Papers by Steven Darmawan
Jurnal Asiimetrik: Jurnal Ilmiah Rekayasa & Inovasi
The cross-flow turbine is one of widely used impulse turbine in power generator system due to it’... more The cross-flow turbine is one of widely used impulse turbine in power generator system due to it’s simple design and ability to be applied to a wide range of head and flow conditions. The flow in a cross-flow turbine flows in a crossed manner and works in 2 stages which could affect the turbine’s performance. Hence the visualization of these flow behavior could indicate the performance. Complexity of the flow inside the runner require the usage of CFD Method to visualize the flow, leaving the gap since numerical model also rely on turbulence model. The purpose of this study is to analyze the flow pattern in the nozzle and runner on a cross-flow turbine using the RNG k-ε turbulence model in ANSYS 2021 R2 Academic Version software. The simulation was carried out with 5 variations of nozzle inlet velocity: 2 m/s, 3 m/s, 4 m/s, 5 m/s and 6.487 m/s. The working fluid is assumed to be 1 phased water, with nozzle inlet pressure of 1.05 Pa, temperature of 24.85 oC and RNG k- ε turbulence mo...
Universitas Indonesia, 2012
POROS, 2021
The problem of fossil fuel crisis, both petroleum and coal, and the phenomenon of climatechange d... more The problem of fossil fuel crisis, both petroleum and coal, and the phenomenon of climatechange due to global warming, trigger the use of renewable energy that can overcome these problems.Cross-flow water turbine is one of the machine that can be used to produce small scale electric energy insmall scope. This turbine can be used in urban areas to assist industrial activities and their usefulness indaily life. The use of the right materials and strong construction can produce a good shape so that thiswater turbine is not only make efficient energy but also efficient and ergonomic in its use. This study isconducted theoretically to a cross-flow turbine which assumed to operate at 10m water height with 1.4L/s, outer diameter 150mm and 75mm thickness. The turbine consist of 15 blades with angle of attack ofthe blades is 30o. The results show that the turbine generate 119 Watt
International Journal of Heat and Technology, 2021
Heat exchanger is usually used in manufacturing process. At present, many researchers have effort... more Heat exchanger is usually used in manufacturing process. At present, many researchers have efforts to increase the performance of the heat exchanger with less of the cost. This research discussed about the performance of heat exchanger using 40% cut segmental baffles compared with modified double segmental baffles disc-and-doughnut type. In this study, the investigation of the computational results consisted of heat flux, velocity profile along the heat exchanger, pressure distribution and, theoretical heat transfer coefficient and heat exchanger effectiveness. The model was calculated using finite difference method forward modeling with Multiphysics Software and focuses on the performance evaluation of the small shell-and-tube heat exchanger (STHE) – laboratory type. The tubes are composed of 14 tubes with 0.583 m length, triangular 30° rotated pitch. The pipe radius of shell and tube are 0.055 m and 0.00635 m, respectively. The baffle radius of disc and doughnut are 0.055 m and 0....
IOP Conference Series: Materials Science and Engineering, 2020
Tool life is an important thing to consider in the process of metal cutting. Before the machining... more Tool life is an important thing to consider in the process of metal cutting. Before the machining process is done, it is necessary to know how long a cutting tool is capable of cutting before wear occurs. However, it is difficult to predict the life of the cutting tool, because each cutting tool has different characteristics in cutting metal. The research was conducted aimed at predicting the life of cutting tool using the Taylor equation, but the n and C constants contained in the equation vary for each type of cutting tool used in cutting workpieces. Through the experiment of cutting metal using a lathe, the cutting tool was observed and measured for wear, so that there was a limit to the value of the wear edge of the VB tool by 0.4 mm. The three cutting speed variants used in the cast iron machining are 180, 210 and 249 m / min. Observations were made every 10 minutes machining was stopped to be measured using a Digital Microscope if the wear value of the cutting tool has not bee...
POROS, 2017
Abstrak: Salah satu penyebab kerusakan lapisan ozon adalah zat pendingin. Kandungan zat pendingin... more Abstrak: Salah satu penyebab kerusakan lapisan ozon adalah zat pendingin. Kandungan zat pendingin akan terurai setelah dicampur dengan sinar ultraviolet. Itu juga molekul refrigeran yang tepat yang melepaskan atom klorin. Klorin yang dikeluarkan akan menghancurkan lapisan ozon dan tingkat sinar ultraviolet yang masuk ke bumi yang lebih tinggi. Tapi tidak semua jenis zat pendingin mengandung klorin. Jenis zat pendingin yang biasa digunakan pada pendingin mesin adalah R22. Refrigeran mengandung unsur klorin sehingga perlu memeriksa penggantian refrigeran R22. Jenis zat pendingin yang memiliki kesamaan namun tidak mengandung unsur klorin adalah zat pendingin R407c. Penelitian dilakukan dengan mengambil beberapa data dari kedua jenis refrigerant tersebut. Tujuan dari penelitian ini adalah untuk menghitung laju kondensor perpindahan panas, kompresor pendingin, kapasitas daya dan koefisien kinerja setiap refrigeran. Penelitian dimulai dengan belajar tentang siklus kompresi uap, komponen u...
POROS, 2017
The study was executed to get a quick calculation method for the design of equipment heat exchang... more The study was executed to get a quick calculation method for the design of equipment heat exchanger type shell and tube with a program shell and tube heat exchanger design. The purpose of this study was to obtain the results of the validation program shell and tube heat exchanger design of a condenser with power 4368.75 kW and the results of the evaluation program shell and tube heat exchanger design on the thermal design condensers nuclear power plant AP1000 PWR type. Input data into the program is done by inserting the parameters temperature, flow rate, physical properties and geometrical dimensions of the available designs of heat exchanger equipment specifications. Parameter for comparison of data can be obtained from the results of other calculations or experimental data. The results of comparison of the validation program shell and tube heat exchanger with condenser design calculations showed the highest difference found on U tube parameter equal to 1.3% lower than the design condition. This occurs because of differences in calculation between the program designed. The result evaluation of program shell and tube heat exchanger design toward the thermal design condensers nuclear power plant PWR type AP1000 obtained unknown parameters from the technical specifications.
IOP Conference Series: Materials Science and Engineering, 2020
Cross-flow turbine is one of prime mover type that is simple, capable to extract water power and ... more Cross-flow turbine is one of prime mover type that is simple, capable to extract water power and easy to be manufactured. The runner is working at 2 stages. The need of high momentum has lead researchers to design water nozzle, blades, as well as the set-up between nozzle and runner. High momentum water nozzle and cross-flow runner has been designed individually with the same design criteria. Unfortunately, experimental testing may not gain specific flow pattern inside the nozzle and the runner. The purpose of this study is to investigate the flow pattern inside the nozzle, runner using CFD method, Ansys 2019 R3 academic version. The CFD simulation done 3-dimensionally with 5 nozzle inlet velocity variations: 2 m/s, 3 m/s, 4 m/s, 5 m/s and 6,487 m/s. The fluid is assumed to be 1 phase, using mesh with 17.750 nodes, inlet fluid pressure 1,05 Pa, and temperature 24,85°C. The results showed that the lowest velocity and pressure for variation 1 at 1st stage (v1) = 6,65 m/s and (p1) = -1...
SINERGI, 2019
In the metal machining process, cutting speed and feed rate are cutting parameters that affect th... more In the metal machining process, cutting speed and feed rate are cutting parameters that affect the surface quality of the workpiece produced. The use of improper cutting parameters can cause the workpiece surface to be rough, and the cutting toolage to be shorter. This study was conducted to determine the effect of cutting parameters and the use of carbide tools on the surface roughness of metal steel workpieces. The research was carried out using the experimental method of AISI 4340 steel metal workpiece turning using cutting tool coated. Five variations of cutting speed used are: 140 m/min, 150 m/min, 160 m/min, 170 m/min, 180 m/min and three variations in feed rate: 0.25 mm/rev, 0.3 mm/rev, 0.35 mm/rev. After the turning process, the surface roughness of the workpiece is measured using a surface tester. From the results of the study, it was found that the surface roughness value was directly proportional to the feed rate and inversely proportional to the cutting speed. The smalle...
Jurnal Energi Dan Manufaktur, 2018
Sistem tata udara pada bidang perhotelan merupakan salah satu aspek penting untuk menunjang kenya... more Sistem tata udara pada bidang perhotelan merupakan salah satu aspek penting untuk menunjang kenyamanan, yang pada daerah pariwisata seperti Bali dengan iklim tropis dilakukan dengan aplikasi pendingin udara (AC). Aliran udara pada hotel bertingkat biasa dibuat terpusat dan dialirkan ke tempat tujuan dengan menggunakan ducting dengan penampang segi empat. Menyesuaikan dengan denah yang ada, seringkali terdapat bagian ducting yang harus dibuat bertingkat pada titik datum yang sama (zona ekspansi). Geometri bertingkat ini dapat menghasilkan kerugian aliran karena pada zona ekspansi tersebut timbul aliran berputar (aliran resirkulasi). Pemahaman terhadap aliran berputar dapat dilakukan dengan lebih mudah, menarik dan berbiaya rendah dengan menggunakan geometri Backward-facing step (BFS). Pada penelitian ini, dilakukan analisis numerik melalui simulasi CFD terhadap aliran resirkulasi pada sebuah geometri backward-facing step, dengan panjang total (L) = 4050 mm, step height (h) = 41 mm, u...
Karya Ilmiah Dosen Teknik Mesin, Jan 12, 2014
Karya Ilmiah Dosen Teknik Mesin, Aug 29, 2014
Shell and tube is one of the most applicable heat exchanger that widely used in many industries: ... more Shell and tube is one of the most applicable heat exchanger that widely used in many industries: petrochemical, power plant, oil and gas, etc. Shell and tube heat exchanger that worked as boiler and reboiler was prone to corrosion. One of the concerned factor is boiling process that may cause oxidation process on the tube surface. That corossion lead to the decrease on the perfomance of heat exchanger. The outer tube near the tubesheet of the CO2 Stripper Reboiler which is used at fertilizer industry often damaged by corrosion. At that location the tube is connected to the hot inlet (LTS Effluent) dan cold outlet (aMDEA Solution) fluid. This research analyzed the boiling corrosion using CFD Solidware. The model was simplified by using porous media 0,13 and heat generated 9600000kW. The results of simulation indicated that the corrosion area had highest temperature and the stagnant fluid. These could damage the oxide protective layer on the surface. The redesain of CO2 Stripper Reboiler is aimed to reduce the occurence of stagnant fluid and to lower the temperature without interfering with the cooling capacity by replacing the outlet near the tube sheet. The resulst showed that the temperature has decreased.
Skripsi S 1 Teknik Mesin, Sep 7, 2010
Pembakaran terjadi apabila bahan bakar bereaksi dengan oksigen. Kebutuhan udara (oksigen) pada mo... more Pembakaran terjadi apabila bahan bakar bereaksi dengan oksigen. Kebutuhan udara (oksigen) pada motor bakar yang mengacu pada nilai rasio udara-bahan bakar, AFR (Air-Fuel Ratio) stoikiometri belum dapat membuat proses pembakaran berjalan kurang baik. Penggunaan udara pembakaran sesuai dengan AFRstoich seringkali membuat pembakaran terjadi dalam keadaan kaya (rich mixture), yang berarti pembakaran kekurangan udara. Pembakaran kaya membuat kenaikan laju bahan bakar, turunnya efisiensi termal, hingga menyebabkan polusi udara. Kurangnya udara yang dibutuhkan dalam keadaan aktual seringkali terjadi karena proses pencampuran antara bahan bakar dan udara yang kurang sempurna. Oleh karena itu, perlu perlu diberikan adanya suplai udara tambahan yang dapat membuat proses pembakaran berlangsung dalam keadaan lebih miskin (lean combustion) . Udara tambahan ini disebut dengan excess air. Nilai excess air yang akan disuplai ke ruang bakar melalui intake manifold akan divariasikan sebesar 5%, 10%, 15%, 20%, 25%, dan 30% dari nilai AFRstoich. Laju alir pada masing-masing excess air dikendalikan melalui orifice yang dilengkapi pipa U yang berisi air. Penggunaan excess air pada variasi mampu memberikan hasil yang berbeda-beda pada parameter-parameter pengujian yang dilakukan pada motor bakar penyalaan busi empat langkah (motor Otto), yaitu torsi, daya, laju bahan bahan bakar spesifik, efisiensi termal, temperatur intake dan exhaust, serta pada emisi gas buang yang merupakan salah satu sumber polusi udara. Secara rata-rata, seluruh variasi excess air mampu memberikan hasil yang positif pada torsi dan laju bahan bakar, namun memberikan hasil yang bervariasi pada parameter-parameter lainnya. Adapun hasil pengujian terbaik dari excess air berada pada variasi excess air 15% dari AFR stoich, dimana dapat memberikan hasil rata-rata yang positif pada berbagai parameter pengujian bila dibandingkan dengan mesin dalam keadaan standar.
Karya Ilmiah Dosen Teknik Mesin, Oct 9, 2014
Pengaruh Secondary flow pada pipa keluar kompresor pada Turbin Gas Mikro Bioenergi Proto ... more Pengaruh Secondary flow pada pipa keluar kompresor pada Turbin Gas Mikro Bioenergi Proto X-2 dianalisis. Analisis numerik dilakukan dengan menggunakan dua model turbulen yang umum digunakan, yaitu model turbulen k-e STD dan model turbulen k-e RNG. Pada sistem perpipaan tersebut, secondary flow terjadi pada belokan pipa keluar kompresor, dengan diameter pipa pada belokan 85mm dan jari-jari 97,205mm terhadap pusat belokan. Secondary flowyang banayk terjadi pada berbagai sistem perpipaan dengan belokan, antara lain dapat dikarakterisasi oleh dua parameter utama, yaitu bilangan Reynolds dan bilangan Dean yang menunjukkan skala aliran yang terjadi. Terjadinyasecondary flow menyebabkan jatuh-tekan dan penurunan kecepatan aliran, sekaligus menghasilkan turbulensi, serta aliran berputar (swirl). Analisis numerik dilakukan dengan menggunakan metode CFD, dengan parameter utama bilangan Reynolds masuk pipa, yaitu Re=40900 dan Re=48100. Karena merupakan aliran yang fluktuatif, pemilihan model turbulen yang tepat mempengaruhi hasil analsisis. Hasil simulasi antara model turbulen k-e STD dan model turbulen k-e RNG pada distribusi kecepatan dianalisis dan dibandingkan untuk memperoleh model turbulen yang paling sesuai untuk digunakan. Diperoleh bahwa secara rata-rata model turbulen k-e RNG memberikan hasil yang lebih tinggi 10%-15% dibandingkan dengan model turbulen k- STD. Vorteks aliran yang dibentuk oleh model turbulen k-e RNG lebih rasional, yang disertai dengan jumlah vorteks yang lebih banyak dibandingkan dengan model turbulen k- STD. Pada model turbulen k-e RNG, instabilitas aliran berputar juga terlihat lebih jelas menuju ke arah sumbu-y. Dengan konsekuensi waktu komputasi yang lebih lama, model turbulen k-e RNG, yang merupakan pengembangan dari model turbulen k- STD mampu memberikan hasil yang lebih baik.
Karya Ilmiah Dosen Teknik Mesin, Oct 9, 2014
To meet increased energy demand, Micro Gas Turbine (MGT) has become an alternative power source f... more To meet increased energy demand, Micro Gas Turbine (MGT) has become an alternative power source for power less than 200kW. MGT has been projected as a prospective power and thermal source in technical, dimension, cost, and environmental aspects. Prototype design of Proto X-2 MGT has been developed with the use of radial turbocharger and planned to use biofuel. Compressor is a important component for combustion air supply. The radial compressor consist of 6 full and 6 spliter blades with inducer and exducer diameter respectively 47.4 mm and 74.9 mm. Blade relative angle and abslotue in inlet and outlet achieved from 3D scanning-reverse engineering-method. Compressor performance parameters; pressure ratio, Mach number, mass and volume flow rate has been found theoritically. CFD method used to understand the flow in meridional surface between full and splitter blade. CFD simulation varying the radius of splitter blade in 3 variant: standard radius 26.75mm, variation a 25.68mm, and b 27.82 mm, based on experimental data done with SolidWorks 2010 and CFDSOF® shows that the variant a radius decreased the blade speed of 0.37% on average compared to standard. The experiment done with varying the fuel mass flow rate. Meanwhile the b variant increased the blade speed of 0.04% on average. Verification of the blade speed between CFD simulation result with theoretical results for standard radius showed that the CFD results are 8.22% lower on average. This Proto X-2 Micro Gas Turbnie designed also planned to be used as a bioenergy power generator. With this concept, our green goal to apply this system to a Zero Energy Building concept based can be reached.
Karya Ilmiah Dosen Teknik Mesin, Oct 9, 2014
Turbin angin adalah sebuah alat yang mengubah energi kinetik angin menjadi energi yang ... more Turbin angin adalah sebuah alat yang mengubah energi kinetik angin menjadi energi yang berguna seperti listrik. Besar-nya energi yang dihasilkan tergantung dari angin dan profil blade menerima angin tersebut. Kecepatan angin merupakan faktor utama dalam sistem kerja turbin angin. Jenis NACA yang digunakan sangat mempengaruhi profil blade memberikan gaya tekanan pada lower surface dan upper surface. Tahap dari penelitian ini dimulai dengan menggunakan software Autodesk Inventor Professional 2013 Student Version Falcon Flow Simulation. Software membantu dalam proses simulasi airflow yang terjadi sehingga didapatkan koefisien drag (CD), drag force (FD), pressure (Pa), kecepatan relatif (W), kecepatan blade, dan kecepatan sudut ( ) dengan nilai maksimum pada kecepatan angin 2.7 m/s yaitu koefisien drag (CD) = 0.025, drag force (FD) = 0.0237 N, pressure (Pa) = 3.731 Pa, kecepatan relatif (W) = 2.701 m/s, kecepatan blade = 13.5 m/s, dan kecepatan sudut ( ) = 90.0456 rad/s.
POROS
Calibration is needed to ensure that the measuring instrument works according to existing standar... more Calibration is needed to ensure that the measuring instrument works according to existing standards. The ability to calibrate measuring instruments is very necessary in the engineering world, especially calibration of temperature measuring instruments due to the importance of measuring temperature in the field of mechanical engineering. The purpose of this practical work report is to operate the Armfield TH1-Temperature Measurement and Calibration tool properly, investigate the thermometric properties of various temperature measuring instruments, also determine the response received by the device to changes in temperature. In testing the thermometric properties, using PT100 REF as a reference for other temperature measuring instruments. Thermistor Reading is the most accurate because it has the smallest difference with the PT100 REF compared to other measuring instruments. Thermistor Reading produces an average temperature difference of 0.036°C compared to PT100 REF. In testing the ...
Evergreen
Existing ROV (Remotely Operated Vehicle) requires optimization in thrust and maneuverability to c... more Existing ROV (Remotely Operated Vehicle) requires optimization in thrust and maneuverability to compete in the next Robotic Event. Investigation to acquire optimum thrust by configuring its thruster is conducted. Variations of configurations consist of number of blades, propeller diameter, and application of kort nozzle. Furthermore, analysis is conducted using CFD (Computational Fluid Dynamics) approach with ANSYS CFX 2021 R1 for open water characteristics with Moving Reference Frame (MRF) method and SST k-ω for turbulent model. CFD results show that kort nozzle configuration is able to generate addition thrust by accelerating fluid flow through inner kort nozzle wall. The result denotes that thruster P3-2020 with kort nozzle obtains the optimum thrust in the amount of 0.0059 N which application of kort nozzle can increase the thrust by 2.253% and reduces turbulent flow distribution for 21.053%.
Jurnal Bakti Masyarakat Indonesia, 2021
AbstrakDesa Girilaya merupakan desa yang terletak di daerah Ciamis Jawa Barat. Berbagai sumber da... more AbstrakDesa Girilaya merupakan desa yang terletak di daerah Ciamis Jawa Barat. Berbagai sumber daya alam yangpotensial dimiliki oleh desa tersebut seperti tanaman ladang padi, jagung, sayuran dan singkong. Pada umumnya masyarakat menjual hasil pertanian tersebut kepasar dengan harga yang relatif murah. Berdasarkan hal tersebut maka perlu dilakukan innovasi terhadap tanaman tersebut agar memiliki nilai ekonomis yang tinggi. Salah satu tanaman yang banyak diperoleh didesa tersebut adalah singkong , olahan singkong menjadi kripik singkong memerlukan adanya penggunaan mesin perajah singkong agar dapat menghasilkan bentuk yang seragam dan dalam jumlah yang relative banyak. Program pengabdikan kepada masyarakat ini dilakukan penerapan dan pelatihan mesin perajangn singkong dan mesin sealer untuk pembungkus kemasan produk singkong goreng yang dihasilkan. Dengan menggunakan mesin perajang singkong ini, produksi dapat dihasilkan sebesar 10 kg/jam dengan bentuk yang seragam dan waktu proses...
EngRN: Metals & Alloys (Topic), 2019
Tool life is machining data which is related to machining process. The aim of this research is to... more Tool life is machining data which is related to machining process. The aim of this research is to determine the tool life, tool wear and Taylor’s tool life equation value of coated carbide insert when used in turning process of AISI 304 stainless steel. By completing this research, the tool life of coated carbide insert will be known and can be estimated when different cutting speed for given feeding speed and depth of cut are used. The experiment was done by using cutting speed which was varied whereas feed rate and depth of cut were fixed during the turning process until the tool wear value of each cutting speed reaches 0.3 mm (VB = 0.3 mm). Taylor’s tool life equation was obtained as VCTL 0.939=2968 and value of tool life of 29 minutes 10 seconds for low cutting speed and 15 minutes 36 seconds for high cutting speed.
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Papers by Steven Darmawan