditions, there were no significant differences among irrigation treatments. Biomass chemical composition did not differ significantly among water treatments suggesting that biofuel quality would not be affected by water deficits.     

恒压变频供水系统的节能效果分析

介绍了恒压变频供水系统的组成、工作原理及节能效果 ,详细分析了效率得以提高的原因。     

Characterising willows for biomass and phytoremediation: growth, nitrogen and water use of 14 willow clones under different irrigation and fertilisation regimes

Fourteen clones of willow (Salix spp.) were characterised in terms of growth, nitrogen and water-use efficiency under different irrigation and fertilisation treatments. Cuttings of willow clones, some commercially introduced and others new material, were pot-grown outdoors in Central Sweden under four experimental treatments in a full-factorial design. The experiment covered the period from bud-break until leaf abscission and the experimental conditions included two irrigation and two fertilisation regimes. The growth of the clones was evaluated in terms of relative growth rate and total biomass production of whole plants and shoots. Nitrogen (N) economy was studied by means of N productivity, N accumulation and N losses by leaf abscission. Water economy was analysed with respect to intrinsic water-use efficiency (foliar carbon isotope ratio; δ¹³C) and the capacity of leaves to retain water (relative water content). Significant differences between clones were found in nearly all parameters measured and the clones varied in the responses to the experimental treatments (clone × factor interaction effects). Thus, clone ranking often changed depending on the experimental treatment. The results are discussed with respect to clone selection for different willow applications such as biomass production and phytoremediation, and willow growth performance under different water and nutrient availabilities. The growth-physiological characterisation of young willows in the short term (several months) is regarded as a suitable approach for pre-selection of promising clones prior to extensive field evaluation.     

Water use efficiency and consumption in different Brazilian genotypes of Jatropha curcas L. subjected to soil water deficit

In order to quantify the water use efficiency and water consumption during the early growth of Jatropha curcas L., three genotypes were grown in pots under greenhouse conditions, and subjected to two watering regimes: irrigated (substrate matric potential (Ψ_m) of −9.8 to −7.4 kPa) and water deficit (Ψ_m = −98.6 to −33.5 kPa). Independent of watering regime, the genotypes did not differ on the variables analyzed. Despite the reduction of substrate water content in water deficit treatment, no significant decrease (p < 0.05) of leaf water potential (Ψ_w) was observed, which suggests some water redistribution from the succulent stems of J. curcas. The values of net photosynthetic rate (A), stomatal conductance (gs), and transpiration (E) were reduced to 80, 90 and 85%, respectively, as compared to control plants. Moreover, drought led to 78% reduction in hydraulic conductance (K_L). At the end of the experiment, the average water consumption in water deficit plants was 27% lower than in control plants. Drought-induced decrease in biomass production led to reduction of water use efficiency of biomass (WUE_Biomass). However, due to the more significant effect on gs and E than A at 66 DAIT, intrinsic (A/gs) and instantaneous efficiency (A/E), water use increased 50% and 27%, respectively. The results showed that there was no intergenotypic variation for the traits evaluated, and that the reduction of water availability in the substrate proved to be an effective technique in the increase of photosynthetic efficiency of water use in plants of J. curcas, reducing water consumption in this species.     

Experimental investigation of the effects of separate hydrogen and nitrogen addition on the emissions and combustion of a diesel engine

An experimental investigation of the effects of separate hydrogen and nitrogen addition on the emissions and combustion of a diesel engine was performed and the results are presented in the current paper.     

Modelling the mitigation of hydrogen deflagrations in a vented cylindrical rig with water fog and nitrogen dilution

Nitrogen dilution and very fine water mist fogs have both been suggested as possible methods of mitigating the overpressure rise, should a hydrogen deflagration in a vented enclosure occur. A numerical CFD gas explosion code (FLACS) has been used to simulate the pressure-time curves and the rate of pressure rise generated following the ignition of different hydrogen–oxygen–nitrogen mixtures in a small scale vented cylindrical explosion rig. This has allowed the potential mitigating effect of nitrogen dilution (reduced oxygen) and very fine water fog, used both alone and in combination, to be explored and permitted their direct comparison with corresponding experimental test data.     

Features of low-temperature oxidation of hydrogen in the medium of nitrogen,carbon dioxide,and water vapor at elevated pressures

The article discusses novel research results on combustion features of high-density Н₂/О₂ mixtures (ρ_H2 = 0.70–1.89 mol/dm³, ρ_O2 = 0.32–0.81 mol/dm³) diluted with nitrogen, carbon dioxide, or water vapor (from 46 to 76% mol.) at the uniform heating (1 K/min) of tubular reactor. Based on time dependencies of temperature increment in the reaction mixtures caused by the heat release during oxidation of H₂, it is found that the self-ignition temperature of Н₂/О₂/N₂ and Н₂/О₂/H₂O mixtures is by ≈ 30 K lower than that of the Н₂/О₂/СО₂ mixture. Unlike combustion of H₂ in the N₂ medium, in the CO₂ and H₂O media a chain-thermal explosion is observed at a certain concentration of reagents. The influencing mechanisms of diluents on the H₂ oxidation dynamics, as well as the contribution of homogeneous and heterogeneous reactions in the heat release are revealed. It is established that high heat capacity of H₂/O₂/CO₂ mixture, chemical interaction between its components, and presence of CO₂ molecules adsorbed on the reactor inner surface, are the factors determining the H₂ oxidation dynamics in CO₂ medium. At oxidation of H₂ in the H₂O medium, the process takes place against the background of water evaporation and, as a consequence, is characterized by increased heat capacity and thermal conductivity of the H₂/O₂/H₂O reaction mixture.     

Effects of saturation medium and pressure on strength parameters of Latrobe Valley brown coal: Carbon dioxide, water and nitrogen saturations

Adsorption of carbon dioxide (CO₂) into coal matrix causes significant change in its chemical and physical structure, resulting in negligible permeability values and overall strength reduction. The main objective of this study is to investigate the effects of water, nitrogen (N₂) and CO₂ saturations at different saturation pressures on the strength of brown coal using uniaxial experiments. A series of uniaxial experiments was conducted on 38 mm diameter by 76 mm height Latrobe Valley brown coal samples with different saturation media (water, N₂, CO₂) and pressures (1, 2 and 3 MPa). According to the test results, water and CO₂ saturations cause the uniaxial compressive strength (UCS) of brown coal to be reduced by about 17% and 10% respectively. In contrast, N₂ saturation causes it to increase by about 2%. Moreover, Young’s modulus of brown coal is reduced by about 8% and 16% due to water and CO₂ saturations respectively, and is increased up to 5.5% due to N₂ saturation. It can be concluded that CO₂ and water saturations cause the strength of brown coal to be reduced while improving its toughness, and N₂ saturation causes the strength of brown coal to increase while reducing its toughness. The fracture propagation pattern of each sample was then observed using advanced acoustic emission (AE). Findings indicate that CO₂ saturation causes early crack initiation due to the CO₂ adsorption-induced swelled layer and early crack damage and failure points due to lower surface energy. In contrast, N₂ saturation causes delays in crack initiation, damage and failure due to the removal of both water and naturally available CO₂ from the coal mass during the saturation.     

Development of a novel,robust, sustainable and low cost self-powered water pump for use in free-flowing liquid streams

The design of water supply infrastructure depends on local conditions such as geophysical features, available technology, traditions, culture, and available human and economic resources. The costs for designing, building, maintaining, monitoring, and replacing the required infrastructure escalate when any of these factors is inadequate or insufficient. Furthermore, effects of global climate change increase the risk associated to existing infrastructure, calling for more robust, flexible, and adaptable technologies. We present the design and development of the first physical prototype of the Filardo Pump™, a low-cost, robust, sustainable, water-powered pump that addresses these challenges with many advantages over existing technologies: 1) it requires no external energy source, 2) it works immersed in a free-flowing, unaltered body of water, 3) it is operable in shallow water and low flow conditions, 4) it has low cost and low weight relative to work performed, and 5) it can be made small for households or scaled up for industrial applications. We show proof of concept for this novel pump and describe its development through scaling geometrical aspects and testing different materials for its operation. The proposed technology presents an opportunity for low-cost, sustainable, low carbon footprint water supplies for households, agricultural and industrial applications everywhere, not just in the rural developing world.     

The use of on-line hydrogen sensor for studying inert gas effects and nitrogen crossover in PEMFC system

The design and construction of a polymer electrolyte membrane fuel cell (PEMFC) system test bench suitable for investigating the effects of inert gas build-up and hydrogen quality on the performance of PEMFC systems is reported. Moreover, a new methodology to measure the inert gas crossover rate using an on-line hydrogen concentration sensor is introduced, and preliminary results are presented for an aged 8 kW PEMFC stack. The system test bench was also characterized using the same stack, whereupon its performance was observed to be close to commercial systems. The effect of inert gas accumulation and hence the quality of hydrogen on the performance of the system was studied by diluting hydrogen gas in the anode supply pipeline with nitrogen. During these experiments, uneven performance between cells was observed for the aged stack.     

Insight into the effects of microstructure and nitrogen doping configuration for hollow graphene spheres on oxygen reduction reaction and sodium-ion storage performance

Herein, the relationship between oxygen reduction reaction (ORR) catalytic activities of N-doped hollow graphene spheres (N-HGSs) and their morphologies, microstructures, and nitrogen doping configuration is deeply investigated. Based on all detection results it can be concluded that all of the level and configuration of doped-N atoms, the surface area, the mesopore structure of fabricated hollow graphene spheres related to the exposure of edges and vacancies correlating with the active sites, will ultimately affect the ORR catalytic performance of N-HGSs. Therefore, the optimized synthesis of N-HGSs can produce efficient electrocatalyst for ORR, which is better than the noble-metal Pt/C catalysts and most highly active graphene-based ORR catalysts reported to date. Additionally, the optimized synthesis of N-HGSs also exhibit excellent performance in sodium-ion storage. Because the large specific surface area, the well-connected hollow spherical and mesopore structures and the increased hydrophilicity induced by the doped-N atoms facilitate a ready transfer of charges and adsorption, diffusion and desorption of Na⁺ ions in and out of the active material, which could enhance sodium ion storage capacity. Additionally, expect the storage of Na⁺ ions by surface electro-adsorption/desorption, the insertion/extraction of Na⁺ through the thinner graphene shell makes a significant contribution to the improvement of sodium-ion storage capacity.     

A review of the effects of hydrogen,carbon dioxide,and water vapor addition on soot formation in hydrocarbon flames

Addition of reactive or inert substances is one of the most effective and practical ways to control soot formation in combustion of hydrocarbon fuels. In this paper, the research progress on the effects of hydrogen, carbon dioxide, and water vapor addition on soot formation in hydrocarbon flames in the last few decades is systematically summarized. The summary shows that the number of studies on the effects of these three common diluents has increased dramatically in the last five years. Although the overall effects of all these three common diluents suppress soot formation, there is inconsistency with regard to the role of their chemical effects. The chemical effect of hydrogen (CE-H₂) mainly acts on the soot nucleation process, followed by the soot surface growth and finally the soot oxidation process. CE-H₂ seems significantly affected by the fuel type, oxygen concentration, and the ambient pressure. The chemical effect of carbon dioxide (CE-CO₂) affects soot formation indirectly mainly through the reaction CO + OH ↔ CO₂ + H. Some studies believe that CE-CO₂ suppresses soot production by increasing the hydroxyl radical (OH) concentration, while other studies believe that it is primarily attributed to the decrease of the hydrogen radical (H) concentration. The reaction H₂O + H ↔ H₂ + OH plays a vital role in the chemical effect of water vapor (CE-H₂O) addition on inhibiting soot formation. Most studies support the view that the chemical effect of water vapor mainly increases the OH concentration and suppresses soot formation by weakening the soot nucleation process. Moreover, we believe that reaction H₂O + O ↔ OH + OH and phenylacetylene also play an essential effect on the CE-H₂O.     

Separate and combined effects of hydrogen and nitrogen additions on diesel engine combustion

Shortage of non-renewable energies, increase in fossil fuel prices and stricter emissions regulations due to high NOx and soot emissions emitted from combustion of heavy diesel fuels by compression ignition engines, has led consumers to use renewable, cleaner and cheap fuels. An investigation has been computationally carried out to explore the influences of hydrogen and nitrogen addition on engine performance such as indicated power and indicated specific energy consumption and amounts of pollutant emissions like NOx, soot, and CO in an HSDI (High-Speed Direct Injection) diesel engine. Optimized sub-models, such as turbulence model, spray model, combustion model and emissions models have selected for the main CFD code. Meanwhile, HF (Homogeneity Factor) has been employed for analysing in-cylinder air-fuel mixing quality under various addition conditions. After validations with experimental data of diesel combustion with a single addition of 4% hydrogen and combined addition of 6% hydrogen + 6% nitrogen, investigations have conducted for modeling mixing and combustion processes with additions of hydrogen and nitrogen by ranges of 2–8% (v/v). Results showed that a single addition of H₂ increased NOx and decreased CO and soot and improved ISEC and IP. In the case of nitrogen addition, NOx decreased, both CO and soot emission increased and ISEC and IP considerably ruined compared with NDC operation. Based on the results obtained for simultaneous addition of N₂ (8% of v/v) and H₂ (8% of v/v), NOx and soot emissions decreased by 11.5% and 42.5% respectively, and ISEC and IP improved 25.7% and 13%, respectively. But amount of CO emissions had an increase of 52% should be paid necessary attention as a main disadvantage.     

Effect of natural,accelerated and saturated salt accelerated aging on the Jatropha curcas L. seeds in optimizing the yield of seed oil as feedstock for biodiesel

Uninterrupted and good quality of feedstock is a key factor for biodiesel. Jatropha curcas L. has emerged as a favorite unconventional source of fuel. This paper aims to map the changes in Jatropha curcas L. oil, extracted from seeds subjected to natural aging (NA), accelerated aging (AA) and saturated salt accelerated aging (SSAA) are two methods employed to mimic natural aging. The results depicted that prolonged and intense aging decreased the oil yield and caused deterioration of the oil with a high free fatty acids content, saponification value, peroxide value, and low iodine value. Decrease in oleic acid content is the result of lipid peroxidation due to prolonged storage. However, Jatropha curcas L. seeds subjected to natural aging even up to one year could still serve as the best feedstock because of its resistance towards deteriorative aging effects.     

Effect of nitrogen and sulfur co-doping on the performance of electrochemical hydrogen storage of graphene

In recent decades, finding a solution to replace metal catalysts with inexpensive and available elements has been investigated extensively. Carbon nanomaterials doped with heteroatom such as (N, B and S) which do not have any metal content can provide sustainable materials with a remarkable electrocatalytic activity that can compete with their metal counterparts. Doped graphene has been considered as an electrode material for oxygen reduction reaction, supercapacitor and Li-ion batteries. In this present account, co-doped graphene with nitrogen and sulfur was studied in order to investigate their electrochemical hydrogen storage performance. The dual doped sample was prepared via a simple hydrothermal method, using thiourea as a nitrogen and sulfur source. The nitrogen and sulfur co-doped graphene (NSG) showed excellent electrical conductivity and electrochemical performance compared with the nitrogen doped graphene (NG) and graphene oxide (GO). Doping graphene with foreign atoms is a method to create a semiconducting gap in it and can act as an n-type semiconductor, therefore the electrochemical performance is remarkable when used as an electrode. According to the results by increasing the electrical conductivity of graphene, the storage capacity of hydrogen was increased. The discharge capacity of GO after 20 cycles was increased from 653 mAh/g to 1663 mAh/g (5.88 wt% hydrogen) and 2418 mAh/g (8.55 wt% hydrogen) in single doped graphene (NG) and co-doped graphene (NSG), respectively. The prepared samples were characterized via X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Brunauer-Emmet-Teller analysis (BET), vibration sample magnetometer (VSM) and infrared spectrum (FT-IR).     

电除尘器高频电源和脉冲电源应用分析

通过宝钢电厂1、2号机组现役电除尘器高频电源和脉冲电源的工程设计、安装、调试和运行维护的实践阐述两种新型电源的供电特性以及对提高除尘效率的应用机理。实践结果显示,将高频电源运用在一、二、三电场,改造后排放质量浓度小于等于100 mg·Nm~(-3),将脉冲电源运用在四、五电场,改造后排放质量浓度在20 mg·Nm~(-3)左右。高频电源适合处理高浓度中低比电阻粉尘,脉冲电源适合处理低浓度高比电阻粉尘。对于选择何种电源为佳,需要根据除尘器进口粉尘浓度以及不同工况条件下粉尘比电阻值来选择。     

The effects of Co and Ni addition on the hydrogen storage properties of Mg3Mm

The effects of Ni and Co addition on the hydrogen storage properties of Mg₃Mm alloy was studied by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX) and pressure-composition isotherm (PCI) measurement. The hydrogen absorption kinetics and the thermodynamic parameters (apparent ΔH, ΔS) for Mg₃Mm dehydrogenation reactions in Mg₃Mm, Mg₃MmNi_0.1 and Mg₃MmNi_0.1Co_0.1 alloys have been also investigated. The maximum hydrogen storage content of Mg₃Mm, Mg₃MmNi_0.1 and Mg₃MmNi_0.1Co_0.1 alloys was improved due to that the addition of Ni and/or Co further spurred the MmH₃ phase transforming to MmH₂ phase. On the other side, the kinetics curves show the addition of Co could enhance hydrogen absorption rate while the addition of Ni change the hydrogenation reaction mechanism.     

An analytic model for the effects of nitrogen dilution and premixing characteristics on NOx formation in turbulent premixed hydrogen flames

Advanced hydrogen gas turbine is a promising technology to achieve near-zero emission of carbon dioxide and higher cycle efficiency. With the increased firing temperature and pressure ratio, nitrogen reinjection combined with dry premixed combustion is promising to achieve the challenging low NOx emission. In this study, the effects of nitrogen dilution and fuel/air premixing characteristics on the flame characteristics and NOx emission are investigated first through simulating one-dimensional premixed flames with a 13-species and 39-reaction mechanism at the elevated engine operation conditions. The variation of flame thicknesses and laminar flame speeds with nitrogen dilution is investigated. The NOx formation is characterized by the flame-front NOx and the constant NOx formation rates in the post-flame region. It is shown that the flame-front NOx is an order of 1 ppm and does not change significantly (within 20%) with nitrogen dilution. In contrast, the NOx formation rates in the post-flame region decrease monotonically with nitrogen dilution due to the decrease of oxygen concentration. A detailed analysis of NOx formation reveals that the N₂O pathway is significant and it can account for at least 20% of the NOx formation in the post-flame region. Then an analytic model considering both the extended Zeldovich mechanism and the N₂O pathway is constructed by assuming the involved radicals being in chemical equilibrium. The model can be employed to efficiently estimate the NOx formation in fully premixed hydrogen gas turbines. Next, the effects of fuel/air premixing characteristics on the mean NOx formation rate in the post-flame region are quantified by reconstructing the PDF of mixture fraction. It is shown that without the nitrogen dilution, the NOx formation rate increases dramatically with fuel/air unmixedness due to the existence of local hot spots. Nitrogen dilution can dramatically reduce the NOx formation rate at the same level of unmixedness through reducing the local hot spots. Moreover, nitrogen dilution reduces the sensitivity of the NOx formation rate to fuel/air unmixedness, which greatly alleviates the mixing requirement for the premixing nozzles in gas turbines. Finally, a model for the estimation of NOx emission is constructed, which builds the connection between NOx emission, nitrogen dilution, unmixedness and flow residence time in combustors.     

Particle size and hydration medium effects on hydration properties and sugar release of wheat straw fibers

Wheat straw is gaining importance as a feedstock for the production of biofuels and high value-added bioproducts. Several pretreatments recover the fermentable fraction involving the use of water or aqueous solutions. Therefore, hydration properties of wheat straw fibers play an important role in improving pretreatment performance. In this study, the water retention capacity (WRC) and swelling of wheat straw fibers were studied using water, propylene glycol (PPG) and an effluent from a H₂-producing reactor as the hydration media with three particle sizes (3.35, 2.00 and 0.212 mm). The effects of swelling were analyzed by optical and confocal laser scanning microscopy (CLSM). The highest WRC was reached with the effluent medium (9.84 ± 0.87 g g⁻¹ in 4 h), followed by PPG (8.52 ± 0.18 g g⁻¹ in 1 h) and water (8.74 ± 0.76 g g⁻¹ in 10 h). The effluent hydration treatment had a synergic effect between the enzymes present and the water. The particle size had a significant effect on the WRC (P < 0.01), the highest values were reached with 3.35 mm fibers. The CLSM images showed that finer fibers were subjected to a shaving effect due to the grinding affecting its capacity to absorb the hydration medium. The microscopic analysis showed the increase in the width of the epidermal cells after the hydration and a more undulating cell wall likely due to the hydration of the amorphous regions in the cellulose microfibrils. The sugar release was determined, achieving the highest glucose content with the effluent hydration treatment.     

The effects of water accumulation at the interface between gas diffusion layer and gas supplying channel on the water distribution in polymer electrolyte membrane fuel cells

The effects of water accumulation at the interface of gas diffusion layer (GDL) and gas supplying channel on the water distribution in polymer electrolyte membrane fuel cells (PEMFCs) is analyzed. The amount of water at the interface and in the GDL are quantified using X-ray. Quantitative analyses show that the value of the criterion of water accumulation that can affect the water distribution is in the water saturation range of 0.22–0.24. The amount of water in the GDL increases with the water accumulated at the beginning of the water generation cycle. However, it remains constant after the water accumulation exceeds a criterion value. The result shows that the water accumulation at the interface should be investigated to understand the water distribution in PEMFC. The water distribution in PEMFC cannot be analyzed based on the steady state concept but can be analyzed based on the concept of cyclic process.