Electrohydrodynamic atomization (EHDA) is a technique which uses the influence of strong electric fields to manipulate the break-up of a liquid, pumped through a capillary nozzle, into droplets. In this work, an extended description of a specific high flow EHDA mode, known as the simple-jet mode, is presented. In it, a review of different works published about the mode is presented as well as results about the droplet population generated with varicose and whipping break-up using water as the atomized liquid. Additionally, experiments were conducted to investigate whether such atomization method could be used to improve the efficiency of droplet inair evaporation, using a single effect evaporation chamber coupled with a EHDA multinozzle system functioning as a shower head. The liquid used in these experiments was a solution of water and NaCl (35 g L−1) to simulate sea water average concentrations. The results have shown that, the manipulation of the droplet diameter, droplet size distribution and spray angle, provided by EHDA, could improve the droplet evaporation efficiency by up to 40% when combinedwith, e.g. forced convection and higher inlet temperatures.
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Even though mango productivity in Ethiopia is low due to moisture stress, there is no report on how such constraint could alleviate using Cocoon water-saving technology. Cocoon is small water reservoir technology which uses for plant growth in dry season. The objectives of this study were to introduce and evaluate effectiveness of water-saving techniques on mango seedlings survival and growth in Mihitsab-Azmati watershed, northern Ethiopia. In this experiment, five treatments of water-saving techniques with mango seedlings were evaluated. These were: Cocoon sprayed by tricel (T1), Cocoon painted by used engine oil (T2), Cocoon without tricel and oil (T3), manually irrigated seedlings (T4) and mango seedlings planted during rainy season (T5). The survival and growth performance of mango seedlings were recorded at six months and one-year after transplanting. Data on plant survival, height, number of leaves per plant, shoot length, stem diameter and crown width were subjected to analysis of variance and t-test. There were significant differences in the treatment effects on mango seedlings transplanted survival, plant height, number of leaves per plant, shoot length, stem diameter and crown width measured at six months and one-year after transplanting. The lowest survival rate (20 %) was found during both data collection time in T5. Six months after transplanting, the highest growth parameters were measured from T1 whereas the lowest was from T5. However, one-year after transplanting, the highest growth parameters were measured from T3. Plant heights increments between the two measurement periods for T3, T2, T1, T4 and T5 were 45.1, 38.5, 24.8, 9.8 and 7.0 cm, respectively; indicating that T3 performed better than the other treatments. The t-test on mean differences between the same growth parameter measured at 12 and six months after transplanting also showed significant differences. The Cocoon water-saving technology was superior in improving mango seedlings survival and growth in the study area. This study generalized that Cocoon seems promising, sustainable and highly scalable with mango seedlings at large-scale in the study area conditions. However, this technology should not be assumed to perform uniformly well in all environmental conditions and with all tree species before demonstrated on a pilot study.
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PowerPointpresentatie gebruikt op de 2e Kennisdeeldag ’Voedselbossen Zuidoost-Nederland’ in Maastricht op 11 december 2019.
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Sedimentation devices have been widely implemented to remove suspended solids and attached pollutants from stormwater before entering surface waters. The treatment performance of these best management practices (BMPs) on fine particles is rarely investigated in a standardized way. To overcome this information gap a reliable and standardized testing procedure is formulated.Four devices have been tested on their suspended sediments removal efficiency at different discharges and particle sizes, using the newly developed standardized full scale test method. The observed removal rates of the facilities with a storage volume in the order of 1.5 m3 and settling surface around 1 m2 drop to low removal efficiencies at flow rates of 10 l/s or more. For small sized sediments (up to 63 μm) the removal efficiency is below 50%. The results of the experiments can be used to improve both the design and the dimensions of stormwater treatment devices.
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Increasing urbanization and the effects of climate change will bring new challenges for cities, such as energy saving and supply of renewable energy, preventing urban heat islands and water retention to deal with more frequent downpours. A major urban surface, the surface of roofs, is nowadays hardly exploited and could be used to make cities more ‘future proof’ or resilient. Many Dutch municipalities have become aware that the use of green roofs as opposed to bituminous roofs positively contributes to these challenges and are stimulating building-owners to retrofit their building with green roofs. This study aims at comparing costs and benefits of roof types, focused on green roofs (intensive and extensive) both on building- and city scale. Core question is the balance between costs and benefits for both scales, given varying local conditions. Which policy measures might be needed in the future in order to apply green roofs strategically in regard to local demands? To answer this question the balance of costs and benefits of green roofs is divided into a public and an individual part. Both balances use a strengths, weaknesses, opportunities and threats framework to determine the chance of success for the application of green roofs, considering that the balance for green roofs on an individual scale influences the balance on a public scale. The outcome of this combined analyses in the conclusion verifies that a responsible policy and a local approach towards green roofs is necessary to prepare the city sufficiently for future climate changes. http://dx.doi.org/10.13044/j.sdewes.d6.0225
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Wind and solar power generation will continue to grow in the energy supply of the future, but its inherent variability (intermittency) requires appropriate energy systems for storing and using power. Storage of possibly temporary excess of power as methane from hydrogen gas and carbon dioxide is a promising option. With electrolysis hydrogen gas can be generated from (renewable) power. The combination of such hydrogen with carbon dioxide results in the energy carrier methane that can be handled well and may may serve as carbon feedstock of the future. Biogas from biomass delivers both methane and carbon dioxide. Anaerobic microorganisms can make additional methane from hydrogen and carbon dioxide in a biomethanation process that compares favourably with its chemical counterpart. Biomethanation for renewable power storage and use makes appropriate use of the existing infrastructure and knowledge base for natural gas. Addition of hydrogen to a dedicated biogas reactor after fermentation optimizes the biomethanation conditions and gives maximum flexibility. The low water solubility of hydrogen gas limits the methane production rate. The use of hollow fibers, nano-bubbles or better-tailored methane-forming microorganisms may overcome this bottleneck. Analyses of patent applications on biomethanation suggest a lot of freedom to operate. Assessment of biomethanation for economic feasibility and environmental value is extremely challenging and will require future data and experiences. Currently biomethanation is not yet economically feasible, but this may be different in the energy systems of the near future.
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This century, greenhouse gas emissions such as carbon dioxide, methane and nitrogen oxides must be significantly reduced. Greenhouse gases absorb and emit infrared radiation that contributes to global warming, which can lead to irreversible negative consequences for humans and the environment. Greenhouse gases are caused by the burning of fossil fuels such as crude oil, coal, and natural gas, but livestock farming, and agriculture are also to blame. In addition, deforestation contributes to more greenhouse gases. Of the natural greenhouse gases, water vapor is the main cause of the greenhouse effect, accounting for 90%. The remaining 10% is caused from high to low by carbon dioxide, methane, nitrogen oxides, chlorofluorocarbons, and ozone. In addition, there are industrial greenhouse gases such as fluorinated hydrocarbons, sulphurhexafluoride and nitrogen trifluoride that contribute to the greenhouse effect too. Greenhouse gases are a major cause of climate change, with far-reaching consequences for the welfare of humans and animals. In some regions, extreme weather events like rainfall are more common, while others are associated with more extreme heat waves and droughts. Sea level rise caused by melting ice and an increase in forest fires are undesirable effects of climate change. Countries in low lying areas fear that sea level rise will force their populations to move to the higher lying areas. Climate change is affecting the entire world. An estimated 30-40% o f the carbon dioxide released by the combustion of fossil fuels dissolves into the surface water resulting in an increased concentration of hydrogen ions. This causes the seawater to become more acidic, resulting in a decreasing of carbonate ions. Carbonate ions are an important building block for forming and maintaining calcium carbonate structures of organisms such as oysters, mussels, sea urchins, shallow water corals, deep sea corals and calcareous plankton.
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Ammonia is heavily used in agriculture as a fertilizer and in industry as a raw material for the production of various organic nitrogen compounds. Its high hydrogen content and its established infrastructure for both storage and distribution makes ammonia a prominent candidate for storing fluctuating renewable energy. The Haber-Bosch heterogenous reaction of hydrogen and nitrogen on an iron-based catalyst is used today at large scale ammonia production sites. The current industrial hydrogen production is dominated by fossil energy sources. The traditional Haber-Bosch process can become green and carbon-free if renewable electricity is used for hydrogen generation. However, a continuous operation of power to ammonia can be challenging with a fluctuating renewable energy source. Techno-economic models show that electrolysis and the hydrogen supply chain is the main dominating cost factor of power to ammonia.
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Abstract: The key challenge of managing Floating Production Storage and Offloading assets (FPSOs) for offshore hydrocarbon production lies in maximizing the economic value and productivity, while minimizing the Total Cost of Ownership and operational risk. This is a comprehensive task, considering the increasing demands of performance contracting, (down)time reduction, safety and sustainability while coping with high levels of phenomenological complexity and relatively low product maturity due to the limited amount of units deployed in varying operating conditions. Presently, design, construction and operational practices are largely influenced by high-cycle fatigue as a primary degradation parameter. Empirical (inspection) practices are deployed as the key instrument to identify and mitigate system anomalies and unanticipated defects, inherently a reactive measure. This paper describes a paradigm-shift from predominant singular methods into a more holistic and pro-active system approach to safeguard structural longevity. This is done through a short review of several synergetic Joint Industry Projects (JIP’s) from different angles of incidence on enhanced design and operations through coherent a-priori fatigue prediction and posteriori anomaly detection and -monitoring.
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