Applied Mechanics and Materials Vol. 786

Abstract: Study on the flow and combustion behavior inside gas turbine combustor used in thermal power plant is described in this paper. The combustion process takes place using synthetic gas and emphasis is given to the effect of pressure variation on flame profile, temperature distribution and emissions as compared to the conventional combustion using methane. The operating pressure of the can-type combustor varies in the range of 1-10 atm. while the syngas composition is assumed to have fixed values of 10% CH₄, 55% CO, 30% H₂ and 5% N_2. Preliminary result shows that the flow inside the can-combustor is highly swirling which indicates good mixing of fuel and air prior to the entrance of the mixture to the main combustion zone. The temperature distribution at combustor mid plane show identical pattern for pressure range between 1-10 atm for both maximum and average temperature magnitude.

Abstract: This paper presents the development of Gamma-type Stirling engine for High Temperature Differential (HTD) and self-pressurized mode of operation. The engine is the up-scaled version from the Low Temperature Differential (LTD) miniaturized gamma-type Stirling engine. The test engine is featured with 85cc power piston and 4357cc displacer piston swept volumes, respectively. The characterization of few critical engine parameters and components that includes heater head section, cooler section, displacer and power pistons material selection and heat source system had been conducted. Air is used as a working fluid and Liquefied Petroleum Gas (LPG) is utilized as the heat source in order to cater for the heater temperature up to 1000°C. The workability test of the engine revealed that the lightweight in mass of the displacer piston and the auxiliary cooling effect at the cooler section had contributed to a significant improvement on the engine rotational motion. The static load test determined that the engine is capable of producing the friction power of 1.2W for stainless steel mesh wire displacer and 0.3W for polystyrene displacer. Based on Beale formula, the estimated power of 4W can be produced by the engine using stainless steel mesh wire displacer and 2.4W of power using polystyrene displacer. Good agreement has been shown, where the potential net power production of 3.8W and 2.1 W for stainless mesh wire displacer and polystyrene displacer, respectively. Further investigation is needed to improve the heat regeneration in between hot and cold sections of the engine to realize the sustainable performance of the engine at higher range of temperature difference and output power.

Abstract: Two different methods for reducing the operating temperatures of non-concentrating photovoltaic panels are analyzed and the performances are compared. Forced air cooling using a low power fan and use of a thermo siphon heat pipe are the modifications proposed for the purpose of efficiency enhancement. Experimental results of the two techniques are compared. It was found that, using a specific flow rate and selection of the proper heat pipe fluid and its operating conditions could help to reduce panel temperature considerably.

Abstract: Bubbling fluidized bed (BFB) is a vital equipment in many applications in the energy, pharmaceuticals, and chemicals process industries due to its numerous advantages such as large heat capacity inside a bed, and rapid heat and mass transfer rate. In spite of numerous research activities, achieving high fluidization performances in BFB process is still a challenge of science. This research is being conducted to study the hydrodynamic regime of a BFB pilot plant gasifier. To this end, a lab-scale cold model was first designed based on the empirical equations and scaling laws. The scaling laws was used to scale down the Tenaga Nasional Berhad-PETRONAS (TNBR-PETRONAS) pilot plant gasifier into a small scale laboratory model. Moreover, the empirical equations were utilized to determine the critical parameters such as bed pressure drop, height of the bed, number of orifices of the distributor plate and the pitch size. Finally a lab-scale hot flow model will be designed based on the cold model geometric dimensions but under a real operating conditions as that of a pilot plant.

Abstract: Gas turbines offer a reduced weight and compact solution for installation on offshore platforms and floating facilities. The purpose of this study is to examine the influence of various parameters on offshore gas turbines performance. Operating measurements of a 23MW gas turbine installed at an offshore oil and gas plant in east of Peninsular Malaysia was used for model verification and evaluation. The results showed that the gas turbine performance improvements involve the study of a wide range of different parameters including ambient temperature, compression ratio, fuel-air ratio and operating load. These achieved relations will help in appropriate assessment of offshore gas turbines thermal efficiency.

Abstract: In this paper, thermal analysis of cup shaped article using finite element method for flash-less cold forging is presented. The work-piece specifications are calculated by developing mathematical relations between volumes of die cavity and work-piece. The three dimensional FE simulation is made by DEFORM F3 V 6.0 and geometrical modeling for the die and the work-piece is performed by SOLIDWORKS 2007 4.0. The work-piece used is of AISI 1045 steel and the die material is steel (AISI D2). The results of numerical simulation and analytical calculations are found in satisfactory agreement with the experimental results.

Abstract: In this paper, the performance of a gliding robotic fish with different wing aspect ratio is investigated. The gliding robotic fish, developed by Michigan State University, has the energy efficient locomotion of an underwater glider and high maneuverability of a robotic fish. ANSYS Computational Fluid Dynamics turbulence model was used to determine lift and drag coefficients for various wing aspect ratios at different angle of attack. Subsequently, the corresponding glide angle and velocity were determined analytically based on its dynamic model. The simulation results compare well with published experimental data and shows that the drag and lift coefficients are inversely proportional to the wing aspect ratio. As such, a gliding robotic fish with a low wing aspect ratio is suitable for shallow waters only, due to the high lift forces generated for a given angle of attack, requiring greater energy to sustain the glide velocity and vice versa.

Abstract: Ostheochondral defects are a lesion on the articular cartilage which happened due to severe twisted knee or a sudden direct impact on the knee during sporting activities. Since, the treatments for this type of injuries which is replacing the articular cartilage with Titanium Alloy has too many disadvantages had caused researchers to develop alternative treatment of scaffolding application. The method of layered manufacturing has allowed AM to be used to produce the scaffold in varying layer of characteristics. Since the injuries of Osteochondral defect have affected many athletes, the scaffold of the articular cartilage has been widely used. However, as the result, there were too many scaffold designs without a clear conscious on what kind of design suits the best. Therefore, a simple program to assist in determining the scaffold design has been developed. It was found that the program was useful to suggest the suitable scaffold design based on the health condition of a patient.

Abstract: Presently the prime task of manufacturing engineers is to make products within a short span by maintaining the best quality at minimum cost. Recent market trends confirm the continuation of New Product Development (NPD) as a change agent for many more years to come with a focus on high product variety and shorter product life cycles. The effective introduction of new products is critical to the performance of manufacturing industries in more industrial sectors. It is a measure of an industry's strength in innovation and competitiveness in NPD. Manufacturing industries are forced to accept that the focus on NPD is on increasing product variety and shorter product life cycle. For many manufacturing industries, mass customization with "voice of customer", agility and leanness are some of the vital prerequisites to survive in the current global competitive environment. NPD is no longer an isolated process; it requires close integration between all active members within the supply chain such as customers, suppliers, manufacturers, etc. and must be viewed as an integrated business process. The proper use of advanced IT has enhanced NPD in manufacturing enterprises. It facilitates shorter product lead-times and increases responsiveness to changes in the market along with improved product quality, as well as maintaining low product cost.

Abstract: This work analyses a ‘Y’ wheel configuration for stair climbing and optimizes the mechanism for a dedicated staircase configuration. This stair climbing mechanism consists of a ‘Y’ shaped wheel with a gear system which changes its mode of operation from a simple gear train to an epicyclic gear train whenever it encounters step. The analysis consists of understanding the mechanics as the ‘Y’ wheel encounters a step, why the ‘Y’ wheel tends to climb the step and how it climbs the step and starts rolling. Each case is analysed by considering governing factors like the ‘Y’ wheel link length, end wheel radius, and weight and staircase configurations, and studied to show the variation in torque requirement and reaction forces. The stair climbing mechanism is optimized using graphical method and verified using linear programing in Matlab.