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The use of commonly used vapor compression cycle cold storage in fishing vessel is facing limitations to be widely applied in Indonesian fishermen since it consumes more energy and requires large space. Thermoelectric refrigerator is believed to be a promising option due to its simple design and low energy requirement. However, the Coefficient of Performance (CoP) of the system in current development is relatively low. Although many researches have been conducted to increase the CoP of the system But there is still lack of studies focused on effects of the important variables to cold storage performance. The present study aimed to investigate the effect of input voltage on thermoelectric cold storage chamber temperature in the form of transient behaviors. As a result, it was found that the increase of input voltage significantly affected the cooling performance, although in 6 V input voltage, the result is only a bit lower than 12 V with much lower energy use. In addition, the time needed to get steady state in 12 V was the fastest compared to the other input voltages. Those results can be used as design consideration of a portable thermoelectric cold storage. [ABSTRACT FROM AUTHOR]

The purpose of this experimental research is to comprehensively investigate the phenomena of successive droplets impacting the aluminum hot surface. It is understood that each region produces different behavior. Therefore, indepth investigation is necessarily needed. This research will be useful to support the development of metal industry, especially in the spray cooling area. In the present work, Aluminum is used as the material. The surface temperature ranged from 110°C - 240°C, where the regime of onset boiling occurs. The droplet diameter was 2.8 mm. In addition to spreading ratio and apex height, the spreading velocity is also measured by using a specific image processing technique. This sequence algorithm works based on the binary recognition process where the object is marked as the white color, and the black color represents the background. It is supported with high-speed video camera data captured on 4000 fps. As a result, the obtained quantitative data successfully reveals the behavior of the successive droplets and can support the further heat transfer analysis study to achieve the most effective spray cooling condition in the aluminum hot surface [ABSTRACT FROM AUTHOR]

The use of microbubbles has grown immensely in many fields such as the petrochemical industry and in wastewater treatment. This phenomenon offers a number of advantages that include the ability to provide larger liquidgas surface contact areas. In addition, in shallow aeration conditions horizontal injection is preferred in order to increase the contact surface area and aeration time, thereby increasing the mass transfer rate. In this study, the orifice type of microbubble generator was set on a rectangular transparent glass box to support visualization. A set of experiments were specifically conducted in order to reveal the effects of varying both the water and air flow rate on the bubble diameter distribution and volumetric mass transfer coefficient. The bubble diameter was measured using image processing method, and the volumetric mass transfer coefficient was measured using the dynamic method. The results showed that increases to the flow rate of water produced smaller bubble diameters, and a more homogeneous bubble diameter distribution. Furthermore, it was apparent that the water flow rate had a more significant effect on changes to volumetric mass transfer coefficient, compared to the air flow rate. [ABSTRACT FROM AUTHOR]

The use of microbubble has grown massively in many fields such as petrochemical industry and waste water treatment. This phenomenon offers some advantages since such as the ability to provide larger liquid-gas surface contact area. In order to achieve in depth understanding related to those phenomena, some of the measurement methods can be applied such as a capillary suction probe, conductivity probes, and, Phase Doppler Anemometry. The present work was conducted to determine the characteristic of microbubble size distribution by using digital image analysis. The orifice type microbubble generator is set on a rectangular transparent glass box to support the visualization study. The air and water flow observed in this present study were set on 0.1 - 1 lpm and 30 - 80 lpm respectively. Each sequence image was processed using MATLAB. Some steps, including image filtering and image complement, is utilized to produce binary image. In addition, watershed method has also been applied in order to separate the merge bubble to produce an accurate measurement. As a result, the effect of gas and liquid flow rate on the bubble size distribution can be revealed. Finally, it can be concluded that the digital image analysis is a useful and potential technique to study the characteristics of microbubble phenomena. [ABSTRACT FROM AUTHOR]

The aim of this research is to reveal the dynamic behavior of the successive multiple 20% ethylene glycol aquades droplet impacting on the hot surface. An experiment has been conducted by utilizing the stainless steel as the hot surface. The diameter of droplet and the impact velocity are 2.8 and 1.1 m/s, respectively. Then, the Weber number is approximately 55. In the present study, an induction heater is utilized to achieve the desired temperature of hot surface. It is set at 110 - 230°C. In addition, image processing technique is applied in order to obtain essential quantitative information from the multiple droplets. Based on the result, it is found that the secondary droplet starts to present at temperature 150°C. While at the temperature 230°C, the bouncing phenomena occurs several times. Finally, the present study has been able to reveal spreading characteristics of the droplet comprehensively and can be used as a starting point to develop further research. [ABSTRACT FROM AUTHOR]

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 [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The effect of material conductivity on the dynamics behavior and the heat transfer phenomena of multiple water droplets impacting onto heated solid surfaces has been studied experimentally. The droplet diameter and Weber number were 2.8 mm 46.2 respectively. The test materials were Stainless Steel, Aluminum, and Cooper. The test temperatures ranged from 110°C - 140°C. The droplet dynamics during the impacting on the hot surfaces were investigated by using a high-speed video camera. To gather the quantitative information, a new developed image processing technique was developed. It is able to track the bubble movement, the contact time and spreading ratio can be determined. As a result, it is noticed that at 110°C, droplet impacting on aluminum showed the highest spreading ratio among the materials. The spreading ratio of droplet impacting on copper is the lowest. At 140°C, it is found that for all materials, the small bubble has started to appear around the first droplet and the contacting solid surface. Meanwhile on stainless steel, although the spreading ratio is low, the solid-liquid contact time is the highest among the test materials. Finally, it is generally concluded that the presence of second droplet improves the wettability, so the effectiveness of cooling process is significantly better. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]