Investigative Study on Emissions Level and Cost Analysis of Diesel Powered and Solar PV-Diesel Hybrid Systems

In this work, a comparative study on emissions and cost implications of diesel powered and solar photovoltaic-diesel hybrid systems was carried out for three commercial banks. With the aid of HOMER Pro software, meteorological data, energy demand, system component data, capital and operating costs were used for analysis of the two systems. The results showed that in Bank A, the diesel generator alone releases 111,618 kg/yr of Carbon dioxide while the hybrid system releases 41,618 kg/yr of Carbon dioxide. For Bank B the quantity of carbon dioxide emissions released from the diesel generator in Bank B is 53,830 kg/yr, while the carbon dioxide released from the hybrid energy system is 24,082 kg/yr. For Bank C, the diesel generator alone released 177,799 kg/yr of Carbon dioxide and 129,060 kg/yr of carbon dioxide was released from the hybrid system. This suggests that the diesel generator alone releases more emissions when compared with the hybrid system in all the three banks. The Net present cost of energy and levelized cost of energy were used to find out the cost effectiveness of hybrid systems. The results showed that the levelized cost of energy for the generator alone and hybrid system, respectively in Bank A is $0.713 and $0.343. While for Bank B, it is $0.568 and $0.2553. Finally for Bank C, it was $0.731 and $0.556. Therefore, solar-diesel hybrid system has a comparatively low emission and can be considered as a more economical option for electricity generation.

Performance Assessment of Installed Solar PV System: A Case Study of Oke-Agunla in Nigeria

Solar Photovoltaic (PV) can be considered as one of the most reliable and promising renewable systems. This is of great importance for developing countries like Nigeria especially in the rural communities where there is little or no access to electricity. The use of solar energy will no doubt contribute to the improvement of the living conditions of these villagers. Solar PV systems have been installed in some villages in Nigeria but unfortunately, the expected benefits from using these systems have been jeopardized. The objective of this work is to embark on performance assessments of in- stalled Solar PV system in Oke-Agunla, Akure local government of Ondo State in Nigeria. Visits were conducted to the village;equipments on ground were examined while the people were interviewed. Both functional and non-functional facilities were traced to their manufacturers using the identification data on them and rated to ensure their efficiencies. Energy demands were also prorated, and observed the need to improve on the present energy supplied. Results of the assessments shows that PV facilities used were inadequate, trained technicians were not available giving room for quacks working on the facilities occasionally resulted in further complications and poor facilities maintenance. The assessment result shows that just 14.52% of the 4.5 kW installed solar PV was utilized due to significant malfunctioning and deterioration in performance. It can be concluded from this study that the installed solar PV systems was inefficient as a result of poor maintenance, lack of technical know-how and inability of the project contractors or managers to take these factors into consideration while embarking on the solar PV installations.

Runge-Kutta Schemes Coefficients Simulation for Comparison and Visual Effects

Runge-Kutta scheme is one of the versatile numerical tools for the simulation of engineering systems. Despite its wide and acceptable engineering use, there is dearth of relevant literature bordering on visual impression possibility among different schemes coefficients which is the strong motivation for the present investigation of the third and fourth order schemes. The present study capitalise on results of tedious computation involving Taylor series expansion equivalent supplemented with Butcher assumptions and constraint equations of well-known works which captures the essential relationship between the coefficients. The simulation proceeds from random but valid specification of two out of the total coefficients possible per scheme. However the remaining coefficients are evaluated with application of appropriate function relationship. Eight and thirteen unknown coefficients were simulated respectively for third and fourth schemes over a total of five thousand cases each for relevant distribution statistics and scatter plots analysis for the purpose of scheme comparison and visual import. The respective three and four coefficients of the slope estimate for the third and fourth schemes have mix sign for large number of simulated cases. However, none of the two schemes have above three of these coefficients lesser than zero. The percentages of simulation results with two coefficients lesser than zero dominate and are respectively 56.88 and 77.10 for third and fourth schemes. It was observed that both popular third and fourth schemes belong to none of the coefficients being zero classification with respective percentage of 0.72 and 3.28 intotal simulated cases. The comparisons of corresponding scatter plots are visually exciting. The overall difference between corresponding scatter plots and distribution results can be used to justify the accuracy of fourth scheme over its counterpart third scheme.

Numerical Analysis of Thermo-Elastic Contact Problem of Disc Brakes for Vehicle on Gradient Surfaces

In this study, the thermo-elastic effects of frictional heat generation in a disc brake system due to braking actions were simulated. The mathematical model that defined the problem was developed from the kinetic and potential energies of moving vehicles on the gradient surfaces. This problem was solved for the selected geometry of disc brake and pad with their material properties selected from existing literatures using the finite element method and the computational results were obtained. The thermal deformation obtained was in good agreement with similar literature results. Also, for the same braking period and conditions, the results showed that a vehicle ascending a hill gave a higher temperature rise, Von Mises stress and thermal deformation on brake contact surfaces than when descending hill. Therefore, the braking period required to bring a moving vehicle in ascendent motion to a lower speed is expected to be shorter because of the gravity effect than horizontal motion, while descendent motion requires longer braking period.