Just like other solar cookers, the solar box cooker needs energy gotten from the sun to operate without producing emissions. In this research, a solar box is fabricated to reduce over-dependence on fossil fuel for energy generation. This reduces the environmental degradation caused by the use of other sources of energy. The ASHRAE empirical model was used to obtain the solar irradiance present in Omu-Aran metropolis. Thereafter, the no-load and load test was conducted to determine the cooker’s thermal performance. The tests were conducted between January 2018 and January 2019 in Landmark University, Omu-Aran, Kwara State, Nigeria with geographical coordinates 8° 8’ 0” North, 5° 6’ 0” East. The average energy and exergy efficiency of the cooker were 32°C and 28°C respectively. A decrease in the efficiency of the cooker was observed. This was because the reflector, which is made from aluminium foil, was degrading. As a result of this degradation caused the sun rays (radiation) to be reflected poorly into the absorber and also caused a myth of overcast sky. Meanwhile, the variation in solar radiation during the sensible heating test resulted in the fluctuation inefficiency. The ratio of water to absorber temperature which was above 0.80 during the pre-boiling heating process indicates that the cooker can be recommended for sterilization.
The present study investigates mixed convective and fluid flow characteristics in a lid-driven enclosure filled with air and its walls subjected to various heating conditions. The vertical (left and right) walls of the enclosure are cooled (Tc), and the bottom wall is heated to (Th) while the horizontal lid-driven upper wall is subjected to sinusoidal heating. The dimensionless governing equations (continuity, momentum, and energy transport) were implemented in COMSOL Multiphysics 5.4 software. The influences of Grashof number (103 ⩽ Gr ⩽ 105
) and Reynold number in the interval of 1 ⩽
Re
⩽ 100 on the average Nusselt number ( NU ) for all walls of the cavity was examined. Furthermore, the results presented in the form of isotherms, streamlines, and the local and average Nusselt numbers in the enclosure for
Re ⩽ 100 and
Gr
in the range of 103
⩽
Gr
⩽ 105
. The results indicated the highest and lowest average rate of heat transfer at the bottom and top walls of the cavity respectively. The top wall region presented a higher velocity as confirmed by the velocity contour plots.
Cellar workplaces are considered as confined environment with challenging indoor air quality having higher than normal pollutants particularly that of soil gas origin. Radon, a major soil gas, infiltrates and accumulates within indoor spaces and becomes harmful in the absence of ventilation. Radon level in bank basements (cellars) in Ilorin, Lagos and Akure have been sampled and analysed in this study. In Nigeria, most workers in basements are unaware of radon, and there is limited documented research on its health hazards. The survey parameters of radon concentrations were floor types, geographical locations and the influence of atmospheric conditions. Corentium monitor, a continuous, digital radon monitor, temperature meters and Prologue wireless weather station were used for the experiments. Annual average indoor radon concentration for the survey period was 23 Bq/m 3 . The calculated mean annual effective doses in basements and different floors were below the recommended ICTR level of 3 mSv/y.
The paper presents an experimental determination of indoor conditions for human thermal comfort for four different structural positions in Ilorin, Kwara State, Nigeria. The Fanger's model was used to determine the optimum productivity level of occupants of the location under investigation. Experimental results and heat balance equation were coupled to determine the heat loss due to regulatory sweating in the zone. The results show the relationship between structural positions, skin temperature and ambient temperature of the enclosed space. For thermal comfortability, the expected indoor conditions for people sitting relaxed in their parlours, offices, and students receiving lectures should be 22°C and a relative humidity of 59.6% while for offices where documentations and businesses are done in seated and typing structural positions, a temperature of 21°C with a relative humidity of 59.3% are required for optimum productivity.
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