Hasil Pencarian  ::  Simpan CSV :: Kembali

"

Telah dilakukan penelitian analisis aliran turbulen dengan menggunakan metode  CFD untuk aliran fluida kompleks pada fluidized bed dengan menggunakan beberapa model turbulen yaitu model turbulen standar (STD) k-ε, Re-normalization Group (RNG) k-ε, dan tiga model turbulen k-ε yang telah dimodifikasi. Fluidized bed adalah merupakan komponen pada sistem turbin mikro bioenergi untuk aplikasi zero energy building (ZEB). Tujuan dari simulasi ini adalah untuk memperoleh model turbulen baru yang memberikan hasil simulasi lebih baik, khususnya aliran fluida kompleks. Simulasi CFD dilakukan dengan perangkat lunak CFDSOF(r) menggunakan model geometri grid dua dimensi 100x200.

Dari hasil simulasi menggunakan 2 model turbulen, yaitu STD k-ε, RNG k-ε, kedua model turbulen tersebut ternyata memberikan hasil yang hampir sama dan mendekati hasil eksperimen untuk parameter beda tekanan pada bed. Namun model STD k-ε memberikan hasil yang lebih mendekati hasil eksperimen atau efektif pada kecepatan superficial 0,40 m/s – 0,80 m/s sementara model RNG k-ε lebih efektif pada kecepatan superficial 0,70 m/s – 1,0 m/s. Dari perbandingan terhadap parameter fisik, kedua model memberikan hasil yang hampir sama untuk parameter fraksi volume dan kecepatan partikel, namun memberikan hasil yang berbeda untuk tekanan statik dan kecepatan gas. Untuk parameter turbulensi, yaitu energi kinetik turbulen, laju disipasi turbulen dan viskositas efektif, kedua model memberikan hasil yang berbeda.

Untuk modifikasi nilai Prandtl kinetik pada model turbulen STD k-ε, dimana dilakukan simulasi dengan nilai Prandtl kinetik (Prandtl-k) 0,8; 0,9; dan 1,1; untuk parameter beda tekanan pada bed nilai Prandtl-k 0,9 memberikan hasil yang paling akurat untuk kecepatan superficial 0,40 – 0,70 m/s, sementara nilai 1,1 akurat untuk kecepatan superficial 0,80 – 0,90 m/s. Hasil simulasi untuk parameter laju disipasi menunjukkan bahwa perubahan nilai Prandtl-k merubah pola kontur laju disipasi. Untuk parameter viskositas efektif gas diperoleh hasil bahwa dengan turunnya nilai Prandtl-k menyebabkan turunnya nilai viskositas efektif gas dan sebaliknya. Sedangkan untuk parameter viskositas efektif partikel diperoleh hasil bahwa untuk nilai Prandtl-k = 0,9 hasilnya tidak berbeda secara signifikan dengan model standar pada kecepatan superficial 0,5 m/s. Berbeda dengan nilai Prandtl-k = 1.1 yang diuji pada kecepatan superficial 0,8 m/s, diperoleh hasil bahwa kenaikan bilangan Prandtl-k menjadi 1,1 menaikkan viskositas efektif partikel.

---

Turbulent flow analysis has been carried out using the CFD method for complex fluid flow in fluidized beds using several turbulent models, i.e. standard k-ε (STD), Re-normalization Group k-ε (RNG), and three modified k -ε turbulent models. Fluidized bed is a component of the bioenergy micro turbine system for zero energy building (ZEB) applications. The purpose of this simulation is to obtain a new turbulent model that provides better simulation results, especially for complex fluid flows. CFD simulation is done with CFDSOF (r) software using a 100 x 200 two-dimensional grid geometry model.

From the simulation results using 2 turbulent models, i.e. STD k-ε, RNG k-ε, the two turbulent models turned out to give almost the same results and approached the experimental results for the parameters of the pressure difference on the bed. However the STD k-ε model gives more accurate results at the superficial velocity of 0.40 m/s - 0.80 m/s and the RNG k-ε model is more accurate at superficial velocities of 0.70 m/s - 1.0 m/s. From the comparison of physical parameters, the two models give almost the same results for the volume fraction and particle velocity parameters, but give different results for static pressure and gas velocity. For turbulent parameters, i.e. turbulent kinetic energy, turbulent dissipation rate and effective viscosity, both models give different results.

The results of modification of the kinetic Prandtl value in the turbulent STD k-ε model, where the simulation is performed with a kinetic Prandtl value of 0.8; 0.9; and 1.1; for pressure difference parameters on bed, Prandtl-k = 0.9 gives the most accurate results for superficial velocities of 0.40 - 0.70 m/s, while Prandtl-k = 1.1 is accurate for superficial velocities of 0.80– 0.90 m/s. The simulation results for disipation rate show that the change of kinetic Prandtl change the disipation rate contour. Meanwhile, decreasing the value of kinetic Prandtl will decrease the effective viscosity of gas and vice versa. The contours of particle effective viscosity for Prandtl-k = 0.9 are not different significantly with the standard model measured at superficial velocity of 0.5 m/s. But the different results are found for the Prandtl-k = 1.1 measured at superficial velocity of 0,8 m/s, where the higher Prandtl-k value the higher the particle effective viscosity.

"

"Serangkaian Investigasi komputasional 3 Dimensi dan eksperimental dilakukan untuk menganalisa pengaruh kontrol aliran aktif berhubungan dengan usaha pengurangan nilai koefisien drag aerodinamika pada Makara Electric Vehicle MEV Untuk mengurangi drag ini model uji dilengkapi oleh dua buah aktuator kontrol aliran jet sintetik yang diletakkan simetris terhadap sumbu tengah dari model pada atap bagian belakang model Tahap Pertama Pengukuran terhadap gaya drag aerodinamika dilakukan dengan mengguakan load cell pada terowongan angin Tahap selanjutnya hasil eksperimen di verifikasi secara teoritis dengan metode numerik menggunakan perangkat lunak CFD Ansys Fluent Penggunaan jet sintetik pada MEV dengan 3 kecepatan upstream berbeda yaitu dan dapat mengurangi ukuran olakan yang terjadi pada sisi belakang model uji meningkatkan tekanan statik dan menurunkan persentase intensitas turbulensi Pada kasus ini 2 metode penelitian yang digunakan menunjukkan bahwa nilai pengurangan hambatan aerodinamika lebih besar terjadi ketika kecepatan upstream aliran udara lebih tinggi.

---

An array of 3D computational and experimental investigation are conducted to analyze the effect of the active flow control to reduce aerodynamic drag on the Universitas Indonesia electric car model Makara Electric Vehicle MEV In order to reduce this drag two synthetic jet actuators are laid down symmetrically from the centerline of the lateral direction on rear end roof of the model In the first instance drag force measurement of the model is undertaken using a load cell on a wind tunnel for two different upstream velocities and Secondly The simulation was carried out in ANSYS FLUENT to verified the experimental result Synthetic jets affects on a reduction of the near wake section and turbulence intensity of air flow behind the model It also increase the static pressure of air flow behind the model This control leads to a slightly drag reduction on the model In this case two research methods yield the more drag reduction on the higher upstream velocity of air."

"Seiring dengan perkembangan jaman dan meningkatnya kebutuhan umat manusia serta diikuti dengan terus menipisnya cadangan sumber daya fosil yang selama ini menjadi sumber energi di seluruh dunia telah melahirkan banyak teknologi pengkonversi sumber daya alam terbarukan sebagai upaya penekanan pemakaian bahan bakar fosil. Salah satu teknologi tersebut adalah Fluidized Bed Combustor (FBC). Fluidized Bed Combustor berfungsi mengubah energi biomassa menjadi energi panas yang dapat dimanfaatkan. Alat ini bekerja dengan memanfaatkan hamparan pasir silika yang difluidisasikan menggunakan udara bertekanan. Hamparan pasir silika yang terfluidisasi ini berfungsi sebagai sarana penyimpan dan pendistribusi panas yang baik. Temperatur pengoperasian fluidized bed combustor berada pada saat bed 750-800ᵒC sehingga bahan bakar dapat terbakar dengan baik sehingga terjadi self sustained combustion. Agar terjadi proses pembakaran yang baik dari pemanasan awal hingga kondisi self sustained combustion diperlukan suplai udara bertekanan yang dihasilkan dari putaran blower. Dalam pengujian ini dilakukan dua kali pengujian dengan suplai udara 0,093 m3/s dan 0,085 m3/s, dengan variasi feeding yang berbeda. Hasil yang terbaik adalah dengan suplai udara 0,093 m3/s.

---

Along with the time changing and the increasing needs of mankind and followed by continuing depletion of fossil resources which has been a source of energy worldwide has spawned many technologies converting renewable natural resources as an effort to emphasis the use of fossil fuels. One such technology is the Fluidized bed combustor (FBC). Fluidized Bed combustor serves convert biomass energy into heat energy that can be utilized. It works by exploiting silica sand which fluidized using pressurized air. Fluidized silica sand that serves as a means of storage and good heat distributor. Operation temperature of fluidized bed combustor to be in 750-800 Celcius degree bed, so that fuel can be burned and resulting in self-sustained combustion. In order to develop good combustion process from the beginning to the heating stage, it is necessary to provide self-sustained combustion air supply resulted by a blower. This test was done twice with testing air supply at 0.093 m3/kg and 0.085m3/kg, with different variations of feeding. Best result is to supply air at 0.093 m3/kg."

"ABSTRAKSeiring dengan bertambahnya gedung bertingkat serta meningkatnya kebutuhan lahan parkir maka pembangunan lantai basement di Jakarta semakin banyak. Lantai basement yang relatif tertutup membutuhkan sistem proteksi kebakaran khusus terutama pada sistem pengendalian asap. Salah satu alat yang digunakan sebagai pengendali asap di lantai basement adalah jet fan atau car park blower. Walaupun jet fan telah banyak digunakan tetapi belum ada aturan yang mengatur spesifikasi dan pemasangannya. Oleh karena ini, penilitian ini melakukan karakterisasi jet fan pada skala laboratorium.Penelitian ini dilakukan dalam beberapa tahap. Pertama, membuat model jet fan dengan menggunakan analisis nondimensional. Kedua, pengukuran kecepatan putaran jet fan. Ketiga, pengukuran debit aliran dengan orifice plates sesuai standar ISO 5167-2. Keempat, pengukuran profil kecepatan pada sisi tiup jet fan. Kelima, visualisai penyebaran asap yang ditiupkan oleh jet fan. Hasil dari penelitian ini menunjukkan kecepatan putar fan mempengaruhi debit aliran, momentum aliran, dan lebar tiupan asap oleh jet fan. Dengan hasil tersebut, diketahui bahwa jet fan yang telah dibuat dapat diterapkan pada ekperimen kebakaran basement sebagai eksperimen selanjutnya.

---

ABSTRACTAs the number of high rise buldings and the need for parking space increases, the need for basement floor also grows.Relatively closed basement floor requires a special fire protection system, especially in the smoke control system. One of the tools used as the controller of smoke in the basement is jet fan or car park blower. Although the jet fan has been widely used, there are no rules governing its specification and installation. Therefore, this research was conducted to characterize the jet fan on a laboratory scale.This research was conducted in several stages. First, creating a model jet fan using nondimensional analysis. Second, measuring the speed of jet fan rotation. Third, measuring the flow rate using orifice plates, in accordance to the ISO 5167-2 standard. Fourth, measuring the speed profile of a jet fan’s discharge outlet. Fifth, visualizating the spread of smoke that was blown by a jet fan. Results from this study indicate that the fan rotational speed affects flow, flow momentum, and the smoke’s width blown by the jet fan.With these results, it is known this jet fan model can be applied to a basement fire experiments as a further experiment."

"[ABSTRAKMaterial Bake Hardening merupakan material yang memiliki sifat mudah dideformasi sebelum diberi perlakuan panas dan sulit dideformasi setelah diberi perlakuan panas. Material ini merupakan material baru yang digunakan pada industri otomotif untuk digunakan pada kerangka mobil dan badan mobil. Material ini akan disambungkan menggunakan mesin Resistance Spot Welding. Resistance Spot Welding merupakan salah satu jenis pengelasan yang banyak digunakan di industri otomotif. Penelitian ini bertujuan untuk mengetahui pengaruh dari parameter kuat arus dari mesin resistance spot welding pada material bake hardening. Penyambungan material bake hardening ini dilakukan dengan menggunakan mesin resistance spot welding dengan pemberian kuat arus 8kA, 9kA, 10kA, 11kA dan 12kA. Pengujian yang dilakukan antara lain pengujian kekerasan, geser, pengamatan SEM, dan metalografi. Hasil penelitian menunjukkan bahwa kekuatan optimum yaitu 5,68kN dan kekerasan optimum yaitu 237,34 VHN didapat pada sampel yang diberi kuat arus sebesar 11kA. Pemberian kuat arus diatas 11kA akan menyebabkan penurunan pada kekuatan dan kekerasan. Pola penjejakan kekerasan menunjukkan bahwa daerah nugget memiliki kekerasan yang lebih tinggi dibandingkan base metal. Struktur mikro juga menunjukkan bahwa semakin ke daerah nugget, butir semakin membesar dan fasa bainite bertambah banyak.

---

ABSTRACT

Bake Hardening material is a material that is easily deformed before being given a heat treatment and become a hard deformed after being heat-treated. This material is a new material used in the automotive industry for car frame and car body. This material will be welded using Resistance Spot Welding machine. Resistance Spot Welding is one type of welding that is widely used in the automotive industry. This study aims to determine the effect of the current welding parameters of resistance spot welding to bake hardening material. The joining of bake hardening material is performed using resistance spot welding machine with current 8kA, 9kA, 10kA, 11kA and 12kA. Tests performed include hardness testing, shear, SEM and metallography. The results showed that the optimum tensile strength is 5,68kN and optimum Vickers hardness is 237.34 VHN samples were obtained at a current of 11kA. Giving current 11kA above will cause a decrease in tensile strength and Vickers hardness. Hardness distribution of Vickers hardness shows that nugget area has a higher hardness than the base metal. Microstructure also shows that the area to the nugget, grain growing and increasing bainite phase.;Bake Hardening material is a material that is easily deformed before being given a heat treatment and become a hard deformed after being heat-treated. This material is a new material used in the automotive industry for car frame and car body. This material will be welded using Resistance Spot Welding machine. Resistance Spot Welding is one type of welding that is widely used in the automotive industry. This study aims to determine the effect of the current welding parameters of resistance spot welding to bake hardening material. The joining of bake hardening material is performed using resistance spot welding machine with current 8kA, 9kA, 10kA, 11kA and 12kA. Tests performed include hardness testing, shear, SEM and metallography. The results showed that the optimum tensile strength is 5,68kN and optimum Vickers hardness is 237.34 VHN samples were obtained at a current of 11kA. Giving current 11kA above will cause a decrease in tensile strength and Vickers hardness. Hardness distribution of Vickers hardness shows that nugget area has a higher hardness than the base metal. Microstructure also shows that the area to the nugget, grain growing and increasing bainite phase., Bake Hardening material is a material that is easily deformed before being given a heat treatment and become a hard deformed after being heat-treated. This material is a new material used in the automotive industry for car frame and car body. This material will be welded using Resistance Spot Welding machine. Resistance Spot Welding is one type of welding that is widely used in the automotive industry. This study aims to determine the effect of the current welding parameters of resistance spot welding to bake hardening material. The joining of bake hardening material is performed using resistance spot welding machine with current 8kA, 9kA, 10kA, 11kA and 12kA. Tests performed include hardness testing, shear, SEM and metallography. The results showed that the optimum tensile strength is 5,68kN and optimum Vickers hardness is 237.34 VHN samples were obtained at a current of 11kA. Giving current 11kA above will cause a decrease in tensile strength and Vickers hardness. Hardness distribution of Vickers hardness shows that nugget area has a higher hardness than the base metal. Microstructure also shows that the area to the nugget, grain growing and increasing bainite phase.]"

"[ ABSTRAK Bitumen merupakan bahan penyusun aspal serta memiliki fungsi sebagai binder pada aspal. Sifat dari bitumen mempengaruhi kinerja dari aspal. Aspal merupakan material yang biasanya digunakan untuk infrastruktur seperti aplikasi pada jalanan. Aspal merupakan material yang relatif murah namun aspal memiliki beberapa kelemahan karena sifat material penyusunya dan kondisi lingkungan sehingga dibutuhkan langkah untuk menangani kelemahan pada aspal tersebut. Salah satu metode yang dapat dilakukan untuk menangani masalah tersebut adalah melakukan pencampuran bitumen (bahan pengikat pada aspal) dengan limbah plastik kresek (high density polyehtylene atau polypropylene) untuk membentuk suatu komposit Polymer Modified Bitumen (PMB) sehingga perfoma dari aspal dapat meningkat dan membuat limbah plastik lebih berguna kembali. Percobaan ini mengunakan 2 buah jenis plastik kresek dan 3 buah variabel berbeda yaitu konsentrasi plastik kresek, waktu, dan temperatur pencampuran. Plastik kresek yang digunakan adalah HDPE dan PP. Konsentrasi High Density Polyethyelene (HDPE) yang digunakan adalah 4%, 5%, dan 6%, konsentrasi Polypropylene (PP) yang digunakan adalah 3%, 4%, dan 5%, waktu pencampuran yang digunakan adalah 15, 30, dan 45 menit, dan juga temperatur pencampuran yang digunakan adalah 140oC sampai dengan 200oC. Metode pencampuran basah digunakan untuk mencampurkan kedua material tersebut. Hasil atau kualitas komposit diketahui dengan melakukan investigasi melalui pengujian penetrasi, daktilitas, titik lembek, Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR), Thermo Gravimetric Analyzer (TGA), dan Differential Scaning Calorimetry (DSC). Hasil penelitian mengenai PMB menyimpulkan bahwa kompatibiltas antara plastik kresek baik HDPE dan PP kurang baik terhadap bitumen namun penambahaan plastik kresek terhadap bitumen meningkatkan sifat mekanik dan kestabilan termal bitumen.

---

ABSTRACT Bitumen is a binder and one of constituents of asphalt so the characteristic of bitumen affects asphalt perfomance. Asphalt is a material that usually used in road application. However, there are also drawbacks of asphalt as material on pathway because of its constituents and environment condition. For the examples, asphalt is brittle in low temperature and will be soften when temperature increase so the action is needed to address this problems. One solution to solve these problems by adding wasted plastic bags made by High Density Polyethylene (HDPE) or Polypropylene (PP) to bitumen so it can increase asphalt efficiency and make wasted plastic bag more useful. This experiment used two type of plastic bags and three variables (concentration of plastic bags, mixing time, and mixing temperature). HDPE concentrations used were 4%, 5%, and 6%, PP concentrations used were 3%, 4%, and 5%, mixing times used were 15, 30, and 45 minutes, and also mixing temperatures were 140oC up to 200oC. Hot melt mixing method was used to mix those material. The quality of mixing material (composite) was tested by some instruments like ductility tester, softening point tester, penetration testing, Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR), Thermo Gravimetric Analyzer (TGA) and Differential Scaning Calorimetry (DSC). The result is compatibilty of HDPE or PP to bitumen is not that enough, however, modification of bitumen by plastic bags increases mechanical properties and thermal resistance of bitumen.;Bitumen is a binder and one of constituents of asphalt so the characteristic of bitumen affects asphalt perfomance. Asphalt is a material that usually used in road application. However, there are also drawbacks of asphalt as material on pathway because of its constituents and environment condition. For the examples, asphalt is brittle in low temperature and will be soften when temperature increase so the action is needed to address this problems. One solution to solve these problems by adding wasted plastic bags made by High Density Polyethylene (HDPE) or Polypropylene (PP) to bitumen so it can increase asphalt efficiency and make wasted plastic bag more useful. This experiment used two type of plastic bags and three variables (concentration of plastic bags, mixing time, and mixing temperature). HDPE concentrations used were 4%, 5%, and 6%, PP concentrations used were 3%, 4%, and 5%, mixing times used were 15, 30, and 45 minutes, and also mixing temperatures were 140oC up to 200oC. Hot melt mixing method was used to mix those material. The quality of mixing material (composite) was tested by some instruments like ductility tester, softening point tester, penetration testing, Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR), Thermo Gravimetric Analyzer (TGA) and Differential Scaning Calorimetry (DSC). The result is compatibilty of HDPE or PP to bitumen is not that enough, however, modification of bitumen by plastic bags increases mechanical properties and thermal resistance of bitumen.;Bitumen is a binder and one of constituents of asphalt so the characteristic of bitumen affects asphalt perfomance. Asphalt is a material that usually used in road application. However, there are also drawbacks of asphalt as material on pathway because of its constituents and environment condition. For the examples, asphalt is brittle in low temperature and will be soften when temperature increase so the action is needed to address this problems. One solution to solve these problems by adding wasted plastic bags made by High Density Polyethylene (HDPE) or Polypropylene (PP) to bitumen so it can increase asphalt efficiency and make wasted plastic bag more useful. This experiment used two type of plastic bags and three variables (concentration of plastic bags, mixing time, and mixing temperature). HDPE concentrations used were 4%, 5%, and 6%, PP concentrations used were 3%, 4%, and 5%, mixing times used were 15, 30, and 45 minutes, and also mixing temperatures were 140oC up to 200oC. Hot melt mixing method was used to mix those material. The quality of mixing material (composite) was tested by some instruments like ductility tester, softening point tester, penetration testing, Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR), Thermo Gravimetric Analyzer (TGA) and Differential Scaning Calorimetry (DSC). The result is compatibilty of HDPE or PP to bitumen is not that enough, however, modification of bitumen by plastic bags increases mechanical properties and thermal resistance of bitumen.;Bitumen is a binder and one of constituents of asphalt so the characteristic of bitumen affects asphalt perfomance. Asphalt is a material that usually used in road application. However, there are also drawbacks of asphalt as material on pathway because of its constituents and environment condition. For the examples, asphalt is brittle in low temperature and will be soften when temperature increase so the action is needed to address this problems. One solution to solve these problems by adding wasted plastic bags made by High Density Polyethylene (HDPE) or Polypropylene (PP) to bitumen so it can increase asphalt efficiency and make wasted plastic bag more useful. This experiment used two type of plastic bags and three variables (concentration of plastic bags, mixing time, and mixing temperature). HDPE concentrations used were 4%, 5%, and 6%, PP concentrations used were 3%, 4%, and 5%, mixing times used were 15, 30, and 45 minutes, and also mixing temperatures were 140oC up to 200oC. Hot melt mixing method was used to mix those material. The quality of mixing material (composite) was tested by some instruments like ductility tester, softening point tester, penetration testing, Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR), Thermo Gravimetric Analyzer (TGA) and Differential Scaning Calorimetry (DSC). The result is compatibilty of HDPE or PP to bitumen is not that enough, however, modification of bitumen by plastic bags increases mechanical properties and thermal resistance of bitumen., Bitumen is a binder and one of constituents of asphalt so the characteristic of bitumen affects asphalt perfomance. Asphalt is a material that usually used in road application. However, there are also drawbacks of asphalt as material on pathway because of its constituents and environment condition. For the examples, asphalt is brittle in low temperature and will be soften when temperature increase so the action is needed to address this problems. One solution to solve these problems by adding wasted plastic bags made by High Density Polyethylene (HDPE) or Polypropylene (PP) to bitumen so it can increase asphalt efficiency and make wasted plastic bag more useful. This experiment used two type of plastic bags and three variables (concentration of plastic bags, mixing time, and mixing temperature). HDPE concentrations used were 4%, 5%, and 6%, PP concentrations used were 3%, 4%, and 5%, mixing times used were 15, 30, and 45 minutes, and also mixing temperatures were 140oC up to 200oC. Hot melt mixing method was used to mix those material. The quality of mixing material (composite) was tested by some instruments like ductility tester, softening point tester, penetration testing, Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR), Thermo Gravimetric Analyzer (TGA) and Differential Scaning Calorimetry (DSC). The result is compatibilty of HDPE or PP to bitumen is not that enough, however, modification of bitumen by plastic bags increases mechanical properties and thermal resistance of bitumen.]"