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Different heat transfer fluids with very high thermal stability are highly desirable for heat exchangers. Inadequate understanding on the basic principle of nanofluid flow, unsatisfactory experimental data on nanofluid heat transfer and general context for heat transfer correlation is yet to be established. The work under focus will be on highlighting working principles, problems hindering practical application of unconventional heat exchangers devices, and the various means of utilizing nanotechnology in improved efficiency. The study investigates experiments on heat exchangers in the last decade, the gap in knowledge and future applications of nanotechnology in improving heat transfer. This review summarizes, the significant advances of various nanotechnology in heat transfer application of recent energy conversion system.

In this study, the Typical Meteorological Year (TMY) data for six locations representing the 6 geo-political zones in Nigeria were generated and analyzed using the Sandia Method. The analysis shows that seasonal variations exist in all the selected locations indicating two distinct seasons: the dry and wet seasons with varying lengths from north to south of the country. Due to its high global radiation levels (21–25 MJ/m2/day), the North is a desirable location for solar-thermal systems. Also, the high monthly mean temperature variations (about 18°C), low relative humidity (15%) and constant wind speeds (4m/s) experienced in the first three months of the year aid the installation of wind energy systems and the application of evaporative cooling techniques that reduce the thermal load and energy consumption of buildings. On the other side, the high relative humidity (80%) and mediocre radiation values derived almost throughout the year in the South-west, South-east and South-south regions discourages the extensive application of evaporative cooling and solar energy based systems in such locations, but the moderate wind speeds (2.9 m/s) and monthly mean temperature variations associated with these regions between the first three months of the year allow for the application of natural ventilation and some passive cooling systems so as to reduce the thermal load of buildings in the regions. The information presented in this work can serve as a guide for design and selection of energy systems and application of energy-related projects in Nigeria.