Advanced Materials Research Vols. 931-932

Abstract: Nowadays, patients with osteoarthritis in Thailand are likely to increase in number every year. There are approximately 462,000 people and most are females than males. The treatment is surgery knee replacement implants which must be imported from abroad and cost is expensive.Total knee prosthesis used in Thailand would not fit with the body of the Thai women because of the design total knee prosthesis use anatomical data of Europe and designed for both male and female, which is different in the knee structure. This research aims to study the size and shape of knee for Thai women and design total knee replacement. The using of finite elements is to assist in the analysis which focuses on the influence of the force active on and the effects of stress distribution on the part of the knee at different stages of gait cycle. The results of the study can measure the average size of Thai knee women base on analytical data. Anthropometric data on the proximal tibia and distal femur of 55 female knees were obtained using three dimensional computer tomographic measurements. The parametric studies are dimension analysis of the femoral mediolateral (fML) and femoral anteroposterior (fAP) dimension on distal femur surface and tibial mediolateral (tML), tibial anteroposterior (tAP) on proximal tibia surface. The measuring average values are 65, 60, 67 and 45 mm respectively. All parameters were compared to the size of the total knee prosthesis which currently used in Thailand. It is found that values are 70, 62, 68 and 48 mm respectively which is larger than the average Thai woman.The study of finite elements can be made aware of the stress distribution and stress in the area of artificial knee while walking and leading to the design of artificial knee joint to have size and shape suitable for Thai women.

Abstract: A differential evolution (DE) algorithm has been employed to approximate the solution of a nonlinear single pendulum equation. The solution has been approximated as a Fourier series expansion form. Then, weighted-residual and penalty functions are employed to transform the problem into a constrained optimization problem while optimum solutions will be carried out by DE. This paper also studies an effect of a scaling factor of DE to the results. The results reveal that the scaling factor significantly affects the convergent speed and accuracy of DE. Approximate solutions well agree with the exact solutions for the scaling factor being 0.5.

Abstract: This paper presents simulation of particle dispersion in an ultrasonic cleaning tank.Contaminants removed from work-pieces by means of ultrasonic waves need to be disposed from the tank during the cleaning process. This is achieved by using water injection from horizontal tubes placed at the bottom inside the tank. It is expected that injection angles could affect the performance of particle disposal. The two-phase flow simulation is adopted to predict disposal capability while the computational fluid dynamic is carried out by means of finite volume analysis. Simulation results of particle dispersion in the tank with various injection angles are conducted, displayed, and concluded.

Abstract: Biogas produced from palm oil mill effluent (POME) is common in Thailand. A 2-step digestion system, which consists of a continuous stirred-tank reactor (CSTR) and a UASB, is being implemented for biohythane (biohydrogen and biomethane) production. This paper describes three-dimensional computational fluid dynamics (CFD) simulations of POME flow in a laboratory-scale CSTR. The study focuses on comparisonof impellers, the Rushton and the paddle turbines, for the best POME mixing with minimum loss of granules. The result of flow patterns in CFD showed that better mixing in the bottom through the middle of the tank can be achieved by proper selection of impellers and baffles to avoid the loss of granules by effluent.

Abstract: This research presents a numerical study of turbulent periodic flow and heat transfer in threedimensional isothermalfluxed square duct with diagonal inclined rib inserted. The fluid flow and heat transfer characteristics are presented for Reynolds numbers in the range of 4000 to 20,000. The computations based on the finite volume method, and the SIMPLE algorithm has been implemented. Effects of rib pitch ratios (0.5 to 2) at a single blockage ratio of 0.2 and attack angle of 60^o on heat transfer and friction factor in the duct are examined and their results of the inclined rib are also compared with those of the smooth duct. It is found that the inclined rib provides higher heat transfer rate and friction factor than the smooth duct for all cases. In addition, the decreasing of the pitch ratio leads to the rise in the Nusselt number and friction factor.

Abstract: This work presents a numerical investigation of laminar periodic flow and heat transfer in a constant heat flux-surfaced square-channel fitted diagonally with 45° V-discrete baffles. The computations are based on the finite volume method, and the SIMPLE algorithm has been implemented. The fluid flow and heat transfer characteristics are presented for Reynolds numbers based on the hydraulic diameter of the channel ranging from 200 to 1,200. Effects of different blockage ratios (BR=b/H), BR in range from 0.05-0.2 with pitch ratio of 1.0 on heat transfer and pressure loss in the channel are studied. It is apparent that vortex flows created by the 45° diagonal V-discrete baffle exist and help to induce impinging flows on wall leading to drastic increase in heat transfer rate over the smooth channel. In addition, the increase in the BR results in the rise of Nusselt number and friction factor values. The computational results reveal that the optimum thermal enhancement factor of the 45° V-discrete baffle is about 2.24 at BR=0.2.

Abstract: At present, the forest fires cause smoke and pollution problem in Chiang Mai that affects human, animal, and ecosystems. Over the past few years, air pollution from forest fire has increased. The resident in northern of Thailand faces problems with air pollution and deforestation. Protecting the forest fires and environmental is the one of top priority in solving this problem in northern of Thailand. Therefore, early burning is one of the solution that has been chosen to used in Chiang Mai forest fire prevention strategies.

Abstract: The air-blast freezer is common freezing technique for shrimps in seafood industry. In many companies encounter with developing this technology for food industry. In this study, Development in effects and behavior of airflow over in pressure chamber of continuous belt air-blast freezer, were investigated by simulating the airflow field by using computational fluid dynamics (CFD). Pattern holes in plenum plate and Modifying shape tunnel were cases study in redesign of development. The average velocity at outlet holes of airflow were determined and the streamline and vector of airflow were analyzed. The effects of redesign could increase the average relative velocity at outlet up 22- 32% compared with the original design.

Abstract: A numerical investigation has been conducted to examine turbulent flow and heat transfer characteristics in a three-dimensional isothermal tube mounted with 60° angled rings (AR). The ARs with pitch spacing ratio, PR=1.0 and various blockage ratios (BR) ranging from 0.025-0.1 are introduced. The computations are based on a finite volume method and the SIMPLE algorithm has been implemented. The fluid flow and heat transfer characteristics are presented for Reynolds number (Re) ranging from 3000 to 12000. To generate a main counter-vortex pair flow in the tube, ARs at an attack angle of 60° are mounted repeatedly in the tube. Effect of different BRs at a single PR and nanofluid, Al₂O₃water, with volume fractions 1% and 5% on heat transfer and friction loss is investigated. It is apparent that two main vortex flows created by the ARs exist and help to induce impinging flows on the tube wall leading to drastic increase in heat transfer rate over the tube. The increment in the BR gives rise to the increase in the Nusselt number and friction factor. The computational results reveal that the maximum thermal enhancement factor for the AR with BR=0.025 is found to be 1.8 at Re =3000. The results show that nanofluid, Al₂O₃ water, can increase the thermal performance when increasing volume fraction to 5%.

Abstract: Effect of 30° rectangular-winglet vortex generators (WVGs) mounted in the central core of a circular tube on convection heat transfer and friction loss is experimentally investigated in the present work. The rectangular-WVGs with two different winglet-height to tube-diameter ratios (called blockage ratio, BR = b/D = 0.1 and 0.2) and three winglet-pitch to tube-diameter ratios (PR=P/D=0.5, 1.0, and 1.5) are introduced. In the experiment, air at ambient condition is passed through the uniform heat-fluxed circular tube for Reynolds numbers (Re) in a range of 500024,000. The use of WVGs is to generate longitudinal vortex flows in the tube. The experimental results of heat transfer and pressure loss presented in terms of Nusselt number and friction factor are compared between the inserted and the smooth tubes. It is found that the BR and PR provide a significant effect on the thermal performance of the test tube. The results reveal that at smaller PR, the WVG with BR=0.2 provides the highest heat transfer and friction factor but the one with BR=0.2, PR=1.5 yields the best thermal performance.