In developing countries, the four-stroke single-cylinder gasoline engine finds wide use. Motorcycles, tricycles and household machines like vegetable grinding machines are but a few of the machinery which run on this engine. Researchers have found that this engine is inefficient and consumes a lot of fuel, in light of sustainability and energy efficiency, this study aimed to perform an exergy analysis of a single-cylinder 4-stroke gasoline engine to determine how best its efficiency can be improved. Parameters such as brake thermal power, exergy efficiency, the quantity of exergy destruction and the component of the engine which is the most influential on its efficiency were determined while varying the engine's torque. A G200K1 Honda engine was used as the study material. At the lowest tested torque of 9.4Nm, a corresponding brake power output of 2.4609kW and efficiency of 17.07% was measured, while at a higher torque 9.70Nm, a corresponding brake power output of 2.5395kW and efficiency of 17.62% was measured. It was also found that for every 1.06% rise in torque there is a corresponding 1.80% rise in brake power and exergy efficiency. It was concluded from the findings that the bulk of energy waste in the system comes from the high-temperature gas released from the engine's exhaust. For the overall efficiency of four-stroke single-cylinder gasoline engines to be improved, the exergy destruction due to combustion should be minimised by optimizing the combustion temperature and reducing heat loss from the combustion chamber.

Polypropylene (PP) as thermoplastic has found use in the production of a variety of items due to its cheapness which is related to its ease of production. However, its usage is limited due to limitations inherent in its mechanical properties. On the other hand, the production of biosilica (BS) from rice husk ash is a relatively easy process and a cheap source for silica. This, therefore, makes the possibility of production of polypropylene-biosilica composite to further reduce the cost of PP and increase its wide range of applications a field of research. This research developed PP-BS composites with varying compositions of BS and tested their mechanical properties. The mechanical properties like tensile strength, flexural strength, toughness and hardness were experimentally determined using ASTM standard test methods. It was found that the addition of BS to PP does not significantly change its ultimate tensile strength. It was also found that the addition of biosilica to PP causes an average rise in other mechanical properties of the PP matrix-like Young’s Modulus and Flexural Modulus. Whereas, for other mechanical properties such as toughness and hardness, the addition of biosilica to the PP matrix caused an average decrease in these properties.