Cooling is an energy-intensive process; and with the effects of global warming, space conditioning poses more load on the scarce and costly energy available for consumption in facilities. Thus, the use of a passive sub-ambient diurnal radiative cooler, which is an effective natural space cooling technology, can help reduce the total energy demand for buildings. A diurnal passive radiative cooler of 40 × 40 cm, has been designed, fabricated, and experimentally investigated. The cooler comprises a photonic solar reflector and thermal emitter made of titanium dioxide embedded in an epoxy resin that reflects 96% of insolation and emits strongly in the 8-13 µm atmospheric window. Design calculations were made under Owerri climatic conditions. The results obtained showed that when the cooler was exposed to direct insolation well above 950 W/m2 , it achieved a drop in temperature of 1-2 °C below ambient between 6 am and 9 am. As the solar radiation increased, the temperature of the cooler increased until it reached 41 °C, which was above the ambient air temperature (30 °C). The cooler temperature decreased as the solar radiation decreased, dropping below the ambient temperature from 5:45 pm, by 3 °C during the remaining hours of the investigation. The photonic radiative cooler has an estimated cooling power of 56.8 W/m2 under a clear night sky and achieved sub-ambient cooling during the early and late hours of the day under low solar radiation. Therefore, passive cooling through the photonic approach offers prospects for energy efficiency. Further works may have the prospects of achieving improved passive sub-ambient daytime cooling.

The increasing demands for low-fuel, highly efficient vehicles with low CO2 emissions have forced the auto-manufacturing industry and other researchers to continuously seek for innovative ways of improving engine performance and passenger comfort without sacrificing safety and increasing operational costs of vehicles. This study, which represents such innovative efforts, employed computational fluid dynamics (CFD) to analyze the flow variables of fluids flowing through a radial turbine, and the dynamic characteristics of the fluid within the turbine. The results obtained indicate that a radial turbine can be used to harvest and convert the waste exhaust gas energy from the internal combustion (IC) engine into useful work, as about 70% of exhaust gas energy was extracted with an isentropic efficiency of 84%.Under ideal operational situations, 59.77 kW of electric power can be produced by the electric generator coupled to the turbine. The study results also show that it is technically possible to provide a separate power source for engine accessories such as water and oil pumps, air conditioner compressors, cooling fans, and alternators in an automobile by using a radial turbine to harness the exhaust gas energy and convert it into useful work for the generation of electricity. This can be achieved by installing a radial flow turbine in the exhaust manifold of an IC engine of an automobile and coupling an electricity generator to the radial turbine shaft. This will serve as a good alternative to the use of expensive superchargers for extra energy requirements in automobiles for example in order to satisfy the energy demands for the automobile's accessories, for improved passenger comfort, with the possible reduction in the cost of fuel and impact of gas emissions to the environment together with a significant improvement in the automobile engine service life.