Overall Assessment of Heat Transfer for a Rarefied Flow in a Microchannel with Obstacles Using Lattice Boltzmann Method

The objective of this investigation is to assess the effect of obstacles on numerical heat transfer and fluid flow momentum in a rectangular microchannel(MC).Two distinct configurations were studied:one without obstacles and the other with alternating obstacles placed on the upper and lower walls.The research utilized the thermal lattice Boltzmann method(LBM),which solves the energy and momentum equations of fluids with the BGK approximation,implemented in a Python coding environment.Temperature jump and slip velocity conditions were utilized in the simulation for the MC and extended to all obstacle boundaries.The study aims to analyze the rarefaction effect,with Knudsen numbers(Kn)of 0.012,0.02,and 0.05.The outcomes indicate that rarefaction has a significant impact on the velocity and temperature distribution.The presence of nine obstacles led to slower fluid movement inside the microchannel MC,resulting in faster cooling at the outlet.In MCs with obstacles,the rarefaction effect plays a crucial role in decreasing the Nusselt number(Nu)and skin friction coefficient(Cf).Furthermore,the study demonstrated that the obstacles played a crucial role in boosting fluid flow and heat transfer in the MC.The findings suggest that the examined configurations could have potential applications as cooling technologies in micro-electro-mechanical systems and microdevice applications.

Evaluation of Mechanical and Microstructural Properties of <i>α</i>-Brass Alloy Produced from Scrap Copper and Zinc Metal through Sand Casting Process

Cu-Zn alloy (Brass) is widely used as an industrial material because of its excellent characteristics such as high corrosion resistance, non-magnetism and good forging ability. This paper evaluates the mechanical and microstructure properties of α-brass alloy gotten from scrap copper and zinc metal, and compares the properties with normal α-brass billets. Five different compositions of the α-brass alloy (Cu-5%Zn, Cu-10%Zn, Cu-15%Zn, Cu-20%Zn, Cu-30%Zn) were produced from scraps of copper wire and zinc batteries casing respectively by method of sand casting. The parts of the cast rods were machined to a specification of 60 mm × 100 mm × 300 mm on a lathe to obtain tensile test specimens. After homogenization annealing, the samples were heated in an electric furnace at 500℃ for 3 hours. The samples were etched with ferric chloride solution for 20 seconds and sent for metallographic examination. The result of the hardness test shows variation in hardness of the cast Cu-Zn alloys with increasing zinc content. The ductility and elongation of the α-brass decrease with increasing zinc content. The colouration of the α-brass changed from red to yellow as the zinc content increases. In conclusion, hard brass can be obtained from recycled Cu and Zn as compared to normal brass billets.

Development and Optimisation of Drying Parameters for Low-Cost Hybrid Solar Dryer Using Response Surface Method

After harvest and storage problems are major dilemma, which requires to be looked into carefully in developing nation like Nigeria. This paper presents a development of low-cost hybrid solar dryer for food preservation with the objective of setting optimum drying parameters for the preservation of cassava and tomato products. The work was carried out by designing, constructing and finally evaluating the hybrid dryer for effective performance. The optimization of the drying parameters was done using composite technique (Response surface method). The assessment of the dryer shows that 150 Kg cassava mesh and 5000 grams of tomato with 35% and 94% moisture content, respectively were dried to 100 Kg and 334 g with 10% moisture level for 4 hours and 11 hours respectively, for cassava and tomato. The optimization result shows that the dryer will perform optimally with drying temperature of 62°C and 48°C for cassava and tomato respectively with 24% and 91% moisture uptake. Therefore, sustainable techniques for preservation of food are essentially required. Hybrid solar dryer is an alternative to consider in the situation.

Characterization of Phosphide Platelets in Eutectic Sand Cast Cu-Sn-P Alloy

A procedure for evaluating the degree of spheroidization of phosphide platelets in cast Cu-4%Sn- 5%P alloys using fractal analysis was investigated. The specimens were obtained by melting copper and tin in an improvised clay mould raised to a temperature of 1850&degC ± 20&degC, holding for a period of 10 minutes to 1 hour to modify the aspect ratio of the phosphide platelets. It was found that these platelets have the tendency to change their shape from being spherical to more Euclidian shapes as time elapses. It was found that the inter-platelets distances are approximately equal with time. This effect was more pronounced in samples with high holding time.

Sustainable Biocomposites Materials for Automotive Brake Pad Application:An Overview

Research into converting waste into viable eco-friendly products has gained global concern.Using natural fibres and pulverized metallic waste becomes necessary to reduce noxious environmental emissions due to indiscriminately occupying the land.This study reviews the literature in the broad area of green composites in search of materials that can be used in automotive brake pads.Materials made by biocomposite,rather than fossil fuels,will be favoured.A database containing the tribo-mechanical performance of numerous potential components for the future green composite was established using the technical details of bio-polymers and natural reinforcements.The development of materials with diverse compositions and varying proportions is now conceivable,and these materials can be permanently connected in fully regulated processes.This explanation demonstrates that all of these variables affect friction coefficient,resistance to wear from friction and high temperatures,and the operating life of brake pads to varying degrees.In this study,renewable materials for the matrix and reinforcement are screened to determine which have sufficient strength,coefficient of friction,wear resistance properties,and reasonable costs,making them a feasible option for a green composite.The most significant,intriguing,and unusual materials used in manufacturing brake pads are gathered in this review,which also analyzes how they affect the tribological characteristics of the pads.

Optimisation of Hybrid Energy System Production Parameters for Electricity Power Generation in Nigeria

Solar and wind energy are two of the most viable and sustainable sources of energy due to the tendency of renewal. The power generating supplies in Nigeria appear unreliable, rapidly diminishing and expensive. Researches are sparse on operating both energy sources alongside fossil fuel for power generation in order to take advantage of their complementary characters. The aim of this study is to explore renewable sources combined with non-renewable source to generate electricity with the objective of establishing an optimal design for a hybrid solar-wind-diesel energy plant that minimizes cost. The capacity factor of the standalone system was determined for the study area. The cost of energy for the hybrid optimal mix was determined. Levelised cost of energy was also used to determine the cost of energy for standalone power system. The result shows that the energy generated 200 MW hybrid system is 392 GWh with a cost of energy of $0.24/kWh (47.8/kWh). The energy produced can power 39,200 homes in a year. The optimisation shows that the number of solar system, wind and diesel are 699, 1 and 300 respectively. The cost of energy for the standalone system was $0.06/kWh, $0.08/kWh and $0.27/kWh for wind, solar and diesel system. The capacity factor was 56%, 21% and 80% for wind, solar and diesel system. There is a reduction in the amount of greenhouse gases released to the environment alongside with cost of energy generation. Hybrid power generation system is good and effective solution for power generation than conventional energy resources.

Effect of Media Material on Biogas Production

The paper investigates the effects of the quantity of media materials with simple appraisal on biogas yields between hard and soft wood subjected to the same atmospheric condition in the Ado-Ekiti, Nigeria, between October 2009 and June 2010. Sixteen digesters were used and the mechanical grinding of cassava peels was done in a clean mortar and pestle. Specific grammes of cow dung and cassava peels (200 g, 150 g, 100 g and 50 g) were seeded with four substrates (woods) mixed up with 1200 cm3 of distilled water respectively. The appropriate ratios of the prepared slurries were transferred into different digesters for bio-degradation process which is third-fourth full with the aid of a funnel, and the tubes were passed into a measuring cylinder as a gas collector?inverted over acidified water in a plastic vessels. The volume of biogas produced ranged from 6964 cm3 to 13,185 cm3 by Mahogany, and Iroko ranged from 5340 cm3 to 10,250 cm3 were obtained for both hard woods used. Likewise, the volumes of gas produced by soft woods were from 2465 cm3 to 6445 cm3 by?Obeche and 3430 cm3 to 6990cm3 by Araba. The results showed that, the highest percentage of the seedling media materials (33% each) on the substrates (cassava peel and cow dung) produced the highest biogas with 2800 cm3 of Mahogany, 2400 cm3 of Iroko, 1200 cm3 of Araba and 1130 cm3 of Obeche woods respectively. It was established that, the rate of biogas yields is directly proportional to the quantity of the seedling materials to obtain a reliable results as an alternative renewable energy.