Papers by shahrir abdullah
The main aim of this work is to predict the design performance based on the stress/strain and the... more The main aim of this work is to predict the design performance based on the stress/strain and thermal stress behaviour of cylinder head under various operating conditions. The effects of engine operating conditions such as combustion gas temperature and maximum internal pressure, components initial temperature and engine speed on the stress and thermal stress behaviour of the cylinder head have been analyzed. The analysis was carried out using a finite element analysis (FEA) software package, MSC.NASTRAN which is use to simulate and predict the von-Mises stress and strain pattern and thermal distribution of the cylinder head structure during the combustion process in the engine and the geometry modelling was carried out using a popular computeraided engineering tool, CATIA V5. The result can be used to determine the quality of the design as well as identify areas which require further improvement. In this investigation, structural analyses of the cylinder head highlight several areas of interest. The maximum stress is found not exceeding the material strength of cylinder head, and thus the basic design criteria, namely no yielding and no structural failure under firing load case, can be satisfied. In addition, the effect of thermal stress/strain provides a good indication on structural integrity and reliability of the cylinder head, which can be improved in the early stages of design. This steadystate finite element method (FEM) stress analysis can play a very effective role in the rapid prototyping of the cylinder head.
This paper presents the thermal performance of a double-pass solar collector with and without por... more This paper presents the thermal performance of a double-pass solar collector with and without porous media in the second or lower channel of the collector. The experimental setup has been designed to study the thermal performance over a range of design and operating conditions. Several important relationships between the design and operating conditions have been obtained. These relationships eect the thermal performance of the double-pass solar collector. The relationships include the eect of changes in upper and lower channel depth on the thermal eciency with and without porous media. Moreover, the eects of mass¯ow rate, solar radiation, and temperature rises on the thermal eciency of the double-pass solar collector have been studied. The study concluded that the presence of porous media in the second channel increases the outlet temperature, therefore increases the thermal eciency of the systems. # : S 0 9 6 0 -1 4 8 1 ( 9 9 ) 0 0 0 0 7 -5 Renewable Energy 18 (1999) 557±564 www.elsevier.com/locate/renene * Corresponding author.
Abstract Problem Statement: Applications of impingement jets in industry for heating and cooling ... more Abstract Problem Statement: Applications of impingement jets in industry for heating and cooling purposes requires a high convective heat transfer coefficient. Numerous studies have been conducted to improve the convective heat transfer coefficient for a steady impinging jet. A pulsating jet has a very high potential in replacing steady jet after it been found able to increase the heat transfer coefficients at certain pulsating frequencies. The objectives of this study were to;(i) determine the velocity profile of a circular pulsating air ...
Increasing concerns over energy security and stricter legislation on automotive exhaust emission ... more Increasing concerns over energy security and stricter legislation on automotive exhaust emission limits have triggered greater efforts in utilizing alternatives to petroleum-based fuels. Compressed natural gas (CNG) is one of the promising candidates in terms of emissions and price. In this paper, methane, the major constituent of natural gas (NG), in used to fuel a Ricardo E6 engine and run in a port injection operation with open-valve and close-valve injection. The compression ratio is set at 10.5:1. Methane at 30 bar was supplied to the injector and injection length was adjusted to achieve the desired air fuel ratio (AFR). The minimum advance for best torque (MBT) was determined for 1100rpm speed by measuring the indicated mean effective pressure (IMEP) for combustion at spark advance between 14 o CA and 35 o CA BTDC. The result is clearly demonstrated that the performance of the open valve port injection (OVPI) is superior to the one of the close valve port injection (CVPI) with better IMEP, fuel conversion efficiency, indicated power and volumetric efficiency. The observation indicates that OVPI shows steadiness of peak pressures shifts toward top dead centre (TDC) as spark ignitions were advanced compared to CVPI. In terms of combustion characteristics, the OVPI operation yields shorter ignition delay and overall burning duration even at the same phasing angle. Therefore, the open valve operation is preferable for NG port injection due to the fact that injections take place while intake valve is open. It accelerates the charge flow into the cylinder causing higher volumetric efficiency and avoiding the back pressure that happen when high pressure methane is injected while intake valve closes.
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Papers by shahrir abdullah