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Analisa Performansi Kolektor Surya Pelat Datar dengan Media Penyimpan Panas Pasir untuk Pemanas Udara Astawa, Ketut; Gunawan Tista, Si Putu Gede; Saputra, I Wayan Hendra
TEKNIKA Vol 10, No 1 (2014): Juli
Publisher : Fakultas Teknik Universitas Sultan Ageng Tirtayasa

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Energi dari sinar matahari dapat dimanfaatkan menggunakan kolektor surya, dimana radiasipanas dari matahari dikumpulkan dan diubah menjadi energi termal. Untuk mendapatkan performakolektor yang tinggi dapat dilakukan dengan penambahan media penyimpan panas berupa padatan.Dalam padatan seperti pasir tentunya memiliki energi internal, jika suatu padatan menyerap panas makaenergi internal yang tersimpan dalam padatan meningkat yang diindikasikan oleh kenaikantemperaturnya. Jadi perubahan energi pada atom-atom dan elektron-bebas menentukan sifat-sifatthermal padatan. Penelitian menggunakan sistem solar energy sederhana bertujuan mendapatkan profiltransformasi energi cahaya dari matahari menjadi energi termal yang dapat diserap oleh bahan pasir.Metode yang digunakan dalam penelitian ini adalah dengan menempatkan pasir sebagai mediapenyimpan panas di luar pipa-pipa aliran udara pada sebuah kolektor surya pelat datar. Udara akandialirkan melalui pipa-pipa yang terpasang pada bagian bawah dari pelat penyerap dengan bantuansebuah Blower. Temperatur dan tekanan udara baik yang masuk atau keluar dari kolektor diukur untukmengetahui terjadinya perubahan besaran temperatur.Dengan penambahan media penyimpan panas akan mampu memanaskan fluida kerja sampaiintensitas yang rendah, sehingga ketika intensitas rendah temperatur udara keluar kolektor tetap tinggimaka energi berguna dan efisiensi yang dihasilkan juga akan meningkat

Pengaruh Penempatan Penghalang Berbentuk Segitiga di Depan Silinder dengan Variasi Kecepatan Aliran Udara terhadap Koefisien Drag Tista, Si Putu Gede Gunawan; Suriadi, I Gusti Agung Kade; Astawa, Putu Pageh
Rekayasa Mesin Vol 6, No 3 (2015)
Publisher : Jurusan Teknik Mesin, Fakultas Teknik, Universitas Brawijaya

One of the ways to preserve energy on the air plane is by decreasing the drag. Drag is closely related to the flow separation, the faster the separation, then the drag will increase more. Because of that, efforts were conducted to decrease drag is by manipulating a fluid flow field that is by installing triangle rod obstacle in front of the cylinder. The purpose of this research is to analyze the effect of installing triangle rod obstacle in front of the cylinder by various air flow velocity on the drag cofficient. In this research, the experiment was conducted in the wind tunnel, which consists of blower, pitot pipe, manometer, cylinder pipe, and triangle rod. The air flow velocity was varied from 6.25 m/s, 5.01 m/s, 4.09 m/s, 3.17 m/s, 2.24 m/s .The Reynold number based on cylinder (D = 42 mm) and air flow velocity is Re =18.100, 14.500, 11.800, 9.170, 6.480 .The distance triangle rod and cylinder is L = 70 mm or L/D=1.67.Pressure distribution is achieved by measuring the cylinder surface on 36 spots with interval of 100. The measured data was pressure of cylinder surface, static pressure, and airflow speed. The research results showed that the triangle rod could decrease the drag of cylinder. Coefficient drag for cylinder without triangle rod was 0,1276 while the less triangle rod was 0,01882 which takes place at speed 6,2479 m/s.

Pengaruh variasi lebar alur berbentuk segi empat pada permukaan silinder terhadap koefisien drag Si Putu Gede Gunawan Tista; Wayan Nata Septiadi; Kadek Papin Prayoga
Jurnal Energi Dan Manufaktur Vol 10 No 2 (2017): Oktober 2017
Publisher : Department of Mechanical Engineering, University of Udayana

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Abstrak Kemajuan ilmu pengetahuan dan teknologi khususnya tentang ilmu mekanika fluida telah berkembang pesat.Ilmu mekanika fluida telah banyak memberikan kontribusi terhadap aspek kehidupan manusia, sebagai contoh adalah aliran fluida melintasi suatu silinder. Dalam aplikasi engineering banyak ditemukan peralatan menggunakan silinder seperti cerobong asap, tiang penyangga jembatan dan sebagainya. Peralatan-peralatan ini mengalami hembusan udara setiap saat sehingga kekuatan konstruksinya mengalami penurunan, hal ini disebabkan adanya drag yang arahnya searah aliran. Upaya yang dilakukan untuk mengurangi drag adalah dengan memanipulasi medan aliran. Manipulasi medan aliran dilakukan dengan membuat alur berbentuk segi empat pada permukaan silinder. Tujuan dari penelitian ini adalah menganalisa pengaruh variasi lebar alur berbentuk segi empat pada permukaan silinder terhadap koefisien drag. Penelitian ini dilakukan pada wind tunnel yang terdiri dari blower, pipa pitot, inclined manometer, U manometer, timbangan digital, dan silinder. Benda uji berupa silinder berdiameter 60 mm dan panjang 420 mm diletakkan vertikal di dalam wind tunnel. Lebar alur pada permukaan silinder divariasikan yaitu 3 mm, 4 mm, dan 5 mm. Pengujian distribusi tekanan diperoleh dengan mengukur tekanan permukaan silinder pada 36 titik dengan interval 10o. Pengujian gaya drag dilakukan dengan menggunakan timbangan digital yang mencatat besarnya massa, untuk mendapatkan gaya drag dikalikan dengan gravitasi. Hasil penelitian menunjukkan terjadi penurunan koefisien drag pada silinder beralur dibandingkan tanpa alur. Nilai koefisien terendah terjadi pada lebar alur 4 mm besarnya CD = 0,3734. Besarnya penurunan drag adalah 22,3 % dibandingkan tanpa alur. Kata kunci: pengurangan drag, lebar alur, alur segi empat, silinder Abstract Advances in science and technology, especially on the science of fluid mechanics has been growing. Science of fluid mechanics has contributed a lot of aspects of human life, for example, fluid flow across a cylinder. In many engineering applications using cylindrical found equipment such as a chimney, a pillar of the bridge, and so on. The equipment is undergoing a puff of air at all times so that the strength of the construction has decreased, this is due to drag him in the direction of flow. Efforts are being made to reduce drag is by manipulating the flow field. Manipulation of the flow field is done by making rectangular-shaped grooves on the surface of the cylinder. The purpose of this study was to analyze the influence of variations in width rectangular-shaped grooves on the surface of the cylinder to the coefficient of drag. This research was conducted in wind tunnel consisting of a blower, pitot pipe, inclined manometer, U manometer, digital scales, and cylinders. The test object in the form of a cylinder diameter of 60 mm and a length of 420 mm is placed vertically in the wind tunnel. The width of the grooves on the surface of the cylinder varied which is 3 mm, 4 mm and 5 mm. The pressure distribution is obtained by measuring the surface pressure cylinders at 36 points with 10o intervals. Drag force testing done using digital scale that records the amount of mass, to get the drag force multiplied by gravity. The results showed a decline in the coefficient of drag on a grooved cylinder compared without grooves. Lowest coefficient values occurred in the magnitude of 4 mm groove width CD = 0.3734. The amount of reduction in drag is 22.3% compared without grooves. Keywords: drag reduction, the width of the groove, rectangular groove, cylindrical

Pengaruh variasi jarak antar ring berbentuk segi empat pada permukaan silinder terhadap koefisien drag Si Putu Gede Gunawan Tista; I Made Astika; Ainul Ghurri
Jurnal Energi Dan Manufaktur Vol 9 No 1 (2016): April 2016
Publisher : Department of Mechanical Engineering, University of Udayana

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Abstrak:Dalam aplikasi engineering banyak ditemukan peralatan yang menggunakan silinder seperti tiang penyangga jembatan,cerobong asap, tiang pancang pengeboran minyak lepas pantai dan sebagainya. Peralatan-peralatan tersebutmengalami hembusan udara setiap saat, yang menyebabkan kekuatan konstruksinya berkurang, akibat adanya drag.Tujuan dari penelitian ini adalah untuk mengetahui pengaruh variasi jarak antar ring berbentuk segi empat padapermukaan silinder terhadap koefisien drag. Penelitian ini dilakukan pada wind tunnel (lorong udara) yang terdiri dariblower (untuk menghembuskan udara), pipa pitot, U tube manometer, inclined manometer, neraca digital, silinderdengan ring segi empat. Pada penelitian ini, dilakukan dengan memvariasikan Jarak antar ring yaitu 30 mm, 40 mm, 50mm, 60 mm dan 70 mm. Silinder diletakkan vertikal dalam wind tunnel dengan diameter D = 60 mm. Gaya dragdiperoleh dengan menggunakan neraca digital yang mencatat besarnya massa, kemudian dikalikan dengan percepatangravitasi. Distribusi tekanan diperoleh dengan mengukur tekanan pada permukaan silinder menggunakan inclinedmanometer pada 36 titik dengan interval 10o. Hasil penelitian menunjukkan semakin besar jarak antar ring koefisiendrag semakin besar. Koefisien Drag terendah terjadi pada jarak antar ring L = 30 mm atau L/D = 0.50, besarnya CD =0,606352. Besarnya penurunan drag dibandingkan tanpa ring adalah 29,3 %.Kata kunci: Silinder, ring segi empat, jarak antar ring, koefisien dragAbstract:In many engineering applications there are many types of equipment that use cylinders, such as smoke chimney, bridgesupport column, etc. The equipment is undergoing drag due to the airflow that flows through it. The existence of the dragwill reduce its lifetime. One of the efforts to reduce drag is to create a rectangular ring on the surface of the cylinder. Thepurpose of this study was to determine the effect of variations in the distance between the ring of a rectangular ring onthe cylinder surface on the drag coefficient.This research was conducted in wind tunnel which consists of a blower (forblowing air), pitot pipe, U-tube manometer, inclined manometer, digital balance, cylinder with a rectangular ring. Theresearch was carried out by varying the distance between the ring i.e. 30 mm, 40 mm, 50 mm, 60 mm and 70 mm,respectively. The cylinder is placed in a vertical wind tunnel with a diameter D = 60 mm. The drag force is obtained byusing a digital balance that records the amount of mass, and then multiplied by the acceleration due to gravity. Thepressure distribution is obtained by measuring the pressure in the cylinder surface using inclined manometer on 36points with 10o intervals. The results showed that the greater the distance between the rings increased the dragcoefficient. The lowest drag coefficient was achieved at rhe distance between ring L = 30 mm or L/D = 0.50, with the CDvalue = 0.606352; that is equivalent to 29.3% drag reduction.Keywords: Cylinder, rectangular ring, space between ring, drag coefficient

Pengaruh Penempatan Penghalang Berbentuk Silinder Pada Posisi Vertikal Dengan Variasi Jarak Horisontal Di Depan Silinder Utama Terhadap Koefisien Drag Si Putu Gede Gunawan Tista
Jurnal Energi Dan Manufaktur Vol 4, No.2 Oktober 2010
Publisher : Department of Mechanical Engineering, University of Udayana

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One of the ways to reduce energy consumption on the air plane and the other bluff bodies are by decreasing the drag. Dragis closely related to the flow separation. The earlier separation, then the drag will increase more. Based of the fact the effortto decrease drag is conducted by manipulating the field of fluid flow. Stream manipulation was be done by installingcylindrical obstacle in front of main cylinder. The purpose of this research is to analyze the effect of placement cylindricalobstacle at vertical position in the various horizontal distance in front of main cylinder on drag coefficient . In thisresearch, the experiment was conducted in the wind tunnel, which consisted of blower, pitot pipe, manometer, cylinder pipe,and cylinder rod. The cylindrical obstacle was positioned at vertical (y=14 mm) in the various horizontal distanceL/D = 1.41, L/D = 1.56, L/D = 1.72, L/D = 1.88, L/D = 2.03, L/D = 2.19, and L/D = 2.81 by upstream from the maincylinder. Diameter cylinder obstacle was 8 mm.. The Reynolds number based on the main cylinder diameter (D = 42 mm)was Re = 3.42 x 104. The research results showed that the cylinder rod could decrease the drag coefficient of main cylinder.Drag coefficient for cylinder without cylinder rod was 0.167 while the biggest decrease of coefficient of drag with cylindricalobstacle was happened at L/D = 1.72 which was 0,0593. It means that the drag coefficient of main cylinder with cylindricalobstacle was 64.5% lower than the cylinder alone.

Pengaruh Variasi Diameter O-ring pada Permukaan Silinder terhadap Koefisien Drag Si Putu Gede Gunawan Tista; Ainul Ghurri; I Ketut Suanjaya Adi Putra
Mesin Vol. 25 No. 2 (2016)
Publisher : Mesin

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Dalam aplikasi engineering banyak ditemukan peralatan yang menggunakan silinder, seperti tiang penyangga jembatan, cerobong asap, dan sebagainya. Peralatan-peralatan ini mengalami hembusan udara setiap saat, yang menyebabkan kekuatan konstruksinya mengalami penurunan, hal ini disebabkan adanya drag yang arahnya searah dengan arah aliran. Upaya yang dilakukan untuk mengurangi drag adalah dengan memanipulasi medan aliran fluida. Manipulasi aliran fluida dapat dilakukan secara pasif antara lain dengan menambahkan helical strake pada permukaan silinder, menambahkan penghalang di depan silinder dan sebagainya. Dalam penelitian ini manipulasi aliran fluida dilakukan dengan menambahkan O-ring pada permukaan silinder. Tujuan penelitian ini adalah menganalisa pengaruh variasi diameter O-ring terhadap koefisien drag. Penelitian ini dilakukan pada sebuah wind tunnel yang terdiri dari blower, pipa pitot, manometer, timbangan digital, dan silinder. Penambahan O-ring diletakkan pada permukaan silinder dengan variasi diameter O-ring yaitu 3mm, 4mm, 5mm, 6mm dan jarak antar O-ring 30mm. Silinder diletakkan ke arah vertikal. Bilangan Reynolds berdasarkan diameter silinder (60mm) adalah Re = 3,64 x .Dari hasil penelitian menunjukkan bahwa terjadi penurunan koefisien drag dibandingkan tanpa variasi O-ring. Nilai koesisien drag terendah didapat dari variasi diameter O-ring 5mm atau d/D=0,08 dengan nilai 0,650259, dimana terjadi penurunan drag sebesar 24,15% dibandingkan dengan silinder tanpa O-ring.

PEMBANGKITAN TEGANGAN MENGGUNAKAN KARBON AKTIF TEMPURUNG KELAPA DENGAN ELEKTROLIT AIR Tista, Si Putu Gede Gunawan; Santhiarsa, I Gusti Ngurah Nitya; Astawa, Ketut; Tenaya, I Gusti Ngurah Putu; Negara, Komang Metty Trisna
Jurnal Rekayasa Mesin Vol. 15 No. 2 (2024)
Publisher : Jurusan Teknik Mesin, Fakultas Teknik, Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/jrm.v15i2.1520

The generation of electrical energy from fossil fuels is currently running low, besides that it can cause global warming due to gas emissions such as carbon dioxide. Besides that, the development of small portable equipment such as watches, handphones, and cameras, requires batteries with small power. Therefore, environmentally friendly materials on a small scale are needed to generate electricity, one of which is coconut shell-activated carbon. The purpose of this research is to generate a voltage from a model using activated coconut shell carbon with a water-electrolyte. The model consists of a counter electrode-electrode counter. The counter electrodes are varied, namely aluminum, zinc, and copper. The electrode used is coconut shell-activated carbon, while the electrolyte is distilled water. The electrolyte is injected into the model between the electrode and the counter electrode and then given the heat. When the electrolyte is injected into the model, electrostatic forces occur between the functional groups, the pores on the surface of the activated carbon, the counter electrode, and the water-electrolyte, resulting in the release of electrons. The results show that the voltage generated by heating to a temperature rise of ΔT = 54 ͦC is 0.795 volts for aluminum counter electrodes, while zinc reaches 0.597 volts and copper reaches 0.034 volts. While the average thermal sensitivity of the resulting voltage (dV/dT) for aluminum is 47.85707 mV/ ͦ C, while zinc is 39.15949 mV/ ͦC, and copper is 1.72348 mV/ ͦC.

PEMBANGKITAN TEGANGAN MENGGUNAKAN KARBON AKTIF TEMPURUNG KELAPA DENGAN VARIASI PROSENTASE NACL Gunawan Tista, Si Putu Gede
POROS Vol. 19 No. 2 (2023): Jurnal Ilmiah Teknik Mesin POROS
Publisher : Program Studi Teknik Mesin Universitas Tarumanagara

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24912/poros.v19i2.29109

Fossil fuels as energy generators have been identified as the main cause of environmental pollution, besides that their supplies are running low. Energy from fossil fuels can cause global warming and climate change due to the carbon dioxide gas emissions produced, causing a greenhouse effect. Therefore, to generate electrical energy, environmentally friendly materials are needed, one of which is coconut shell-activated carbon. This research aims to generate voltage using coconut shell-activated carbon with varying percentages of NaCl. The voltage generation model is composed of counter electrodes – electrodes – counter electrodes. The electrode used is coconut shell-activated carbon, while the counter electrode is copper. The electrolyte used was a NaCl solution with NaCl percentages of 5%, 10% and 15% respectively. The NaCl electrolyte is injected into the model between the electrode and the counter electrode, then heat is applied. An electrostatic force occurs between the ions from the NaCl electrolyte and the surface of the coconut shell-activated carbon, namely the functional groups, pores, and copper counter electrode. The results show that the higher the percentage of NaCl electrolyte, the higher the voltage produced. The resulting voltage is 0.091 volts at a NaCl percentage of 5%, 0.181 volts at a NaCl percentage of 10%, and 0.212 volts at a NaCl percentage of 15%.

The analysis of semiconducting charateristic of rice husk-based carbon nanomaterial bio-activated by pineapple peel juice Dwidiani, Ni Made; Suardana, Ngakan Putu Gede; Wardana, I Nyoman Gede; Nugroho, Willy Satrio; Puja, I Gusti Ketut; Septiadi, Wayan Nata; Santhiarsa, I Gusti Ngurah Nitya; Tista, Si Putu Gede Gunawan
Mechanical Engineering for Society and Industry Vol 5 No 1 (2025)
Publisher : Universitas Muhammadiyah Magelang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31603/mesi.12733

This study investigates the synthesis and characterization of semiconducting materials derived from rice husk bio-activated by pineapple peel juice, presenting an eco-friendly and sustainable approach. The organic photo-active semiconducting material from rice husk ash (RHA) is synthesized. RHA was activated by immersion in the pineapple juice solution. Distinct structural disparities among RHA, Sunken Carbon nanomaterial (SCNM), and Floating Carbon Nanomaterial (FCNM) materials are revealed through SEM imaging, showcasing the tailored nature of each material. The SEM images also indicate the role of bromelain from the pineapple juice to provide defects on the RHA carbon surface. The crack on the nano particles on the surface of SCNM and FCNM were formed due to the bromelain electrostatic interaction with the surface. Elemental analysis indicates a higher probability of CuO and Si presence in SCNM, suggesting its potential for semiconductor extraction. The Cu to Si ratio implies photoactivity, confirmed by UV-Vis characterization showing absorption peaks in the UV region. FTIR analysis highlights enhanced polar interactions in SCNM and FCNM, attributed to the activation process involving bromelain in pineapple juice. The photoelectric effect testing shows FCNM and SCNM generates more electrical current as exposed to light which. The current was generated due to the electron transport phenomenon of CuO and Si content triggered by photons. The study provides insights into the materials' molecular structures and potential applications in sensors, energy devices, and semiconductor-related technologies, leveraging the unique properties of bio-derived nanomaterials for practical implementation.

PEMBANGKITAN TEGANGAN MENGGUNAKAN KARBON AKTIF TEMPURUNG KELAPA DENGAN ELEKTROLIT AIR Tista, Si Putu Gede Gunawan; Santhiarsa, I Gusti Ngurah Nitya; Astawa, Ketut; Tenaya, I Gusti Ngurah Putu; Negara, Komang Metty Trisna
Jurnal Rekayasa Mesin Vol. 15 No. 2 (2024)
Publisher : Jurusan Teknik Mesin, Fakultas Teknik, Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/jrm.v15i2.1520

The generation of electrical energy from fossil fuels is currently running low, besides that it can cause global warming due to gas emissions such as carbon dioxide. Besides that, the development of small portable equipment such as watches, handphones, and cameras, requires batteries with small power. Therefore, environmentally friendly materials on a small scale are needed to generate electricity, one of which is coconut shell-activated carbon. The purpose of this research is to generate a voltage from a model using activated coconut shell carbon with a water-electrolyte. The model consists of a counter electrode-electrode counter. The counter electrodes are varied, namely aluminum, zinc, and copper. The electrode used is coconut shell-activated carbon, while the electrolyte is distilled water. The electrolyte is injected into the model between the electrode and the counter electrode and then given the heat. When the electrolyte is injected into the model, electrostatic forces occur between the functional groups, the pores on the surface of the activated carbon, the counter electrode, and the water-electrolyte, resulting in the release of electrons. The results show that the voltage generated by heating to a temperature rise of ΔT = 54 ͦC is 0.795 volts for aluminum counter electrodes, while zinc reaches 0.597 volts and copper reaches 0.034 volts. While the average thermal sensitivity of the resulting voltage (dV/dT) for aluminum is 47.85707 mV/ ͦ C, while zinc is 39.15949 mV/ ͦC, and copper is 1.72348 mV/ ͦC.

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