ANALYSIS ON FLOW PRESSURE IN THE PNEUMATIC BRAKING SYSTEM OF FHS-RDE USING FLUENT 6.3 SOFTWARE

The High Temperature Gas Cooled Reactor (HTGR) is considered as one of the nuclear reactors of generation-IV type in the future. The fuel handling system is one of the important processes in HTGR as well as in the design of Reaktor Daya Eksperimental (RDE). In the Fuel Handling System (FHS), the fuel pebble is transferred pneumatically along the pipe using carrier gas into the core of the reactor. Therefore, the pneumatic is an important system in operation stability of FHS. During the developing process of FHS-RDE, a branch pipe as a braking pipe system is provided on top of the pneumatic system to reduce the speed of the fuel discharged from the pneumatic pipe. The pneumatic pipe has an inner diameter of 65 mm and 20 m in length, whereas a branch pipe diameter for the braking system is 30 mm. The pneumatic system pressure is greater than the reactor cooling system pressure of 3.0 MPa. This work was performed to investigate the pressure drop and flow pattern of the braking system of FHS by various carrier gas inlet pressure. The analysis was carried out by Fluent 6.3 Software. Based on the design parameter of FHS used in the analysis, the results show that the performance of the braking system is not significant to reduce the pressure in the top region of the pneumatic pipe. To obtaining a significant reduction in pressure, and evaluation on the design of the branch pipe as well as the radius of curvature of the bend at the top pipe is suggested.Keywords: Pneumatic pipe, pressure, braking system, fuel handling of RDE, carrier gas

KARAKTERISTIK ALIRAN DI SEKITAR SILINDER SIRKULAR DAN SILINDER BERSIRIP

Aliran yang melalui suatu benda akan menghasilkan karakeristik aliran yang sangat tergantung pada beberapa parameter fisik, diantaranya; bentuk benda, kondisi permukaan, maupun orientasi benda yang dilintasi. Penelitian ini, penulis menggunakan software Gambit 2.4 dan Fluent 6.3 untuk memodelkan silinder bersirip dengan variasi jarak antar fin. Diameter silinder, panjang silinder, panjang fin, dan tebal fin adalah variabel yang tetap konstan. Variabel yang diubah adalah jarak antar fin, yaitu 10 mm, 14 mm, dan 18 mm. Simulasi numerik pada penelitian ini dilakukan dengan pendekatan 3D-steady flow Reynolds Averaged-Navier Stokes (RANS) dan RNG k-ε. Properties udara yang digunakan pada kondisi STP dengan temperatur 28oC adalah, densitas (ρ) = 1,17 kg/m3 dan viskositas (μ)=1,85 x 10-5 N.s/m2. Kondisi inlet aliran udara, velocity inlet 16 m/s dan intensitas turbulensi 1,56 % diterapkan pada kondisi batas inlet domain simulasi numerik. Aliran fluida yang melalui silinder yang terdapat clearance antara silinder dan dinding tidak terbentuk pasangan vorteks dengan arah aliran tertutup (close loop) sebagaimana umumnya vorteks aliran 2D di belakang sililnder sirkular. Terbentuk vorteks pada celah antar fin terutama pada celah antar fin di dekat clearance antara silinder bersirip dan dinding. Semakin banyak vorteks yang terbentuk, maka akan menghasilkan induced drag yang besar terutama pada silinder bersirip dengan jarak antar fin yang lebih sempit. Silinder bersirip menghasilkan daerah wake yang lebih panjang sebelum terjadi attached flow.

Analisis Distribusi Temperatur Media Penampung Bahan Bakar Bekas Reaktor Daya Eksperimental (RDE) Menggunakan FLUENT 6.3

ANALISIS DISTRIBUSI TEMPERATUR MEDIA PENAMPUNG BAHAN BAKAR BEKAS REAKTOR DAYA EKSPERIMENTAL (RDE) MENGGUNAKAN FLUENT 6.3. Konsep dan desain reaktor daya eksperimental (RDE) adalah mengacu pada HTGR (High Temperature Gas-cooled Reactor) dari teknologi Jerman yang telah diterapkan pada HTR-10 di Cina yang dirancang menggunakan bahan bakar yang berbentuk pebble bed. Setelah bahan bakar nuklir dimanfaatkan dalam reaktor nuklir, bahan bakar bekas tersebut kemudian akan masuk ke dalam tempat penampungan sementara. Penelitian ini dikhususkan pada aspek temohidrolik karena peranannya yang sangat penting untuk menjamin keselamatan media penampung bahan bakar bekas Reaktor Daya Eksperimental (RDE). Oleh karena itu diperlukan alat bantu berupa progam (software) komputer dalam proses penganalisaan distribusi temperatur media penampung bahan bakar bekas Reaktor Daya Eksperimental (RDE). Program yang digunakan adalah FLUENT 6.3. Hasil perhitungan menunjukan bahwa terjadi penurunaan temperatur secara bertahap pada bahan bakar bekas di setiap posisinya, dari titik pusat di posisi 0 m sebesar 110°C ke dinding media penampung di posisi 0,3 m sebesar 30°C. Sehingga dari hasil tersebut distribusi temperatur media penampung bahan bakar bekas reaktor daya eksperimental dapat dianggap aman tanpa kerusakan akibat dari panas

Computational Fluid Dynamics (CFD) Simulation of Cross-flow Mode Operation of Membrane for Downstream Processing

Background: Membrane filtration process produced good quality of permeate flux due to which it is used in different industries like dairy, pharmaceutical, sugar, starch and sweetener industry, bioseparation, purification of biomedical materials, and downstream polishing etc. The cross-flow mode of operation has also been used to improve the quality of the Rubber Industrial effluent of Tripura, India. </P><P> Method: The Computational Fluid Dynamics (CFD) simulation of the cross-flow membrane is done by using ANSYS Fluent 6.3. The meshing of the geometry of the membrane is done by Gambit 2.4.6 and a grid size of 100674, the number of faces is 151651 and number of nodes being 50978 has been selected for the simulation purpose from the grid independence test. We have revised and included all patents in the manuscripts related to the membrane filtration unit. </P><P> Results: Single phase Pressure-Velocity coupled Simple Algorithm and laminar model is used for the simulation of the developed model and Fluent 6.3 used for the prediction of pressure, pressure drop, flow phenomena, wall shear stress and shear strain rate inside the module is studied for cross flow membrane. </P><P> Conclusion: From the study, it has been found that CFD simulated results hold good agreement with the experimental values.

Optimal tube diameter on heat exchanger shell and tube type with 15 mega watt thermal power using fluent 6.3

Heat exchanger shell and tube type is a set of tools that serve to move the heat from the side shell (hot fluid) to the tube (cold fluid). RSG-GAS Heat Exchangers is a heat exchanger shell and tube type 2-2. Since the age of Heat Exchanger operation long enough allow for new designs of heat transfer better. This is one reason the presence of micro modeling using Computational Fluid Dynamics (CFD), as one of them using the software FLUENT 6.3. Tube and shell modeled in GAMBIT with the variation ID (inner diameter) tube. As for the physical data such as flow rate, pressure, and temperature refers to the RSG-GAS Heat Exchangers. The first variation is the different mesh sizes for the tube that has the same diameter. Mesh size of 0.8 mm had the best result so do the meshing used as a benchmark for other models. Variations of 2D models use inner diameter from 20 mm until 26m. From CFD calculations using FLUENT 6.3 for 2D models, in the can that ID 20 mm, 23 mm and 26 mm can be used as models for 3D calculations. Of 3D calculations it can be concluded that the tube with an ID of 26 mm have the most optimal heat transfer is equal to 273,24669 K with a pressure drop of 450 Pa.

A Study of Influence of Dual Axial Fans Arrangement on Airflow Fluid Field of Special Vehicle Power Cabin

In this paper, an 3D model of a special vehicle power cabin is developed. Using FLUENT 6.3 the simulation on different helix hand of dual axial fans and different arrangement of with/without bulkhead are conducted. The influence law of different arrangements on airflow fluid field of power cabin is obtained on the condition of dual axial fans. Simulation results mean important recommendation to the design of power cabin dual axial fans.

Simulation Research on a Subsonic Flow around Plane Cascade

The paper deals with an analysis of a gas flow through two sets of plane cascade at various angles of attack (0 o, +20 o, -20 o) of different inlet Mach numbers (0.6,0.4, 0.2) by commercial CFD code FLUENT 6.3. Plane cascade aerodynamic research was performed with k-ε model and its flow characteristic was obtained. Its boundary separation and wake were observed. Then their influence factor and development characteristic were studied. Meanwhile, two sets of plane cascade are compared and their aerodynamic characteristics are analyzed.

Effect of Negative Pressure on Yarn Quality in Compact Spinning with Inspiratory Groove

The flow field in condensing zone of compact spinning with inspiratory groove was developed with Fluent 6.3 and the distribution of velocity was analyzed too. Also the effect of negative pressure on the yarn quality was analyzed and the experiment was done to prove the effect of negative pressure on the yarn qualities. The results show that the fiber can not be compacted well when negative pressure is too small, but it will add the energy consumption, attach the fibers firmly to the bottom of the compact groove by the effect of flow field and reduce the fiber migration, cause the fibers to be absorbed from the holes or the holes to be plugged when the negative pressure is too big. Therefore, in order to ensure the fibers being compacted well and reduce the energy consumption, the selection of negative pressure in compact spinning with inspiratory groove should be less than -3000pa.

VARIASI KECEPATAN ALIR GAS PADA PROSES PELAPISAN KERNEL UO2 DENGAN COMPUTATIONAL FLUID DYNAMIC (CFD)

VARIASI KECEPATAN ALIR GAS PADA PROSES PELAPISAN KERNEL UO2 DENGAN COMPUTATIONALFLUID DYNAMIC (CFD). Pelapisan kernel UO2, merupakan salah satu tahap dalam pembuatan bahan bakarnuklir yang sangat menentukan terhadap hasil akhir bahan bakar reaktor suhu tinggi. Kernel hasil prosessintering, yang merupakan partikel bulat UO2 diameter sekitar 0,8 mm, dikenakan proses pelapisan pirokarbondan silika karbida secara chemical vapor deposition (CVD). Aspek utama yang ditinjau dalam fluidisasi adalahmekanika fluida yang menggambarkan apa yang terjadi dalam proses fluidisasi. Kemampuan untukmemprediksi awal terjadinya fluidisasi sangat penting di dalam proses fluidisasi. Hal ini dilakukan untukmemperoleh hasil operasi yang bagus, life time tinggi, penentuan kecepatan minimum fluidisasi dan kecepatanmaksimum fluidisasi. Cairan atau gas apabila dilewatkan dari bawah ke atas pada partikel padat padakecepatan rendah, maka partikel tidak bergerak dan apabila kecepatan ditambah, pada titik tertentu partikelmulai bergerak. Kecepatan alir ini disebut sebagai kecepatan minimum fluidisasi. Dalam fluidisasi apabilakecepatan fluida yang melewati partikel dinaikkan maka perbedaan tekanan di sepanjang reaktor akanmeningkat pula. Partikel-partikel ini akan bergerak-gerak dan mempunyai perilaku sebagai fluida. Keadaanseperti ini dikenal sebagai partikel terfluidisasi (fluidized bed). Reaksi kimia yang terjadi dalam fluidisasi jugaberpengaruh terhadap kondisi proses dan terjadi perpindahan massa selama fluidisasi. Dalam penelitian initelah dilakukan modeling proses pelapisan pirokarbon dan silika karbida dengan Computational Fluid Dynamic(CFD) Fluent 6.3. Pelaksanaan penelitian, pertama-tama digambar reaktor dengan program Gambit 2.2.30 dandijalankan dengan program Fluent 6.3. Proses fluidisasi dihitung dengan model multiphase Eulerian dengan gassebagai fase primer dan kernel sebagai fase sekunder. Model dipilih untuk proses unsteady dan aliran laminar.Teori Syamlal-Obrien digunakan untuk perhitungan interaksi antar fase. Dari perhitungan Fluent 6.3, ternyatakecepatan alir gas masuk 8 m/dt masih ada kernel yang jatuh ke bawah, sehingga ini sesuai denganperhitungan menggunakan persamaan kecepatan minimum fluidisasi yang terhitung = 8,6 m/dt. Pada percobaanmenggunakan reaktor gelas juga diperoleh data pada kecepatan 9,49 m/dt sudah terjadi fluidisasi yang baikdibandingkan dengan fluidisasi pada kecepatan 7,11 m/dt masih terlihat ada kernel yang jatuh ke penampung.Data perhitungan nantinya bisa digunakan untuk operasi reaktor fluidisasi alat pelapisan kernel bahan bakar diPTAPB BATAN Yogyakarta.Kata kunci : kernel, reaktor suhu tinggi, fluidisasi, pirokarbon

Influence of Geometry on the Position and the Intensity of Maximum Kinetic Energy in a Combustion Chamber

We analyzed the hydrodynamics of the flow into an axis-symmetrical combustion chamber with a central bluff body. Using an axis-symmetrical turbulent flow model we determined the extent of the recirculation region behind the bluff body as well as the location and intensity of maximum kinetic energy as a function of the cone angle of the chamber wall. We showed that by shortening the convergent conical section of the chamber we obtain a compact recirculation with higher turbulence intensity, with positive influence on gas mixing. We used the software FLUENT 6.3 for the numerical simulation of the gas flow inside the combustion chamber. The simplified geometry of the two types of combustion chambers was built using the pre-processor GAMBIT 2.4. Two structured meshes were obtained for the domains of numerical analysis with approximately 170,000 cells each. For modelling the turbulence of the flow we used three different turbulence models which were implemented in FLUENT 6.3.