Nuraini Abdul Aziz

Homogeneous Charge Compression Ignition Combustion: Challenges and Proposed Solutions

Engine and car manufacturers are experiencing the demand concerning fuel efficiency and low emissions from both consumers and governments. Homogeneous charge compression ignition (HCCI) is an alternative combustion technology that is cleaner and more efficient than the other types of combustion. Although the thermal efficiency and emission of HCCI engine are greater in comparison with traditional engines, HCCI combustion has several main difficulties such as controlling of ignition timing, limited power output, and weak cold-start capability. In this study a literature review on HCCI engine has been performed and HCCI challenges and proposed solutions have been investigated from the point view of Ignition Timing that is the main problem of this engine. HCCI challenges are investigated by many IC engine researchers during the last decade, but practical solutions have not been presented for a fully HCCI engine. Some of the solutions are slow response time and some of them are technically difficult to implement. So it seems that fully HCCI engine needs more investigation to meet its mass-production and the future research and application should be considered as part of an effort to achieve low-temperature combustion in a wide range of operating conditions in an IC engine.

Effects of Intake Temperature and Equivalence Ratio on HCCI Ignition Timing and Emissions of a 2-Stroke Engine

Homogeneous charge compression ignition (HCCI) combustion, when applied to a gasoline engine, offers the potential for a noticeable improvement in fuel economy and dramatic reductions in NOx emissions. In this study, Computational Fluid Dynamic (CFD) is used coupled with detailed chemical mechanism (38 species and 69 reactions) for simulation of HCCI combustion of iso-octane and transitional flow inside the combustion chamber of a 2-stroke engine. Results show that increasing the overall gas temperature significantly advances the HCCI combustion timing. Concerning the equivalence ratio, by increasing it the ignition timing has been advanced and the maximum cylinder pressure has been increased. When equivalence ratio increases to more than 0.5 , NOx emissions significantly increases and go beyond 1000 [ppm].

Life Cycle Assessment of Natural Fiber Polymer Composites

Widespread environmental awareness towards achieving product sustainability has spurred great efforts in using more environmental-friendly materials in product design. Among the most promising solutions to address the needs is by using natural fibers to reduce the dependence on synthetic fibers as reinforcement and filler materials for polymer composites’ construction. Many efforts have been made to fully quantify the advantages of natural fiber composites (NFC) for diverse applications such as automotive, building materials, and household appliances. Life cycle assessment (LCA) is among the efforts being undertaken related to NFC with the primary aim to determine the overall potential environmental impact of using such materials on the surroundings. Among the major advantages of performing LCA is its capability to provide a more holistic overview of the environmental impact whereby it covers the whole product life cycles from raw material extraction to end-of-life stages, hence enabling justified decisions on the suitability of using NFC for specific applications to be made scientifically. In this chapter, an overview of the LCA method is explained and subsequently followed by description of its applications involving NFC in different applications. The advantages and limitations of the LCA method related to the NFCs are also discussed as well as a final conclusion on the future directions of LCA application for NFC.

Performance of Automotive Composite Bumper Beams and Hood Subjected to Frontal Impacts

Abstract Performance of automotive composite bumper beam subjected to frontal impact is presented and discussed in this paper. The aim of this study is to analyze the effect of steel and composite materials on internal energy of the automotive front bumper beam and with respect to pedestrian head injury at the hood. The front bumper beams and hood made of aluminum AA5182, e-glass/epoxy composite and carbon epoxy composite were studied and characterized by impact modeling using LS-DYNA V971, according to United States New Car Assessment Program (US-NCAP) defining the frontal impact velocity and based on European Enhanced Vehicle-Safety Committee. The most important variables of this structure were mass, material, internal energy, and the so-called Head Injury Criterion (HIC). The results are compared with a bumper beam and a hood made of mild steel. The in-plane failure behaviors of the composites were evaluated by using the Tsai Wu failure criterion. LS-DYNA Finite Element Analysis software was used. The results showed that a carbon fiber/epoxy composite bumper can reduce the bumper mass and has the highest value of internal energy followed by the glass fiber/epoxy composite. The FE model of a production hood was introduced and validated. In order to evaluate the protective performance of the baseline hood, the FE models for a 50 percentile of an adult pedestrian dummy were used to impact the hood. It was found that the aluminum AA5182 hood can obviously reduce the Head Injury Criterion (HIC) values compared to the baseline hood. The HIC values of the dummy model were further reduced to much lower than 1000.

The mechanism of mangrove tree in wave energy propagation

The role of mangrove trees in reducing the tsunami waves during the tragedy of Andaman tsunami occurred on December 26, 2004, has been credited and these indirectly raise awareness about the role of mangroves forest as a natural breakwater on the beach. This paper will focus on the mangrove trees from Avicennia and Rhizophora species in order to identify the methods of breaking wave energy that has been carried out by the mangrove roots and stems. Analysis of the mangrove roots coordination pattern had been conducted by gathering data at study site located at Kemaman, Terengganu and the data had been plotted in Gambit software for simulation purpose in Fluent Inc software. Hence, the simulation result showed that the ratio of wave height and velocity reduction may vary depending on factors such as the species of the mangrove trees and density of the roots that grow around the tree. Consequently, the study will be examining the waveform that is mitigated by the both species Avicennia and Rhizophora using turbulent flow and experiment will be conducted to validate the data obtained by the simulation.

Investigation on alternative methods to enhance the cooling capacity of an open pool reactor

It is a common phenomenon for any research reactor with less than 1MWth to have very limited applications. Thus, many of such reactors have undertaken upgrading exercises to increase its capacity. Most of the research reactor which have undergone power or flux upgrading, increased the cooling performance through the installation of higher capacity heat removal system along with forced convection mechanism inside the pool. This approach would require higher cost as well as major modification of the reactor pool. Other alternatives which require less modification and cost have been investigated using computed fluid dynamic simulation. This study has shown that the installation of in-pool pumps and conduction rods inside the existing pool system have promising potential to enhance the heat removal capacity of a natural convection cooling system.

Effect of Chemical Treatment on Oil Palm Empty Fruit Bunch (OPEFB) Fiber on Water Absorption and Tensile Properties of OPEFB Fiber Reinforced Epoxy Composite

Natural fibers have proved to be an excellent reinforcement material for various polymers. In this study, oil palm empty fruit bunch (OPEFB) fiber was incorporated in epoxy and an investigation on water absorption and tensile characteristics has been carried out. A fiber surface modification utilizing alkaline treatment with 2% sodium hydroxide solution was used in order to increase the fiber matrix bond in the composite. The investigation was carried out for 0.5% and 1% short and random fiber loading with fiber length range between 3mm to 5mm and diameter of 300μm. Result showed that surface modifications upon treatment changed the strength on the fiber matrix bond and the composites water absorption behavior. Alkaline treatment reduced overall water uptake and increased the tensile strength of the composites. However, increased in fiber loadings has resulted in increased amount of water absorbed and reduced the overall tensile strength.

Improvement in CAM Shaft Design: An Experimental Application and Recommendation

A new design of CAM shaft has been investigated for Campro engine 3.0L V4 engine. The new design adds a modification to Cam profile peak point in the Camshaft to be controllable at different speeds through a hydraulic system. The new design was simulated in CFD for tolerating stresses. The new design promotes Cams to give the exact heights at different engine speed depending on the optimize value valve opening time. At the same time this paper discusses the prediction of power performance of internal combustion engines with the new design. The expected result will significantly improve the engine speed-torque curve, reduce emission gases, and reduce fuel consumption. The new design model predictions need to be tested experimentally for further improvement in the hydraulic system before the commercial use.

Evaluation of Different Factors in Implementation of JIT Production System by Applying Simulation and Entropy Weighting Method

Competitive advantage and more profit and eliminating wastes will cause organizations to use new methods and techniques to enhance their performance and reduce the wastes and inventory in their production process. To achieve these goals, statistical methods such as simulation and mathematically method such as Entropy weighting is used to evaluate the weight and importance of factors in implementation of Just in Time philosophy in manufacturing systems. To certify the results of this research a case study is presented which is a part of production line of one company in IRAN. The result will be discussed about the effects of factors on production line and decision making process for managers.