Aluminum alloy are gaining huge industrial significance because of their outstanding combination of mechanical, physical and tribological properties over the base metal. Alloying elements are selected based on their individual properties as they impact on the structure and performance characteristics. The choice of this modifier affects the materials integrity in service resulting to improved corrosion, tribological and mechanical behavior. Hence, the need to understand typically the exact inoculants that could relatively impact on the low strength, unstable mechanical properties is envisage with the help of liquid stir casting technique. In this contribution, sufficient knowledge on Al alloy produced by stir casting will be reviewed with close attention on how the structural properties impact on the mechanical performance.

The negative influence of refrigerants on the climate and the immediate environment in terms of their higher global warming potential (GWP) and ozone depletion potential (ODP) has prompted this study. Currently, natural refrigerants are the preferred alternative refrigerants and hydrocarbon is numbered among these natural refrigerants with zero ODP and negligible GWP. In order to improve and enhance the performance of the refrigeration system, the performance characteristics of the system were investigated experimentally using eco-friendly refrigerant HC600a as alternative to HFC134a. In addition, comparisons were made using refrigerant mass charge of 46 g of isobutane (HC600a) and 70 g of conventional refrigerant (HFC134a). Thermodynamic parametric analysis was conducted using electric power consumption, coefficient of performance (COP), cooling load and pull-down time (PDT) for the used mass charges. REFPROP software was applied to capture the thermodynamic properties of the vapour compression system (VCS). The results showed that the COP increased by 32.2 % when using 46g charge of hydrocarbon refrigerant with energy reduction of 4.5 %. Furthermore, the vapour compression system while using 46 g of isobutane (HC600a) attained an evaporating temperature of -21 °C in 60 minutes while 70 g of HFC134a attained the same temperature in 2 hours 15 minutes, which makes HC600a alternative refrigerant to run in the traditional refrigerator.

The inability of metals to resist degradation as a result of corrosion remains a unique global problem that depend on different metals for daily operations. Therefore, knowing the appropriate method to use is a key to ameliorate corrosion effect on metals. Green inhibitors serve as a modern, cheaper and environmentally favorable method to retard the effects of corrosion. Drugs are corrosion inhibitors which can reduce the action of corrosion without being hazardous to the environment as they are synthesized from natural products. The review studies the metal protection techniques and the use of drug as corrosion inhibitors. The importance of copper as a useful metal as good corrosion resistance due to inherent properties alongside its malleability was also discussed.

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