Densification of agro-residues for sustainable energy generation: an overview.

The global demand for sustainable energy is increasing due to urbanization, industrialization, population, and developmental growth. Transforming the large quantities of biomass resources such as agro-residues/wastes could raise the energy supply and promote energy mix. Residues of biomass instituted in the rural and industrial centers are enormous, and poor management of these residues results in several indescribable environmental threats. The energy potential of these residues can provide job opportunities and income for nations. The generation and utilization of dissimilar biomass as feedstock for energy production via densification could advance the diversity of energy crops. An increase in renewable and clean energy demand will likely increase the request for biomass residues for renewable energy generation via densification. This will reduce the environmental challenges associated with burning and dumping of these residues in an open field. Densification is the process of compacting particles together through the application of pressure to form solid fuels. Marketable densification is usually carried out using conventional pressure-driven processes such as extrusion, screw press, piston type, hydraulic piston press, roller press, and pallet press (ring and flat die). Based on compaction, densification methods can be categorized into high-pressure, medium-pressure, and low-pressure compactions. The common densification processes are briquetting, pelletizing, bailing, and cubing. They manufacture solid fuel with desirable fuel characteristics-physical, mechanical, chemical, thermal, and combustion characteristics. Fuel briquettes and pellets have numerous advantages and applications both in domestic and industrial settings. However, for biomass to be rationally and efficiently utilized as solid fuel, it must be characterized to determine its fuel properties. Herein, an overview of the densification of biomass residues as a source of sustainable energy is presented.

Comprehensive data on the mechanical properties and biodegradation profile of polylactide composites developed for hard tissue repairs.

Polylactide (PLA), a biopolymer, was reinforced with three fillers (two organic reinforcements and one inorganic filler). The processing technique used to fabricate the composites was the melt-blending technique. The composites and the unreinforced PLA were subjected to microhardness, compression and biodegradation characterisations. Data obtained are presented in this article as raw data. Data from microhardness and compression tests were used to predict the fracture toughness. The biodegradation of the composites was also examined, and the data obtained reported in this article. The data presented in this article allow for a comprehensive understanding of the mechanical behaviour and the biodegradation profile of three composites of PLA with respect to their applications as biodegradable implants. It also helps in the selection of fillers for biopolymers such as PLA.

Data on microhardness and structural analysis of friction stir spot welded lap joints of AA5083-H116.

Friction stir spot welding (FSSW) was established to compete reasonably with the reverting, bolting, adhesive bonding as well as resistance spot welding (RSW) which have been used in the past for lap joining in automobile, aerospace, marine, railways, defence and shipbuilding industries. The use of these ancient and conventional joining techniques had led to increasing material cost, installation labour, and additional weight in the aircraft, shipbuilding, and other areas of applications. All these are disadvantages that can be overcome using FSSW. This research work carried out friction stir spot welding on 5058-H116 aluminium alloy by employing rotational speed in the step of 300 rpm ranges from 600 rpm to 1200 rpm with a no travel speed. It was noted that the dwell times were in the step of 5 s varying from 5 s to 15 s while the tool plunge rate was maintained at 30 mm/min. In this dataset, a cylindrical tapered rotating H13 Hot-working steel tool was used with a probe length of 5 mm and probe diameter of 6 mm, it has a shoulder diameter of 18 mm. The tool penetration depth (plunge) was maintained at 0.2 mm and the tool tilt angle at 2°. Structural integrity was carried out using Rigaku ultima IV multifunctional X-ray diffractometer (XRD) with a scan voltage of 40 kV and scan current of 30 mA. This was used to determine crystallite sizes, peak intensity, d-spacing, full width at half maximum intensity (FWHM) of the diffraction peak. TH713 digital microhardness equipment with diamond indenter was used for microhardness data acquisition following ASTM E92-82 standard test. The average Vickers hardness data values at different zones of the spot-welds were captured and presented.

Dataset showing thermal conductivity of South-Eastern Nigerian kaolinite clay admixtures with sawdust and iron filings for fired-bricks production.

In this dataset, the influence of admixture of sawdust and iron filings on the kaolinite clay was experimented. This was done by blending various samples of kaolinite clay with varying percentages of sawdust and iron filings. Thermal analysis of the clay samples was carried out at different ratios of sawdust and iron filings blended with the clay samples. The blended ratio of sawdust and iron fillings ranges from 0%, 5%, 10%, 20%, 30%-40%. These samples were fired in a local kiln that achieved temperature of 900 °C - 1200 °C to burn-off the sawdust consequently creating pores/cavities where the sawdust had been burnt and to fuse the iron particles with the clay material. The experimental data on the thermal characteristics and refractory properties of the clay sample were then acquired. The data were acquired, processed and presented. Thermocouple and thermometer were used to acquire the temperature during the firing of the bricks. Finally, thermal conductivities and bulk densities of the samples were computed following an established standard.

Experimental data on surface roughness and force feedback analysis in friction stir processed AA7075 - T651 aluminium metal composites.

Friction Stir Processing (FSP) is a surface modification technique used to enhance the mechanical properties and improve the surface integrity of the processed material. In the present data collection, aluminium alloy 7075-T651 was studied under different reinforcement conditions. Microchannel of dimension 3.5 mm depth and 2.0 mm width were machined on the aluminium plates to accommodate the particles. The process was conducted at different rotational speed of 1200 rpm, 1500 rpm and 1800 rpm with constant processing speed of 20 mm/min, plunge depth of 0.3 mm and tilt angles of 3°. Double passes were achieved for each parameter with 100% inter-pass overlap. A cylindrical tapped, AISI H13 steel tool with shoulder diameter 18 mm, pin length of 5.0 mm, pin diameter 5 mm at the top and 6 mm at the end with 10° taper was used during friction stir process. Surface integrity analysis was carried out with the aid of mitutoyo surftest SJ-210 surface roughness tester (SRT). The analysis was carried out at three different points on a parameter for a particular workpiece and the average reading for each parameter is calculated in order to ensure precision of the measurements and the coverage surface area. The following surface roughness parameters were measured and recorded, arithmetical mean roughness value (Ra), maximum height (Ry), mean roughness depth (Rz) and root mean square roughness (Rq). Force feedback from the machine data for selected reinforcement particles with respected to processing times and x-positions are also presented.

A streamlined life cycle assessment of a coal-fired power plant: the South African case study.

Non-renewable energy sources have detrimental environmental effects, which directly and indirectly affect the biosphere as environmental deposits from their use for energy generation exceed a threshold. This study performs a streamlined life cycle assessment (LCA) of a coal-fired plant in South Africa. The cradle-to-grave LCA focuses on the coal cycle to determine hotspots with high environmental impacts in the process. Four impact categories were considered in this study: global warming potential, photochemical ozone creation potential, eutrophication potential, and acidification potential. Coal transportation, coal pulverization, water use, and ash management were identified as hotspots in the coal cycle. The coal process has 95% potential for global warming, 4% potential for eutrophication, 1% potential for acidification, and a negligible percentage for photochemical ozone creation. Susceptibility to climate change, eutrophication, acid rain, soil degradation, and water contamination among others are major concerns of the coal cycle. Outsourcing coal from nearby mines with train as medium of transportation reduces environmental impact. Similarly, the use of mitigation technologies like flue gas desulphurization, carbon capture storage, or selective catalytic reduction will reduce the concentration of the flue gas emitted. Ultimately, substituting the coal process with renewable energy sources will ensure environmental sustainability in South Africa. This study will serve as a good resource for further studies on LCA of coal power plants not only in other African countries but in other developing countries with similar situation.

Data showing the effects of vibratory disc milling time on the microstructural characteristics of Coconut Shell Nanoparticles (CS-NPs).

Coconut Shell (CS) as agricultural lignocellulosic biomaterial and agro-waste is predominantly available in India, Malaysia, Nigeria, Thailand, Sri Lanka, and Indonesia. It has proven to have effective durability characteristic, good abstractive resistance, high toughness, and good adsorption properties, and is most suitable for long standing use in many applications such as reinforcement, source of energy, fillers as well as activated carbon and its performance, efficiency and effectiveness depend wholly on whether is in form of nano-, micro-, and macro- particles. In this data, effects of milling time on morphological characteristics was experimented using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), and X-Ray Fluorescence (XRF) analyses. The SEM images were taken at magnifications of 1.00kx, 2.00kx and 5.00kx which gives respective 50 µm, 20 µm and 10 µm in different milling time of 0, 20, 40 and 60 mins. Digital Vibratory Disc Milling Machine (VDMM) rated 380 V/50 Hz at 940 rpm was employed for the grinding and the morphology of the milled nanoparticles were characterised. It was revealed from the data collected that 0 min (i.e. 75 µm sieved) has the highest mean area value of 16.105 µm2 and area standard deviation of 200.738 µm2 with least value of a number of particle size distribution of 809 µm. In contrast, 60 mins milled has the lowest values for mean area and area standard deviation of 8.945 µm2 and 115.851 µm2 respectively with the highest number of particle size distribution of 2032 µm. It was observed that milling time increases the number of particle sizes distributions and reduces the area of particle size.