Azmahani Sadikin

The Comparison of Preheat Fuel Characteristics of Biodiesel and Straight Vegetable Oil

Biodiesel is an alternative fuel derived from varies sources of vegetable oils, animal fat, or waste frying oil to give the corresponding fatty acid methyl ester. The properties of alternative fuel of CPO biodiesel and SVO biodiesel have been investigated at different temperature. The biodiesel was blended up palm oil blending ratio from 515vol% (B5B15) and straight vegetable oil ratio from 515vol% (S5S15). The properties were tested at 27.5°C, 40°C, 50°C and 60°C with observed the changes of the density, kinematic viscosity, flash point, water contents, and acid value. In this study, properties of CPO biodiesel were found to have a higher value and diesel fuel under all ambient temperature. Under all ambient temperature, preheating CPO fuel increased value of density, kinematic viscosity, water contents, and acid value than SVO biodiesel.

Investigation of Boiling Heat Transfer and Flow Regimes in a Heat Exchanger

Experimental and numerical simulation of heat transfer and flow regimes for vertical flow across horizontal tubes are presented for mass flow rate in the range 0.03 – 0.17 kg/s and heat fluxes in the range 1.07–1.35 kW/m2. The tubes had a diameter of 9.75 mm and a pitch to diameter ratio of 1.85. The CFX version 14.0 from ANSYS was used to predict the flow regimes and the temperature distribution in the tube bundles. These data and the predictions from numerical simulation were compared with the data available in the literature. It is found that the circulation zone in the shell becomes bigger as the mass flow rate is increases. The flow patterns identified in this experiment are bubbly, intermittent and annular flow. These data agrees well with the published data.

Two-Phase Flow Pressure Drop Model for a Shell Side of a Shell of Heat Exchanger

This paper present a two-phase pressure drop model for a in-line tube bundle for airwater mixtures flowing through an idealised shell and tube, in-line heat exchanger. The model used momentum flux and entrained liquid fraction to predict the acceleration pressure drop. The model predicts the pressure drop well using both accelaration and gravitational pressure drop deduced from data available in open literature. The model is shown to be mass flux dependence.

Two-Phase Flow on the Shell Side of a Shell and Tube Heat Exchanger

Two-phase flow on the shell side of a shell and tube heat exchanger is complex. Several studies have produced flow pattern maps that show surprising differences in flow regime boundaries for data sets that contain relatively small variations in fluid and flow properties. Despite this, correlations for void fraction and pressure drop are sufficiently accurate to allow the thermal-fluid design of heat exchangers to be completed. However, these correlations are based on experimental data taken from tube bundles containing tubes with diameters less than 20 mm. This study examines their applicability to tube bundles containing tubes with a diameter of 38 mm. Results for void fraction and pressure drop are presented for air-water flows near atmospheric pressure. The results were obtained for flows through a thin-slice, in-line tube bundle containing 10 rows. The tube bundle contained a central column of tubes with half tubes placed on the shell wall to simulate the presence of other columns. The tubes were 38 mm in diameter and 50 mm long with a pitch to diameter ratio of 1.32. Previous studies have shown that the void fraction in a shell-side, gas-liquid flow becomes constant after only a few rows. Thus, the void fraction was only measured at one location. A single-beam, gamma-ray densitometer was used to measure void fractions near row 7 in the maximum gap between the rows. Corresponding pressure drops were obtained between rows 3 and 10. Data are presented for a mass flux range of 25-688 kg/m2s and a gas mass fraction range of 0.0005-0.6. The measurements are shown to compare reasonably well with predictions from correlations available in the open literature. This shows that these methods can be used for tube-bundles containing larger diameter tubes. Some elements of a heat-exchanger design require a more complex analysis. For example, tube vibration calculations require the distribution of void and phase velocity along the tube length. Such analysis can be provided by multiphase computational fluid dynamic (CFD) simulations. CFD approaches to modelling these flows require empirical inputs for the drag coefficient and the force on the fluid by the tubes. These are deduced from the measured data. The wall forces are shown to scale well with increased tube diameter, however, caution is required when selecting the drag coefficients.

Experimental Study of Splitting Device for Horizontal Pipeline

The flow distribution within a reduced scale model pipeline to study and determine the best splitting device for a horizontal pipeline through experiments were conducted. In this research, five splitting devices are designed and tested on the model rig. Out of five, only one splitting device has been chosen that achieved the objective the best; to improve airflow to be a homogeneous flow in the pipe, or at least reducing and improving from the roping condition. The process of selecting the best device had been done through qualitative analysis of velocity profile and airflow distribution obtained from Pitot Tube measurements, besides the airflow pattern and behavior through PIV results.

Flow Separation Prediction in a Single-Phase Flow in an Inline Tube Bundles

The vertical single-phase flow was studied on the shell side of a horizontal tube bundle. In the present study, CFX version 14.0 from ANSYS was used to predict the flow regimes in the two tube bundles; i.e. the 19 mm and 38 mm arranged in an in-line configuration with a pitch to diameter ratio of 1.32. The simulations were undertaken to inform on how the fluid flowed within the tube passages in different tube bundle diameter that gives different gaps between the tubes, where the fluid must pass. The results show that the maximum gaps between the tubes have no clear effect to the flow where the flow separation and re-attachment and the average velocity is the same when increasing the tube bundle. This is consistent with other published data.

Performance and Emission of a Diesel Engine Fuelled With Preheated Palm Oil Biodiesel under High Load Conditions

Crude palm oil (CPO) is one of the vegetable oil that has potential for use as a fuel in diesel engine. Despite years of improvement attempts, the high viscosity and the major chemically bound oxygen component in the biodiesel fuel play as a key element during combustion process. Purpose of this study is to explore how significant the effect of preheated biodiesel blends on the engine performance and emission. The blending of biodiesel was varied from 5vol%(B5)~ 45vol%(B45) and preheated fuel temperature from 40°C~60°C. The engine speed was varied from 1500 rpm~3000 rpm and the load test conditions of 100% are considered. The performances parameter study of diesel engine in brake power, torque and flywheel torque are described together with the emissions parameter such as opacity, hydrocarbon (HC), nitrogen oxide (NOx), carbon oxide (CO), carbon dioxide (CO2) and oxygen (O2). Under high load condition, preheated biodiesel blends were found enhancing the combustion process, resulting in better performances. Increased preheated fuel temperature, higher in torque value and brake power increases significantly as the engine speed increases.

Investigation of the Piston Bowl Shape Effect on the Diesel Spray Development

The combustion in a diesel engine is a very complex process. Even more when compared to a gasoline engine where the combustion is triggered using spark plugs, since the diesel engine depends on the auto ignition of the fuel-air mixture. This auto ignition phenomenon depends on many variables, especially on the fuel-air mixing condition and this makes the piston bowl geometry an important role on the combustion characteristics of diesel engines. Each piston bowl design was tailored to work well under certain specific conditions. The usage of biomass diesel mixtures in diesel engines increases the fuel viscosity and requires that the piston bowl geometry is carefully studied. The objective of this study is to compare the effect of certain piston bowl shapes, namely the Flat Bottom to the diesel spray development. Simulations were done using the ANSYS FLUENT 16.1 computational fluid dynamics (CFD) software. The simulation was performed on different injection pressures of 40 and 100 MPa, with the ambient temperature in the combustion chamber that is holding the piston at 500 and 900 K. Results showed that if the pressure and ambient temperature increase, the spray cone angle increases. In addition, the geometry shape of the piston bowl makes the spray to head downward after the wall impingement to the bottom section and prevents spillage of fuel over the piston bowl.

Flame Spread Behavior over Kenaf Fabric, Polyester Fabric, and Kenaf/Polyester Combined Fabric

Flame spread behavior is one of the important topics related to fire safety engineering. It is essential to examine factors, which influence the flame spread behavior over fabrics. It is known that natural fibers exhibit a different flame spread behavior than the one of synthetic fibers. This difference may influence the flame spread behavior over combined fabrics. The purpose of this research is to study the effect of materials on the flame spread behavior over kenaf/polyester fabrics. Before analyzing this effect, it is important also to know the flame spread behavior over 100% kenaf fabric and 100% polyester fabric. Thus, several experiments have been conducted for different materials of fabric made up of 100% kenaf, 100% polyester, and combined fabric of kenaf/polyester. For the combined fabric, experiments have been done for different weft thread angle of θ = 0° and θ = 90°. A burner is used for igniting the fabric at a point on its top edge. The data collected is recorded via videos and captured images for measuring the flame spread rate and detail observation of characteristics during the burning process. From the results obtained, it is seen that the material and thread angle influence on the flame spread behavior over fabrics. The flame spread rate on kenaf is lower than the flame spread rate on combined fabrics of kenaf/polyester while the flame spread rate on polyester is undetermined. The flame spread velocity also changes when the weft thread angle change from θ = 0° to θ = 90°.

Effect of triggering angles on the crushing mechanisms of hybrid woven kenaf/aluminum hollow cylinders

This paper presents the effect of triggering angles constructed on the top of hybrid woven kenaf/aluminium hollow cylinders on the energy absorption performances. The crushing performances of aluminium tubes can be found widely in open literature. However, lack number of work on the hybridizing the aluminium tubes with woven kenaf fibre is found. Woven kenaf mats are produced and bathed with polymeric resin before they are wrapped around the aluminium tubes twice. Different fibre orientations, +-θ° are used where θ = 0, 15, 30 and 45. Once the hybrid composite hardened, one of their end are chamfered using different angles of 0o, 30o, 45o and 60o. The tubes are quasi-statically compressed in order to obtain their force-displacement responses and crashworthiness parameters are extracted and discussed with the relation of fibre orientations and chamfering angles. It is found that the chamfering angles are only affected the force-displacement curves during the first stage of elastic deformation whereas there is no obvious effect in the second stage. However, varying the fibre orientations are slightly increased the force-displacement curves especially when the fibre is orientated with 30o. Based on the fracture mechanism observations, most of composite experienced large fragmentation indicating that the composites absorbed the crushing energy ineffectively.