Mohamad Shukri Zakaria

Computational Simulation of Boil-Off Gas Formation inside Liquefied Natural Gas Tank Using Evaporation Model in ANSYS Fluent

Research on the waste energy and emission has been quite intensive recently. The formation, venting and flared the Boil-off gas (BOG) considered as one of the contribution to the Greenhouse Gas (GHG) emission nowadays. The current model or method appearing in the literature is unable to analyze the real behavior of the vapor inside Liquefied Natural Gas (LNG) tank and unable to accurately estimate the amount of boil-off gas formation. In this paper, evaporation model is used to estimate LNG Boil-Off rate (BOR) inside LNG tank. Using User Define Function (UDF) hooked to the software ANSYS Fluent. The application enable drag law and alternative heat transfer coefficient to be included. Three dimensional membrane type LNG cargos are simulated with selected boundary condition located in the United States Gulf Coast based on average weather conditions. The result shows that the value of BOR agrees well with the previous study done with another model and with International Marine organization (IMO) standard which is less than 0.15% weight per day. The results also enable us to visualize the LNG evaporation behaviors inside LNG tanks.

Boil-Off Gas Formation inside Large Scale Liquefied Natural Gas (LNG) Tank Based on Specific Parameters

Liquefied Natural Gas (LNG) fleets are coasting with various condition and behavior. These variable leads to different type of LNG fleets build every year with unavoidable generated Boil-off Gas (BOG). Estimation of BOG generated inside LNG tank play significant role in determines the ship specification and management method of BOG including venting, propulsion or requalification. Hence, in the present study, the right choices of boundary condition and parameter have been implementing in order to have good estimation amount of BOG evaporates for specific LNG tank. Three dimensional model of cargo with capacity 160000 m3 LNG carrier are simulate using ANSYS Fluent with specific ambient air temperature of 5oC and ambient seawater temperature of 0oC have been chosen as a calculation case, gain the total heat transfer rate and Boil-off Rate (BOR). The result shows that the calculation model and simulation are feasible with typical LNG fleet specification and International Marine Organization (IMO) standard.

Modeling of Flywheel Hybrid Powertrain to Optimize Energy Consumption in Mechanical Hybrid Motorcycle

The creation of internal combustion engine is a significant milestone in power engineering world which simplified high mechanical energy demand jobs like moving vehicle and machinery. Even though the internal combustion engine gives lot of advantages, however, this type of engine is incapable to convert the heat energy from fuel combustion to the mechanical energy efficiently. Small capacity engine e.g. motorcycle engine having the power conversion efficiency between 25-30%. Therefore, alternative power source is required to support the internal combustion engine in order to increase the overall system efficiency. These phenomena give encouragement to implement the hybridization process. This is to increase the system efficiency in transferring power to the wheel. Hybridization processes e.g. flywheel as secondary power source can increase power transfer efficiency between 30%-80%. Hence, the purpose of this research is to develop the mathematical model of the power transfer efficiency of flywheel hybrid motorcycle by using back trace simulation method. This model will record the amount of energy use in acceleration phase of the driving cycle. Subsequently, the efficiency ratio of motorcycle power transfer is calculated and comparison of those ratios between the conventional motorcycle and the hybrid motorcycle is made. The outstanding results show that the hybrid motorcycle is capable to conserve the energy used up to 36% compare to the conventional motorcycle that wasted energy up to 200%. As a conclusion, flywheel as the secondary power source is capable to supply enough energy to propel the motorcycle forward.

SOOT PARTICLE TRAJECTORIES OF A DI DIESEL ENGINE AT 18° ATDC CRANKSHAFT ANGLE

Among the major pollutants of diesel engine is soot. Soot is formed as an unwelcome product in combustion systems. Soot emission to the atmosphere leads to global air warming and health problems. Furthermore, deposition of soot particles on cylinder walls contaminates lubricant oil hence increases its viscosity. This reduces durability of lubricant oil, causing pumpability problems and increasing wear. Therefore, it is necessary to study soot formation and its movement in diesel engines. This study focuses on soot particle trajectories in diesel engines by considering the diameter of soot particles that were formed at 18° ATDC crankshaft angle. These soot particle movements are under the influence of drag force with different radial, axial and angular settings and simulated by using MATLAB routine. The mathematical algorithm which was used in the MATLAB routine is trilinear interpolation and 4th order of Runge Kutta. Simulation was carried out for a combustion system of 4 valves DI diesel engine from inlet valve closing (IVC) to exhaust valve opening (EVO). The results show that small diameter of soot particles were transferred near the cylinder wall while bigger soot particle mostly moved in inner radius of the combustion chamber.

Analysis of Soot Particle Movement in Diesel Engine under the Influence of Drag Force

The formation of soot is influenced by the composition of air entrainment and structure of hydrocarbon in the fuel. Soot will then form during combustion in a diesel engine. Some of the soot particles will be released from the engine through the exhaust nozzle and some will stick to the cylinder walls. The soot that sticks to the cylinder wall can affect the lifetime of the lubricant oil. Subsequently this will decrease the durability of the diesel engine. By understanding the movement of the soot particles, the effect to the engine can be decreased. Therefore, the initial position and last position of soot particle was recognized through this study. The data for the formation of soot particles in the diesel engine was obtained from previous investigation. The study of soot movement at 8° crankshaft angle under the influence of drag force with different radial, axial and angular settings were carried out using a MATLAB routine. The results showed that the movement of soot particle will change with different parameter settings. Besides that, comparison of the results of soot particle movement influenced by drag force and without drag force has been carried out. It was observed that drag force caused shorter soot particle movement path and moves them away from the cylinder wall.

Numerical Analysis on the Effects of Cavity Geometry with Heat towards Contaminant Removal

Contaminants are recently discovered at the joint of large piping system and causing defect to industrial product. A computational analysis can be used as a solution of the hydrodynamic contaminant removal without any modification needed. In this paper, the effect of heat is introduced to analyze the heat transfer and flow field in a channel with cavity heated at the bottom sides coupled with different shape of cavity. The cavity shape used comes with three shapes i.e. square, triangle and semicircle. The process of fluid dynamic in a cavity is modeled via numerical solution of the NavierStokes equations using Cubic Interpolated Profile (CIP) method. By using the simulation of hydrodynamic contaminant removal, the flow of streamlines and vortices pattern was investigated in the cavities. In order to remove all of the contaminant, hydrodynamic need to take part in this simulation which is flow from the inlet of the channel and create vortices to remove it from the cavities. The result shows that the percentage of contaminant removal is higher for semicircle cavity with higher Grashof number. The result also indicates that vortices formation is highly dependent on the cavity geometry and creates a buoyancy effect.

Mini acceleration and deceleration driving strategy to increase the operational time of flywheel hybrid module

This paper presents a new driving strategy to increase the operational time of flywheel hybrid module. The flywheel hybrid module contains low cost mechanical parts which installed on the small motorcycle. Based on normal driving cycles characteristics, the Mini-AD driving strategy is develop. It is involved a series of short or mini acceleration cycle and short deceleration cycle on top of the normal driving cycles. The new strategy is simulated for flywheel hybrid module, aimed for acceleration phase only. Simulations show that the new driving strategy can increase the operational time of flywheel hybrid module up to 62.5%.

Modeling the hole configuration on gas turbine blade vane

The performance of Gas Turbine can be improved by increasing the inlet temperature gradually. The high level temperature of component that contact with hot gases due to internal combustion in gas turbine will make possibility failure especially on turbine vane. Thus, this study aims to identify the best hole arrangement of cooling on turbine vane, and investigate the critical region for failure possibilities occur on turbine vane caused by the hot gases that considered into two parameter which are steady temperature profile and average temperature decreasing on blade. This study will implement C3X type vane in order to improve the process in turbine blades. An arrangement of two dimensional blade hole will be model Commercial software ANSYS Fluent. It is found that best arrangement and configuration between the hole shape can improve resistances in relation to thermal collapse and satisfied the blade cooling goal.

Fluid structure interaction computational analysis of hydraulic intensifier

Fluid Structure Interaction (FSI) is relatively new branch of Computational Fluid Dynamics (CFD). Modelling of hydraulic accumulator to withstand high pressure is needed to be used using FSI method. This method utilize Arbitrary Langrarian Eulerian (ALE) in order to solve Navier Stokes Equation coupling with structure coupling of the accumulator.The usable of excessive material in designing the thickness of bore without knowing the optimum thickness for high pressure stored should be avoided. In this study, three dimensional (3D) models of the accumulator were designed and analyze using commercial CFD package ANSYS 14.0 coupling between ANSYS Fluent and ANSYS Static Structural in order to investigate effect of high pressure to the stress of the accumulator body. This study aims to find the optimum thickness to withstand the pressure in order to reduce the usage of highly cost material via FSI method. High pressure fluid will keep enclose inside the accumulator for different range of pressure value. It is ...

Simulation of mixed convection in a channel with cavity heated from different sides using fluent

Computational Fluid Dynamic (CFD) is one of the methods used in industry and in education to solve problems related to fluid flow in closed channel. Through simulation, the type of fluid flow, streamlines and vorticity can be seen to determine the ability of the airway is produced through a rectangular shape to remove contaminants that are trapped in it. In addition, the project is also looking at the effects of conductive heat transfer that being supply at the sided wall to the water flow and it will be seen whether able to help the flow of air to remove pollutants altogether. Time is the element that is reviewed and any. Interest in the rate of contaminants being transfer was varied by the investigated ratio of neither 2:1, 4:1 nor 1:2 to the length and width in 2D simulation for best possible cavity design. The removal percentage shown that as the aspect ratio increase, the removal rate also increase with steady flow constant.