In this study, the heat transfer characteristics of a new class of nanofluids made from mango bark was numerically simulated and studied during turbulent flow through a double pipe heat exchanger. A range of volume fractions was considered for a particle size of 100 nm. A two-phase flow was considered using the mixture model. The mixture model governing equations of continuity, momentum, energy and volume fraction were solved using the finite-volume method. The results showed an increase of the Nusselt number by 68% for a Reynolds number of 5,000 and 45% for a Reynolds number of 13 000, and the heat transfer coefficient of the nanofluid was about twice that of the base fluid. In addition, the Nusselt number decreased by an average value of 0.76 with an increase of volume fraction by 1%. It was also found that there was a range of Reynolds numbers in which the trend of the average heat transfer coefficient of the nanofluid was completely reversed, and several plots showing zones of higher heat transfer which if taken advantage of in design will lead to higher heat transfer while avoiding other zones that have low heat transfer. It is hoped that these results will influence the thermal design of new heat exchangers.

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A two-dimensional along the channel micro-scale isothermal model of a SOFC is developed and validated against experimental data and other simulated results from literature. The steady state behaviour of the cell was determined by numerical solution of the combined transport, continuity and kinetic equations. An important characteristic of the model is the consideration of the triple phase boundary as a distinct layer. The model is capable of predicting the cell performance including polarisation behaviour and power output. The model is used to study the effect of the support structure, geometric parameters and the effect of operating conditions on cell performance. Several parametric studies include the effect of operating conditions and geometric parameters on cell performance with a view to optimising the cell. The simulation results showed that the anode supported SOFC displayed the best performance with the activation and ohmic overpotentials being responsible for most of the voltage losses in the cell.

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A significant amount of energy gets lost through the exhaust of simple gas turbine plants, more often than not, this energy can be used to run another power cycle or a combined heat and power setup, leading to an increase in the overall efficiency of the plant, reduce air pollution and energy wastage. In this study, a retrofitted performance analysis of incorporating a steam power cycle to the existing gas turbine cycle in Delta IV power station is carried out, the analysis is carried out using first law of thermodynamics and energy cost comparison to describe the effect of combining both cycles on power output, thermal efficiency and energy cost. Operating data were obtained from existing gas thermal plant in Ughelli (Delta IV) and steam thermal plant in Lagos (Egbin). Preliminary assessment shows that power output increases by a further 51.5MW, thus raising the overall combined efficiency to 41.85%. Analysis on cost savings accruable from incorporating a heat recovery steam generation was also done and significant savings in cost was obtained.