Current Issue : April - June Volume : 2020 Issue Number : 2 Articles : 5 Articles
A bioenergy summit was organized by Advanced Hardwood Biofuels Northwest (AHB) to\ndebate the barriers to the commercialization of a hybrid poplar biofuels industry for the alternative\njet fuels market from the perspective of five years of AHB research and development and two recent\nsurveys of the North American cellulosic biofuels industry. The summit showed that: (1) Growing\nand converting poplar feedstock to aviation fuels is technically sound, (2) an adequate land base\nencompassing 6.03 and 12.86 million respective hectares of croplands and rangelands is potentially\navailable for poplar feedstock production, (3) biofuel production is accompanied by a global warming\npotential that meets the threshold 60% reduction mandated for advanced renewable fuels but (4) the\nmain obstruction to achieving a workable poplar aviation fuels market is making the price competitive\nwith conventional jet fuels. Returns on investment into biomass farms and biorefineries are therefore\ninsufficient to attract private-sector capital the fact notwithstanding that the demand for a reliable and\nsustainable supply of environmentally well-graded biofuels for civilian and military aviation is clear.\nEleven key findings and recommendations are presented as a guide to a strategic plan for a renewed\npathway to poplar alternative jet fuels production based upon co-products, refinery co-location with\nexisting industries, monetization of ecosystem services, public-private financing, and researching\nmore efficient and lower-costs conversion methods such as consolidated bioprocessing....
Recently, many people around the world have been concerned with environmental protection\nand sustainability. The goal of various countriesâ?? research has been focused on how to regenerate existing\nresources. Circulation fluidized bed combustion (CFBC) technology is one of the emerging combustion\ntechnologies for electricity generation and produces more than 800,000 tons of CFBC fly ash (CFA)\nper year for combustion. CFA has been widely applied in cement additive, new building materials\nand cement-based materials. The goal of this study was to discuss the engineering properties of\nroller-compacted concrete containing CFA. Test subjects included compressive strength, flexural\nstrength, absorption, setting time, unit weight, sulfate resistance, SEM microscopic observations and\nXRD ingredient analysis. Test results indicate the following: (1) using CFA as a substitute of fine\naggregates up to 10 wt.% would improve the development of later flexural strength; (2) the increases\nin pre-pressure would increase the compressive strength and unit weight and decrease absorption;\n(3) using CFA would reduce the initial setting time by 30%â??60% and reduce the final setting time\nby 16%â??20%; (4) using CFA would reduce the absorption; (5) using CFA would reduce the unit \nweight by 0.5%â??2.8%, and the increases in pre-pressure would increase the unit weight by about\n0.9%â??2.1%; (6) CaO in CFA helps to improve sulfate resistance; (7) scanning electron microscopy\n(SEM) observation shows that the increases in pre-pressure would reduce the pores; and (8) X-ray\ndiffraction (XRD) analysis shows that the inclusion of CFA would increase the content of Ca(OH)2\nin concrete....
The aim of the work is a comparison of two combustion systems of fuels with different\nreactivity. The first is combustion of the fuel mixture and the second is combustion in a dual-fuel\nengine. Diesel fuel was burned with pure ethanol. Both methods of co-firing fuels have both\nadvantages and disadvantages. Attention was paid to the combustion stability aspect determined\nby COVIMEP as well as the probability density function of IMEP. It was analyzed also the spread of\nthe maximum pressure value, the angle of the position of maximum pressure. The influence of\nethanol on ignition delay time spread and end of combustion process was evaluated. The\nexperimental investigation was conducted on 1-cylinder air cooled compression ignition engine.\nThe test engine operated with constant rpm equal to 1500 rpm and constant angle of start of diesel\nfuel injection. The engine was operated with ethanol up to 50% of its energy fraction....
The differences in the pollutant emissions from the combustion of bituminous coal and\nbiofuels (wood, straw, and miscanthus pellets) under real-world boiler operating conditions were\ninvestigated. The experiments were performed on an experimental installation that comprised an\n18 kW boiler, used in domestic central heating systems, equipped with a retort furnace, an automatic\nfuel feeder, a combustion air fan, and a fuel storage bin. The emission factors of gaseous pollutants,\nparticulate matter, organic carbon, elemental carbon, and polycyclic aromatic hydrocarbons (PAHs),\nas well as some PAH concentration ratios for coal and biofuel combustion, were determined.\nThe obtained results indicate that fuel properties have a strong influence on the emission factors of\ngaseous and carbonaceous pollutants. The total particulate matter (PM) emissions from the biofuel\ncombustion were about 5-fold lower than those from the coal burned in the same boiler. The emission\nfactors of the total carbons from the biofuel combustion were between 10 and 20 times lower than\nthose from the coal combustion. The mean organic carbon (OC) and elemental carbon (EC) emission\nfactors, based on the burned fuel, were 161-232 and 42-221 mg/kg for the biofuels and 1264 and\n3410 g/kg for the coal, respectively. The obtained results indicate that molecular diagnostic ratios,\nbased on the concentration of PAHs, vary significantly, depending on the fuel type....
We study the generalized Riemann problem of the Chapman-Jouguet model\nfor an ideal combustible Chaplygin gas. By analyzing the wave curves in the\nphase plane, we construct uniquely the solution of the generalized Riemann\nproblem under the global entropy conditions. We find that although there is\nno combustion wave of the corresponding Riemann solution, the combustion\nwave may occur after perturbation which reveals the instability of the unburnt\ngas....
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