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This study investigated the optimum value of Archimedes Screw Turbine (AST) performance by taking into account blades number. This paper also addressed the design approach based on a fixed incline angle of 30°, where this paper also addressed the design approach. Variations of the single and double blades were experimentally carried out concerning the turbine power output, torque, and rotation speed. This study's aim was related to the optimum power output between two blade variations, while the manufacturing and design steps were addressed as well. In the design process, the obtained blade length dimension was 0.180 m and 0.269 m for the single and double blades. Furthermore, the overall turbine's length was 1.7m, and the inner and outer of the turbine's radius were 0.069m and 0.128m. Meanwhile, the manufacturing process began with turbine modeling, plate cutting, plate withdrawal (thread formation), welding, and attained finishing process. Based on the experimental result, a double blade turbine generated turbine power by 48.8W at an average rotational speed of 115.3 rpm. Moreover, a single blade turbine produced 37.5W with turbine power averaging a rotational speed of 109.8 rpm. It was obtained that the values of turbine efficiency were 42% and 38% for double and single turbine types, respectively. Based on this finding, it can be suggested that a double blade was more efficient than a single one. This study is beneficial for the design consideration of the AST system.

In an unmanned aircraft vehicle, a navigation system is needed to calculate its orientation and translation. The navigation system can utilize data from the accelerometer, gyroscope, magnetometer, and GPS. The orientation can be precisely calculated from the accelerometer and magnetometer data when the sensor is in a static state. Meanwhile, under dynamic conditions, the orientation can be more precisely calculated from the gyroscope data. In order to obtain the robust navigation system, a data fusion based on Kalman filter is built to calculate the orientation from the accelerometer, gyroscope, and magnetometer. The Kalman filter trusts more in the data from the accelerometer and magnetometer when the UAV is static and trusts more in to the gyroscope data when the UAV is in dynamic conditions. Meanwhile, the UAV translation is obtained by performing data fusion of the accelerometer data with location data from the GPS sensor. The Kalman filter combines data from the accelerometer and GPS when available, otherwise trusts in data from the accelerometer only. The trust level shifting is done by changing the measurement noise covariance. The data fusion based on Kalman filter provides more accurately the orientation and translation data. The orientation as a result of the calculation from the gyroscope has an average error of 18.12%, while the orientation as a result of the accelerometer and magnetometer has an error of 1.3%. By using Kalman filter-based data fusion, the error of the orientation decreases to 0.87%

The understanding of the interfacial wave structure and its effect to the interfacial friction factor is important to reveal the transition from stratified to the slug flows. However, the available theoretical of models, as well as the correlations to predict the wave interfacial characteristics, is quite rare. The discrepancy among researchers is often found. In the present work, the wave characteristics of air-water stratified flow were investigated experimentally. The inner diameter was 26 mm. The liquid superficial velocity (JL) raised from between 0.02 m/s and 0.075 m/s while the gas superficial velocity (JG) ranged from 4 m/s to 16 m/s. A high speed camera was used to capture high-quality visual data which was later processed with the image processing technique. As a result, the quantitative parameters of the stratified flow were successfully determined and analyzed. Next, the dimensional analysis was carried out to develop correlation to predict the flow parameters of the wave such as the wave frequency, the wave velocity, the wave amplitude, and the wavelength. Furthermore, it is found that the ratio of gas and liquid Reynolds number and Martinelli Parameter plays important role in almost all of the proposed correlation.

The knowledge of the slug flow is essential the design safety of hydrocarbon transportation in the pipeline system of petroleum industries. However, the suitable models to predict the transition condition to slug flow are limited due to insufficient availability of experimental data. In the present study, the hydrodynamic characteristics of the near the transition to slug flow of air-water two-phase flow in horizontal pipes were investigated experimentally for inner pipe diameters of 16 mm, 26 mm, and 50 mm. The superficial velocities of water and air ranged from JL = 0.03 to 0.30 m/s and JG = 0.7 to 10.0 m/s. The hydrodynamic behavior was obtained from the combination of the visualization detected by using a high-speed video camera, the pressure gradient, and instantaneous volumetric liquid fraction measurements. The experimental results indicate that the wave growth and the wave coalescence are involved in the mechanism of the slug flow formation. Both gas and liquid superficial velocities have a significant effect also of those mechanisms. The average volumetric liquid fraction near the transition to slug flow is not affected by superficial gas velocities. Next, under a constant superficial gas velocity, an increase in the inner pipe diameter requires a larger superficial liquid velocity to change the flow patterns from stratified smooth to slug flow, and from pseudo-slug to slug flow.

The first geothermal binary system in Indonesia that has successfully implemented is a 500kW binary system in Lahendong. Yet, there is still a plenty room of improvement for binary system development in Lahendong. This study aims to give an alternative design of the binary system by using an organic Rankine cycle. The investigations of thermodynamic analysis based on the law of thermodynamics, silica scaling analysis, and optimization of working fluid selection are presented. Flashing process from separator produces vapor and liquid-brine with mass flow rates 48.6 kg/s and 173.6 kg/s at separator pressure of 10.23 bar. Based on second law thermodynamics analysis, obtained the maximum useful energy from brine flow is 7.2MW. Based on the simulation results, it is achieved that the potential power generated by waste heat from the Lahendong plant is 2.46MW with the net thermal and exergy efficiency by 11% and 34%, respectively. Compared to the current operating binary system, still, much available energy needs to be harnessed in the future from the Lahendong plant.

The study on the interfacial phenomena of flooding during the counter-current flow of gas-liquid in a complex pipe was carried-out experimentally. It consists of a combination of the horizontal pipe, elbow and inclined pipes to simulate the hot leg pipe in a PWR. The inner diameter was 25.4 mm as scale down of real hot leg pipe of German Konvoi type reactor. The visual observations were performed using high-speed video cameras. The measured parameters were the liquid film thickness and the pressure difference between reactor pressure vessel (RPV) simulator and steam generator (SG) simulator. The film thickness inside the test pipe was determined by using the processed image of visual data. As a result, three different mechanisms at the onset of flooding in counter-current were clarified, and are strongly affected by liquid superficial velocity. At low liquid superficial velocity (J L ), the flooding mechanism is triggered by the presence of wavy interface along the horizontal pipes in the form of a liquid blockage on the elbow. At the medium J L , the slug was detected along the horizontal pipe. However, the slug collapses immediately since the water is insufficient to maintain the blockage. At high J L , the slug occurs and travels along the horizontal pipe until the elbow. Moreover, the effect of the length of horizontal pipe on the interfacial behavior of air water counter current flow also can be explained. As the length of the horizontal pipe decreases, the onset of flooding occurs at a higher gas liquid mass flow rate.

The aim of the present paper is to propose an image processing technique in order to study the interfacial behavior of air-water slug two-phase flow in horizontal pipes. Here, the experiments were performed in two sets of transparent acrylic pipes with inner pipe diameters of 16 mm and 50 mm. To observe the interfacial behavior of slug flow, the liquid and gas superficial velocities were set to 0.2–0.77 m/s and 0.7–2.83 m/s, respectively. Visualization studies by using high speed video camera combined with image processing techniques were since it offered numerous advantages. Moreover, a sequential procedure was implemented for processing of each image. This technique has succeeded to enhance the image contrast and remove the uneven background. Next, a number of steps applied to binary image were also performed in order to remove the dispersed bubble attached on bubble tail which becomes one of the biggest challenges for the visualization studies of slug flow. As a result, the developed image processing technique was able to minimize the errors in order to produce the accurate measurement. Moreover, the processed image have been utilized to gather the quantitative information. It reveals the comprehensive characteristics of slug flow in horizontal pipes. Finally, a good agreement between the present and previous works proves the reliability of the developed technique.

Slug flow is the most prevalent problem of two-phase fluid transportation in the petroleum industries. Here, large amplitude waves lead to the pipe blockage that possible to cause the damage of the mechanical structure. The experimental investigation of gas-liquid slug two-phase flow in a horizontal pipe was carried out to investigate the initiation and flow development mechanisms. Air and water were used as the working fluids. The inner pipe diameter was 26 mm. In the present experimental study, the slug initiation mechanisms were explained by visual observation and pressure fluctuations. Moreover, the initiation frequency of slug flow and the evolution of passing slug frequency along the pipeline were also observed by using two high video cameras. As a result, several basic mechanisms of slug flow initiation in a horizontal pipe were clarified. Those were the wave coalescences, the wave growth mechanism, and the large disturbance waves. A flow initiation map was proposed to address those mechanisms. Here, the slug initiation frequency and the passing slug frequency were obtained in relation to the pipe length position. The static pressure measurement was also used to verify the image processing results on the characteristics of slug initiation mechanisms. The obtained qualitative and quantitative results from the investigation can be used to evaluate the recent available models.

In order to improve the understanding of transient behavior of gas-liquid plug two-phase flow in a horizontal pipe, CFD simulations and experimental studies on the relevant phenomena were carried-out. The pipe diameter and pipe length were 26 and 9.5 m respectively. The transient calculations were carried out using a Volume of Fluid (VoF) multiphase flow model of the commercial CFD code of FLUENT 6.3. The corresponding CFD solution has been obtained by using the Best Practice Guidelines of CFD for thermal engineering purposes. In the present works, the series of high quality experimental data was used to validate the CFD calculations in terms of time and space. A comparison with the high-speed video observations shows a good qualitative agreement. The results indicate also a quantitative agreement between calculations and experimental data for the elongated bubble length and the time variation of the liquid hold-up.

Buck-boost converters are widely used in the development of DC-DC converters. Several techniques and algorithms have been introduced to improve the transient response of buck-boost converters. However, due to the opposite trends of the output current change and the output voltage change, undershoot or overshoot in the output voltage still seems to be inevitable. In order to overcome this problem, a novel boost-buck converter architecture is proposed to build a fast transient response DC-DC converter. The converter consists of a cascaded configuration of the boost and buck stages. The boost stage converts the input voltage to the shared capacitor voltage and the buck stage supplies energy to the load by converting the shared capacitor voltage to the output voltage. By harnessing the energy stored in the shared capacitor, the transient response of the boost buck converter can be improved to 2 µs in a step-up load current change of 1 A with an output-voltage ripple of 15 mV.

The slug flow phenomena are often encountered in various industrial applications such as petroleum, process, and power plant. The presence of slug flow should be avoided as it causes structural damage due to resonance, corrosion and pipes blast. From the view point of multiphase flow, the understanding of the slug initiation mechanism is very important in pipeline design. This research is conducted using horizontal transparent acrylic pipes with diameters of 50 mm with a variation on the superficial velocity of water between 0,1 m/s and 0,77 m/s and superficial velocity of air between 0,31 m/s and 6,2 m/s. In the present experimental study, the slug initiation mechanisms was explained by visual observation by using high speed video cameras. As the results, the slug flow initiation mechanism were clarified. Furthermore, the proposed of flow initiation map was introduced.

The aim of this research is to investigate the characteristics of the sub regime of slug flow in horizontal pipe. Here, a 16 mm inner diameter horizontal pipe is utilized in order to observe the specific behavior of each flow pattern. The air and water superficial velocity are 0.7 – 8 m/s and 0.2 m/s – 1.13 m/s, respectively. To obtain thorough insight through visualization, a high speed video camera is installed on the area 190 D where the flow is fully developed. A pair of CECM sensor is also placed to gather the quantitative data from the liquid slug hold up. Furthermore, the pressure characteristics of each sub regime flow pattern are recorded by using pressure transducer. As a result, the present study has been able to provide a comprehensive data of the slug flow sub regime. Broadly, there are four observed sub regime on the slug flow. Slug and plug flow is characterized by the presence of plug flow intermittently. The less aerated slug and highly aerated slug can be distinguished by the degree of aeration which can be verified by liquid hold up measurement. While the slug and wavy flow contains wavy interface on the stratified layer. The analysis of each flow pattern is followed by the propose of a slug flow sub regime flow pattern map which can be a reference for conducting further study or fulfilling industrial need.

Slug is one of the most avoided flows in the piping system network. The high pressure fluctuations can cause damage to the pipes. Therefore, prevention of the slug flow is very important. To understand the phenomenon, an experimental study to investigate the pattern of stratified to slug flow transition has been examined. The present work was conducted on a 26 mm diameter acrylic horizontal pipe with the length of 10 m. Air and water are used as working fluids. Visual image capture is done using Phantom Miro M310 High speed camera on L/D 180-210 from inlet. As a supporting visual observation result, CECM method is also used to measure liquid holdup of fluid flow. The onset of slugging mechanism due to change of both gas and liquid superficial velocity will be discussed. As a result, it is found that the slug formation from stratified flow is at least divided into two basic mechanisms. At low gas velocity, the slug stability condition is created by wave growth mechanism. The increase of JG resulted in the increase of aeration and the of the liquid slug length. When the gas velocity is above 3 m/s, wave coalescence and large disturbance waves initiated the onset of slugging. The Increase of JL on the high JG makes the roll waves higher to create a pseudo slug. In addition, it is found that the formation of high aeration slug is seen at JL = 0.3 m/s when JG is maintained at 3.77 m/s.

The Liquid hold-up and the Interfacial Friction Factor on the Air-Water Stratified Two-Phase Flow in a Horizontal Pipe have been experimentally investigated using superficial gas and liquid velocity of 4 – 16 m/s and 0.02 to 0.1 m/s, respectively. The stratified flow is observed on the horizontal acrylic pipe with 26 mm inner diameter and 9 m length. This present work has utilized the various methods of observation: visual observation through high speed video camera, hold up measurement by using CECM, and pressure gradient analysis which is gathered from the Validyne pressure transducer. The pressure gradient and liquid hold-up signal are sent through amplifier than converted into digital signal by Analog to Digital Converter (ADC). As a result, the characteristics of stratified flow is successfully revealed. Furthermore, a new correlation for hold-up which is based on the gas and liquid superficial velocity, and Froude number is proposed. The R2 which reaches 0.971 and the small value of error band (around 30 %) shows that the proposed correlation produce a good performance. Similarly, a new correlation for interfacial friction factor is also proposed which is arranged as a function of liquid hold-up, gas, and liquid Reynolds number. It produces a satisfying performance which is proven by the high value of R2, 0.999. Moreover, the error band between the proposed correlation and the experimental data is quite small, around 5 % on most of all data.

The co-current air-water two-phase stratified flow is desired to occur in the application of pipelines system, such as natural gas gathering, long distance pipelines, and transmission pipelines, because this flow characteristics offers some advantages related to the safety factor of operational condition. The characteristics of pressure drop in stratified flow is considered as one of an important factor in the capital and operation costs for the simultaneous transportation of gas and liquid in various industries. The main objective of this study is to examine the effect of gas and liquid superficial velocities, and pipes diameter on the characteristics of pressure drop air-water two-phase stratified flow. Experiment has been conducted in 26 and 16 mm i.d. acrylic horizontal pipe with length 9.5 m. Air-water flow was recorded 190 D from the inlet using high speed video camera, and pressure difference was measured between 180 D and 210 D from the inlet using validyne pressure transducer. The common parameters such as visualization, pressure gradient signal in time series, probability density function (PDF), and mean of pressure gradient was analyzed. As a result the effect of gas and liquid superficial velocity, and pipes diameter on the characteristics of pressure gradient can be understood.

The two-phase flow application was commonly found in industrial processes, such as oil and gas production in wells, gas and oil pipelines, etc. The characteristic of two-phase flow had various aspects depending on its interfacial behaviour. The interfacial structures of air-water two-phase flow in a horizontal pipe were experimentally investigated by using visualization method with high speed camera. The experiments were conducted in a horizontal two-phase flow facility, total length 10 m pipe made from acrylic with 26 mm ID. To obtain the flow pattern, a total of 132 flow condition were observed. The superficial gas and liquid velocities were set to 0.31 m/s – 20 m/s and 0.016 m/s – 0.77 m/s, respectively.High Speed Camera observation successfully characterized and demonstrated two-phase flow regime in a horizontal pipe. Its also developed flow regime maps. Air-water two-phase flow is characterized by bubble breakup and coalescence in the transition from plug to slug flow. Interfacial instabilities form in stratified to wavy flow, then small waves, larger waves and the droplet entrainment in transition to annular flow. High amplitude wave was required to form the slug flow. This flow pattern maps is a two-phase flow regime transition including stratified flow, plug flow, slug flow, annular flow and sub-regime of each patterns. The influence of superficial velocity of air and water has a significant effect on the flow patterns and sub-regime types.The two-phase flow application was commonly found in industrial processes, such as oil and gas production in wells, gas and oil pipelines, etc. The characteristic of two-phase flow had various aspects depending on its interfacial behaviour. The interfacial structures of air-water two-phase flow in a horizontal pipe were experimentally investigated by using visualization method with high speed camera. The experiments were conducted in a horizontal two-phase flow facility, total length 10 m pipe made from acrylic with 26 mm ID. To obtain the flow pattern, a total of 132 flow condition were observed. The superficial gas and liquid velocities were set to 0.31 m/s – 20 m/s and 0.016 m/s – 0.77 m/s, respectively.High Speed Camera observation successfully characterized and demonstrated two-phase flow regime in a horizontal pipe. Its also developed flow regime maps. Air-water two-phase flow is characterized by bubble breakup and coalescence in the transition from plug to slug flow. Interfacial instabilities form ...

The interfacial wave characteristics of stratified air-water two-phase flow in a horizontal pipe were experimentally investigated by using the flush-mounted constant electric current method (CECM) sensors. The experiments were conducted in a horizontal two-phase flow loop 9.5 m long (L) consisting of transparent acrylic pipe of 26 mm i.d. (D). To obtain the stratified flow pattern, the superficial gas and liquid velocities were set to 1.02 – 3.77 m/s and 0.016 – 0.92 m/s, respectively. Several interfacial wave patterns as described by several investigators were identified. The common parameters such as liquid hold-up, probability distribution function, wave velocity and wave frequency were investigated as the function of the liquid and gas flow rates. The interfacial curvature was calculated on the basis of the liquid hold-up data from the CECM sensors and the liquid film thickness data from the image processing technique in the previous work. As a result, it was found that the mean liquid hold-up decreases with the increase of the superficial gas velocity. In the same sub flow pattern, the wave velocity increases as the superficial gas velocity increases. On the other hand, in the two-dimensional wave region, the dominant frequency decreases with the increase of the superficial liquid velocity.

Slug flow is a part of intermittent flow which is avoided in industrial application because of its irregularity and high pressure fluctuation. Those characteristics cause some problems such as internal corrosion and the damage of the pipeline construction. In order to understand the slug characteristics, some of the measurement techniques can be applied such as wire-mesh sensors, CECM, and high speed camera. The present study was aimed to determine slug characteristics by using image processing techniques. Experiment has been carried out in 26 mm i.d. acrylic horizontal pipe with 9 m long. Air-water flow was recorded 5 m from the air-water mixer using high speed video camera. Each of image sequence was processed using MATLAB. There are some steps including image complement, background subtraction, and image filtering that used in this algorithm to produce binary images. Special treatments also were applied to reduce the disturbance effect of dispersed bubble around the bubble. Furthermore, binary images were used to describe bubble contour and calculate slug parameter such as gas slug length, gas slug velocity, and slug frequency. As a result the effect of superficial gas velocity and superficial liquid velocity on the fundamental parameters can be understood. After comparing the results to the previous experimental results, the image processing techniques is a useful and potential technique to explain the slug characteristics.

Adaptive traffic controller systems based on image processing have been developed widely. Nevertheless, in a developing country, the systems often could not be easily applied because all types of vehicle use the same road. Therefore, to overcome the problem, the new concept of the systems is proposed. The systems were developed from a pre-timed traffic controller system that based on AVR microcontroller. By default, the systems use the signal-timing plans to control the vehicle flow. To accommodate the traffic variations, a new method of vehicle detection has been built. The method calculated an intensity histogram standard deviation of the image representing a detection area to determine traffic density of each intersection lane. The systems modified the green-time of each lane based on the traffic density. The method could detect all types of vehicles and work properly in a day and a night time.

The major weaknesses of traffic controllers in Indonesia are unable to accommodate the variety of traffic volume and unable to be coordinated. To solve the problem, a pre-timed and coordinated traffic controller system is build. The system consists of a master and a local controller. Each controller has a database containing signal-timing plans that would be allocated to manage vehicle flows. To synchronize the signal-timing, the master controller sends the synchronization data to the local controller wirelessly and the local controller shifts the end of a cycle by adding or subtracting the green interval of any phases. The transition time for synchronization only takes one to several cycles. The algorithm for controlling the traffic including coordination can be done by an AVR microcontroller. Memory usage of the microcontroller is lower than 10% meanwhile the CPU utilization is no more than 1%, thus the systems could be widely developed.