Heoy Geok How

The present study investigated the geometrically necessary dislocation (GND) with the influence of the surface roughness by establishing the relation of roughness in GND for indentation. The single crystal copper with (111) oriented surface plane was chosen and polished to various roughness levels ranging from 32.7 to 224 nm and subjected to indentation. The increase in surface roughness revealed to increase in the GND and statistically stored dislocation density. As the indentation force decrease from 9.8 to 0.245 N, the plastic strain gradient related to GND increase from 0.0001 up to 0.0017 µm⁻¹ for each 1 nm increment of surface roughness.

The key feature of air-cooled dynamometer is the geometry of the rotor, which played a vital role in effective heat rejection. Dual application is limited for air cooled eddy current dynamometer due to excessive heat generation when the operating speed is up to a certain range. The aim of this research is to observe the air flow pattern and temperature distribution on the rotor of the air-cooled dynamometer with different geometry designs. In addition, the air flow and heat transfer simulation were carried out by using ANSYS software. Besides, the setting of normal size mesh was proposed in all design cases to reduce the computational time and the mesh files size of the simulation. Furthermore, a total of four configurations of rotating domain were designed and created using SolidWorks software, with each one differentiated with the features of holes and cover. The results of air flow velocity contour were compared with those of without the cover and holes on the rotor design. The optimum design in air motion distributed within all cases of numerical simulation were then observed and compared. To validate the simulation setup, experimental data were used to validate the airflow and heat transfer coupling simulation models. The results revealed that an improvement with more air volume movement can be observed at medium range and high velocity range for all models with cover features over the models without cover. Besides, the results also shows that the influences of hole features on air flow velocity were less significant as compared to the one with cover features. Also, the rotor design with cover and without holes were found to be the best configuration as it allows the as high as 27.7% greater air flow dynamic to achieved lowest steady state temperature as compared with those of baseline design. The Design C also improved in term of temperature as compared to the simple model of plane rotor, with as high as 11.6% reduction in overall temperature. Through the results of this analysis, it was justifiable that the Design C can be suggested as the best-case scenario for further experimental study. These results will serve as a basis for rotor design to improve the performance of the air-cooled eddy current dynamometer.

Lubricants are commonly utilized in industry to minimize friction and wear for tools and components, and additives play indispensable roles in lubricants to attain overall enhanced tribological properties. Because of environmental concerns, the introduction of nanoparticles is regarded as a promising lubricant additive capable of replacing conventional additives and improving lubricant tribological properties. This study investigated the tribological behaviour of 5W30 PAO+ester fully synthetic oil (SO) with and without the addition of graphene nanoplatelets. Besides, this study also focuses on the tribological effect of graphene's concentration (0.01, 0.02, 0.05, 0.1 and 0.2 wt%). The experiments were conducted using a four-ball tester according to ASTM D4172 and surface analysis was done on the worn surfaces using scanning electron microscopy and energy-dispersive x-ray spectroscopy. The results show that the presence of graphene significantly improves the tribological properties. SO enriched 0.05 wt% graphene exhibits the lowest coefficient of friction and wear scar diameter, and the friction and wear were reduced by 33.78% and 34.42%, respectively. The protective film formed on the worn surface is responsible for friction and wear reduction. In addition, the worn surface becomes smoother after being lubricated by nanolubricants, which can be observed through the SEM analysis. EDX analysis revealed the presence of element carbon on the worn surface, implying that nanoparticles had deposited on the worn surface.

Biomass is the organic matter formed by photosynthesis that occurs on the earth’s surface. They contain all forms of waste compost, including urban solid waste, municipal bio solids, animal wastes, forestry and agricultural wastes, and some industrial wastes. Efficient use of biomass oil would aid in the resolution of issues caused by fossil fuels. However, the biggest issue about using this energy is due to the gas composition of biomass material. As a result, properties of biomass are the critical parameter for assessing the fuel content of a special biomass substance in energetic applications. Gasification is the most mature thermo-chemical conversion technique available among the various methods of transforming biomass materials to bio resources. In this context, proximate and ultimate analysis has been used to classify two groups of biomass material that carry out in this experiment. The proximate analysis results have been obtained by the TGA technique while the ultimate analysis results will obtain by the GC mechanism. Then, based on the proximate analysis data various empirical equations containing linear and nonlinear terms were evaluated in order to predict the higher heating values (HHV) of the entire sample range. Since, the biomasses used in this analysis have different properties and fuel characteristics, the estimated HHV for the wood pellet sample are between 15.33 and 19.71 MJ/kg, while the rubber seed sample is between 15.18 and 18.64 MJ/kg. According to the experimental findings, the HHV of wood pellet is at around 2.95 MJ/Nm3 while the HHV of rubber seed of about 4.99MJ/Nm3. The comparison on the theoretical analysis have been show 0.19% compared to the results on wood pellet while the rubber seed have at around 2.07% difference compare each other. The experimental results on wood pellets, the findings reveal a 15.35% difference, while rubber seed indicates a 13.81% difference. Nonetheless, the finding and analysis on the properties, the results can be considered within reasonable limits.

An effective analytical technique for biomass characterisation is inevitable for biomass utilisation in energy production. To improve biomass processing, various thermal conversion methods such as torrefaction, pyrolysis, combustion, hydrothermal liquefaction, and gasification have been widely used to improve biomass processing. Thermogravimetric analysers (TG) and gas chromatography (GC) are among the most fundamental analytical techniques utilised in biomass thermal analysis. Thus, GC and TG, in combination with MS, FTIR, or two-dimensional analysis, were used to examine the key parameters of biomass feedstock and increase the productivity of energy crops. We can also determine the optimal ratio for combining two separate biomass or coals during co-pyrolysis and co-gasification to achieve the best synergetic relationship. This review discusses thermochemical conversion processes such as torrefaction, combustion, hydrothermal liquefaction, pyrolysis, and gasification. Then, the thermochemical conversion of biomass using TG and GC is discussed in detail. The usual emphasis on the various applications of biomass or bacteria is also discussed in the comparison of the TG and GC. Finally, this study investigates the application of technologies for analysing the composition and developed gas from the thermochemical processing of biomass feedstocks.

Two main aspects of the transportation industry are pollution to the environment and depletion of fossil fuels. In the transportation industry, the pollution to the environment can be reduced with the use of cleaner fuel, such as gas-to-liquid fuel, to reduce the exhaust emissions from engines. However, the depletion of fossil fuels is still significant. Biodiesel is a non-toxic, renewable, and biodegradable fuel that is considered an alternative resource to conventional diesel fuel. Even though biodiesel shows advantages as a renewable source, there are still minor drawbacks while operating in diesel engines. Modern vehicle engines are designed to be powered by conventional diesel fuel or gasoline fuel. In this review, the performance, emissions, combustion, and endurance characteristics of different types of diesel engines with various conditions are assessed with biodiesel and blended fuel as well as the effect of biodiesel on the diesel engines. The results show that biodiesel and blended fuel had fewer emissions of CO, HC, and PM but higher NOx emissions than the diesel-fuelled engine. In the endurance test, biodiesel and blended fuel showed less wear and carbon deposits. A high concentration of wear debris was found inside the lubricating oil while the engine operated with biodiesel and blends. The performance, emissions, and combustion characteristics of biodiesel and its blends showed that it can be used in a diesel engine. However, further research on long-term endurance tests is required to obtain a better understanding of endurance characteristics about engine wear of the diesel engine using biodiesel and its blends.

Homogeneous charge compression ignition (HCCI) is considered an advanced combustion method for internal combustion engines that offers simultaneous reductions in oxides of nitrogen (NO_x) emissions and increased fuel efficiency. The present study examines the influence of intake air temperature (IAT) and premixed diesel fuel on fuel self-ignition characteristics in a light-duty compression ignition engine. Partial HCCI was achieved by port injection of the diesel fuel through air-assisted injection while sustaining direct diesel fuel injection into the cylinder for initiating combustion. The self-ignition of diesel fuel under such a set-up was studied with variations in premixed ratios (0–0.60) and inlet temperatures (40–100 °C) under a constant 1600 rpm engine speed with 20 Nm load. Variations in performance, emissions and combustion characteristics with premixed fuel and inlet air heating were analysed in comparison with those recorded without. Heat release rate profiles determined from recorded in-cylinder pressure depicted evident multiple-stage ignitions (up to three-stage ignition in several cases) in this study. Compared with the premixed ratio, the inlet air temperature had a greater effect on low-temperature reaction and HCCI combustion timing. Nonetheless, an increase in the premixed ratio was found to be influential in reducing nitric oxides emissions.

This study investigated the tribological behaviour of Pongamia oil (PO) and 15W–40 mineral engine oil (MO) with and without the addition of graphene nanoplatelets (GNPs). The friction and wear characteristics were evaluated in four-ball anti-wear tests according to the ASTM D4172 standard. The morphology of worn surfaces and the lubrication mechanism of GNPs were investigated via SEM and EDS. This study also focuses on the tribological effect of GNP concentration at various concentrations. The addition of 0.05 wt % GNPs in PO and MO exhibits the lowest friction and wear with 17.5% and 12.24% friction reduction, respectively, and 11.96% and 5.14% wear reduction, respectively. Through SEM and EDS surface analysis, the surface enhancement on the worn surface by the polishing effect of GNPs was confirmed. The deposition of GNPs on the friction surface and the formation of a protective film prevent the interacting surfaces from rubbing, resulting in friction and wear reduction.

Biodiesel has gained popularity in diesel engines as a result of the rapid decline of fossil fuels and population growth. The processing of biodiesel from non-edible Moringa Oleifera was investigated using a single-step transesterification technique. Both fuels had their key physicochemical properties measured and investigated. In a common-rail diesel engine, the effects of MB50 fuel blend on the symmetric characteristics of engine-out responses were evaluated under five load settings and at 1000 rpm. As compared to standard diesel, MB50 increased brake thermal efficiency (BTE), and nitrogen oxides (NO_x) emissions while lowering brake specific fuel consumption (BSFC), and smoke emissions for all engine loads. A further study of injection pressure and start of injection (SOI) timing for MB50 fuel was optimized using response surface methodology (RSM). The RSM optimization resulted in improved combustion dynamics due to symmetry operating parameters, resulting in a simultaneous decrease in NO_x and smoke emissions without sacrificing BTE. RSM is an efficient optimization method for achieving optimal fuel injection parameter settings, as can be deduced. As a result, a clearer understanding of the use of MB50 fuel in diesel engines can be given, allowing for the best possible engine efficiency.

The objective of this paper is to study the effect of coconut oil biodiesel (COB)-diesel blends on exhaust particulate matter (PM) emissions and fuel injection responses in an unmodified turbocharged four-stroke common-rail direct injection (CRDI) diesel engine. Characterization of COB and their blends has been conducted to ascertain the applicability of these fuels for the existing engine. The test fuels used were fossil diesel fuel, COB10, COB20, COB30 and COB50 of biodiesel-diesel fuels. A test cycle which composed of 16 different steady-state modes at various loads and speed conditions was followed. Generally, the results showed a marginally advanced SOI timing and longer injection duration with increasing COB blends at higher load as compared to diesel fuel. Additionally, the lower calorific value (CV) and higher viscosity of the COB fuel blends have resulted in reduced turbo boost pressure and increased common-rail fuel injection pressure, respectively, across all engine speeds and loads. On the aspects of PM emissions characterization, results indicated that the blending of COB with conventional diesel had benefits over diesel in PM reduction. In fact, the largest achievable PM mass reduction of 38.55% was attained with COB50. In addition, it was noticed that the size of PM particles accumulated such that the granular size increased with higher diesel content in the blend. Additionally, the composition analysis on the PM collected by EDX spectroscopy has revealed that the C, O and Si as three main elements that made up the PM particles in descending order. Overall, the results indicated that COB biodiesel is a clean-burning alternative fuel and can be used satisfactorily in an unmodified diesel engine without the needs for engine remapping.