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Muhammad Harits Muttaqin

Pengaruh jenis isolator terhadap kecepatan pendinginan dalam pembentukan lapisan kulit dan sifat mekanis besi tuang nodular dinding tipis = The effect of insulator types towards cooling rate on skin effect formation and mechanical properties of thin wall ductile iron

"Penggunaan energi yang tidak terbarukan seperti minyak bumi dan batu bara secara perlahan telah membawa dunia ini ke dalam krisis energi, sehingga diperlukan upaya penghematan energi. Isu dunia mengenai penghematan energi tersebut sangat berkaitan erat dengan industri otomotif. Industri otomotif dituntut untuk menghasilkan produk dengan emisi kendaraan yang rendah dan kendaraan yang hemat bahan bakar. Material TWDI (thin wall ductile iron) yang dapat dilakukan pemrosesan lanjut menjadi TWADI (thin wall austempered ductile iron) menjadi kandidat yang paling menarik karena sifat mekanisnya yang baik serta biaya yang lebih murah jika dibandingkan dengan aluminium. Tantangan yang dihadapi pada proses pembuatan material TWDI saat ini yaitu kecenderungan terbentuknya lapisan kulit (skin effect) pada permukaan logam hasil pengecoran yang dapat menurunkan sifat mekanis.

Penelitian ini dilakukan untuk mendapatkan pengaruh penggunaan isolator berupa glasswool, kayu, dan rockwool dengan ketebalan 40 mm terhadap kecepatan pendinginan. Pengujian yang dilakukan adalah pengujian komposisi kimia, pengamatan makro, pengamatan struktur mikro, dan pengujian tarik. Pengamatan struktur mikro dilakukan secara kualitatif dan kuantitatif, dengan bantuan program image analysis. Sedangkan analisis kecepatan pendinginan didapatkan secara kualitatif.

Hasil dari penelitian ini diketahui bahwa kecepatan pendinginan merupakan fungsi dari jumlah nodul, karbida, nodularitas, dan diameter rata-rata nodul. Kecepatan pendinginan tercepat hingga terlambat yaitu pada penggunaan isolator rockwool (P9M1), kayu (P8M1), dan glasswool (P6M1). Untuk ketebalan lapisan kulit rata-rata terbesar hingga terkecil yaitu P8M1 32,58 μm, P9M1 25,59 μm, dan P6M1 25,45 μm. Dari karakteristik nodul, P8M1 memiliki nodularitas tertinggi sebesar 81% lalu diikuti P6M1 sebesar 79% dan P9M1 sebesar 76%. P6M1 memiliki 1605 nodul/mm2, P9M1 1274 nodul/mm2 dan P8M1 1141 nodul/mm2. Sedangkan, diameter nodul P6M1 10,20 μm, P8M1 9,71 μm, dan P9M1 9,09 μm. Matriks yang didapatkan adalah ferit dan karbida dengan tingkat keparahan karbida tertinggi hingga terendah yaitu P9M1, P8M1, dan P6M1. Nilai kekuatan tarik P6M1 367 MPa, P9M1 329 MPa, dan P8M1 146 MPa. Sedangkan elongasi P6M1 2%, P9M1 1,1%, dan P8M1 1%. Sifat mekanis yang didapatkan masih berada di bawah nilai standar.

Nowadays, the use of unsustainable energy such as petroleum and coal subsequently has brought us to the energy crisis. So that the effort of saving energy is crucial. World issues regarding energy savings is very closely related to the automotive industry. The automotive industry is required to produce products with lower emissions and fuel-efficient vehicles. TWDI (thin wall ductile iron) which can be processed to TWADI (thin wall austemperd ductile iron) became the best candidate due to good mechanical properties and lower cost comparing to aluminum. The challenge confronted in the process of TWDI making is the tendency of skin formation on the surface of the metal casting reduced its mechanical properties.
This research is conducted to obtain the effect of insulators utilization such as glasswool, wood, and rockwool with the thickness of 40 mm towards the cooling rate. Methods performed are chemical composition, visual observation, microstructure observation, and tensile testing. While, microstructure observation is conducted qualitatively and quantitatively using image analysis program, the analysis of the cooling rate is obtained qualitatively.
The cooling rate, from the fastest to the slowest, is rockwool (P9M1), wood (P8M1), and glasswool (P6M1). Where as, for the average skin thickness, from the biggest to the smallest, is P8M1 32.58 μm, P9M1 25.59 μm, and P6M1 25.45 μm. For nodule characteristics, P8M1 has the 81% nodularity and then followed by P6M1 with 79% and P9M1 with 76%. While, P6M1 has 1605 nodule/mm2, P9M1 and P8M1 has 1274 and 1141 nodul/mm2, respectively. While, the biggest nodule diameter is P6M1 with 10.20 μm, the next is P8M1 with 9.71 μm and then P9M1 with 9.09 μm. Ferrite and carbide is found in the matrix. The severity level of carbide, from the highest to the lowest, is P9M1, P8M1 and P6M1. From mechanical aspects, the highest ultimate tensile strength is obtained by P6M1 with 367 MPa, then followed by P9M1 with 329 MPa and P8M1 with 146 MPa. Where as, for the elongation, P6M1 is 2%, P9M1 is 1.1% and P8M1 is 1%. The mechanical properties obtained don't fulfill the standardfollowed by P6M1 with 79 and P9M1 with 76 While P6M1 has 1605 nodule mm2 P9M1 and P8M1 has 1274 and 1141 nodul mm2 respectively While the biggest nodule diameter is P6M1 with 10 20 m the next is P8M1 with 9 71 m and then P9M1 with 9 09 m Ferrite and carbide is found in the matrix The severity level of carbide from the highest to the lowest is P9M1 P8M1 and P6M1 From mechanical aspects the highest ultimate tensile strength is obtained by P6M1 with 367 MPa then followed by P9M1 with 329 MPa and P8M1 with 146 MPa Where as for the elongation P6M1 is 2 P9M1 is 1 1 and P8M1 is 1 The mechanical properties obtained don rsquo t fulfill the standard."

Depok: Fakultas Teknik Universitas Indonesia, 2015

S60439

UI - Skripsi Membership Universitas Indonesia Library

Fadhil Azharrisman

Studi performa pendinginan pada palka ikan 30GT = Study on cooling performance of fish hold 30 GT

"Penelitian ini membahas mengenai perancangan dan perhitungan palka ikan untuk kapal ikan 30 GT menggunakan kapal yang dirancang khusus. Pada penelitian ini pendinginan palka ikan menggunakan sistem refrigerasi untuk mengoptimalkan volume ruangan palka karena, dalam pengoperasiannya palka berpendingin es membutuhkan 50% dari kapasitas ruang palka untuk memuat es. Dalam penelitian ini, dilakukan studi literatur guna menentukkan parameter perhitungan, desain geometrik palka, dan dilakukan simulasi CFD menggunakan Ansys Fluent untuk menilai bentuk aliran fluida pendingin dan waktu pendinginan produk, lalu dilanjutkan dengan perhitungan beban pendinginan dan kebutuhan daya listrik yang dibutuhkan untuk sistem pendingin yang telah dirancang. Berdasarkan hasil simulasi didapatkan waktu pendinginan paling cepat terjadi ketika kecepatan inlet fluida pendingin 8 m/s pada kapasitas pemuatan 100% dengan waktu pendinginan ikan dari 27°C sampai 0°C membutuhkan waktu selama 4 jam 15 menit, serta kebutuhan daya total untuk sisterm refrigerasi yaitu 5,88 kW.

This study discusses the design and calculation of fish hold for 30 GT fishing vessels using specially designed vessels. In this study, fish hold cooling uses a refrigeration system to optimize the volume of the hold because, in its operation, the ice-cooled hatch requires 50% of the capacity of the hold to load ice. In this study, a literature study was conducted to determine the calculation parameters, geometric design of the hold, and a CFD simulation was carried out using Ansys Fluent to review the shape of the cooling fluid flow and product cooling time then continued with the calculation of the cooling load and the electrical power required for the cooling system has been designed. Based on the simulation results, the fastest cooling time occurs when the cooling fluid inlet velocity is 8 m/s at a loading capacity of 100% with a cooling time of fish from 27°C to 0°C which takes 4 hours 15 minutes, as well as the total power requirement for the refrigeration system is 5.88 kW."

Depok: Fakultas Teknik Universitas Indonesia, 2021

S-pdf

UI - Skripsi Membership Universitas Indonesia Library

Yusuf Tri Wicaksono

Pengaruh ketebalan isolator glasswool terhadap kecepatan pendingingan dalam pembentukan lapisan kulit pada besi tuang nodular dinding tipis = The influence of thickness glasswool isolator on cooling rate in skin effect formation of thin wall ductile iron

"Pada pengecoran Besi Tuang Dinding Tipis terjadi fenomena unik, yaitu terbentuknya lapisan kulit. Lapisan tersebut menjadi pusat stress konsentrasi untuk terjadinya retak material. Salah satu cara untuk meminimalisir terbentuknya lapisan kulit adalah menjaga kecepatan pendinginan pada keadaan optimum. Penelitian ini dilakukan untuk mengetahui pengaruh ketebalan isolator glasswool terhadap kecepatan pendinginan dalam pembentukan lapisan kulit. Variasi modifikasi cetakan yang digunakan adalah tanpa isolator (P4M1), isolator glasswool tebal 40mm sebelah kiri benda dan 50mm sebelah kanan benda(P5M1), dan isolator ketebalan 50mm dikedua sisi benda(P7M1). Dilakukan karakterisasi metalografi non etsa dan etsa, uji mekanis berupa uji tarik, dan uji kecepatan pendinginan pada plat urutan ketiga masing-masing benda cor.

Hasil menunjukkan bahwa adanya pengaruh ketebalan isolator terhadap kecepatan pendinginan benda cor. Kecepatan pendinginan tertinggi hingga terendah adalah 21,59⁰C/menit, 3,75⁰C/menit, dan 3,61⁰C/menit. Lapisan kulit ketebalan rata-rata yang didapat P7M1 324μm, P4M1 105μm dan P5M1 71μm. Jumlah nodul tertinggi hingga terendah P4M1 1121 nodul/mm2, P7M1 916 nodul/mm2, dan P5M1 801 nodul/mm2. Nodularitas yang didapat P4M1 78%, P5M1 75% dan P7M1 64%. Nilai tensile strength yang didapat dengan nilai 287MPa, 288MPa sampai 383 MPa. Matriks yang didapat adalah full ferit.

Thin wall ductile iron has unique phenomena in manufacturing called skin effect. Skin effect becomes stress concentration to form crack initiation. One of many methods to decrease skin effect is providing optimum cooling rate. This research used the influence of glasswool isolator thickness leading to different cooling rate as variable. Variation of casting also investigated which are molding without isolator (P4M1), molding using isolator glasswool with thickness 40mm on the left side and 50mm on the left side of plate (P5M1) and the last is molding using isolator glaswool with 50mm on both of sides (P7M1). Samples were characterized using metallograpy technique (etching and non etching), mechanical testing especially tensile test and cooling rate testing.
The result shows that thickness of isolator glasswool has influences on cooling rate. The cooling rate varies from fastest to slowest which are 21,59⁰C/minutes, 3,75⁰C/minutes, and 3,61⁰C/minutes. The skin thickness is produced from the thickest to thinnest on the mold using 50mm thickness glaswool isolator, the mold without glasswool isolator and the mold using 40mm glasswool isolator on left side and 50mm glasswool isolator on the right side. High nodul counting resulted from the mold without isolator, the mold using 50mm glasswool isolator and the mold using 40mm glasswool isolator on left side and 50mm glasswool isolator on the right side. Highest nodularity was produced on the mold without isolator which is 78%, the mold using isolator glasswool 40mm and 50mm thickness produced 75% nodularity dan the mold using glasswool isolator 50mm produced 64% nodularity. Tensile test showed tensile strength alter from 287MPa, 288MPa until 383 MPa. The matrix obtains full ferritic"

Depok: Fakultas Teknik Universitas Indonesia, 2015

S60454

UI - Skripsi Membership Universitas Indonesia Library

Damora Rhakasywi

Pengembangan sistem pendinginan komponen mikroelektronik hemat energi melalui pengelolaan aliran termal berbasis teknologi jet sintetik = Development of microelectronics cooling system components energy efficient through flow thermal management technology based synthetic jet

"Perkembangan industri elektronik untuk produk berkinerja tinggi yang ditandai dengan munculnya piranti elektronika berukuran minimalis serta menggunakan daya yang rendah memerlukan sebuah sistem pendinginan yang handal dan efisien sehingga mampu beroperasi secara optimum. Pada penelitian ini teknologi yang digunakan untuk mendinginkan komponen piranti elektronika tersebut menggunakan jet sintetik yang memanfaatkan gerakan membran secara kontinyu dengan menghasilkan cincin vortex untuk mempercepat proses perpindahan panas.

Penelitian yang dilakukan pada study ini bertujuan untuk mencari nilai frekuensi, jenis gelombang eksitasi, serta bentuk orifis jet sintetik yang menghasilkan performa pendinginan yang baik untuk model jet sintetik impinging, mencari pengaruh jarak tumbukan (impact) jet sintetik impinging terhadap laju perpindahan panas konveksi untuk proses pendinginan, mencari model cavity jet sintetik impinging dan jet sintetik cross flow yang memiliki kehandalan dalam proses pendinginan.

Penelitian ini dikerjakan menggunakan pendekatan komputasional dan eksperimental. Pada pendekatan komputasional digunakan software CFD (computational fluid dynamics) yang mendefinisikan kondisi batas jet sintetik dengan asumsi dinding bergerak (moving wall) dan model turbulensi k-omega SST (Shear Stress Transport). Kemudian model uji eksperimental menggunakan model jet sintetik tipe impinging dan model jet sintetik tipe cross flow. Model-model tersebut memiliki perbedaan dalam hal arah aliran jet sintetik terhadap media yang akan didinginkan berupa heatsink. Modus eksitasi yang dipergunakan untuk menghasilkan aliran jet sintetik tersebut menggunakan sinyal listrik berupa gelombang sinusoidal, square dan triangular dengan variasi frekuensi 80 Hz, 120 Hz dan 160 Hz. Sinyal listrik tersebut dihasilkan oleh sweep function generator.

Hasil yang diperoleh dari kajian komputasional dan eksperimental tersebut memberikan informasi bahwa jet sintetik mampu memberikan efek pendinginan pada objek yang akan didinginkan. Parameter dari variasi frekuensi eksitasi jet sintetik dan arah aliran jet sintetik memberikan efek yang beragam dalam hal pendinginan. Dari hasil penelitian yang dilakukan tersebut diperoleh modus eksitasi yang paling baik menggunakan gelombang eksitasi square 120 Hz untuk model jet sintetik impinging kemudian kombinasi gelombang eksitasi sinusoidal 120 Hz dan square 80 Hz memberikan efek pendinginan yang paling optimum untuk tipe jet sintetik cross flow. Konsumsi energi yang dibutuhkan oleh jet sintetik sebanyak 1,78 joule untuk menurunkan temperatur dari 53°C menjadi 48,2°C sedangkan kipas menghabiskan konsumsi energi sebanyak 142,2 joule untuk dapat menurunkan temperatur dari 53°C menjadi 48,2°C.

The development of the electronics industry for high performance products are characterized by the emergence of electronic devices minimalist size and low power required to use a cooling system that is reliable and efficient thus able to operate at its optimum. In this study, the technology used to cool electronic devices such components using synthetic jet which utilizes a continuous membrane movement by generating vortek ring to accelerate the process of heat transfer. Research conducted in this study aimed to explore the value of frequency, type of wave excitation, as well as the shape of the synthetic jet orifice produces good cooling performance for the model synthetic jet impinging, collision distance for influence synthetic jet impinging on the rate of convection heat transfer to the cooling process, looking for synthetic jet impinging cavity models and synthetic jet cross flow which has reliability in the process of cooling.
The study is done using the method of using computational and experimental approaches. In the computational approach used CFD (computational fluid dynamics) software which defines the boundary conditions assuming a synthetic jet moving wall model with k-omega SST (Shear Stress Transport) turbulence. Then test the model using the experimental model of type impinging synthetic jet and model of synthetic jet cross flow type. The models differ in terms of synthetic jet flow direction of the media that will be cooled heatsink. Mode excitation is used to produce the synthetic jet flow using electrical signals in the form of waves sinusoidal, square dan triangular with variations in frequency of 80 hz, 120 hz and 160 hz. The electrical signals generated from the tool named sweep function generator.
Results obtained from the computational and experimental information that synthetic jets can provide a cooling effect on the object to be cooled. Parameters of synthetic jet excitation frequency variation and direction of flow of synthetic jet placement varied effects in terms of cooling. From the results of the research conducted most excitation modes obtained using either 120 hz square wave excitation for the type of impinging synthetic jet models then the combination of 120 hz sinusoidal excitation wave and 80 hz square provide the most optimum cooling effect for condition type cross flow model of synthetic jet. Energy consumption required by the synthetic jet 1.78 joules to lower the temperature of 53°C - 48.2°C while fans spend energy consumption 142.2 joule to be able to lower the temperature of 53°C-48.2°C."

Depok: Fakultas Teknik Universitas Indonesia, 2014

D1899

UI - Disertasi Membership Universitas Indonesia Library

Kemal Rahadian

Simulasi dan optimasi solar thermal cooling system pada gedung manufacturing research center untuk mereduksi biaya operasional dengan menggunakan perangkat lunak energyplus dan genopt = Simulation and optimization of solar thermal cooling system in manufacturing research center building to reduce operational cost using software energyplus and genopt / Kemal Rahadian

"ABSTRAK

Solar Thermal Cooling System with its absorption cycle is expected to

replace the conventional air conditioning system with vapor compression cycle

because it is more efficient in terms of cost and energy. However, due to the heat

of the sun is not always stable, the system needs to be equipped with a backup

energy source, one of which is CNG. In the Manufacturing Research Center

building, the lack of facilities that support availability of CNG causes large

operating costs. Therefore, Optimization efforts with the aim to reduce operating

costs are needed. Simulation and optimization performed with EnergyPlus and

GenOpt. The conclusion is that the installation of 100 kW electric heater tankless

hot water storage tank is able to reduce total operating costs by 34.95% compared

to the use of a combination of solar thermal and CNG and 49.92% compared with

the full use of CNG.

ABSTRACT