Hasil Pencarian  ::  Simpan CSV :: Kembali

"Kebutuhan energi semakin meningkat dengan bertambahanya populasi manusia pada saat ini. Salah satu konsumsi energi terbesar adalah pada bidang industri khususnya pada gedung-gedung. Phase Change Material (PCM) merupaka salah satu solusi terhadap permasalahan kebutuhan energi ini. Beeswax merupakan salah satu PCM dengan kapasitas kalor yang tinggi. Material ini akan diuji dan dianalisis pada penelitian ini. Tujuan dari penelitian ini adalah untuk mengetahui sifat-sifat termal dari komposit beeswax dan nanopartikel CuO. Titik leleh dan kapasitas termal dari nano-PCM akan dianalisis dengan metodologi DSC (Different Scanning Calorymeter). Titik leleh dari nano-PCM menurun sebesar 0.6,0.63,0.66,1.07,1.41oC untuk 0.05,0.1,0.15,0.2,0.25 wt % secara berurutan. Tidak ada reaksi kimia diantara beeswax dan nanopartikel CuO berdasarkan hasil dari tes FTIR. Penambahan nanopartikel CuO akan meningkatkan kemampuan perpindahan kalor dari komposit, akan tetapi menurunkan kapasitas kalor dari komposit tersebut. Berdasarkan hasil yang telah didapatkan, penambahan nanopartikel akan meningkatkan kecepatan penghantaran kalor dibandingkan dengan material dasar.The demand of energy is increased in recent days. Experimental and implementation of phase change material as thermal storage is gained greater attention as solution to energy issue. Beeswax as one of phase change material with high thermal capacity is investigated in this paper. The objective of this paper is to analyze thermal properties and behaviors of beeswax-CuO Nano-PCM. The melting temperature and thermal capacity of nano-PCMs were determined by differential scanning calorimetry test. The melting temperature of nano-PCM decreased by 0.6,0.63,0.66,1.07,1.41oC for 0.05,0.1,0.15,0.2,0.25 wt %,respectively. There was no chemical reaction between CuO and beeswax based on FTIR test. Existing of CuO nanoparticles enhanced thermal conductivity of beeswax. Addition of CuO nanoparticles reduced heat capacity of beeswax. However, the change of latent heat would not cause significant effect towards the performance of beeswax-CuO. Thus, based on result, heat transfer of composite beeswax-CuO could be faster than base phase change material."

"[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.]"

"Pengurangan hambatan karboksimetil selulosa dalam larutan air telah dipelajari sebagai fungsi konsentrasi dengan menggunakan pipa kotak 6x6 mm. Percobaan dilakukan dengan mengukur tekanan jatuh (pressure drop). Tujuan penelitian ini untuk meneliti pressure drop dalam pipa kotak 6x6 mm dengan penambahan konsentrasi karboksimetil selulosa dalam larutan air. Pipa kotak berdimensi 6x6 mm digunakan dalam penelitian ini dengan variasi larutan karboksimetil selulosa konsentrasi 200 ppm, 400 ppm dan 600 ppm. Percobaan dilakukan hingga bilangan Reynolds 28000. Rasio penurunan hambatan (drag reduction) maksimum yaitu 51,63% pada bilangan Reynolds 25500. Penurunan koefisien gesek mengindikasikan keefektifan fluida uji karboksimetil selulosa yang dapat dilihat dari grafik koefisien gesek terhadap garis grafik Blasius."

"Wick atau sumbu kapiler pada heat pipe berfungsi untuk menghantarkan kalor melalui fluida cair dari kondensor menuju evaporator akibat adanya tekanan kapilaritas yang menyebabkan fluida kerja dapat mengalir melalui pori – pori pada wick. Tekanan kapilaritas dipengaruhi oleh sudut kontak yang terbentuk antara fluida cair dengan wick. Semakin tinggi wetability, maka semakin kecil sudut kontak yang terbentuk sehingga tekanan kapilaritas pun akan semakin besar. Penelitian ini bertujuan untuk mengetahui pengaruh dari ukuran butir tembaga, gaya kompaksi dan temperatur sintering pada proses pembuatan wick serta pengaruh paparan udara pada temperatur ruang terhadap sudut kontak yang terbentuk pada permukaan wick dengan air (H2O) sebagai fluidanya. Dengan begitu dapat diketahui parameter pabrikasi yang paling baik untuk menghasilkan wick dengan wetability yang tinggi dengan kata lain sudut kontak terkecil.Dari percobaan diperoleh dengan meningkatnya ukuran butir tembaga maka sudut kontak yang terbentuk akan semakin kecil. Sedangkan peningkatan gaya kompaksi dan temperatur sintering menyebabkan kenaikan pada sudut kontak. Sudut kontak terkecil didapatkan dengan menggunakan serbuk tembaga 200 μm dikompaksi pada tekanan 40 kN dan disintering pada temperatur 800°C, yaitu sebesar 32,131°. Semakin lama wick terpapar pada udara bebas, maka sudut kontak yang terbentuk akan semakin besar, dan setelah hari ke-7 permukaan wick berubah menjadi hidropobik (sudut kontak > 90°).

---

The wicks in heat pipe are used to transfer the heat with liquid from the condenser to the evaporator due to capillary pressure. Capillary presssure is affected by contact angle between liquid and the wick. The capillary pressure become higher as the increasing contact angle. The aim this study is to investigate the effect of copper powder diameter, forming force and sintering temperature, and the effect of room ambient air on contact angle so that fabrication parameters can be controlled to get the minimum contact angle that used a water as the working fluid.

It is demonstrated that when copper powder diameter become higher, the contact angle become smaller. Moreover, when the forming force and sintering temperature increase, the contact angle become higher. The minimum contact angle value (32,131°) obtained when the diameter of the copper powder 200 μm that formed with 40 kN and sintered at 800°C. In addition, the contact angle get higher in time when exposed to room ambient air. After 7 days, the wick surface become hydrophobic (contact angle >90°)."

"Pembaraan atau smoldering merupakan tipe pembakaran yang unik, karena merupakan tipe pembakaran yang tidak memiliki lidah api. Fenomena smoldering dapat menjadi bahaya, karena dapat berlangsung dalam jangka waktu yang lama sebelum bertransisi menjadi flaming combustion. Sehingga smoldering menjadi sumber bahaya, terutama dalam keberadaan material organik, yang dapat mengakibatkan kebakaran hutan / wildland fire. Salah satu bentuk pembakaran smoldering juga dapat dilihat pada rokok, terutama rokok kretek. Rokok kretek adalah tipe rokok dengan campuran tembakau dan cengkeh. Penelitian mengenai proses pembakaran smoldering pada rokok diharapkan dapat menjadi batu loncatan untuk penelitian fenomena smoldering lainnya. Dengan menggunakan parameter berupa sudut, tulisan ini menganalisis hubungan sudut dengan static burn rate dan mass loss rate. Selain itu, eksperimen dilanjutkan dengan melihat interaksi antara rokok dengan material uji berupa kertas. Hasil dari eksperimen ini adalah, sudut sangat berpengaruh dalam proses smoldering, karena posisi dari rokok menentukan oxygen attacknya. Sudut 270º merupakan sudut dengan static burn rate dan mass loss rate paling cepat. Sedangkan, pada eksperimen interaksi dengan kertas, didapatkan penyebaran luasan kertas yang terbakar dengan rokok, dengan parameter sudut kontak. Didapatkan bahwa sudut 50º memiliki luasan area bakar paling besar, hal ini diakibatkan besarnya kontak area antara rokok dengan kertas uji.

---

Smoldering has long been a unique type of combustion. Its self sustained, slow, and flameless form of burning, can be extremely hazardous in certain situations; especially in the presence of organic matters. Peat and wildland fire, for example, usually occur as an aftermath of smoldering of organic matter. Another example of smoldering combustion is the burning process of a cigarette, namely Kretek Cigarette, a type of cigarette with a mixture of tobacco and clove. Experimentation about the smoldering combustion of a kretek cigarette is expected to be a stepping stone towards a thorough analysis about smoldering combustion as a whole. With inclination as the main parameter, the experiment conducted are aimed towards the the relation between inclination and smoldering combustion, with static burn rate and mass loss rate as the main data gathered. Further more, an analysis about the interaction of cigarette an paper as contacting materia are conducted. The results showed that smoldering combustion are affected by inclination, due to the positioning of the cigarette, and the allowance of oxygen attack. The results showed a cigarette in a 270º position has the fastest static burn rate and mass loss rate. Another result showed that propagation of burned area, caused by a burning cigarette, are influenced by contacting angle, and contacting surface area. The results showed that a 50º angle of cigarette and paper contact produced the largest burned area propagation."

"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."

"[ 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.]"