This study carried out a comparative analysis of the rates of production of biogas from various organic wastes and weeds which enabled the determination of optimal ratio of poultry droppings to domestic wastes. Digester was prepared for the anaerobic fermentation of the domestic wastes and weeds. The gas production did not begin until the 7th day and increased steadily at first, and then increased sharply until it reached its peak on the 18th day before declining. The total gas produced within the 22days of experimentation was 1771cm3. The maximum volume of gas amounting to 809cm3 was produced by the sample containing 50% poultry dropping and 50% weeds. This indicates that this sample possesses the best C/N ratio of all the samples prepared. For restarted digester, gas production began on the 2nd day as against the 7th day with no restarted digester and the gas production peaked earlier

This research was performed to optimize the performance characteristics of the Nigerian Jebba Hydropower Plant in order to enhance its generation of electricity. Pertinent hydropower data were hourly collected from the plant from 8:00 am to 5:00 pm between 2016 and 2018. The coefficient of determination obtained from the response surface methodology (RSM) showed that discharge, pressure drop, stator temperature and water pressure strongly influenced the generation of estimated power. Also, the contour and surface plots suggested that the discharge (D) 8200.00–8600.00 m³/s and pressure drop (Pd) ranging from 27.50–28.50 m gave the optimal power generation indicating that both factors must be kept high when the hydropower plant is in operation. The instability of power generation was attributed to the reduction in the net available head as turbine inlet decreased. The study, therefore, showed that net power output, speed of the turbine, and efficiency of the hydropower plant could be optimized with increase discharge and gross head. Predicted optimal values for discharge, pressure drop, stator temperature, and water pressure were 8783.3667 m³, 28.59 m, 58.00°C, and 31.00 N/m² respectively.

This paper presents performance analysis of a domestic refrigeration system using R600a as refrigerant. Investigation was conducted experimentally to select an appropriate refrigerant mass charge for the system and to compute the cooling system performance characteristics under ambient temperature of 29°C. The choice of the hydrocarbon refrigerant (R600a) became so imperative due to notable influence of chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) on global warming and ozone depletion. UNFCCC and Montreal Protocol regulation have banned the use of halogenated refrigerants in cooling and heating systems. The paper reveals that the power consumed by the system using mass charge of 15 g refrigerant was reduced by 9.3 and 10.9% compared with the 10 and 25 g refrigerant mass charges respectively. In addition, the results show that the coefficient of performance (COP) of the refrigeration system while working with 15 g is 24.7 and 20.2% higher than when the system worked with 10 and 25 g refrigerants mass charge respectively. More so, the system attained an evaporator air temperature of -12 °C in 2 hours, which makes 15 g charge refrigerant appropriate for the running of the developed system that has a volume capacity of 68 liters.

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.