Sawdust and rice husk are available in abundance and indigenous in Nigeria but have not been exploited because they cannot be used directly in combustion processes due to their loose form unless by pelleting or briquetting. This experimental study assesses the potential of pellets from sawdust (SD) and rice husk (RH). Pallet samples collected from mills were thereafter optimized in ratios (i.e. 90%RH:10%SD, 80%RH:20%SD, 70RH:30SD, 60%RH:40%SD, 50%RH:50%SD, 100%RH and 100%SD) using mixing ratio optimization model. Seven samples were produced using a manual screw press machine and were subsequently categorized in terms of calorific value (CV), proximate and ultimate analyses using the ASTM standards. Results showed that the 100%RH pellets have higher CV of 31,026.3kJ/kg and the 100%SD a value of 26,088.3kJ/kg while the optimized pellets range from 25,867.39kJ/kg to 27,063.60kJ/kg. The CV decreases with increasing ash content of the pellets. It was also observed from the proximate analysis that the 100%RH has low percentages of moisture content, volatile matter and ash content compared to others. The optimized pellets showed that SD has the tendency to reduce the sulfur content in RH; hence, a promising alternative source of energy to the conventional fossil fuel.
Devastating environmental issues and the cost of replacement of batteries in autonomous low-powered electrical, electronic, and mechatronic systems, the interest in ambient energy harvesting has witnessed steady growth recently. The maximization and utilization of these eco-friendly energies have given rise to efficient hybrid energy harvesting, which involves the combination of two or more standalone energy harvesting mechanisms such as Vibrational, thermoelectric, pyroelectric, photovoltaic, etc. The comparison of the recent development, applications, and challenges of the major standalone and hybrid harvesting mechanisms in both large and small-scale mechanisms are the main emphasis of this article. Also, this review holistically discussed the latest optimal techniques utilized in hybrid energy harvesting mechanisms for the effective performance of systems and to guarantee stable power to autonomous electronics and wireless sensor networks. The study will help research scholars to understand and focus on the high-potential techniques to achieve maximum power from hybrid harvesters.
AbstractIn this study, the effect of elaeis guineensis in the production of pellets from coal was investigated. Coal and elaeis guineensis were collected and pulverised. A locally fabricated screw press machine was used to produce three types of pellets in the same ratio (i.e. 80C:20R) while the fourth pellet is100% coal. These pellets are: coal palm kernel shell (CPKS), coal palm fibre (CPF), coal empty fruit bunch (CEFB) as well as raw coal (C). Thereafter, the pellets were sundried and characterised base on ASTM Standards. These include the calorific value, proximate and ultimate analysis. From the results, it was observed that the calorific value of CPKS, CPF, CEFB and C were 28033.38 kJ/kg, 27695.4 kJ/kg, 27687.5 kJ/kg and 22021.99 kJ/kg respectively. The sulphur content of the pellets is 0.7%, 0.71%, 0.73% and 0.76% respectively. The results revealed that the 100% coal pellet has the lowest percentage CV and the highest percentage sulphur and ash content. Essentially, this study has been able to established that elaeis guineensis residues is a good energy source for enhancing the calorific value of coal and also has the tendency of reducing the sulphur and ash contents of coal especially the PKS.
This paper presents biharmonic modelling and simulations of surface wind flow, which identify windy locales through wind speed gradients. The bulk measured and meteosat wind speed data encapsulate the wind isotachs and wind flow gradients, which are very useful in identifying windy locales. Thus, this paper presents a biharmonic wind flow model, BWFM for the development of wind isotachs and gradients to identify locales suitable for installing solar photovoltaic power plants within the study areas. The techniques include the acquisition of wind speed data (1980–2020) from the National Aeronautic and Space Administration (NASA), development of multiple BWFM solutions (free and forced) depending on the presence and absence of forcing function, respectively. The forcing function represents the topographic and orographic features of the study areas. The spatial development of isopleth of the study areas, unveiled the isotachs. The wind speed gradients were obtained by scalar computation of 2-D wind speed gradients. Comparison of forced solution with the threshold or maximum free solution engendered the identification of windy locales. The results of the model were validated against NASA data. The average wind speed threshold isotach (2.83 m/s) and wind gradient ([Formula: see text]) for the study areas (All Regions) were established by scalar computation of free solution gradients. The study areas include Northern, Eastern, Central and Western Regions recorded the following maximum forced average wind speeds (2.725, 2.755, 2.875 and 1.794 m/s, respectively) and maximum wind flow gradients (insignificant, 0.03767, 0.08469 and infinitesimal [Formula: see text], respectively). These results are useful for identifying windy locales for installation of solar and wind facilities.
This research examined the performance of a roof type solar distillation system. A model was developed that captured the influence of the cover angle on still performance in terms of evaluating the heat transfer coefficient, yield and efficiency. The previous models of evaluating these matric has been shown to be unsatisfactory due to over prediction. The objectives are to clarify the misconception on the efficiency, to validate the derived expression for the Nusselt’s number of condensation under an inclined surface and to perform sensitivity analysis on the dimensionless parameters with derived models. The derived model has a practical significance because it provides much information on the dependence of the heat transfer coefficient on the cover angle. The model was solved with MATLAB, and results show a well correlated trends with the established work of literature and the proposed model having the lest efficiency as the model is without the over prediction inherent in other models due to non-inclusion of evaporation in the analysis of free convection of air. The peak yield of all the models occurs at about 11:00 AM, with the proposed model having a peak yield of about 0.045kg.
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