Cooking consumes a tremendous amount of energy on a regular basis. Solar energy is a very versatile and free energy source that could be used for different applications, including solar cooking. The aim this study is intended to experimentally investigate the effect of different reflectors on the performance of solar box cookers. Box-type solar cooker has been produced and tested with no reflector, aluminum foil reflectors, and mirror glass reflectors cases. Load and no-load tests have been conducted for all three reflector cases and the performances of cookers for each cases reflector have been determined. Several cooking tests was conducted in the outdoors, to investigate the thermal performance of the cooker using water as the absorbing medium. The results of the experimental demonstrate that, the cooker with three side mirror glass reflectors could reach a reasonably high temperature with better efficiency. 1.5 kg of water boiled in 51 min and its second figure of merit was found as 0.533 using mirror glass reflectors. The mirror glass reflector increases the efficiency of the experimental box-type solar cooker by 134% as compared with the cooker having no reflector. The experimental cooker with no reflector did not boil water during the testing period, so it is not recommended for cooking applications; whereas the cooker with the mirror glass reflector has been confirmed to cook most Ethiopian dishes with reasonable performance.

Metal–air batteries, such as zinc–air, are known for their high specific capacity and environmental friendliness. Operational longevity and energy efficiency, however, remain constrained by sluggish reaction kinetics, elevated overpotential, and interfacial instability during charge–discharge cycles. While noble metal catalysts have historically addressed these gaps, strategic resource allocation now prioritizes abundant, commercially reachable, and cost‐effective alternatives. Biomass, a sustainable resource, is crucial in the development of metal‐free heteroatom‐doped biomass carbon nanostructured electrocatalysts and porous air electrodes with excellent performance for such batteries. These novel materials emerge as critical enablers, leveraging inherent heteroatom density, tunable pore architectures, and the potential for transition metal doping and codoping to optimize bifunctional activity. They have also been identified as prospective alternatives for the next generation of bifunctional electrocatalysts for oxygen reduction and evolution reactions. This review provides a comprehensive overview of the potential of metal‐free heteroatom‐doped biomass carbon nanostructured electrocatalysts for the forthcoming generations of oxygen reduction and evolution processes, as well as bifunctional electrocatalysts and porous electrodes for zinc–air rechargeable batteries. The physicochemical features of these batteries, stabilization techniques for zinc electrodes, reaction processes, and the dynamic evolution of the electrolyte–electrode interface have also been conferred.

The rectangular channel louvered-fin compact heat exchanger (LFCHE) is the most efficient type that has been served in a radiator. However, with this type of heat exchanger, the pressure drop rises by three to four times as the heat transfer increases, which results in decreasing performance. This research is aimed to numerically investigate the louver edges (vertical, inclined, and horizontal) effect on LFCHE performance at different louver angle ($\theta$) with air inlet velocities ranging from 1 to 30 m/s. A total of twelve models are made and simulated. The result revealed that the horizontal edge decreases the pressure drop up to 24.2% with a 1.01% increase in outlet air temperature over the base model (inclined edge). Thus, louver edge has design which results in higher and lower effect on pressure drop and temperature change, respectively. The research investigated the effects of louver edges using different performance evaluation criteria. At 10 m/s (${Re}_{lp}$ = 972.33) the horizontal edge increases the volume goodness (jf) factor up to 21.49% over the base model. Similarly, the horizontal edged fins resulted in maximum increment of jf-factor by 22% and 25% as compared with inclined edge for louver angles $\theta$ of 24 $°$ (at low ${Re}_{lp}$) and 20 $°$ (at high ${Re}_{lp}$), respectively. Generally, the horizontally edged LFCHE is proven to have higher performance in cooling the coolant with a minimum air side pressure drop.