ANALISIS EFISIENSI DAN PENURUNAN TEKANAN PADA SIKLON PERSEGI MENGGUNAKAN CFD

Artikel ini memaparkan hasil penelitian yang diperoleh melalui aplikasi komputasi dinamika fluida (Computational Fluida Dynamic,CFD) untuk mensimulasi medan alir di dalam siklon persegi. Perangkat lunak Gambit digunakan sebagai pre-processor untuk menggambar konfigurasi, diskritisasi, dan pendefinisian kondisi batas siklon. Geometri siklon silinder Lapple dan persegi ditinjau dari volume yang sama. Diameter siklon yang digunakan 0,2 m menyesuaikan dengan diameter siklon silinder Lapple yang digunakan Wang pada eksperimennya, dengan kondisi operasi  ditentukan pada laju alir gas sebesar 0,1m3/s sementara beban partikel dalam  laju alir gas sebesar 0,01kg/m3. Perangkat lunak CFD FLUENT 6.2.16 digunakan untuk simulasi medan alir dan dinamika partikel dalam siklon. Penelitian ini bertujuan untuk mengetahui pengaruh geometri siklon persegi terhadap medan alir, efisiensi dan penurunan tekanan. Prediksi yang dihasilkan memberikan informasi mengenai medan alir berupa kecepatan axial dan tangensial di dalam siklon serta informasi efisiensi dan penurunan tekanan. Hasil kajian menunjukkan bahwa kecepatan tangensial mendominasi medan alir di luar garis tengah siklon, sementara kecepatan aksial mendominasi medan alir di daerah garis tengah siklon. Penurunan tekanan yang terjadi pada siklon persegi lebih tinggi dari siklon silinder, namun efisiensi untuk siklon persegi lebih tinggi dibandingkan siklon Lapple

PEMANFAATAN KERTAS HVS BEKAS SEBAGAI ADSORBEN UNTUK MENURUNKAN KADAR TIMBAL (Pb) DALAM LIMBAH ARTIFISIAL

Salah satu pencemar yang berbahaya dalam limbah buangan industri yaitu logam berat timbal (Pb). Adsorpsi sering digunakan karena prosesnya yang sederhana dan efektif untuk mengurangi kadar logam berat. Penelitian ini bertujuan untuk menganalisis efektifitas kertas HVS sebagai adsorben, menganalisis pengaruh waktu kontak dan massa adsorben terhadap kapasitas adsorpsi dan %removal serta mekanisme penyerapan melalui pendekatan isotermis adsorpsi Langmuir dan isotermis adsorpsi Freundlich.  Penelitian ini dilakukan dalam tiga tahap yaitu pembuatan adsorben, pembuatan limbah artifisial, dan proses adsorpsi dengan variasi massa adsorben dan waktu kontak. Hasil yang diperoleh menunjukkan bahwa % removal maksimum yaitu 95,41% pada massa adsorben 1 gr dan kapasitas adsorpsi maksimum yaitu 18.123,4 mg/g pada massa adsorben 0,05 gr, konsetrasi limbah 20 ppm dengan waktu kontak 120 menit. Mekanisme adsorpsi yang terjadi mendekati persamaan isotherm Freundlich dengan nilai R2 = 0,8746, diduga proses penyerapan terjadi secara multilayer. Semakin lama waktu kontak dan semakin banyak massa adsorben dalam konsentrasi limbah yang sama maka semakin rendah kapasitas adsorpsi dan semakin tinggi %removal Pb yang diperoleh

Modification of Recycled HDPE Composite with OPEFB Microfibers Through the Melt Blend Extruder Process

Oil palm empty fruit bunches (OPEFB), have not many been used as a have economic value material. OPEFB fiber content can be using as a filler to composites fabrication. The fiber contained in the OPEFB can be increase composites quality because have high thermal and mechanical properties. SEM analysis shows that OPEFB waste with a size of 63 and 90 ?m is suitable to be use as a filler because of the compatibility of the fiber and matrix matrix. As with the results of the DSC analysis, the melting point of HDPE-TKKS composite with 63 ?m fiber size reaches 133.58 0C while the melting point of HDPE-TKKS composite with 90 ?m fiber size reaches 134.41 0C. The FTIR test results also show that the indications of the two samples have the same chemical composition, namely lignicellulose. The best tensile strength is obtained which is equal to 21.11 MPa and the force required to break the composite is 391.56 N, these results were obtained from composites with a ratio of 60: 40 (matrix : filler) and 90 µm fiber size.Key words: Plastic, HDPE, fiber, OPEFB, composite

KAJIAN PENGARUH ANGIN SILANG TERHADAP KARAKTERISTIK NYALA HIDROKARBON

Artikel ini memaparkan hasil yang diperoleh dari kajian dinamika fluida komputasi (DFK) untuk mensimulasi nyala turbulen tak pra-campur akibat pengaruh angin silang. Konfigurasi, diskretisasi dan kondisi batas nyala digambarkan menggunakan perangkat lunak pra-prosessor Gambit.  Pengaruh angin silang terhadap nyala hidrokarbon (nyala dengan pengaruh angin silang) dilakukan pada kondisi kecepatan bahan bakar tetap 20 m/s dengan kecepatan angin berubah-rubah dan pada kondisi kecepatan angin silang tetap 1,1 m/s dengan kecepatan bahan bakar berubah - ubah . Hasil penelitian dengan kondisi bahan bakar tetap menunjukkan bahwa peningkatan kecepatan angin silang memberikan pengaruh yang signifikan terhadap medan alir dan temperatur. Pada kajian dengan kondisi bahan bakar berubah - ubah ketika kecepatan angin silang tetap, terlihat bahwa peningkatan kecepatan bahan bakar memberikan dampak positif pada nyala, karena nyala semakin mampu melawan pengaruh angin silang terhadap nyala

LAPORAN INDIVIDU PRAKTIK PENGALAMAN LAPANGAN (PPL) SMK NEGERI 3 MAGELANG

Praktik Pengalaman Lapangan (PPL) Universitas Negeri Yogyakarta semester khusus 2014 yang berlokasi di SMK Negeri 3 Magelang telah dilaksanakan oleh mahasiswa pada tanggal 15 Juli 2014 sampai 15 September 2014. Kelompok PPL di lokasi ini terdiri dari 12 mahasiswa dari program pendidikan teknik boga, pendidikan teknik busana. Praktikan Melaksanakan Kegiatan Belajar Mengajar dimulai pada tanggal 21 Juli 2016. Selama kegiatan PPL, praktikan melakukan praktik mengajar mandiri dan terbimbing di 2 kelas, yaitu kelas X JB 3, XII JB 3 untuk mata pelajaran Boga Dasar membuat Rencana Pelaksanaan Pembelajaran Sebanyak 5 Kompetensi Dasar, untuk Pengolahan Makanan Indonesia membuat rencana pelaksanaan pembelajaraan sebanyak 3 Kompetensi Dasar. Praktikan melaksanakan kegiatan mengajar sebanyak lebih dari 6 kali dengan intensitas pertemuan 1 minggu 2. Secara umum, program- program yang telahdirencanakan dapat berjalan dengan baik dan lancar. Praktikan telah berusaha untuk menekan semua hambatan yang terjadi selama melaksanakan program kerja, sehingga program tersebut akhirnya berhasil dilaksanakan. Munculnya hambatan selama pelaksanaan kegiatan merupakan hal yang wajar. Praktikan berharap, semoga laporan ini dapat bermanfaat bagi semua pihak yang terkait

Comparative performance study of two simple soot models for the prediction of soot level in atmospheric turbulent non-premixed flames

The increase of current fossil fuel consumption has led to an increase of soot emission into atmosphere.  Accurate prediction of soot production and destruction in a combustion system is not only important for the purpose of the design of the system, but also vital for the operation of the combustor. Numerous soot models have been proposed to predict the soot production and destruction in a flame, categorized as empirical, semi-empirical and detailed soot models.  Although the detailed model represents the highest level of soot modelling, its use has been impaired by substantial requirement of resources of computer and time. Therefore, empirical and semi-empirical approaches still have their position in soot modelling of practical combustors. In this study, two soot models, single-step and two-step models are examined in the simulation of atmospheric turbulent non-premixed sooting flames. The soot models are compared and evaluated for their performance in predicting soot level in methane and ethylene non-premixed flames.  The commercial software Fluent 6.3 was used to perform the calculations of flow and mixing fields, combustion and soot. Standard k-ε and eddy dissipation models were selected as solvers for the representation of the turbulence and combustion, respectively.  The two soot models used in the study are available directly from the code for evaluation. The results show that the two-step model clearly performed far better than the single-step model in predicting the soot level in both methane and ethylene non-premixed flames. With a slight modification in the constant a of the soot formation equation, the two-step model was capable of producing prediction of soot level closer to experimental data.  In contrast, the single-soot model produced very poor results, leading to a significant under-prediction of soot levels in both flames

CFD analysis of efficiency and pressure drop in a gas-solid square cyclones separator

In this paper, two small cyclones with the same hydraulic diameter and volume, which one is square and the other one is round (Lapple cyclone), are numerically compared. A pre-processor software GAMBIT was employed to set up the configuration, discretisation, and boundary conditions of the cyclone. The characteristics of the cyclone being studied was 0.2 m in diameter, receiving a gas flow rate of 0.1 m3/s with a particle mass loading of 0.01 kg/s. A commercial CFD code FLUENT 6.2.16 was employed to simulate the flow field and particle dynamics in the cyclone. The Reynolds averaged Navier–Stokes equations with Reynolds Stress Turbulence Model (RSTM) are solved by use of the finite volume method based on the SIMPLE pressure correction algorithm in the computational domain. The Eulerian–Lagrangian computational procedure is used to predict particles tracking in the cyclones. The velocity fluctuations are simulated using the Discrete Random Walk (DRW).The results show that collection efficiency of square cyclone is the better with increasing flow rate than round cyclone. The pressure drop in square cyclone is higher than the pressure drop in small round one

Simulation of the crosswind and the steam addition effect on the flare flame

This paper presents the results obtained from the application of computational fluid dynamics (CFD) to modelling the crosswind and steam addition effect on a turbulent non-premixed flame. A pre-processor software GAMBIT was employed to set up the configuration, discretisation, and boundary conditions of the flame being investigated.  The commercial software Fluent 6.3 was used to perform the calculations of flow and mixing fields as well as combustion. Standard k-ε and eddy dissipation models were selected as solvers for the representation of the turbulence and combustion, respectively.  The results of all calculations are presented in the forms of contour profiles.  During the investigation, the treatment was performed by setting a  velocity of fuel at 20 m/s with varied cross-wind velocity at  3.77 m/s, 7.5 m/s and 10 m/s,  and steam/fuel ratio at 0.14, 0.25 and 2.35.  The results of the investigation showed that the standard k-ε turbulence model in conjunction with Eddy Dissipation Model representing the combustion was capable of producing reliable phenomena of the flow field and reactive scalars field in the turbulent non-premixed flame being investigated. Other results of the investigation showed that increasing the velocity of the crosswind, when the fuel velocity was kept constant, significantly affected the flow field, temperature and species concentrations in the flare flame. On the other hand, when the velocity of the fuel was varied at the constant crosswind velocity, the increasing velocity of the fuel gave positive impact as it enabled to counteract the effect of crosswind on the flare flame. The velocity of the crosswind very influence of combustion efficiency, from result of the investigation showed that increasing the velocity of the crosswind significantly affected the combustion efficiency, other result of the inverstigation showed that steam addition will very influencing combustion, excelsior the steam/fuel ratio results the combustion efficiency decreas

Performance Comparison of Turbulence Models for Predicting Axial and Tangential Velocities in a Cyclone Separator

This paper presents the results obtained from the application of a computational fluid dynamics (C F D) calculation to predicting the flow field, particularly axial and tangential velocities, of a cyclone separator. A pre-processor software GAMBIT was employed to set up the configuration, discretisation, and boundary conditions of the cyclone. The characteristics of the cyclone being studied was 0.2 m in diameter, receiving a gas flow rate of 0.1 m3/s with a particle mass loading of 0.01 kg/m3. A commercial CFD code FLUENT 6.2.16 was employed to simulate the flow field and particle dynamics in the cyclone. The objective of this research was to investigate the performance of several turbulence models towards the prediction of axial and tangential velocities in the cyclone. A number of five turbulence models under Reynolds Averaged Navier Stokes (RANS) category, including Spallart- Allmaras, standard k---model, and Reynolds Stress Model (RSM) were examined in the simulation. The validation of all calculation was performed by comparing the predicted results in terms of axial and tangential velocities, against experimental data of a Lapple cyclone taken from literature. Predictions of axial and tangential velocities at for each turbulence model were performed at three positions in the cyclone, i.e.: 1.5 D, 2.0 D and 3.25 D. Results of the simulation shows that the tangential velocity governs the flow field outside of the centre-line of the cyclone, forcing the particle towards to the wall and causing the particles to fall towards to the cones region for collection. On the other hand, the axial velocity dominates the flow field in the centre line of the cyclone, especially closer to the outlet pipe! Among five turbulence models being tested in this study, it was observed that the RSM is the most suitable one to represent the flow field and particle dynamics inside the cyclone separator