A Brief on Optical-based Investigation towards The Interfacial Behaviors during High Viscous Liquid/Gas Countercurrent Two-Phase Flow in a Complex Conduit Representing 1/30 Down-Scaled of PWR Hot Leg Geometry

The present work briefly investigates liquid/gas countercurrent two-phase flow phenomena which can be specifically found in a mitigation during an accidental scenario in the operation of a nuclear reactor. A comprehensive knowledge on the corresponding phenomena is obviously important to avoid the failure on the cooling mechanism. Here, a pair of fluid containing high viscous liquid/gas flows through a complex conduit representing 1/30 scaled-down of PWR hot leg’s typical geometry. Furthermore, the flow structures were visually observed, while the film thicknesses are extracted by an image processing algorithm through the corresponding optical-tabulated data. The obtained results reveal that a rather sharp decrease in liquid film corresponds to the flow regime transition.Keywords: Countercurrent two-phase flow, liquid film thickness, high viscous liquid, complex condui

STUDI PENGARUH DINAMIKA TUMBUKAN MULTIPLE DROPLETS TERHADAP NILAI SPREADING RATIO PADA PERMUKAAN BIDANG PANAS YANG MIRING

ABSTRAKSpray cooling merupakan aplikasi dari droplets yang digunakan sebagai salah satu teknik pendinginan. Pemanfaatan dari multiple droplets ini banyak dikaji sebagai sistem pendinginan pada peralatan elektronik dan pembuatan material quenching. Dinamika tumbukan multiple droplets pada permukaan bidang miring yang dipanaskan akan dikaji pada penelitian ini. Material uji yang digunakan adalah stainless steel 304 . Temperatur permukaan yang diamati adalah 120 ºC, 180 ºC dan 220 ºC pada bilangan Weber medium 70 dengan variasi bidang kemiringan adalah  sebesar 10º, 20º dan 30º. Dinamika droplet selama tumbukan diamati menggunakan high-speed camera dengan kecepatan 4000 fps kemudian hasilnya diolah menggunakan image processing. Telah diperoleh hasil bahwa spreading ratio tertinggi terjadi saat temperatur permukaan 180 ºC pada  sudut kemiringan 30 º dan terendah pada temperatur 220 ºC. Fenomena secondary droplet dapat meningkatkan nilai spreading ratio. Adapun fenomena bounching terjadi pada temperatur 220 ºC.Kata kunci: Spray cooling, multiple droplets, stainless steel, image processing, spreading ratio ABSTRACTSpray cooling is an application of the use of droplet on a cooling system. Spray cooling is usually used in a cooling system of electronic devices, and material quenching. In this study, the dynamic behavior of multiple droplets impacting into inclined hot surfaces will be investigated. The material used in the present work is stainless steel 304 with the temperature 120 ºC,180 ºC,dan 220 ºC   at medium Weber number 70. The inclined surface varied at  10º, 20º dan 30º.  The droplet dynamics during the impact have been observed using high-speed camera with the frame rate of 4000 fps then the results were analized by using image processing technique. The result of this study shows that The presence of second droplets and the higher of inclined surfaces can increases value of spreading ratio ,it is noticed that at 180°C, droplet impacting at 30º showed the highest spreading ratio and at 220 ºC is the lowest. The presence of secondary droplet can increases value of spreading ratio and  bouncing phenomena occurs at 220 ºC. Keyword: Spray cooling, multiple droplets, stainless steel, image processing, spreading rati

Penentuan Sub-sub Daerah Aliran Stratified Udara-Air pada Pipa Horisontal Menggunakan Constant Electric Current Method (CECM)

ABSTRAK Visualisasi dan liquid hold-up aliran stratified udara-air pada pipa horizontal sebagai fungsi waktu (dia. dalam pipa 26,0 mm dan total panjang seksi uji 9,5 m) telah diteliti secara eksperimental. Pada penelitian ini, studi visualisasi dilakukan dari analisa data visual yang dihasilkan kamera video kecepatan tinggi dan perilaku tebal film aliran diteliti dengan mengukur liquid hold-up menggunakan Constant Electric Current Method (CECM). Prinsip dari metode ini didasarkan atas perbedaan konduktivitas pada cairan dan gas. Pada penelitian ini digunakan sensor CECM sebanyak 3 buah dengan jarak aksial antar sensor 215 mm. Hasil penelitian ini menunjukkan bahwa karakteristik gelombang antarmuka yang dihasilkan dari pemprosesan sinyal CECM dan studi visual dapat digunakan untuk menentukan sub-sub daerah aliran stratified . Peta pola aliran stratified Udara-Air pada Pipa Horisontal yang dihasilkan dari penelitian ini dipresentasikan dan dibandingkan dengan peta-peta yang ada dari penelitian-penelitian terdahulu. Kata Kunci : Sub-sub daerah aliran, aliran stratified, CECM, gelombang antarmuk

Fraksi Hampa Campuran Gliserin-Air dan Udara Pada Pipa Horizontal Berukuran Mini

Penelitian ini bertujuan untuk mendapatkan informasi tentang karakteristik aliran air-udara. Salah satu karakteristik yang penting dalam aliran dua fasa adalah Fraksi hampa. Penelitian ini dilakukan pada seksi uji berupa pipa kaca dengan diameter 1,6 mm posisi horisontal. Fluida yang digunakan adalah air-udara dan campuran air-gliserin dengan konsentrasi 20%. Kecepatan superfisial gas (JG)=0,033 – 4,935 m/s, dan kecepatan superfisial cairan (JL)=0,025 – 66,3 m/s. Data fraksi hampa diperoleh dari pengambilan gambar pada seksi uji menggunakan kamera berkecepatan tinggi. Hasil penelitian menunjukkan bahwa hubungan antara pola aliran dan fraksi hampa sangatlah berpengaruh didalam menentukan karakteristik aliran dua fasa. Pola aliran bubbly dan slug, fraksi hampanya meningkat dengan meningkatnya JG. Fraksi hampa yang diukur adalah sama atau lebih besar dari fraksi hampa homogen. Pola aliran churn, slug-annular, dan annular, tidak ada hubungan yang jelas antara JG dan fraksi hampa diamati ketika JG meningkat, karena tingginya slip rasio antara gas dan cairan. Pembuktian bahwa, untuk aliran bubbly dan slug, fraksi hampa dekat dengan garis homogen, sedangkan untuk aliran churn, annular, dan slug-annular yang jauh di bawah garis homogen. Ini menunjukkan bahwa rasio slip untuk kelompok kedua pola aliran lebih tinggi daripada

ENERGY CONSUMPTION PROJECTION IN YOGYAKARTA CITY

Availability of energy is an important aspect for the success of regional development. Yogyakarta city does not have any non-renewable energy sources such as liquid fossil fuels, coal and natural gas. Consequently,these energy must be supplied from other provinces. The renewable energy potential in Yogyakarta city is not being utilized yet. Final energy consumption continues to rise along with population and economic growth.Energy planning and development need be done carefully in order to ensure the energy sustainability. This study aim to provide long-term projections in 2012-2025 periods on energy balance, energy demand andsupply based on energy reserves and current condition in order to meet energy elasticity to less than 1. Energy demand projection is calculated based on trend forecasting analysis by LEAP (Long-range Energy Alternatives Planning System).This result shows that the highest energy user sector in Yogyakarta city period 2012-2025 is transportation sector and the highest of energy demand by type is electricity and gasoline. Renewable energypotential such as biogas, solar energy, biomass and biodiesel (from using vegetable oil waste) could be developed in Yogyakarta city. Using biodiesel and solar energy could decrease diesel fuel and electricity.According to the baseline scenario, CO2 emission reached 2,176,182 tons, the first alternative scenario reached 1,925,089 tons and the second alternative scenario reached 1,877,839. Investment cost to build renewable energy in the baseline scenario reached USD 42,045 – USD 546,585. Investment cost to build renewable energy in the first alternative scenario reached USD 10,470,775 – USD 31,002,775. Investment cost to build renewable energy in the second alternative scenario reached USD 31,641,925 - USD 52,173,925

ENERGY MODELLING AND FORECASTING OF DAERAH ISTIMEWA YOGYAKARTA 2025

Daerah Istimewa Yogyakarta (DIY) is one of the provinces in Indonesia which does not have a backup or potential sources of non-renewable primary energy. The non-renewable energy demand until this time, such as oil,coal and gas is supplied from the outside. DIY is in Java Madura Bali (JAMALI) interconnerction system and has not had a large-scale power systems. While DIY has renewable energy sources such as hydro, solar, wind, wave and biomass energy. These renewable energy sources are alternative energy that have not been optimally used. The lack of reserve energy resources that resulting dependence of energy supply from other areas should receive special attention from DIY government. To meet energy demand, the energy resources development is required. Due to the energy resources development requires a long time and high cost, it is necessary to be supported by good planning in energy policy.The purpose of this study is to determine the balance of energy demand and supply of  DIY until 2025. Furthermore, the purpose of this study is to find out a mix number of renewable energy. The Indonesian government has launched a vision of 25/25 which expection in 2025, the mix number of renewable energy will be 25%.The results of this study indicate that in 2025, the Transportion Sector is the largest energy user sector in DIY at 52.37%, followed by Household Sector (32.70%), Commercial Sector (8.26%), Other Sector (4.64%), and Industrial Sector (2.04%). The high level of energy consumption in the Transportation Sector is caused by the increasing number of vehicles especially motorcycles and passenger cars considering DIY is a student and tourism city. In term of the type of energy used, in 2025, the gasoline is the greatest type of energy demand (41.8%), followed by LPG (23.97%), electricity (18.14%) and diesel oil (11, 74%). This indicates that the fuel oil is still the main energy source for the DIY community activities. When viewed from supply side, most of the energy needs in DIY are supplied from outside. If the development of enewable energy targets DIY reached, the renewable energy mix is obtained by 0.53 %

KAJI EKSPERIMEN KECEPATAN POLA ALIRAN SLUG AIR-UDARA PADA ALIRAN DUA FASE SEARAH PIPA HORISONTAL MENGGUNAKAN HIGH SPEED VIDEO CAMERA

The purpose of this study was to examine velocity of the slug flow pattern of air-water. The method used is the visualization of flow patterns using high-speed video camera. The study was conducted on the water superficial velocity 0.139 m/s - 1.952 m/s and the air superficial velocity 1.043 m/s - 3.652 m/s on a horizontal pipe with a diameter of 24 mm pipe. Increase in superficial gas velocity causes the aeration mechanism (gas-phase entry in the form of small bubbles into the liquid phase) to produce slug flow. Constant value C0 in equation Nicklin (1962) obtained in this study correspond to the value proposed by Bendiksen (1984) for Fr> 3.5

The Identification of Gas-liquid Co-current Two Phase Flow Pattern in a Horizontal Pipe Using the Power Spectral Density and the Artificial Neural Network (ANN)

This paper presents a new method of the flow pattern identification on the basis of the analysis of Power Spectral Density (PSD) from the pressure difference data of horizontal flow. Seven parameters of PSD curve such as mean (K1), variance (K2), mean at 1-3 Hz (K3), mean at 3-8 Hz (K4), mean at 8-13 Hz (K5), mean at 13-25 Hz (K6) and mean at 25-30 Hz (K7) were used as training vector input of Artificial Neural Networks (ANN) in order to identify the flow patterns. From the obtained experimental of 123 operating conditions consisting of stratified flow, plug and slug, ANN was trained by using 100 data operation and 23 tested data. The results showed that the new method has a capability to identify the flow patterns of gas-liquid two phase flow with a high accuracy