Optimization of Metal Inert Gas Pulse Brazing Process on Galvanized Steel Sheets Based on Taguchi Method

AbstractThe purpose of this research was to identify the optimal conditions of the galvanized steel sheets based on the Metal inert gas pulse brazing process (MIGPBP). The study used the Taguchi method to experimentally design the L25 orthogonal array, including five main parameters: 1) wire feed speed, 2) arc voltage, 3) travel speed, 4) peak current, and  5) pulse frequency. Each of these parameters consisted of 5 levels, and thus the experiment runs 25 times with 3 replications (75 experiments in total) to find the characteristics of the MIGPBP that were considered important parameters and were exhibited significantly, including: 1) zinc coated balance of joint (ZB), 2) area for penetration of filler metal into the fit-up (ARP), and 3) tensile shear strength (TSS). The results demonstrated that the optimum conditions of the MIGPBP of galvanized steel sheets for the ARP and TSS were 4 meter/minute wire feed speed, 18 V arc voltages; 0.6 meter/minute travel speed, 450 ampere peak current and  35 Hz pulse frequency. For the ZB, the finding indicated the wire feed speed at 3.25 m/min, the arc voltages at 18 V, the travel speed at 0.9 m/min, the peak current at 425 A, and the pulse frequency at 35 Hz to be such optimal conditions which effected the quality of zinc coated balance of joint

Grey–Taguchi method to optimize the percent zinc coating balances edge joints for galvanized steel sheets using metal inert gas pulse brazing process

The objective of this work was to optimize the percent zinc coating balances edge joints of galvanized steel sheets using the metal inert gas pulse brazing process. The Taguchi method and grey relational analysis were used to determine the relationship between the metal inert gas pulse brazing process parameters and percent zinc coating balances edge joints. The metal inert gas pulse brazing process parameters used in this study included wire feed speeds, arc voltages, travel speed, peak currents, and pulse frequency. The characteristics of metal inert gas pulse brazing process that were considered to find response were percent zinc coating balances edge joints on the upper edge joint (PZBEJ1), the lower edge joint (PZBEJ2), and the back sides of the edge joint (PZBEJ3). Analysis of variance was performed to determine the impact of an individual process parameter on the quality parameters. The results showed that the optimal parameters in which grey relational grade increases at the highest level were wire feed speeds at 3.25 m/min, arc voltages at 16 V, travel speeds at 0.9 m/min, peak currents at 425 A, and pulse frequency at 35 Hz. These parameters gave a 74.90% higher response value than those of the initial parameters of metal inert gas pulse brazing process

Reducing Heat Loss in The Adiabatic Section of a Two-Phase Closed Thermosyphon (TPCT) Using Acrylic Tube

This study aims to present a method of reducing heat loss in a two-phase closed thermosyphon (TPCT) by replacing copper tubing with acrylic in the adiabatic section. The designs used included total lengths of (LT) 150, 300 and 450 mm. The evaporator section (LE), Adiabatic section (LA) and Condenser section (LC) lengths were all alike at 50, 100 and 150 mm. The copper and acrylic tubes were of 15 mm external diameter and 12 mm internally. The temperatures applied at the evaporator section (TE) were 60ºC and 80ºC. The angles of inclination were 0º, 20º, 40º, 60º, 80º and 90º, and air velocity at the condenser section was 1 m/s. The working fluid used was plain water with a filling ratio of 50% of the evaporator section volume. The experiment showed that as TE increased so did heat flux, however shorter LTs resulted in lower heat flux, and the maximum heat flux achieved was 5 kW/m2 at TE 80ºC, LE 150 mm, with an angle of inclination at 80º to 90º using acrylic tube in the adiabatic section. When acrylic tube was installed instead of copper tube at LA the resulting thermal resistance (Rtube) Cº/W decreased and heat flux increased. The maximum Rtube result was recorded at around 2.78Cº/W with the acrylic tube of LE 150 mm. with a TE of 80ºC

Corrosion behavior in heat pipe

The aim of this study was to perform life testing and determine the effect of working fluid on the corrosion of a heat pipe with a sintered wick. The heat pipe was made from a copper tube. The inner heat pipe was filled with 99.97% pure copper powder as a dendritic for the sintering process. The heat pipe had an outer diameter of 6 mm with a length of 200 mm, and distilled water and ethanol were the working fluids. The operating temperature at the evaporator was 125°C. The analysis consisted of using a scanning electron microscope, energy dispersive X-ray spectrometry and atomic absorption spectroscopy. The results of the scanning electron microscope and energy dispersive X-ray spectrometry analysis showed that the corrosion of the heat pipe was uniform. The result of the atomic absorption spectroscopy indicated that the concentration of the copper in the ethanol as the working fluid was greater than in the distilled water as the working fluid, and the highest concentration of copper particles in the ethanol was 22.7499 ppm or 0.0409 mg after testing for 3000 h. The concentration of copper was higher when the length of the life test increased due to corrosion of the heat pipe

Study of Microstructure and Mechanical Properties Effects on Workpiece Quality in Sheet Metal Extrusion Process

Sheet metal extrusion is a metal forming process in which the movement of a punch penetrates a sheet metal surface and it flows through a die orifice; the extruded parts can be deflected to have an extrusion cavity and protrusion on the opposite side. Therefore, this process results in a narrow region of highly localized plastic deformation due to the formation and microstructure effect on the work piece. This research investigated the characteristics of the material-flow behavior during the formation and its effect on the microstructure of the extruded sheet metal using the finite element method (FEM). The actual parts and FEM simulation model were developed using a blank material made from AISI-1045 steel with a thickness of 5 mm; the material’s behavior was determined subject to the punch penetration depths of 20%, 40%, 60%, and 80% of the sheet thickness. The results indicated the formation and microstructure effects on the sheet metal extrusion parts and defects. Namely, when increasing penetration, narrowing the die orifice the material flows through, the material was formed by extruding, and defects were visibility, and the microstructure of the material’s grains’ size was flat and very fine. Extrusion defects were not found in the control material flow. The region of highly localized plastic deformation affected the material gain and mechanical properties. The FEM simulation results agreed with the experimental results. Moreover, FEM could be investigated as a tool to decrease the cost and time in trial and error procedures

Mathematical model to predict heat transfer in transient condition of helical oscillating heat pipe

This research aims to study the heat transfer with a numerical model and experimental evaluation of a helical oscillating heat pipe (HOHP). Firstly, we created a numeric model of the HOHP to predict the time required to reach the steady state temperature and the heat transfer of the HOHP under transient conditions. Secondly, we measured the temperature at the pipe wall and evaluated the heat transfer rate from experiments and compared them with the numeric model. The results showed that the transient temperature and the heat transfer profiles of the HOHP from the numerical model were similar with the results measured from the experimental data. The results from numeric model predicted temperature profiles for attaining a steady state temperature were in close agreement, when compared to the numerical simulation of Boothaisong et al. (2015)

ศึกษาตัวแปรที่มีผลต่อท่อความร้อนที่ติดตั้งวัสดุพรุนชนิดตาข่าย

วารสารวิชาการและวิจัย มทร.พระนคร, 12 (2) : 172-183This research aims to study the parameters have affected the pipe which was studied the heat transfer characteristics of a heat pipe with a mesh wick. The heat pipe made from copper tubes with intemal (ID) as 10 and 12 mm and length of 30 cm which was installed a copper mesh wick inside a tube. Three working fluids are distilled water, ethanol and refrigerants-11 (R-11). The filling ratios is 50% with respect to evaporator volume. The operating temperature at the evaporator section is: 50, 70 and 90 oC. The condenser section has cooked by water with a flow rate of 0.5 L/min. Then, all of the experimental data were compared with the heat pipe without copper mesh wick. It was found that heat pipe at ID 12 mm yielded a better heat transfer rate when compared with heat pipe without a mesh wick. The heat pipe produced a heat transfer rate value of 7.3 W and heat pipe efficiency of 58.5 at evaporator section’s temperature of 90oC. In addition, the mesh wicks will help transfer the working fluid in the condenser section return to the evaporator section. The condensed liquid had spread around the walls of the heat pipe. The working fluid was condensed to the evaporator section then affected to a higher heat transfer rate.Rajamangala University of Technology Phra Nakho

การทำนายอัตราการถ่ายเทความร้อนในเงื่อนไขสถานะชั่วครู่ของเครื่องแลกเปลี่ยนความร้อนชนิดท่อความร้อนโดยใช้แบบจำลองสามมิติ

วารสารวิชาการและวิจัย มทร.พระนคร, 10 (1) : 51-64The aim of this study was to develop a three-dimensional transient condition model to predict the heat transfer rate of a heat pipe heat exchanger. This paper presents the details of the calculated domains, which consist of the wall, wick, and vapor core. They were numerically simulated using the finite element method. The heat transfer rate values obtained from the model simulation can be used to design heat pipe heat exchangers. The values obtained from the model calculation were then compared with the results from experiments, and the differences were 10.3%, 10.4%, and 6.7% for the working fluids of distilled water, ethanol, and R134a, respectively. The working fluids of distilled water, ethanol, and R134a obtained heat transfer rates of 627.3 watts, 522.8 watts, and 836.4 watts from the experiments, respectively.Rajamangala University of Technology Phra Nakho