Abdul Rashid Abdul Aziz

Diesel engines are frequently used because of their high efficiency and durability. However, they are also known for emitting high amounts of pollutants, including CO2, CO, NOx and particulate matter. Current studies have focused on alternate fuel techniques to reduce these emissions. An effective method involves using oxyhydrogen (HHO) with diesel and biodiesel can increase combustion efficiency and minimize harmful emissions. Additionally, HHO serves as a viable alternative to hydrogen, especially considering the current challenges in global hydrogen production and storage, which may not be sufficient to meet the increasing demand for transportation applications. Hence, the current study investigated the effect of using a diesel-HHO dual fuel on the emission characteristics of a single-cylinder, four-stroke diesel engine. The engine was operated at a constant speed of 1500 rpm and was tested under varying loads of 0%, 50% and 75%, with diesel (D100) serving as the primary fuel and HHO gas as the inducted fuel. The HHO gas, produced at a constant flow rate of 0.80 LPM through alkaline water electrolysis was continuously injected into the combustion chamber through air suction manifold. The results revealed that compared to diesel fuel, the injection of HHO has increased the CO2 emissions by 23.08, 23.81 and 20.0% at an engine load of 0, 50 and 100%. The CO emissions were reduced by 23.53, 34.78 and 41.38% at 0, 50 and 100% engine load. Similarly, the HC emissions were reduced by 26.09, 23.08 and 23.33% at 0, 50 and 100% engine load. The NOx emissions were increased by 25.0, 10.53 and 4.17% at 0, 50 and 100% engine load. Overall, introducing HHO has increased the CO2 and NOx emissions as the hydrogen and additional oxygen in the HHO gas promote more complete combustion and higher combustion temperatures. However, this enhancement in combustion efficiency has resulted in a significant reduction in CO and HC emissions.

Use of an alternative water-in-diesel emulsion (WiDE) fuel instead of pure diesel in a diesel engine reduces emissions and environmental pollution. However, as time passes, water from the emulsified fuel separates. Emulsion stability is affected by the amount of water, type of surfactant, and emulsion technique. Since biodiesel and biosurfactants are environmentally friendly as compared to pure diesel and chemical surfactants, biodiesel-emulsified fuel can reduce emissions, improve combustion, and improve engine performance. Water-in-diesel droplets split into tiny droplets during secondary atomization, which is believed to be caused by microexplosions. In this study, the effect of biosurfactant on the stability and microscopic behaviour of water-in-biodiesel emulsion (WiBDE) fuel were examined. A mixture of B10 biodiesel, 5% water, and a mixture of surfactant (63% lecithin and 37% TWEEN 85 (0.5–3%)) was emulsified for 20 minutes by using a magnetic stirrer at 1500 rpm. Six WiBDE fuel samples were observed for 10 days, and the microscopic behaviour of fuel droplets was examined. The evolution of droplets leading to micro-explosions was captured at 200 °C, 300 °C, and 400 °C. WiBDE-5, having a 2.5% surfactant concentration, is highly stable and reduces the time of micro-explosion of droplets, which can improve combustion and engine performance.

Large-scale turbulent flow features in liquid (water) and gas (air) phases in the film region of two-phase slug flow are identified by using proper orthogonal decomposition (POD) of the vorticity fields. Linear combination of POD vorticity modes is used for the qualitative visualization of coherent structures. The vorticity fields are computed from the instantaneous two-dimensional velocity fields measured using a combined particle image velocimetry and laser-induced fluorescence technique (PIV-LIF). Vorticity modes are calculated and compared with the curl of POD velocity mode. POD analysis revealed the presence of dominant vortical structures embedded in both liquid and the gas phases. It is also observed that the gas phase revealed more eddies than the liquid phase. The proportion of enstrophy is higher in the gas phase as first POD vorticity mode contained 7.5% of the total enstrophy, while for the liquid phase; the first mode captured 6.8%. Linear combination of vorticity modes provided effective qualitative information of the coherent structures in both phases. POD-vorticity modes when compared with POD-velocity modes revealed few similarities among the pair of identified vortical structures. Based on the results, it is concluded that POD vorticity revealed hidden flow features of both phases of slug flow, which eventually provides in-depth and comprehensive description of this complex slug flow phenomenon.

Vehicle driveability is one of the important attributes in range-extender electric vehicles due to the electric motor torque characteristics at low-speed events. Physical vehicle prototypes are typically used to validate and rectify vehicle driveability attributes. However, this can be expensive and require several design iterations. In this paper, a model-based energy method to assess vehicle driveability is presented based on high-fidelity 49 degree-of-freedom powertrain and vehicle systems. Multibody dynamic components were built according to their true centre of gravity relative to the vehicle datum to provide an accurate system interaction. The work covered a frequency of less than 20 Hz. The results consist of the components’ frequency domination, which was structured and examined to identify the low-frequency resonances sensitivity based on different operating parameters such as road surface coefficients. An energy path method was also implemented on the dominant component by decoupling its compliances to study the effect on the vehicle driveability and low-frequency resonances. The outcomes of the research provided a good understanding of the interaction across the sub-systems levels. The powertrain rubber mounts were the dominant component that controlled the low-frequency resonances (<15.33 Hz) and can change the vehicle driveability quality.

A free-piston linear generator (FPLG) has a number of advantages compared to a traditional crank-slider internal combustion engine, including better thermal and mechanical efficiencies, different fuel compatibility, and a higher power-to-weight ratio. For electric vehicle propulsion and generation of portable power, an FPLG is a very attractive alternative source of energy. This paper presents the development of an FPLG simulation model using MATLAB-Simulink and investigates the impact of combustion variance on its operation. Results provided insight into various characteristics of system behavior through variation of structural dimension and operational parameters. In steady-state operation with fixed electrical load and fixed ignition for combustion, it was found that consecutively low combustion pressures can easily lead to engine stoppage, pointing to the significance of control for continuous operation. Due to the absence of the moment of inertia and flywheel character of the rotating engine, a linear engine-generator is subject to ceased operation even after two consecutively low combustions under 10% variance. This will not be a fundamental problem in an ordinary crank-slider engine-generator, but in a linear engine-generator, control measure will be necessary to ensure sustained operation.

This paper demonstrates the design of an electric trike’s energy management system for a goods delivery service via various possible component configurations. A model of the energy management system was first developed based on general engineering vehicles’ equations using Matlab software. Various component configurations, such as the usage of two battery types (lithium iron phosphate (LFP) and lithium nickel cobalt aluminum oxide (NCA)), implementation of three braking strategies (full mechanical, parallel, and series strategies), the presence of a range extender (RE), and various masses of range extenders were simulated by using the model. The driving cycle of the e-trike as input data in the simulation was obtained by driving the vehicle around Bandung City. Speed, distance, and elevation were obtained by using GPS-based software. The simulation results showed that the most efficient and effective component configuration was to use the serial regenerative braking strategy with no RE equipped. This configuration achieved an efficiency of 18.07 km/kWh. However, for a longer route, the usage of a 20-kg RE was required to prevent the state of charge drop below 30%. The NCA with serial regenerative braking and 20-kg RE had an efficiency of 17.47 km/kWh for the complete route.