Fuel Communications最新文献

Universities bear the important responsibility of training capable individuals and imbibing into the society plans, programs and policies that are sustainable. However, they have failed to live up to this expectation/responsibility in developing nations like Nigeria. As a result, various publication domains like the Elsevier, Engineering village, Science Direct, Taylor and Francis, Springer books, Research gate, etc. were explored to understand different approaches by various authors on the strategies of managing solid waste generated in universities around the world so as to recommend better strategies for managing the solid wastes generated in Nigerian universities for a sustainable development. The solid wastes that are prevalent in most studies reviewed include organic, plastic, polythene, paper/cardboard, e-waste, metal/cans, sanitary, wood, leather/textiles, glass/bottle, polystyrene food pack, medical and rubber. However, there are four major categories that pose the most challenges to the environment, the atmosphere, the entire populace and during all stages of management because they contribute the most percentage both by volume and weight. They include: organic, paper, polythene and plastic. Consequently, the strategies for the four major categories were discussed in this work. Some of the strategies include prevention of the generation of avoidable wastes, reduction of the generated waste through recovery, reuse of the recovered wastes, recycling of the recyclables, composting of organic wastes for energy/electricity generation, and eventual disposal at sanitary landfills. The strategies were based on the principles of the Integrated Solid Waste Management (ISWM) approach (3Rs) of an efficient and effective sustainable waste management, viz; Reduce, Reuse and Recycle.

Esters of levulinic acid constitute a promising class of renewable fuel additives that improve the cold properties of diesel and reduce soot emissions. However, the production of levulinic acid via thermolysis of biomass has low selectivity, a problem that compromises both yield and reactor operability, with impacts on cost. The main undesirable byproducts of this process are called humins, a dark insoluble residue. This work proposes and simulates an alternative reactor arrangement based on experimental results and analyzes reaction conditions via design of experiments to determine the factors that influence humins formation in the production of levulinic acid from sugarcane bagasse. Results indicate that a high residence time in hydrolysis increases humins formation, and a high temperature was found to deteriorate selectivity even further. Therefore, a high catalyst loading combined with low residence time and temperature is required to decrease losses. Considering the limitations of the simulated model, the conditions that minimize humins formation led to yields of 109 kg of furfural (from hemicelluloses) and 74 kg of levulinic acid (from cellulose) per dry tonne of sugarcane bagasse, with the production of 58 kg of humins. Results of economic analysis demonstrated that if humins disposal is associated with a high cost, low biomass conversion is required to yield a promising economic result, even though this might compromise the yield of levulinic acid and furfural. On the other hand, if value-added applications for humins become available, a similar conclusion applies if their production compromises reactor operability.

The quest for cleaner energy sources and renewable energy has become a drive force in the current energy market, creating a gradual shift from total dependence on fossil fuel. Production of biogas through the anaerobic digestion of organic wastes provides an alternative for energy supply, recovery and waste treatment. The University of Ibadan Dairy Farm, Abadina has a digester which was abandoned due to its inefficiencies. The digester has been modified a couple of times over the years without yielding any biogas, hence, the need for a functional digester.

A modified Gobar design was adopted in the construction of a new digester. An agitator was introduced in the design for stirring of the slurry. The designed digester was a plant capacity of 4m³ with a retention time of 35 days. The existing digester was demolished and the new digester was erected in its stead. The entire plant was made of reinforced concrete. The digester was loaded with 180 kg of dung daily, with a mix ratio (dung to water) of 1:1.

A 2 m³ gas bag was connected to the gas outlet for collection of the produced gas. Gas production started after the 7th day of loading the digester with substrate. The collected gas was tested for burnability. The initial burn test quenched the flame and the digester was allowed for a week without feeding. The biogas burnt with a blue flame during the second test. A biogas cooking stove was made available to enable utilization of the produced gas.

This study focused on the effects of introducing pine sawdust and bituminous coal in a down fired combustion reactor. Co-combustion of coal and biomass waste provides an alternative to biomass waste management as well as efficiency improvement with regards to boiler optimisation if correctly applied. A Computational Fluid Dynamics model, using ANSYS Fluent, was employed alongside experimental data to study the behaviour of this co-combustion process. The co-combustion model employed was based on the discrete phase submodel which tracks discrete solid fuel particles in a fluid continuum comprising of the gaseous oxidant, intermediate species, and products. The other important submodels used in this study comprised of the single kinetic devolatilisation submodel and the multiple surface heterogenous char reaction submodel. Two homogenous volatile combustion mechanisms were tested which were the refined Westbrook and Dryer 2-step reaction mechanism as well as the refined Jones and Lindstedt 4-step reaction mechanism. The effect of particle size was monitored in detail by employing a shape factor of 0.87 for biomass particles towards the drag law and the radiative heat transfer tested the effect of using the Discrete Ordinate and P1 radiation submodels. The results showed an increase in burnout for 0.2 s residence time from 37% to 72% when sawdust was introduced in the combustion chamber whilst the temperature profiles showed a general decrease in maximum temperatures attainable as the sawdust proportion increased.

In recent times, effort has been made by researchers all over the world to develop composite materials that will be eco-friendly and affordable. Based on this, this study focused on the development of improved thermal and fire properties of the polymer (epoxy) using Cucumeropsis mannii shell granules (CMSg). Epoxy + 20wt% CMSg composite was produced by solution casting method. The thermogravimetric (TGA) and cone calorimetry were used to determine the relevant characteristics of the composite. The temperature of thermal maximum decomposition was shifted to a higher temperature for the composite. The epoxy released 6.63% heat during burring and 6.73% mass loss over that of the developed composite. About 58.93% delayed time was obtained for the composite before burning commenced. The results show that the tested material can be used for increasing the thermal and fire properties of epoxy matrix composites for engineering application.

This paper presents second law analytical approach in reducing gaseous emission at gas turbine plant in Geregu, Nigeria. The study analyzed the system's components separately to locate the component with highest exergy destruction ratio for possible improvement. Results show that the combustion chamber has highest exergy destruction ratio. Improvements made include increment in: (i) turbine inlet temperature at constant pressure ratio, (ii) combustion chamber pressure ratio at constant turbine inlet temperature, (iii) both  turbine inlet temperature and pressure ratio, and changing ambient temperature at power plant location. The multiple criteria for change indicate that the first approach decreased the environmental effect factor by 6.96 % and the sustainability index factor increased by 7.41% as the temperature increased from 1060 – 1080 ^oC at constant pressure ratio of 11. The second approach reduced the environmental effect factor by 2.74% and increased the sustainability index factor by 2.82% when the pressure ratio rose from 11 to 15. However, simultaneous increments in turbine inlet temperature and pressure ratio by 20^oC and 4bar decreased the environmental effect factor further by 8.41%. Thus, raising the sustainability index factor by 9.19%. The results show that changing the ambient temperature from 20°C to 35°C resulted in equal changes in environmental effect factor and sustainability index factor by 0.02%. This work has revealed that gaseous emission from the plant can be reduced by second law analysis. Overall, simultaneous increases in pressure ratio and turbine inlet temperature gave the best result.

The energy efficiency of the aluminum melting furnace was evaluated for a Nigerian cast-coiled plant. The energy input was evaluated using the daily production data of the company while the energy output was determined through the second law of thermodynamics. The energy intensity for processing 876,357 kg of aluminum scrap was estimated as 6.07 MJ/kg. The energy efficiency of the melting furnace was evaluated as 18% in which the overall excess energy of the system was 82% (4.36 TJ) of the supplied energy. The heat released to the surrounding from the stack gas was significant, accounting for almost half of the energy output (46.2%) (2.4 TJ). The lost energy from the furnace is around 36% (1.9 TJ) of the total input energy. The installation of the recuperator and waste heat recovery systems was proposed to increase the energy efficiency of the reverberatory furnace. The results of this work has shown the area of energy wastage and the information would be beneficial for the designs of new furnace or for the modification of the existing one.

This paper deals with the effect of catalyst loading on the activity and selectivity of CuO_x−MnO_y catalysts on alumina-silicate supports (fiber material-Al₂O₃(44)/SiO₂(56)). A special focus lies on the oxidation of CO, on mixtures of VOC from 1-butene, isobutane, n-butane, propane, ethene, and ethane, as well as on CO oxidation in the presence of NO₂. The catalysts are prepared through wet impregnation of the filter section with an aqueous solution of copper and manganese nitrate. The rate of CO oxidation for small carbon monoxide concentrations of up to 1 vol.% is independent of catalyst loading in the filter material. In contrast, at a carbon monoxide concentration of around 3 vol.%, it is found that the rate of CO oxidation increased rapidly with increasing catalyst loading of the filter material. The highest catalytic activity of over 93% CO elimination is achieved at 290 °C for 1 vol.% CO and smaller catalyst loading and for 3 vol.% CO with higher catalyst loading. In long-term stability tests, complete CO conversion is measured without deactivating the catalyst at 390 °C for at least 100 h. The highest catalytic activity for VOC elimination of 90% is achieved in the temperature range of 350–420 °C. During the CONO₂ reaction with and without O₂, a constant decrease in the CO oxidation rate is observed, while the NO₂ reduction rate remained constant at a temperature below 300 °C.

Startup capacity is always a concern to low wind speed turbines, especially the vertical axis wind turbine (VAWT). Efforts at developing low wind speed models still persist. Hence, the focus of this study is on the development of a new airfoil for VAWT, with better startup capacity, low tip loss, and devoid of dynamic stall, from the synergistic properties of four standard airfoils. The standard airfoils are DU06-W-200-dt, NACA0012h-sa, S822, and S823. The coordinates of these airfoils were employed to generate eleven new airfoils via the interpolation of the coordinate points. The airfoils were then analysed using QBlade v0.963 64bit, to determine the coefficients of lift (C_L), drag (C_D), pitching moment, and minimum pressure for various angles of attack, at a specific flow characteristics such as Reynold's number, density, kinematic viscosity, and Mach number. The Reynold's and Mach numbers were modified over a range of values to generate polar of airfoil performance for every wind speed. Variations of glide ratio, C_L, and C_D with angle of attack at constant Reynolds number were employed to determine the optimum airfoil. High aspect ratio was used to minimise the effect of tip loss. The outcome showed that the developed airfoil exhibits better performance, good startup capacity, with potential to generate up to 1, 11 and 13 kW at speeds of 2, 11 and 16 m/s, respectively. Flow, and pressure analysis show that the turbine with the blade airfoil will not experience dynamic stall as a result of pressure differences, irrespective of the azimuth.

The chemical recycling of different kinds of mixed, dirty, or filled plastic waste is carried out in a fluidized bed process. The high heat transfer is one of the advantages for using a fluidized bed reaktor. The cracking process is fast and less side reactions happen. Olefins and oil are produced by pyrolysis of polyolefin. If the pyrolysis gas is cycled as fluidizing gas aromatics are formed. Up to 98 % of methylmethacrylate can be obtained by pyrolysis of poly(methylmethacrylate) and 77 % styrene from polystyrene. The hydrolysis and pyrolysis of polyester produced terephthalic acid and only smal amounts of soot.The pyrolysis of plastics in a fluidized bed has the potential for an up-scale to recycle great amouns of plastic waste.