Advanced Materials Research Vols. 931-932

Abstract: Combustion study of municipal solid waste combustion in a pilot scale fluidized bed combustor had been carried out. The work was aimed at demonstrating sustainable combustion of municipal solid waste by employing operating parameters gained from previous studies. The primary and secondary air factor used were AF = 0.8 and AF = 0.6 respectively. The fluidization number was 5U_mf and both in-bed and freeboard region temperature distributions were monitored continuously. Results on the combustion studies revealed that the initial bed temperature could be sustained due to high thermal capacity of sand but later dropped due to problem related to the mixing of bulky and heterogeneous components of municipal solid waste and sand.

Abstract: Methane gas obtained from coal sources can be classified into two categories i.e Coal Bed Methane (CBM) and Underground Coal Gasification (UCG) gases. The Industry today often neglects the importance of capturing the UCG as important source of methane potential besides the surface gasification potential. This research will evaluate on the new resource estimation of methane as reserves with application of new technological advances in exploitation. As an analysis, the UCG energy return is significantly higher than that of CBM. Both CBM and UCG output gas can be liquefied, or used as a direct feedstock to local power stations. The CO₂ generated from UCG process may be used for Enhanced Coal Bed Methane (ECBM) process because of more adsorption capacity than methane, may lead to additional methane potential. Deeper coal seams may be targeted for CBM, followed by UCG for additional resources in the form of coal gas. A depleted CBM area may be targeted for UCG with some modification on the well profile. Developing an integrated and centrally controlled approach to exploit the coal resources in which, the appropriate extraction methodology should be identified for each particular target coal-seam or groups of coal seam. It is important to strategize the sequencing of energy extraction methods to provide an optimal balance between the energy delivery for sustainable future and its true socio-economic value. As from this analysis, with 245.6 acres of coal, estimated gas can be produced is 3.25 TSCF which is 101 BSCF is coming from CBM, 3.14 TSCF from UCG and another 14.45 BSCF is from ECBM.

Abstract: A micro scale model of a solid oxide fuel cell (SOFC) involving the mass transfer together with the electrochemical reaction, the electron and ion transports through respective cylindrical shaped electron-and ion-conducting particles inside the electrodes was mathematically developed. The predicted cell performance was showed according to the operating and design condition. The effects of micro-scale electrode geometry on the cell performance were also taken into account. This present study reveals the working mechanisms of SOFC at the micro-scale level, while demonstrating the use of micro-scale relations to enhance the SOFC performance. The accuracy of the presented model was validated by comparing to already existing experimental results from the available literatures.

Abstract: This research presents the effect of fuel type on temperature profile within the pyrolysis-, combustion-and reduction-zone of the pilot-scale downdraft gasifier, and the replacement potential of LPG with syngas for electricity production. The experimental results showed that gasification of different fuels have the distinctions of temperature level in each zone. More stable syngas production was obtained either from wood chips (WC) or plastic carrier bag (PCB). In contrast, gasification of aluminum coated plastic bag (ACPB) showed the unsatisfied syngas. From the operation with the dual mode of LPG and syngas for electric production, LPG consumption was reduced about 27.08%, 14.58% and 8.33% when PCB-, WC-and ACPB-syngas were used, respectively.

Abstract: In this work, response surface methodology (RSM), with 5-level and 2-factor central composite design (CCD) was used to optimize the condition of base-catalyzed transesterification from refined palm oil. The two main parameters; methanol concentration and potassium hydroxide concentration, were varied to investigate the effect on the methyl ester purity. The result indicated that the KOH concentration was the most significant to produce methyl ester (the lowest p-values occurs in all response models). From excel solver, full quadratic model was obtained for predicting the response surface models. The suitable condition: 23.81 vol.% methanol and 11.80 wt.% KOH under temperature of 60°C and reaction time of 60 min, is the optimum condition.

Abstract: The present research attempted to characterize fuel spray pattern, such as spray angle, spray penetration and their mixture formation by recourse to images analysis. Diesel and biodiesel were used to investigate via a single hole injector (solinoild type) in a constant volume high-pressure chamber. In this experimental study, the spray characteristics of diesel and biodiesel fuel were comparatively evaluated. Initial conditions were ambient temperature, ambient density of 21 kg/m³, injection durations varied from 0.5 and 1 ms and rail pressure of 400 and 800 bar. The series of images were captured by high speed video camera with resolution of 7,500 frames per second and shutter speed of 1/10,000 sec under Schlieren photography technique. The result showed the biodiesel spray penetration was longer than that of the diesel, and spray angle of biodiesel in start injection was larger than biodiesel. From the results, it can be concluded that the higher the density and viscosity of biodiesel, the stronger the effect on the spray mixture formation.

Abstract: In industrial hard disk drive research and development laboratories, an environmental chamber is normally used to perform a mechanical verification test of Head Gimbal Assembly (HGA). It is very important to verify that the airflow pattern in the chamber is comparable to that in a real hard disk drive. Hence, we applied a transition shear stress transportation turbulence model (transition SST), one of the robust mathematical models in computer fluid dynamics, to simulate the airflow behavior inside both an environmental chamber and a hard disk drive (HDD). We found that, overall, the two patterns of airflow were not comparable at all. The air velocity vectors around the HGA in VENA were smaller than that in HDD. The reason for this is likely to be that there was more space between the top cover of the chamber and the platter than the space between the top cover of the hard disk drive and its platter.

Abstract: The objective of this work is to develop fracture simulations of rubber undergoing a combined tensile and out-of-plane shear loading. Rubber sheets are tested under mode-I (opening mode), mode-III (tearing mode) and mixed-mode [I/II of fracture. The experiments are simulated in finite element software to evaluate the J-integral for each mode of deformation. Comparison between simulation and testing results are in good agreement. The simulations serve as test cases and evaluation tools for the development of mixed mode fracture criterion of rubber.

Abstract: The particle trajectories and the number of them trapped by circulating filter of a 2.5 inch dual platter hard disk drive (HDD) were numerically investigated using a transition shear stress transport turbulence model (transition SST). Four head gimbal assemblies (HGAs) were placed at the outer diameter positions where tiny particles of alumina were released. The simulation revealed the results of airflow, particle trajectories and efficiency of a circulating filter. This result can be applied as fundamental information to design HDD layout in order to reduce its contamination. Keywords: Airflow, Circulating Filter, Hard Disk Drive, Particle Trajectory, Computational Fluid Dynamics

Abstract: Today, the hard disk drive (HDD) industry is using assembly automation machine (AAM) to construct head stack assembly (HSA) from smaller parts. AAM needs to operate in a clean environment with very low particle counts. To achieve this end, fan filter Unit (FFU) is used to supply purified air into the environment by filtering out airborne particles from recirculating air. In this study, we investigated numerically the airflow induced by FFUs inside a microenvironment that houses an AAM in an HDD factory. The boundary conditions chosen for simulation were directly derived from the real ambient conditions in this HDD factory. We found that the FFUs not only filter out airborne particles from the air supplied into the microenvironment but also act as a particle blocker, pushing away the nearby particles in the air surrounding the openings of the microenvironment. The findings from this study can be applied to cases where other kinds of machinery need to be protected from airborne particles.