Applied Mechanics and Materials Vol. 819

Abstract: Microchannel of micron-to milimeter in dimension has been immensely used for fluid handling in transporting, mixing and separating biological cells in Lab-on-Chip (LoC) applications. In this paper, design, simulation and fabrication of Polydimethylsiloxane (PDMS) microfluidic channel are presented. The microchannel is designed with one inlet and outlet. A reservoir or chamber is proposed as an extra component in the microchannel design for ease of separating the intended biological cells as used in LoC magnetic separator and micro-incubator. Finite Element Analysis (FEA) shows laminar flow characteristic is maintained in the proposed microchannel design operating at volumetric flow rate between 0.5 to 1000 μL/min. In addition, pressure drop data across the microchannel are also been obtained from the FEA in determining the safe operation limit of the microchannel. The PDMS microchannels of two different chamber geometries have been successfully fabricated using replica molding technique from SU-8 negative photoresist mold. The fabricated SU-8 mold and the PDMS microchannel structure dimension are characterized using Scanning Electron Microscopy (SEM). Reversible bonding of PDMS microchannel layer and PDMS tubing layer has successfully accomplished by activating the PDMS surfaces using corona discharge. The preliminary testing of the microchannel confirmed its function for LoC continuous flow applications.

Abstract: Every engine needs a cooling system in order to maintain the performance of engine. In this study the cooling system is applied in naval ship with the exchange of freshwater and seawater. Since the seawater contains biological fouling, then it is scaled in the heat exchanger so that the performance of heat exchanger is decreasing from time to time. This makes the heat transfer rate in cooler is less efficient so that to maintain the BHP of the engine it needs to consume more fuel. The result shows that the effect could incur a loss of about USD 463,852.8/month. This condition makes the importance of cooling system maintenance in order to keep the temperature of the naval ship engine and to minimize the additional fuel cost. For cooling system itself, to keep the cooler in a good condition, it needs to clean the cooler for every 720 hours, or once a month.

Abstract: Large amount of heat energy is wasted in Internal Combustion (IC) engine through the exhaust manifold, coolant, convective and radiative heat transfer. Significant amount of thermal energy waste occurring at the exhaust manifold of the IC engine can be recovered using various contemporary heat recovering techniques. The paper presented the viability of using turbo compounding waste heat recovering technique in recovering a significant amount of waste energy occurring at the exhaust of a heavily downsized engine. Electric turbo compounding (ETC) simulation using Ford Eco-Boost base line engine with modification using Hy-Boost modelled with AVL Boost software was carried out for the analysis. The simulation results show a 3% reduction in Brake Specific Fuel Consumption (BSFC), 0.5 bar Brake Mean Effective Pressure (BMEP) increase and up to 2 kW of power output were realized at engine speed of 2500 rpm. The result clearly indicates the effectiveness, viability and commercialization potentials of this waste heat recovery technique.

Abstract: The hydrogen permeation with a flat sheet Pd/Ag membrane for mixture of hydrogen and carbon dioxide was investigated experimentally. A flat sheet, dense 77wt.%Pd/23wt.%Ag purification membrane with thickness of 25μm and diameter of 0.02m was used. The membrane temperature, total upstream pressure and inlet H₂ mole fraction were set to 623K, 0.25MPa and 0.75, respectively. Meanwhile, the downstream pressure was set at atmospheric. Mean mole flux (feed flow rate/effective membrane surface area) was varied between 0.089-0.62mol.s^-1.m^-2. When the mean mole flux is increased, hydrogen permeation flux increases, which is supposed due to the effect of flow velocity. In addition, the analytical result based on Sieverts’ equation with the effect of permeation is found to be very close with the experimentally obtained hydrogen permeation flux. For permeation with H₂:CO₂ mixture, future work is necessary to investigate the variation in permeation flux with time.

Abstract: In automotive engine applications, the spark ignition (SI) engines can operate at various engine speed and load conditions. However, most of the time was spend at part load operations, where they operate below their rated output especially during cruising or idling. The needs of improvement in term of engine efficiency at part load operation become more popular among the engine manufacturers. One of the main reasons for efficiency dropped at part load conditions is the flow restrictions at the throttle valve opening area due to nearly-close position to control amount of inducted air into the cylinder, which leads to increasing in pumping losses. Hence, there are a lot of studies and investigations have been carried out to tackle these problems without sacrificing the original performance. This paper will investigate further the engine efficiency, performance as well as fuel economy by using one-dimensional (1-D) simulation tool. A baseline simulation model of a 1.6 liters four cylinders, port fuel injection engine has been developed based on the actual engine geometries. This baseline model applied predictive combustion to predict the amount of cylinder pressure based on actual ignition and injection timing on bench. The simulated results show a very good agreement with the measured data. Additionally, this study also proved that the deactivation half of the cylinders can significantly reduce the pumping losses of fired cylinder while eliminated the pumping work of unfired cylinders.

Abstract: The permeation characteristic of a flat sheet Pd/Ag membrane was investigated experimentally by using pure hydrogen. A 77wt.%Pd/23wt.%Ag membrane with 25μm thickness and 0.02m diameter was used. The hydrogen permeation mole flux was investigated under various reference membrane temperatures (423-723K), for upstream pressures of 0.21-0.29MPa, and feed flow rate of 1.39x10^-4mol/s. In all cases, the downstream pressure was set at atmospheric. Experimental results demonstrate the linear relationship between the hydrogen permeation flux and difference in square root of hydrogen partial pressure between the upstream side and downstream side, regardless of reference temperatures. This indicates the compatibility of the Pd/Ag membrane used in the present study with Sieverts’ Law. At sufficiently low temperature level, the hydrogen permeation flux is found to be very sensitive with the changes in the temperature.

Abstract: The variation in hydrogen concentration distribution on Pd/Ag membrane surface for permeation with H₂/N₂ mixture was investigated numerically, by varying the diameter of the mixture inlet. A 77wt.%Pd/23wt.%Ag purification membrane with thickness of 25μm and effective surface area of 3.14x10^-4m² was considered. The membrane temperature, total upstream pressure, and inlet H₂ mole fraction were set to 623K, 0.25MPa and 0.75, respectively. Meanwhile, the downstream pressure was set at atmospheric. Mean mole flux (feed flow rate/effective membrane surface area) was varied between 0.19-0.95 mol.s^-1.m^-2. The hydrogen concentration distribution was investigated for various ratios of inlet radius to membrane radius (0.22:1, 0.50:1 and 0.75:1). It is found that hydrogen permeation flux obtained from various hydrogen concentration distributions are almost same, and quantitatively fit with analytical result based on the Sieverts’ equation with the effect of H₂ permeation.

Abstract: There are many technologies that being developed to increase the efficiency of internal combustion engines as well as reducing their fuel consumption. In this paper, the main research area is focus on cylinder deactivation (CDA) technology. CDA mostly being applied on multi cylinders engines. CDA has the advantage in improving fuel consumption by reducing pumping losses at part load engine conditions. Here, the application of CDA on 1.6L four cylinders gasoline engine was studied. One-dimensional (1D) engine modeling is performed to investigate the effect of intake valve strategy on engine performance with CDA. 1D engine model is constructed according to the 1.6L actual engine geometries. The model is simulated at various engine speeds at full load conditions. The simulated results show that the constructed model is well correlated to measured data. This correlated model used to investigate the CDA application at part load conditions. Also, the effects on the in-cylinder combustion as well as pumping losses are presented. The study shows that the effect of intake valve strategy is very significant on engine performance. Pumping losses is found to be reduced, thus improving fuel consumption and engine efficiency.

Abstract: In this paper, the effect of metal-to-metal contact from the application of plant-based lubricants, RBD palm olein and jatropa were investigated by cold work forward plane strain extrusion experiments. A pair of taper die and a symmetrical workpiece (billet) was placed inside extrusion rig which acted as main experimental apparatus. The billet material was annealed pure aluminum A1100 with radius 5 mm in deformation area. The experimental result shows that the lower viscosity index, will lead to lower friction effect to the deformed area, as well as product area.

Abstract: This paper presents an analysis of porous layered long journal bearing lubricated with ferrofluid using displaced infinitely long wire magnetic field model. The ferrofluid flow in the porous region is analyzed using modified Brinkman model. Nondimensional pressure and shear stress expressions are derived using Reynolds boundary conditions. Nondimensional load capacity and coefficient of friction are evaluated under the influence of permeability of porous media, porous layer thickness, lubricant layer thickness, magnetic field intensity and distance ratio parameter. A porous layered journal bearing lubricated with ferrofluid increases the load carrying capacity and reduces the coefficient of friction.