Applied Mechanics and Materials Vols. 465-466

Abstract: As the usage of composites materials are significant in the industries of automobiles, shipping and constructions due to their non-corrosive and high strength to weight ratio. Anyway, the production of composites needed to be increased to meet the demand. At this stage, problem faced by Small and Medium Industries / Entrepreneurs (SMI/E) is the confined and limited space available that restricts the optimum productivity. They commonly cure the composites horizontally that requires ample space and unable to afford for high-end equipment such as mechanical oven and autoclave in the production as a result of high capital cost.This research is carried out to study the feasibility of the gravity effects on curing position of the laminated composite structures to enhance the curing space needed. The aim of the research was to investigate the tensile properties of the thermosetting laminated composite by curing the laminate at different angle using vacuum bagging technique. From the testing, SN 5 which denominated to be 60 ̊ found to have the best tensile properties in term of maximum force exerted and Youngs modulus.

Abstract: In this paper, steady state, incompressible, swirling turbulent flow through circle grid fractal plate has been simulated. The aim of the simulation is to investigate an effect of the circle grid fractal plate thickness in order to reduce swirling due to swirl disturbance in pipe flow. The simulation and analysis were carried out using finite volume CFD solver ANSYS CFX. Three different thickness of fractal plate were used in the simulation work with the thickness of 1 mm, 3 mm and 6 mm. The simulation results were compared with the pressure drop correlation of BS EN ISO 5167-2:2003 and turbulent model used, standard k-ε model gave the best agreement with the ISO pressure drop correlation. The effects of circle grid fractal plate thickness on the flow characteristics which are swirl angle and tangential velocity have been investigated as well.

Abstract: Waste heat recovery in automotive engineering is part of the sustainable energy effort to optimize energy utilization. For vehicles running on hydrogen fuel cells, the potential of heat recovery is perceived to be limited due to the low quality energy generated from the fuel cell stack. It has been established in fuel cell operation that increasing the inlet hydrogen temperature improves the conversion efficiency through higher kinetic reaction rates. A fuel cell power plant for a mini vehicle that will be competing in Shell Eco Marathon Asia 2014 was studied to identify the potential energy recovery limits for an improved power plant design with regenerative hydrogen pre-heater. Using modeling approach for fuel cell power generation and efficiency relationships, the first-order waste energy potential was identified based on test bench studies on the electrical and thermal power relationship of the fuel cell stack performance. The corresponding result is then mapped to a driving cycle to investigate the thermal power generated during the race in both aggressive and passive driving cycle. The energy recovery potential for 4 laps course under aggressive and passive driving cycle are 529 kJ and 501.8 kJ consecutively. The mean thermal powers are 485 W and 410 W respectively which is the reference energy for extended heat exchanger design purposes.

Abstract: In this contribution, we present an in-depth analysis of an alkali catalyzed biodiesel production using waste palm oil. In view of the limited availability of non-renewable energy sources and the environmental concerns due to the high polluting nature of fossil fuels, biodiesel is seen as a future fuel alternative. We consider a waste palm oil with 6 % free fatty acids as a feedstock, which makes this process economically attractive. A complete process including esterification and transesterification is simulated using the Aspen Plus process simulator. The quality of a produced biodiesel is compared against different standards. In the subsequent part, the effect free fatty acid in feed oil on the overall biodiesel production is tested. In the last section of this paper, a techno-economic analysis and the scale-up study is carried out to determine the dependence of the feasibility of process on production capacity. The results show that higher capacity is desirable.

Abstract: The scarcity of oil resources and the rise of crude oil price had driven the whole world to seek for an alternative fuel for automotive industry. One of the prospective alternative fuels for compression ignition (C.I.) engine is compressed natural gas (CNG). In order to operate CNG in a C.I. engine as mono-gas engine (RE), several modifications are required. The modifications that involves are compression ratio, fuel injection type, addition of spark plug and fuel itself. So as to reduce the time in preparing the experimental test bed and high cost analytical study a 1-dimensional simulation software GT-Power was introduce. The GT-Power simulation model for a 4 cylinder medium duty C.I. engine (DE) and RE has been built to study the effects of conversion process to the performance and emissions of the engine at various operational conditions: low, medium and high load conditions. As compared with DE model, results from RE model showed loss in brake power (BP) and brake thermal efficiency (BTE) by 37.3% and 19% respectively. Meanwhile, for brake specific air consumption (BSAC) RE predicted to undergo an average of 19412.6 g/kW-h and increment in volumetric efficiency by percentage of difference 22%. In other side, oxides of nitrogen (NO_x) RE engine model predicted reduction of 48.1% (engine mode 1-9) and increased in hydrocarbons (HC) by 90.3.

Abstract: Diesel engines are widely used in almost all professions and cannot be dispensed with in the near future. Now the fossil fuels which are mainly used in diesel engines are depleting continually accompanied by increasing consumption and prices, there is the need to find alternative fuel to fulfil the worlds energy demand. Alternative fuels like biodiesel, are being used as effective alternative for diesel. The feasibility of biodiesel production from palm oil was investigated with respect to its fuel properties. Though biodiesel can replace diesel satisfactorily, problems related to fuel properties persist. In this study an oxygenated additive 1-butanol (BU) was blended with palm oil biodiesel (POME) in the ratios of 1%, 3%, 5% and 7% and tested for their properties improvement. These blends were tested for energy content and various fuel properties according to ASTM standards. Qualifying of the effect of additive on palm biodiesel fuel properties can serve the researchers who work on biodiesel fuels to indicate the fuel suitability for diesel engines according to fuel standards. Blends of BU in POME resulted in an improvement in acid value, viscosity, density and pour point with increasing content of BU in the blend. Further improvement in the pour point temperature of the palm oil methyl esters 1-butanol blends (B-BU) at 7°C can be achieved by adding 7% BU additive to POME, accompanied by 8.07% decrease in energy content of biodiesel.

Abstract: The increasing energy demand challenge, in addition to the crises of mineral oils depletion that becoming a very serious topic. As the main fuel used in energy production for all scopes of life now is the fossil fuels, there is an urgent need to find out an alternative fuel to fulfill the energy demand of the world. The feasibility of biodiesel production from palm oil was investigated with respect to its fuel properties and blending characteristics with petroleum diesel. Though biodiesel can replace diesel satisfactorily, problems related to fuel properties persist. In this study an oxygenated additive butanol (BU) was added to palm oil biodiesel (POME)-diesel blend B50 (50% POME + 50% diesel) in the ratios of 1%, 3%, 5% and 7% and tested for their properties improvement. The results showed slight improvement in acid value, significant viscosity and density. Maximum decrease in pour point by 6 °C at 5% butanol, on the other hand maximum decrease in energy contenent about 11% at 7% butanol compare to blended fuel B50.

Abstract: A theoretical exergetic analysis of a small-scale gas-turbine system fueled with two different syngas fuels is discussed in this paper. For carrying out the analysis, a micro-gas turbine system with a thermal heat input of 50 kW was simulated using ASPEN plus simulator. Quantitative exergy balance was applied for each component in the cycle. The effects of excess air, ambient air temperature, and heat input on the exergy destruction and exergetic efficiency for each component were evaluated and compared with those resulted from fueling the system with liquefied petroleum gas (LPG). For 50 kW heat input and 50% excess air, the total exergy destruction for LPG, Syngas1, and Syngas2 were found to be 17.3, 14.3, and 13.6 kW, respectively. It was found that increasing the excess air ratio to 100% increased the combustion chamber exergetic efficiency by 8%-10% but it reduced the exergetic efficiency of other components. The same trend was observed when tested ambient air temperature. The results also showed a reduction in the combustion chamber exergetic efficiency by 2%-4% when a 20% heat input increase was applied.

Abstract: Theoretical analysis of unsteady magnetohydrodynamic free convection flow of a viscous incompressible radiative fluid past an infinite vertical plate with constant heat and mass flux is presented. The dimensionless governing linear partial differential equations have been solved using the Laplace transform technique. The exact solutions for the velocity, temperature and concentration fields are derived. The effects of radiation, magnetic field and buoyancy ratio parameters on the velocity and temperature fields are discussed through graphs. It is found that the velocity increases with increasing radiation parameter whereas it decreases with increasing magnetic field parameter for buoyancy assisted flows.

Abstract: It has been proved that creation of vacuum between the absorber and the cover of a solar collector is resulting in a substantial improvement in the collector efficiency due to reduction in the heat loss through convection ad conduction. In this work, the performance of evacuated tube collectors is investigated using TRNSYS simulation model. Different levels of concentrations have been considered in the simulation to predict the power generation. The simulation results showed that the thermal performance of evacuated tube collectors with high concentration ratio can provide a good improvement to the receiver output.