The importance of heat transfer by natural convection in enclosures can be found in many engineering applications, such as energy transfer in buildings, solar collectors, nuclear reactors and electronic packaging. An experimental study was conducted to investigate heat transfer by natural convection in a rectangular fin plate with circular perforations as heat sinks. The patterns of the perforations included 24 circular perforations (holes) for the first fin; the number of perforations increased by eight for each fin to 56 in the fifth fin. These perforations were distributed in 6-14 rows and four columns. Experiments were carried out in an experimental facility that was specifically designed and constructed for this purpose. It was observed that the temperature along the non-perforated fin dropped from 30 to 25°C, but the temperature drop for the perforated fins was from 30 to 23.7°C at low power (6 W). The drop in temperature between the fin base and the tip increased as the diameter of the perforations increased. The temperature drop at the highest power (220 W) was from 250 to 49°C for the nonperforated fin and from 250 to 36°C for the perforated fins. The heat transfer rate and the coefficient of heat transfer increased with an increased number of perforations.

Biodiesel from waste sources can be considered as the cheapest and most viable fuel alternative to depleting mineral diesel. In this work, biodiesel has been produced from different sources of waste oil; grilled chicken waste oil (GCWO) which is animal based source and waste cooking oil (WCO) which is vegetable based using transesterification method. The impact of different variables such as temperature, transesterification time, and amount of catalyst on the conversion and yield of biodiesel were investigated. Produced biodiesel was characterizes using ASTM standard methods for biodiesel property testing to determine the fuel properties including; kinematic viscosity, specific gravity, flash point, pour point, cloud point and acid number. Engine test has been conducted at increasing speed and constant load to evaluate the engine performance using the produced fuel. The results obtained indicate that the yield and conversion of bio-diesel from grilled chicken waste oil are greater than waste cooking oil. Both produced biodiesel fuel properties are within the standard biodiesel fuel specifications ASTM D6751. The maximum conversion and yield of biodiesel obtained by 97.76% and 94.4% suing GWCO and WCO respectively at optimum operating variables of 600C temperature, 3 h reaction time, and 0.4 wt% potassium hydroxide. Engine test results show similar trends for both biodiesels compared to diesel in term of engine brake power (BP) and brake specific fuel consumption (BSFC) with increasing engine speed. The maximum reduction in BP is found to be about 19% at 2400 rpm and a maximum increase in BSFC of 17% is obtained at 1800 rpm engine speed with both biodiesels compared to diesel fuel. Accordingly, though both biodiesels show comparable engine performance, GWCO presents higher biodiesel yield.

This study focuses on perforated pin fin convection heat transfer. This study's goal is to see if perforated pin fins may help transmit heat. Perforation diameter and hole count are evaluated on each pin. The Nusselt number of perforated pins is 47% higher than solid pins, and it increases with perforation count. Unperforated solid pins have a 19% lower pressure drop. Using pin fins with circular holes as heat sinks, we examined forced convection heat transfer. There were circular perforations. They were conducted in a specifically designed laboratory. At low power, non-perforated fins lose 35 to 31 degrees Celsius, while perforated fins lose only 29.8 degrees (50 W). At 55°C, unperforated fins hit 55°C at full power, while perforated fins hit 38°C (600 W). The model had 16 pin fins and was built of aluminum alloy. When compared to solid pin fins, perforated fins were found to be the best way to improve heat transfer because they were 40% lighter and improved thermal efficiency by 30% to 85% by increasing the Nusselt number and the convective heat transfer coefficient and reducing the pressure gradient.