Conjugate Heat Transfer for a Vertical Flat Plate with Heat Generation Effect

The heat generation effect on natural convection flow along and conduction inside a vertical flat plate is investigated. The developed governing equations with the associated boundary conditions for this analysis are transferred to dimensionless forms using a local non-similar transformation. The transformed non-linear equations of the non-dimensional equations are then solved using the implicit finite difference method with Keller box-scheme. Numerical results are found for different values of the heat generation parameter, conjugate conduction parameter and Prandtl number. The overall investigation of the velocity, temperature, skin friction and heat transfer rate are presented graphically

TIG torch surfacing of metallic materials - a critical review

This article aims to review and highlight the significant features and development of tungsten inert gas (TIG) torch surfacing of metallic materials. The emphasis is on the surfacing method for metallic materials using a melting processing route. The fusion surfacing methods such as powder injection, wire feed and pre-place powder are elaborated. The comparisons of TIG torch surfacing methods to electron beam welding, laser cladding and thermal spraying are tabulated to give a better understanding of each surfacing method. The application of TIG torch surfacing techniques on various metallic materials is reviewed based on a number of studies from previous researchers. The significance of processing variables of TIG torch surfacing techniques is highlighted with the heat input and welding speed being the most influential factors. This paper also shows the potential application of TIG torch surfacing for the hybridisation of composite coated hard surface layer formation in metallic materials

Sugar palm starch biopolymer: extraction and processing

Chapter 3 describes the extraction and processing of sugar palm starch (SPS) biopolymer. A systematic step for extracting the starch using an alkaline method followed by hydrolysis using protease is explained. A modified method using antimicrobial agents is also presented which provides shorter soaking times with less enzyme and shorter centrifugation time during extraction. It was found that the process of extracting starch from the stem of the sugar palm is the same as the process of extracting commercially available starch from the sago palm. It was postulated that SPS can behave like thermoplastic starch in the presence of glycerol whereby glycerol has been widely used as plasticizer due to its good behavior as an additive to the starch

Hard-hydrophobic nano-CuO coating via electrochemical oxidation for heat transfer performance enhancement

The heat transfer performance of a material is mainly affected by the surface-to-volume ratio and specific surface area. This paper presents an evaluation of hard-hydrophobic nano-CuO coating on the heat transfer performance of copper. Granular coating consisting of nano-sized CuO grains was developed using the electrochemical oxidation method in 0.1 M oxalate solution at ambient temperature. The nano-CuO coating was characterized using electrical resistivity meter, X-ray diffraction, energy-dispersive X-ray Spectroscopy, cyclic voltammetry and field emission scanning electron microscopy. The average grain size of the coated material was 47 nm with an average coating thickness of 13 μm. The nano-CuO-coated samples’ thermal resistance was lower than that of the uncoated specimens with an increment in thermal conductivity. The nano-CuO coating demonstrated a hard coat with a hydrophobic characteristic feature on the surface. The maximum coatings hardness attainment was 178 H.V. The nano-coating also enhanced the efficiency of heat transfer (∆Q%) by ~ 95%. This enhancement was due to the increase in the specific surface area by 272 times, which in turn increased heat transfer performance across the nano-coated surface by about 22 times compared to the uncoated surface. This result confirmed the feasibility of this current hard-hydrophobic nano-CuO coating for enhancement of hardness, hydrophobicity, and heat transfer performance of the copper material in cooling and heating technology, especially for the reduction in the required size of heat transfer equipment, increasing reliability, and improvement of surface protection characteristics

Experimental investigation on properties of hybrid nanofluids (TiO2 and ZnO) in water–ethylene glycol mixture

This paper presents an experimental investigation on properties and stability of hybrid nanofluids (TiO2 and ZnO) in water-ethylene glycol mixture. The nanofluids are important in heat enhanced due to its inherent operative performance. The performance of hybrid nanofluids in mixture based fluids is not explored vigorously yet. The properties of TiO2 and ZnO nanoparticle dispersed in mixture of water and ethyelene glycol (EG) were considered in this study. The outcome of base fluid proportion (water: EG) to hybrid nanofluids was investigated. Hybrid nanofluids with different volume concentration up to 0.1-1.5% were prepared with 21nm particle size of TiO2 and 10-30nm ZnO nanoparticle. The nanoparticle were suspended in various ratio of TiO2 : ZnO including 70:30, 80:20 and 90:10 by volume percent. The measurements of viscosity were performed using Brookfield LVDV III Ultra Rheometer for hybrid nanofluid temperature of 50 to 70 oC, while the measurements of thermal conductivity were performed using KD2 PRO thermal conductivity. Viscosity and thermal conductivity of hybrid nanofluids were perceived to impact by hybrid nanofluids concentration, temperature and waterethelene glycol as base fluid strongly

Nitride alloy layer formation of duplex stainless steel using nitriding process

Duplex stainless steel (DSS) shows a good corrosion resistance as well as the mechanical properties. However, DSS performance decrease as it works under aggressive environment and at high temperature. At the mentioned environment, the DSS become susceptible to wear failure. Surface modification is the favourable technique to widen the application of duplex stainless steel and improve the wear resistance and its hardness properties. Therefore, the main aim of this work is to nitride alloy layer on the surface of duplex stainless steel by the nitriding process temperature of 400°C and 450°C at different time and ammonia composition using a horizontal tube furnace. The scanning electron microscopy and x-ray diffraction analyzer are used to analyse the morphology, composition and the nitrided alloy layer for treated DSS. The micro hardnesss Vickers tester was used to measure hardness on cross-sectional area of nitrided DSS. After nitriding, it was observed that the hardness performance increased until 1100 Hv0.5kgf compared to substrate material of 250 Hv0.5kgf. The thickness layer of nitride alloy also increased from 5μm until 100μm due to diffusion of nitrogen on the surface of DSS. The x-ray diffraction results showed that the nitride layer consists of iron nitride, expanded austenite and chromium nitride. It can be concluded that nitride alloy layer can be produced via nitriding process using tube furnace with significant improvement of microstructural and hardness properties

Natural and industrial origin reinforced LM6 aluminum composite materials – A comparative study

Aluminum alloy is one of the most common and basic metallic alloys used as a composite material due to its higher strength-to-weight ratio, thermal conductivity, stiffness as well as wear and corrosion resistance properties. Aluminum based composite materials have become an obvious entry into many industries such as automobile, aerospace, construction, household appliances, and food packaging industries. The commonly reinforcement materials to fabricate aluminum composites are aluminium oxide, silicon carbide, boron carbide, boron nitride, titanium carbide, tungsten carbide and titanium diboride. However, most of the ceramic based reinforcement materials are expensive and not environmentally or human friendly. Recent research has been tailored to the use of industrial waste as a reinforcement for aluminum composites such as slag, red mud, fly ash, arc furnace dust and waste glass. The use of natural materials such as glass and marble waste is promising which also cheaper than conventional ceramic reinforcement and also might enhance the properties of the composite. Therefore, the aim of this study is to compare LM6 aluminum- matrix composite with two different types of new reinforcement materials. This paper present experimental work on the new synthesized composite using 5% marble wastes as a natural reinforcement and 5% graphene oxide as an industrial origin reinforcement with LM6 aluminum with the results from laboratory tests on mechanical characterization like tensile strength, hardness and impact test. Elemental analysis and microstructure properties using optical microscope and SEM as well as XRD and EDS

Efficacy evaluation of empty palm oil fruit bunch compost in improving soil characteristics, plant growth and disease suppression of tomato plants under tropical acid soils

Aim: Tomato is one of the most important crops worldwide as it is the second most important vegetable in the world after potato. A study was conducted to investigate the efficacy of empty fruit bunch (EFB) compost in improving soil characteristics, plant growth and disease suppression of tomato plants under tropical acid soil. Methodology: Twelve tomato seedling cv MT-11 were transplanted on each planting bed. The growth of tomato plant was assessed based on plant height, leaf area, dry matter weight and incidence of bacterial wilt disease. Soil sampling was done at 45 and 60 day after transplanting (DAT) for physio-chemical and microbial properties. Results: Applying EFB compost increased plant height, leaf area, dry matter accumulation, and suppressed development of bacterial wilt disease compared to using chicken manure. A higher disease reduction (16.7 %) occurred with 15 mg ha⁻¹ EFB compost, followed by 22.5 mg ha⁻¹ EFB compost (14.3 %), and 7.5 mg ha⁻¹ EFB compost (8.33 %). Interpretation: Organic amendment in tomato cultivation affects soil properties, plant development and disease suppression. Application of EFB compost at 15 mg ha⁻¹ appeared as the best treatment soil amendment in tomato cultivation under tropical acidicsoil condition

Wear behaviour at 600°C of surface engineered low-alloy steel containing TiC particles

The work aimed to develop surfaces that could resist wear at high temperatures, thus achieving a prolonged component life. Surface modification of a low-alloy steel by incorporating TiC particles has been undertaken by melting the surface using a tungsten inert gas torch. The dry sliding wear behaviour at 600°C of the original and modified surfaces was compared. Microscopic examination of both surfaces showed glazed layers across the wear tracks, with differing amounts of oxide and homogeneity. Extensive wear occurred on the steel surface, which showed deformation of the wear scar tracks and a steadily increased friction coefficient. The TiC addition reduced the wear loss, coinciding with a glazed layer 33% thinner than that on the low-alloy steel sample