ISSN PROCEEDINGS. Sponsored by: Organized by:

ISSN 2355-6927

PROCEEDINGS Organized by:

Sponsored by:

ISSN 2355 – 6927

PROCEEDING SEMINAR NASIONAL THERMOFLUID VI 2014 29 April 2014 Yogyakarta, Indonesia

DISELENGGARAKAN OLEH: JURUSAN TEKNIK MESIN DAN INDUSTRI FAKULTAS TEKNIK UNIVERSITAS GADJAH MADA

SEMINAR NASIONAL THERMOFLUID 2014

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SEMINAR NASIONAL THERMOFLUID VI 2014 Yogyakarta, 29 April 2014

Untuk segala pertanyaan mengenai makalah Thermofluid VI: Ruang Administrasi S2 Jurusan Teknik Mesin dan Industri Fakultas Teknik - Universitas Gadjah Mada Jalan Grafika No.2 Yogyakarta 55281 Phone: (0274) 521673 Email: [email protected] Website: thermofluid.ugm.ac.id

Reviewer: Prof. Dr. Ir. H. Djatmiko Ichsani, M.Eng. (ITS) Prof. Dr. Ir. Harinaldi, M. Eng. (UI) Dr. Ir. Anhar Riza Antariksawan (BATAN) Prof. Ir. I Made Bendiyasa, M.Sc., Ph.D. (UGM) Prof. Dr.-Ing. Ir. Harwin Saptoadi, M.SE. (UGM) Dr.Eng. Tri Agung Rohmat, B.Eng., M.Eng. (UGM) Indro Pranoto, S.T., M.Eng. (UGM) Adhika Widyaparaga, S.T., M.Biomed.Sc., Ph.D. (UGM)

Editor: Dimas Dwi Ananda Avila Dhanu Kurniawan Ogy Satria Ramadhan Muhammad Ilham Kurniawan Ilham Adityarsena F Putra Juliansen Siregar

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DEWAN REDAKSI

Penanggung Jawab

: Prof. Ir. Jamasri, Ph.D. (Ketua Jurusan Teknik Mesin dan Industri, Fakultas Teknik UGM)

Panitia Pengarah

: 1. Sugiyono, ST., MT., Ph.D. (Kepala Lab. Mekanika Fluida) 2. Dr.Eng. Tri Agung Rohmat, B.Eng., M.Eng. (Kepala Lab. Konversi Energi) 3. Dr. Ir. Prajitno, MT. (Kepala Lab. Perpindahan Kalor dan Massa)

Reviewer

: 1. Prof. Dr. Ir. H. Djatmiko Ichsani, M.Eng. (ITS) 2. Prof. Dr. Ir. Harinaldi, M. Eng. (UI) 3. Dr. Ir. Anhar Riza Antariksawan (BATAN) 4. Prof. Ir. I Made Bendiyasa, M.Sc., Ph.D (UGM) 5. Prof. Dr.-Ing. Ir. Harwin Saptoadi, M.SE. (UGM) 6. Dr.Eng. Tri Agung Rohmat, B.Eng., M.Eng. (UGM) 7. Indro Pranoto, S.T., M.Eng. (UGM) 8. Adhika Widyaparaga, S.T., M.Biomed.Sc., Ph.D.

Ketua Panitia

: Dr. Eng. Khasani, S.T., M.Eng.

Sekretaris

: Adhika Widyaparaga, S.T., M.Biomed.Sc., Ph.D.

Bendahara

: Fauzun, S.T., M.T., Ph.D.

Koord. Pelaksana

: Fadhli Akbar

Sekretaris Pelaksana

: Puput Iin Qur’aini

Bendahara Pelaksana

: Arfin Aruni Silma

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DAFTAR ISI Halaman Judul ....................................................................................................................

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Dewan Redaksi ................................................................................................................... iii Kata Pengantar .....................................................................................................................

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Daftar Isi .............................................................................................................................

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A. Combustion Engineering 1. Gelombang Detonasi Marginal Campuran Bahan Bakar Hidrogen & Udara dengan Pengencer Argon Jayan Sentanuhady, Ari Dwi Prasetiyo ......................................................................... 1 2. Pengaruh Excess Air terhadap Karakteristik Pembakaran dalam Bubbling Fluidized Bed Combustor (BFBC) Fransisko Pandiangan, Tri Agung Rohmat, Purnomo ................................................... 6 3. Perambatan Gelombang Detonasi Campuran Stoikiometris LPG-Oksigen di Belakang Model Media Porous dengan Variasi Massa Jayan Sentanuhady, Jannati Adnin Tuasikal ................................................................. 11 4. Studi Eksperimental Kestabilan Api Difusi Biogas pada Counterflow Burner Configuration Mega Nur Sasongko ..................................................................................................... 17 5. Studi Eksperimental Pengaruh Swirling Intensity terhadap Efisiensi Termal RFM Swirl Burner I Made Kartika Dhiputra, Mekro Permana Pinem ......................................................... 23 6. Simulasi CFD untuk Mengetahui Pengaruh Penambahan Batu Bara Jenis Medium Rank Coal pada Boiler Jenis Low Rank Coal di Power Plant PLTU Suralaya Unit 8 Nur Ikwan, Giri Nugroho, Wawan Aries Widodo .......................................................... 28 7. Pengaruh hot-EGR dan cooled-EGR Terhadap Daya Mesin Dan Emisi Jelaga (Soot) Pada Mesin Diesel Direct Injection (DI) Dengan Menggunakan Bahan Bakar Campuran Biosolar-Jatropha-High Purity Methanol (HPM) Sobri, Syaiful ................................................................................................................ 33

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8. Pengaruh Tinggi Bed Terhadap Kecepatan Minimum Fluidisasi dan Distribusi Temperatur Dalam Fluidized Bed Combustor Kevin Kristiantana, Tri Agung Rohmat, Purnomo ......................................................... 39

B. Energy and Renewable Energy 9. Thermoelectric sebagai Heat Collector untuk Meningkatkan Efisiensi Photovoltaic pada Daerah Tropis Andhita Mustikaningtyas, Sindu Daniarta, Yollanda Zilviana Devi ............................... 45 10. Panas Bumi Sebagai Energi Masa Depan Dan Terbarukan Sumatera Barat Armila .......................................................................................................................... 50 11. Studi Eksperimental Optimasi Campuran Metanol (96%) Etanol (10%) sebagai Bahan Bakar Alternatif Terbarukan Pengganti Minyak Tanah Jarot Hari Astanto, Dwi Aris Himawanto, D.Danardono Dwi Prija T ............................ 61 12. Analisis Resistivitas Daerah Geothermal ”T” Berdasarkan Hasil Inversi Finite Element Data 2D Magnetotelurik Nur Rachmaningtias, Agus Setyawan, Imam Baru Raharjo ........................................... 67 13. Sistem Irigasi Buatan dengan Photovoltaic dan Thermoelectric untuk Meningkatkan Pertanian di Indonesia Pandhu Picahyo, Sindu Daniarta, Galih Pambudi .......................................................... 70 14. Microhydro Power Plant Pest As Energy Source Electromagnetic Wave Technology With Environmentally Friendly Syahrial Shaddiq, Dery Januarizki, Gunawan Eka Prasetyo, Ismail Mukti, Fikriyan, Fajar Al Farobi, Ramadoni Syahputra ........................................................................... 75

C. Fluid Mechanics 15. Pengaruh Penambahan Inlet Disturbance Body Terhadap Karakteristik Aliran Melintasi Silinder Sirkular Tersusun Tandem Aida Annisa Amin Daman, Wawan Aries Widodo ........................................................ 79 16. Analisis Numerik Karakteristik Pressure Drop pada Instalasi Sistem Pneumatik menggunakan CFD Amam Fachrur Rozie, Yuda Trimardana, Sumadi, Ahmad Indra Siswantara ................ 85 17. Studi Komparasi Jumlah Sudu Turbin pada Rancangan PLTMH Head Rendah dengan Daya 2Kw Budi Triyono, Haryadi dan Sugianto ............................................................................ 93

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18. Analisis Eksperimental dan Simulasi Numerik Karaktristik Aliran Fluida melalui Silinder Persegi dan Segitiga H. Nasaruddin Salam, Muh. Noor Umar, Ibnu Sidig ...................................................... 98 19. Studi Eksperimen tentang Karakteristik Tekanan dan Kemungkinan Kavitasi Aliran Fluida melalui Katup Kupu-Kupu Muh. Hasbi, Sutardi ...................................................................................................... 105 20. Simulasi Numerik Aliran di Sekitar Circular Cylinder dengan Dua Square Cylinder sebagai Disturbance Body pada Saluran Sempit Rina, Wawan Aries Widodo .......................................................................................... 111 21. Analisis Penurunan Tekanan pada Instalasi Sistem Hidrolik Alat Uji Tarik menggunakan CFD di Laboraturium Fenomena Mesin UIKA Bogor Rio Adika Cahya, Hady Hidayat, Sumadi1, Edi Sutoyo ................................................. 117 22. Studi Parametrik Pengaruh Roughness Terhadap Profil Kecepatan Lapisan Batas pada Simulasi Atmospheric Boundary Layer di Wind Tunnel Subagyo ....................................................................................................................... 125 23. Simulasi Numerik Aliran Internal Muffler Kendaraan 2D Subagyo ....................................................................................................................... 134 24. Aplikasi Reliability Centred Maintenance (RCM) pada Sistem Pemipaan Industri Kertas yang Beroperasi Kontinyu Sumadi.......................................................................................................................... 138 25. Analisa Instalasi Sistem Pneumatik untuk Air Service di Laboratorium Proses Produksi Wahyu Nuri. Sumadi .................................................................................................... 145

D. Heat – Mass Transfer 26. Kinerja Termal Green Roof sebagai Pendingin Pasif di Iklim Tropis Nandy Putra, Wayan Nata Septiadi, Bambang Ariantara, Retsa Anugrah Menteng .....

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27. Alat Uji Sirkulasi Air Akibat Efek Thermosyphon pada Sistem Pemanas Air Surya Caturwati NK, Ipick S, Alief ........................................................................................ 157 28. Proses Pembuatan Membran Silika MCM-41untuk Alat Penukar Kalor Udara Hens Saputra, Murbantan Tandirerung, Hananto Widoyoko ......................................... 162 29. Fenomena Pendidihan dan Dinamika Gelembung dari Porous Graphite Foams Indro Pranoto ............................................................................................................... 168

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30. Aplikasi Heat Pipe pada Thermoelectric Generator Rio Wirawan, M. Hadi Kusuma, Ranggi Sahmura, Wayan Nata Septiadi, Nandy Putra ................................................................................................................. 174 31. Efek Orientasi Sudut Delta-Winglet Vortex Generator Terhadap Performa Termal dan Hidrodinamik Penukar Kalor Jenis Fin-Tube dengan Susunan Pipa Sejajar Untuk Aplikasi EGR Cooler Syaiful dan Rahmat Purnomojati ................................................................................. 180 32. Penentuan Sudut Kontak dengan Pengolahan Citra Windy Hermawan Mitrakusuma, Deendarlianto, Syamsul Kamal, M. Nuryadi, Rudi Rustandi .............................................................................................................. 186

E. Internal Combustion Engines 33. Efek Campuran High Purity Methanol (HPM) – Diesel dan Sistem Cooled EGR terhadap Smoke Opacity dan Brake Specific Fuel Consumption (BSFC) pada Mesin Diesel Injeksi Langsung Aa Setiawan, Syaiful .................................................................................................... 191 34. Karakteristik Pelumas Campuran Zinc Oxide Nanopowder untuk Kendaraan Agung Sudrajad, Aditya Yuda Anggara ........................................................................ 196 35. Efek High Purity Methanol (HPM) dan Hot EGR terhadap Brake Spesific Fuel Consumption (BSFC) dan Emisi Jelaga pada Mesin Diesel Injeksi Langsung Angga Septiyanto, Syaiful ............................................................................................ 200 36. Pengaruh Diameter Exhaust Valve terhadap Unjuk Kerja dan Emisi Gas Motor Bensin 4 Langkah Slamet Wahyudi, Lilis Yulianti, Hastono Wijaya dan Alfian Kusuma ........................... 206

F. Multiphase Flow 37. Quantitative Visualization of the Wave Characteristics for Horizontal Co-Current Gas-Liquid Plug Two-Phase Flow by Using an Image Processing Technique Akmal Irfan Majid, Okto Dinaryanto, Deendarlianto, Indarto ........................................ 212 38. Experimental Study on the Liquid Holdup Characteristics of Air-Water Horizontal Stratified Flow by Using an Image Processing Technique Hadiyan Yusuf Kuntoro, Deendarlianto ........................................................................ 218

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39. Visualisasi dan Signal Processing Aliran Slug Air-Udara Berdasarkan Karakteristik Lokal Pada Pipa Horisontal Yuli Purwanto, Indarto, Khasani, Deendarlianto ........................................................... 224

G. Thermodynamics 40. Analisis Performa Organic Rankine Cycles Berdasarkan Data Pengujian Evaporator dengan Menggunakan Solar Panel Plat Datar untuk Fluida Kerja R22 dan R134a Edi Marzuki, Seftian Haryadi, Yogi Sirodz Gaoz, Mulya Juarsa, Muhamad Yulianto ....................................................................................................... 230 41. Analisa Pengaruh Variasi Kecepatan Aliran Udara pada Evaporator Terhadap Performansi Mesin Refrigerasi Kompresi Uap Air Conditioner dengan Refrigeran R134a Mahendra, Hendradinata .............................................................................................. 236 42. Analisis Performa ORC dengan Fluida Kerja R-134a Menggunakan Simulasi Komputer Berdasarkan Data Eksperimental Variasi Laju Aliran Massa Air di Kolektor Termal-Surya tipe Plat Datar Mulya Juarsa, Seftian Haryadi, Muhamad Yulianto, Edi Marzuki, Yogi Sirods Gaos .... 241 43. Studi Simulasi pada Ventilasi, Kualitas Udara Interior dan Konsumsi Energi Ozkar F. Homzah, Haryanto ......................................................................................... 246 44. Kaji Eksperimental Kinerja Mesin Pendingin Kompresi Uap (Freezer) terhadap Variasi Massa Refrigeran Hidrokarbon Jenis Propan sebagai Pengganti R-22 Tandi Sutandi, Berkah Fajar ......................................................................................... 251

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A. Multiphase Flow

Proceeding Seminar Nasional Thermofluid VI Yogyakarta, 29 April 2014

Quantitative Visualization of the Wave Characteristics for Horizontal Co-Current Gas-Liquid Plug Two-Phase Flow by Using an Image Processing Technique 1

Akmal Irfan Majid*1, Okto Dinaryanto2, Deendarlianto3, Indarto3

Master Program (Fast-track) in Mechanical Engineering, Dept. of Mechanical and Industrial Engineering, Faculty of Engineering, Universitas Gadjah Mada, Jalan Grafika 2 Kampus UGM Yogyakarta 55281 2 Doctoral Program in Mechanical Engineering, Dept. of Mechanical and Industrial Engineering, Faculty of Engineering, Universitas Gadjah Mada, Jalan Grafika 2 Kampus UGM Yogyakarta 55281 3 Dept. of Mechanical and Industrial Engineering, Faculty of Engineering, Universitas Gadjah Mada, Jalan Grafika 2 Kampus UGM Yogyakarta 55281 E-mail: [email protected],id

Abstract Gas-liquid plug flow, as a part of the intermittent flow, has received more attention as the initiation of the slugging phenomena in fluid transportation. This pattern has particular characteristics such as the large pressure fluctuation, irregularity, and intermittency which possible to lead the internal pipe corrosion and the pipe blasting. The presence of the large amplitude waves can be generated since gas flows with high slip velocity through the liquid-phase. Due to that reason, “pipe blockage” phenomenon can be occurred. The purpose of the present experimental study is to conduct a better understanding on the wave characteristics of air-water co-current plug two-phase flow by using an advanced visualization method named image processing technique. The novel technique has been applied to elucidate quantitative result of liquid-phase level by analyzing sequence of recorded images. Water and pressurized air flowed co-currently inside the horizontal acrylic pipe with 26 mm internal diameters. A high-speed video camera (640 x 480 pixels; 120 frame per seconds) was used to visualize the pattern. Those observed images were converted from RGB into binary mode by image segmentation operation by using MATLAB®. In order to improve the images quality, several image filtering types including Median and Wiener filtering were utilized. Moreover, the non-linear statistics analysis such as cross-correlation function, power spectra density, and probability distribution function were implemented to obtain the quantitative information. Here, the wave characteristics such as wave velocity and wave frequency are determined. It reveals the information of plug flow liquid hold up distribution. It can be inferred that the wave characteristics in a horizontal gas-liquid plug flow are strongly affected by gas and liquid superficial velocities. Furthermore, the data can be potentially used to investigate the plug flow mechanism in horizontal pipe, even to validate the CFD codes. Keywords: Visualization studies, Plug flow, Wave characteristics, Image processing technique, Interfacial behavior

1.

Introduction The gas-liquid plug and slug flow has been investigated since couple years ago due to its standout characteristics of high pressure fluctuation, random, irregular motion, and large amplitude waves. Specifically, the initiation of slugging is classified into hydrodynamic and terrain slugging. Hydrodynamic slugging is caused by a flow disturbance to the gas– liquid interface in a stratified flow close to the pipeline entrance region. A small wave forms on the interface and grows to block the pipe cross section, forming a slug [1]. Terrain slugging results from liquid accumulation in local dips of flow lines with variable topography [2]. The occurrence of the flow intermittency inflicts these patterns to be commonly avoided in related safety issues, pipe erosion, and

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design of the pipeline and pumping system, especially in offshore, boiling industries, nuclear reactors, and fluid lines. Particularly, plug flow takes part as the initiation of highly-turbulent slug flow. By increasing liquid flow rates, plug flow is considered as a transition from stratified into slug flow in a low gas velocity [3, 4]. Under the rise of liquid level, the waves are formed and tend to block the pipe cross-sectional area. Otherwise, the gas velocity, liquid Froude number, and the bridging location influence the air-water slug initiation and its frequency [5]. However, this model has a contradiction with one-dimensional two-fluid model of Taitel and Dukler [6] which conducted that slug is initiated by a long wavelength disturbances in a stratified layer until the waves grow to block the pipe [2]. A different criteria and definition on the onset of

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slugging was also occurred. For all those studies, there is no deal which confirms an absolute concept on the plug and slug formation. On the other hand, it is agreed that a slug initiation process is basically occurred when the wave characteristics are changed. Those facts lead the strong reasons to build up a good understanding on the unique plug flow wave characteristics to support the systematical data on the slugging mechanisms. Various methods have been proposed in order to determine the interfacial behavior of this regime. For instances, the use of wire mesh sensor [7] which has a shortage of its intrusive characteristics. The other techniques such as the capacitance sensor [8] and Constant Electric Current Method (CECM) signal processing [9] were also used to obtain time-series data. Nevertheless, for a few case, those methods could only be applied in a specific condition. Consequently, the different results between those specified methods are ensued due to the diverse measurement technique. Moreover, the visualization methods are used to conduct a profound observation on the flow behavior. However, the method were previously used as the escort study to support the obtained results from the other measuring devices. In the previous work, this method just applied for assigning the flow pattern [10, 11]. Thus, the qualitative data are only performed through this case. Recently, the visual studies is continued to grow in the field of advanced visualization methods. The CFD codes [12] have been already applied. A more accurate result is expected due to the implementation

only a few studies addressing a comprehensive data including the flow topology and the important wave parameters for the plug flow in a horizontal pipe. Specifically, Mayor et al. [13] conducted an image processing technique for vertical slug flow while Amaral et al. [14] applied a different algorithm (watershed and H-minima) for determining slug flow topology. In this present work, a simple algorithm based on noise reduction and image segmentation was developed to obtain both the gas-liquid plug flow topologies and the quantitative evaluation of the wave parameters. The purpose of this present study are to obtain a better understanding on the interfacial analysis of gas-liquid plug flow in a horizontal pipe. The available previous studies were also compared with the obtained data of this present work. 2.

Experimental Methods Experiments were performed at the horizontal two-phase flow test facility of the Fluid Mechanics Laboratory, Department of Mechanical and Industrial Engineering, Gadjah Mada University. It consists of 26-mm inner diameter of transparent acrylic pipe with 9.5-m total length. Air and water were used as working fluid. The present work was an adiabatically work which carried out under atmospheric pressure and room temperature. A depth visual observation of the gas-liquid flow behavior was conducted by a high-speed video camera with resolution of 640-pixel width and 480-pixel height. The camera has rates of 120 frame per second (fps). A rectangular correction box was used to reduce the image distortion due to

of those methods. However, the shortcomings of the the different refraction index. The 1.2-m length of Experimental apparatus PIV and X-Ray tomography application areFig. the1.facts transparent box was filled by water which has close that they need a complicated installation and advanced value of acrylic reflective index. About 1-m length of post-data processing. Else, by using CFD codes, a the visualization test area was positioned in around 7number of parameters such as the boundary condition, m from the initial pipe to ensure fully developed meshing criteria, and exact flow parameters should be flow. A schematic layout of the experimental well prepared. On the other hand, an image processing apparatus is briefly represented in Fig. 1 above. technique is appropriate to be implemented in the This present work is involving 25 experimental interfacial analysis due to its simplicity, accuracy, and data which covers the liquid superficial velocity (JL) easy to be used. The non-intrusive method has an from 0.25 to 1.13 m/s and that of gas superficial ability to establish both of the qualitative and the velocity (JG) from 0.12 to 0.51 m/s. The experimental quantitative assessment. data range is presented in Fig. 2 in the form of coAlthough this technique has been previously current horizontal flow pattern maps comparison applied for investigating slug flow characteristics, among Mandhane et al. (1974), Taitel & Dukler


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(1976), Weismann et al. (1978), and Lin & Hanratty (1987). All observed data meet the appropriate plug regime that proposed by these maps. The physical experiments and investigation on the liquid hold-up by using CECM (Constant Electric Current Method) have also been conducted [15, 16]. Three pairs of liquid hold-up sensors are located in 215-mm spacing line between each sensors. The available results of the signal processing experiment were used as data comparison of the plug flow wave characteristics.

Fig. 2. Flow pattern maps comparison 3.

Image Processing Technique Each obtained video was extracted into sequences of images. Through the Virtual Dub software, a video was splatted into the consecutive images. This operation produces 3600 image frames from each 30-seconds video. A specific algorithm which aimed to measure liquid-phase level was developed in MATLAB® R2013a. Particularly, this engineering software was commonly used in digital image processing application by providing the friendly features in Image Processing Toolbox. Each of digital image was treated as matrix data (row and column processing) in pixel unit. This work was used the thresholding method of image segmentation to make the binary images to find binary image. Thus, a statistical analysis support the data analysis for example to find the liquid hold-up distribution and wave frequency. The algorithm was started by loading the extracted images. At the first, those images were in form of 8-bits RGB (red-green-blue). Due to the imperfection in capturing the images, an inappropriate orientation of the loaded images often occurs. An image rotation should be obtained to reach the best image orientation. This step is aimed to ensure best input for the next operation steps. The 3-layers RGB images need to convert into 1layer grayscale images. As the results, the output images have 256 grey level index ranging from 0 (black) to 255 (white) pixel. The use of MATLAB® command of ‘rgb2gray’ allow the easiest way for the grayscale conversion by eliminating the hue and saturation information while retaining the luminance [17]. Those images were then cropped into desired size depend on the essential informations. Next, in


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order to eliminate the image noise, sequence operations were performed. The noise reduction process was begun with the image complementary operation (Fig. 3b) which underlies the next step of the artificial backgrounds construction. They were prepared after a combination with non-flat structuring element function for ensuring more uniform luminosity level. After that, a subtraction between the grayscale complement images and the new backgrounds was undertaken (Fig. 3c). Moreover, Median filtering and Wiener Filtering were implemented to reduce the different types of image noise. Each output pixel is determined by the median value of the neighborhood pixels for Median Filtering while Wiener filtering is a type of linear filtering which worked adaptively into the images by tailoring itself to the local image variance [17]. Result of image filtering operation is presented as well in Fig. 3d. One of the significant steps in image processing technique is image segmentation which covers the binary images conversion (thresholding). A threshold value corresponds to change the pixel value to be 1 (white) – for higher value and 0 (black) – for lower value than threshold value. Due to random and irregular characteristics in this flow pattern, the threshold value needs to be determined manually rather than automatic graytresh method (Otsu’s method). Hence, the binary images were performed (Fig. 3e). Through the bwperim function, the binary image perimeter (Fig. 3f) can be performed. The command help encourage an improvement on the apparent gas-liquid interfacial boundary.

Fig. 3. The following steps of image processing operation: (A) Result of cropped image (B) result of image complementary (C) after background subtraction (D) after image filtering (E) after conversion to binary mode (F) result of image perimeter. (JG=0.24 m/s and JL=0.77 m/s) A quantitative analysis which combined of the non-linear statistics such as cross-correlation function, power spectral density (PSD), and Probability distribution function were involved to analyze this phenomena. A local analysis was adapted to determine liquid film thickness by dividing each image frame into three selected zones (Fig. 4). Each divided zone has 1-pixel column width. The object tracking algorithm ensured the obtainment of the lowest point

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white object (gas-plug). The liquid film thickness () could be obtained by this following equation: (1)   [( h  1)  t G ]  calibratio n (mm) where h is the column height (pipe diameter), tG is the gas-phase thickness, and the calculation was calibrated from pixel to mm unit.

Fig 4. Illustration of the image division (160th, 320th, 480th column) and liquid film thickness measurement 4. Results and Discussion 4.1 Flow Pattern Plug flow pattern is characterized by the presence of the elongated bubble that located in upper layer of the pipe. This pattern consist of liquidplug and gas-plugs (often recognized as Taylor bubble or elongated bubble) without any tiny aerated bubbles behind the gas-plug. Specifically, for the horizontal flow, the gas-phase (very low-density phase) took place at the top of the pipe whereas liquid phase at the bottom of it due to the gravity effect. Image processing technique was decisively recognized the important flow parameters, bubblecontours, and the boundary among gas and liquid through image segmentation operation.

Fig. 6. Comparison among the image processing result CFD codes and visual observation (JG=0.12 m/s and JL=0.25 m/s) 4.2 Liquid hold-up characteristics The measurement of liquid film thickness brings on the calculation of the liquid hold-up. Basically, the obtained data at the 2nd zone (x/L = 0.5) of local analysis (that showed in fig. 4) was chosen due to the best object condition. However, the observation just produced one-dimensional side-view data that should be converted into 3-D liquid hold-up which involves the cross-sectional analysis. Those following assumptions has been used by Majid [20] to solve the same problem. As shown in fig. 7, the waves are periodically fluctuated by showing high values (for liquid-plug) and low values (for gas-plug). In this case, the gas movement was hampered because the liquid film always tended to block the pipe. Meanwhile, the pressure drop in this regime was also in the chaotic condition.

Fig. 7. Typical transient liquid hold-up data (for JG=0.12 m/s and JL=0.31 m/s)

Fig. 5. Comparison among the obtained visualization result from photograph view and image processing The comparison of single elongated bubble topology which observed by visual study and image processing technique is suitably illustrated in Fig. 5. It can be seen that the image processing results perform a better interface for the bubble nose and tail contours. Therefore, this technique can be potentially used to validate the CFD codes. A comparison with the previous visual observation [18] and CFD codes [19] are also depicted in Fig. 6.


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Fig. 8. The effect of gas superficial velocities on the average liquid hold-up Fig. 8 is revealed that the average liquid hold-up decreases as the increase of gas superficial velocities. In a constant duct, the increase of JG was also contribute to increase the gas volume flow rate. Therefore, the liquid film was shoved by the presence of gas-phase. Thus, the liquid hold-up value decreased. The non-linear statistics such as PSD and PDF conclude the liquid hold-up frequency and distribution. As can be seen in Fig. 9, the gas-liquid plug flow has twin peaks of liquid hold-up distribution in PDF calculation. They are liquid dominant zone

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(which has =1) and the else for gas dominant zone. The PSD data leads the wave frequency calculation.

Fig. 9. Example of (a) PSD and (b) PDF analysis (JG=0.51 m/s and JL=1.13 m/s) 4.3 Wave Velocity The wave velocity data was obtained by the cross correlation function. The measurement used two waves which obtained from the 160th column pixel (x/L = 0.25) and the 480th column pixel (x/L = 0.75) of each image frame. The wave velocity can be calculated through this following equation: Wave velocity =

(m/s)

(2)

An image processing technique shows a good performance in the wave velocity measurement. The wave velocity data comparison is shown in Fig. 10. The present data are well agree with the previous studies such as CECM Measurement [15] and bubble translational analysis [18]. The data is also compared with the drift-flux model [21], which use the Eq. (3), as follows: Ug = C0 Jm + vgj (3)

Fig. 11. The effect of (a) JG and (b) JL on the wave velocity 4.4 Wave Frequency The PSD analysis which based on Fast Fourier Transform (FFT) produces the exact wave frequency for each matrix data. The influence of liquid superficial velocity (JL) through the wave frequency is shown in Fig. 12. Under the constant JG, the wave frequency increases as the increase of JL. For high liquid flow rates, a high wave frequency also occurred. For instances, the wave frequency can be obtained as the plug frequency. This term also refers to the frequency of waves that pass a specific reference point.

where C0 = 0.98 and vgj = 0.16, for plug flow.

Fig. 10. Relationship between the available previous studies and averaged wave velocity The increase of JG and JL induced the less lags time between two waves. It has a meaning that these variables give a significant contribution in wave velocity enhancement. Moreover, by increasing JG in constant JL and vice versa, the increase of the wave velocities was also occurred. Fig 11 (a) and (b) depict the effect of JG and JL on the increase of wave velocities, respectively.


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Fig. 12. Relationship between the liquid superficial velocity and the wave frequency 5.

Conclusion An image processing technique was used to determine the wave characteristics of horizontal cocurrent gas-liquid plug flow. The method has an ability both for qualitatively ensuring a better point of air-water interface and proceeding detailed quantitative results on the important wave parameters. As the results, an apparent flow pattern, the liquid hold-up characteristics and distributions, the wave velocity, and the wave frequency could be automatically determined through this technique.

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A specific study was conducted that the gas and liquid superficial velocity strongly affected the wave characteristics. The results are summarized as follows: 1. Under a constant JG, wave frequency increases with increase of JL 2. Under a constant JL, liquid film thickness and liquid hold-up decrease as the increase of JG. 3. Under the increase of JG and JL wave velocity is also increased. References [1] E. Al-Safran, 2009, Investigation and Prediction of Slug Frequency In Gas/Liquid Horizontal Pipe Flow, Journal of Petroleum Science and Engineering,, Vol. 69, 143-155. [2] Ujang, P.M., Lawrence, C.J., Hale, C.P., Hewitt, G.F., 2006, Slug Initiation and Evolution in TwoPhase Horizontal Flow, International Journal of Multiphase Flow, Vol. 32, 527-552. [3] Taitel, Y., Dukler, A.E., 1976, A Model for Predicting Flow Regime Transitions in Horizontal and Near Horizontal Gas-Liquid Flow, AIChE Journal, Vol. 22, No. 1, 47-55. [4] Hurlburt, E.T., Hanratty, T.J., 2002, Prediction of the Transition from Stratiﬁed to Slug and Plug ﬂow for long pipes, International Journal of Multiphase Flow, Vol. 28, 707-729. [5] Woods, B.D., Hanratty, T.J., 1999, Influence of Froude Number on the Physical Processes Determining Frequency of Slugging In Horizontal Gas–Liquid Flows, International Journal of Multiphase Flow, Vol. 25, 1195–1223. [6] Taitel, Y., Dukler, A.E., 1977, A Model for Slug Frequency During Gas–Liquid Flow in Horizontal and Near Horizontal Pipes, International Journal of Multiphase Flow, Vol. 3, 585–596. [7] Da Silva, M.J., Hampel, U., Arruda, L.V.R., do Amaral, C.E.F., Morales, R.E.M., 2011, Experimental Investigation of Horizontal GasLiquid Slug Flow by Means of Wire-Mesh Sensor, J. of the Braz. Soc. Of Mech. Sci. & Eng., Vol. XXXIII, 237-242. [8] Teysedou, A., Tye, P., 1999, A Capacitive TwoPhase Flow Slug Detection System, Review of Scientific Instruments, Vol. 70, No. 10, 3492-3948. [9] Fukano, T., 1998, Measurement of Time Varying Thickness of Liquid Film Flowing with High speed Gas Flow by a Constant Electric Current Method (CECM), Nuclear Eng. Design, Vol. 184, 363 377. [10] Gopal, M., Jepson, W.P., 1998, The Study of Dynamic Slug Flow Characteristics Using Digital Image Analysis – Part I: Flow Visualization, Journal of Energy Resources Technology, Vol. 120, 97-101. [11] Rosa, E.S., 2004, Flow Structure in the Horizontal Slug Flow, Engenharia Termica (Thermal Engineering), Vol. 3, No. 2, 151-160. [12] Vallee, C., Hohne, T., Prasser, H.M., Suhnel, T., 2006, Experimental Investigation and CFD Simulation of Horizontal Air/Water Slug Flow, Kerntechnik, Vol. 71, No. 3, 95-103.


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[13] Mayor, T.S., Pinto, A.M.F.R., Campos, J.B.L.M., 2007, An Image Analysis Technique for The Study of Gas-Liquid Slug Flow Along Vertical Pipes – Associated Uncertainty, Flow Measurement and Instrumentation, Vol. 18, 139-147. [14] do Amaral, C.E.F., Alves, R.F., da Silva, M.J., Arruda, L.V.R., Dorini, L., Morales, R.E.M., Pipa, D.R., 2013, Image Processing Techniques for HighSpeed Videometry in Horizontal Two-Phase Slug Flows, Flow Measurement and Instrumentation, Vol. 33, 257-264 [15] Dinaryanto, O., 2012, Sifat-Sifat Aliran Slug Ditinjau dari Karakteristik Lokal (Visualisasi, Liquid Hold-Up, dan Signal Processing) pada Pipa Horizontal, Master Thesis of Mechanical Engineering, UGM, Yogyakarta, (in Bahasa Indonesia). [16] Deendarlianto, Dinaryanto, O., Hudaya, A.Z., Indarto, 2013, Experimental Study on the Interfacial Behavior of Air-Water Plug Two-Phase Flow in A Horizontal Pipe, Proceeding of SNTTM XII, 149-155. [17] Anonym, 2013, Image Processing ToolboxTM User’s Guide R2013a, The Mathworks, Inc., Natick MA, United Stated of America. [18] Widarmiko, N, 2012, Visualisasi Aliran Plug Air Udara Searah pada Horizontal, Bachelor Thesis of Mechanical Engineering, UGM, Yogyakarta. (in Bahasa Indonesia). [19] Moeso, A, Deendarlianto, Khasani, Indarto. 2013, A CFD Modelling on the Slug Flow Mechanism of Air-Water Two-Phase Flow. Proceeding of Seminar Nasional Thermofluid V 2013, Vol. 1, No.1, 118-124. [20] Majid, A.I., 2014, The Interfacial Characteristics of Gas-Liquid Plug Two-Phase Flow in A Horizontal Pipe by Using An Image Processing Technique, Bachelor Thesis of Mechanical Engineering, UGM, Yogyakarta. [21] Franca, F., Lahey Jr., R.T., 1992. The Use of DriftFlux Techniques for The Analysis of Horizontal Two-Phase Flows, Int. J. Multiphase Flow, Vol 18, No.6, 787-801.

Acknowledgement The authors gratefully thanks to Directorate General of Higher Education, Ministry of Education and Culture, Republic of Indonesia for supporting this present work as a part of the “Hibah Penelitian Unggulan Perguruan Tinggi” research scheme through “Dana DIPA Universitas Gadjah Mada 2013” with the contract number: LPPM-UGM/1448/LIT/2013.

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