Rosli Abu Bakar

The effect of nanofluid volume concentration on heat transfer and friction factor inside a horizontal tube

The additives of solid nanoparticles to liquids are significant enhancement of heat transfer and hydrodynamic flow. In this study, the thermal properties of three types of nanoparticles (Al2O3, TiO2, and SiO2) dispersed in water as a base fluid were measured experimentally. Forced convection heat transfer turbulent flow inside heated flat tube was numerically simulated. The heat flux around flat tube is 5000 W/m2 and Reynolds number is in the range of 5×103 to 50×103. CFD model by finite volume method used commercial software to find hydrodynamic and heat transfer coefficient. Simulation study concluded that the thermal properties measured and Reynolds number as input and friction factor and Nusselt number as output parameters. Data measured showed that thermal conductivity and viscosity increase with increasing the volume concentration of nanofluids with maximum deviation 19% and 6%, respectively. Simulation results concluded that the friction factor and Nusselt number increase with increasing the volume concentration. On the other hand, the flat tube enhances heat transfer and decreases pressure drop by 6% and -4%, respectively, as compared with circular tube. Comparison of numerical analysis with experimental data available showed good agreement with deviation not more than 2%.

Influence of Operation Conditions and Ambient Temperature on Performance of Gas Turbine Power Plant

This paper presents the effect of ambient temperature and operation conditions (compression ratio, turbine inlet temperature, air to fuel ratio and efficiency of compressor and turbine) on the performance of gas turbine power plant. The computational model was developed utilizing the MATLAB codes. Turbine work found to be decreases as ambient temperature increases as well as the thermal efficiency decreases. It can be seen that the thermal efficiency increases linearly with increases of compression ratio while decreases of ambient temperature. The specific fuel consumption increases with increases of ambient temperature and lower turbine inlet temperature. The effect of variation of SFC is more significance at higher ambient temperature than lower temperature. It is observed that the thermal efficiency linearly increases at lower compressor ratio as well as higher turbine inlet temperature until certain value of compression ratio. The variation of thermal efficiency is more significance at higher compression ratio and lower turbine inlet temperature. Even though at lower turbine inlet temperature is decrement the thermal efficiency dramatically and the SFC decreases linearly with increases of compression ratio and turbine inlet temperature at lower range until certain value then increases dramatically for lower turbine inlet temperature.

Optimization of Machining Parameters on Tool Wear Rate of Ti-6Al-4V through EDM using Copper Tungsten Electrode A Statistical Approach

Electrical discharge machining (EDM) is relatively modern machining process having distinct advantages over other machining processes and able to machine Ti-alloys effectively. This paper attempts to investigate the effects of peak ampere, pulse on time and pulse off time on tool wear rate (TWR) of titanium alloy Ti-6Al-4V in EDM utilizing copper tungsten as an electrode and positive polarity of the electrode. A mathematical model for electrode wear rate is developed in this paper. Design of experiments method and response surface methodology techniques are implemented. The validity test of the fit and adequacy of the proposed models has been carried out through analysis of variance. It can be seen that as the peak current increases the TWR decreases till certain ampere and then increases. The excellent surface finish is investigated in this study at short pulse on time and in contrast the long pulse duration causes the lowest TWR. Long pulse off time provides minimum TWR and the impact of pulse interval on TWR depends on peak current. The result leads to wear rate of electrode and economical industrial machining by optimizing the input parameters.

Optimization of Machining Parameters on Surface Roughness in EDM of Ti-6Al-4V Using Response Surface Method

This paper presents the influence of EDM parameters in terms of peak ampere, pulse on time and pulse off time on surface roughness of titanium alloy (Ti-6Al-4V). A mathematical model for surface finish is developed using response surface method (RSM) and optimum machining setting in favor of surface finish are evaluated. Design of experiments (DOE) techniques is implemented. Analysis of variance (ANOVA) has been performed to verify the fit and adequacy of the developed mathematical models. The acquired results yield that the increasing pulse on time causes fine surface till a certain value and then deteriorates the surface finish. It is investigated that about 200 µs pulse off time produce superior surface finish. These results lead to desirable surface roughness and economical industrial machining by optimizing the input parameters.

Mass Fraction Burn Comparison of Compressed Natural Gas and Gasoline

Vehicle efficiency relates to pollutants and cost savings in third world countries. In term of subcompact cars, the vehicle characteristics are governed by the engine for alternative fuels. The main focus of this paper was to evaluate a sub compact car engine for its performance and burn rate of gasoline and Compressed Natural Gas (CNG). A bi-fuel sequential system was used to do this evaluation. Measurements of engine speed, torque and fuel were done on an eddy current dynamometer, while measurements or in-cylinder pressure, crank angle and spark were analyzed from results taken by data acquisition system. The emissions readings were also compared from an emission analyzer. The results were analyzed for burn rate based on the first law of thermodynamic. The comparison shows a drop of 18.6% was seen for the power, brake specific fuel consumption (BSFC) loss was 7% and efficiency loss was at 17.3% in average for all engine speed. Pressure analysis shows peak pressure dropped by 16%. Burn rate shows why CNG had a slower burning speed on the small engine. The engine speed of 4000 rpm at Maximum Brake Torque (MBT) produced the most nearest results to gasoline.

Heat Transfer Characteristics in Exhaust Port for Hydrogen Fueled Port Injection Engine: A Transient Approach

This paper was investigated the transient heat transfer characteristics in exhaust port for hydrogen fueled port injection internal combustion engine (H2ICE). One dimensional gas dynamics was described the flow and heat transfer in the components of the engine model. The engine model is simulated with variable engine speed and air fuel ratio (AFR). Engine speed varied from 2000 rpm to 5000 rpm with increment equal to 1000 rpm and AFR was varies from stoichiometric to lean limit. The effects of AFR and engine speed on heat transfer characteristics for the exhaust port are also investigated. The baseline engine model is verified with previous published results. The obtained results clarify that transient heat transfer process inside exhaust port for port injection H2ICE were affected by the engine speed and AFR. It can be seen that for obtained results clarify that for transient analysis, the fluctuation with very small amplitudes for heat transfer coefficient and heat transfer rate during the compression, intake and part of power stroke. The rapid change for both of them occurs during the exhaust and part of power stroke due to the exhaust valve is open. The obtained results from the simulation can be employed to examine the emission production and engine performance.

Application of Natural Gas for Internal Combustion Engines

It is well known that the fossil-fuel reserves in the world are diminishing at an alarming rate and a lack of crude oil is expected at the early decades of this century (Aslam et al., 2006). Gasoline and diesel fuel becomes scarce and most expensive (Catania et al., 2004). Alternative fuel becomes more conventional fuel in the coming decades for internalcombustion engines. Nowadays, the alternative fuel has been growing due to concerns that the reserves of fossil fuel all over the area are limited. Furthermore, the world energy crisis made the fossil-fuel price increases.

Modeling of Common Rail Fuel Injection System of Four Cylinder Hydrogen Fueled Engine

This work presents the fundamentals and application of transient model-based leak detection and localization technique for crude oil pipelines. The dynamic parameters involved in this model such as pressure, flow and temperature were acquired by SCADA (Supervisory Control and Data Acquisition) system. The characteristic changes in the flowmechanics and thermodynamics along a given length of pipeline were used in detecting, localizing and determining the flow rate of the leak. Measurement of pressure, temperature and flow data at both the inlet and outlet of the pipeline were used in formulating the equations obtained from the inconsistency in the continuity and law of conservation of momentum equations. This model located a leak incident in a horizontal pipeline of length 2000m and diameter 0.3556m carrying Nigeria bonny light crude oil from the Nigeria Petroleum Development Company Limited, Olomoro flowstation into UPS (Ughelli Pump Station) truck line. But the leak located by the model at 1088.12m from the inlet is 11.88m behind the actual leak position of 1100m as discovered during the pipeline leak remedial works.

Simulation study of turbulent convective heat transfer enhancement in heated tube flow using TiO2-water nanofluid

Simulation by convenient software, the same as FLUENT, was used to predict the friction factor and Nusselt number for forced convection heat transfer of TiO2-water nanofluid. The range of Reynolds number is from 10000 to 100000 to be turbulent flow in a horizontal straight tube with heat flux 5000 w/m2 around it. The volume fraction of nanoparticle was (0.25%, 0.5%, 0.75% and 1%) and diameter of particle is 27 nm. The results show that the friction factor and Nusselt number are increasing with increasing of volume fraction. Results compared with the experimental data available in literature and there are good agreements.

Linear Static Response of Suspension Arm based on Artificial Neural Network Technique

Modeling and simulation are indispensable when dealing with complex engineering systems. This study deals with intelligent techniques modeling for linear response of suspension arm. The finite element analysis and Radial Basis Function Neural Network (RBFNN) technique is used to predict the response of suspension arm. The linear static analysis was performed utilizing the finite element analysis code. The neural network model has 3 inputs representing the load, mesh size and material while 4 output representing the maximum displacement, maximum Principal stress, von Mises and Tresca. Finally, regression analysis between finite element results and values predicted by the neural network model was made. It can be seen that the RBFNN proposed approach was found to be highly effective with least error in identification of stress-displacement of suspension arm. Simulated results show that RBF can be very successively used for reduction of the effort and time required to predict the stress-displacement response of suspension arm as FE methods usually deal with only a single problem for each run.