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Ditemukan: 5 dokumenUJI KETAKINTEGRALAN SISTEM PERSAMAAN DIFERENSIAL NON-LINEAR DENGAN PENDEKATAN GELOMBANG BERJALAN
Pengujian keterintegralan suatu sistem pada umumnya memerlukan identifikasi struktur khusus yang terkait dengan keterintegralannya, seperti pasangan Lax, struktur bi- Hamilton, atau kuantitas konservatif, yang mana merupakan proses yang panjang dan sulit. Oleh karena itu, penelitian ini bertujuan untuk menguji ketidakterintegralan suatu sistem melalui pendekatan yang lebih sederhana dibandingkan dengan uji keterintegralan. Uji dilakukan dengan memandang sistem sebagai sistem dinamik yang dapat diamati evolusinya terhadap waktu. Untuk melakukan hal tersebut, sistem akan ditransformasi dengan menggunakan ansatz gelombang berjalan untuk membentuk moving coordinate frame dan menghasilkan kondisi awal untuk mengintegrasikan persamaan diferensial secara numerik terhadap spasial menggunakan Fast Fourier Transform (FFT) dan Inverse Fast Fourier Transform (IFFT), dan terhadap waktu menggunakan Runge-Kutta Orde 4. Setelah itu, dilakukan simulasi satu gelombang dan simulasi interaksi dua gelombang dari formula yang sama untuk mengamati perilaku sistem setelah tumbukan. Sistem terintegralkan umumnya menunjukkan perilaku khusus tertentu. Oleh karena itu, apabila hasil simulasi menunjukkan perilaku yang menyimpang dari karakteristik tersebut, maka hal tersebut dapat dijadikan indikasi bahwa sistem yang ditinjau tidak terintegralkan.
PERANCANGAN DAN EVALUASI KONFIGURASI CHILLER PLANT UNTUK DISTRICT COOLING SYSTEM MENGGUNAKAN SIMULASI DINAMIS BERBASIS OPENMODELICA PADA SKALA KLASTER KAMPUS
istem pendinginan kawasan dapat meningkatkan efisiensi penyediaan pendinginan pada klaster kampus melalui produksi air dingin secara terpusat. Kinerja energi chiller plant dipengaruhi oleh jenis chiller, strategi aliran air dingin, kapasitas unit, dan chiller staging, terutama pada operasi beban parsial. Penelitian ini bertujuan mengidentifikasi konfigurasi chiller plant yang paling efisien secara energi untuk profil beban pendinginan kampus. Simulasi dinamis berbasis OpenModelica digunakan untuk membandingkan konfigurasi air-cooled constant flow, air-cooled variable primary flow, water-cooled constant flow, dan water-cooled variable primary flow. Profil beban 24 jam disusun dari perhitungan beban pendinginan Gedung Laboratorium Teknik V-VIII dan pola konsumsi listrik harian. Setiap konfigurasi diuji pada kapasitas 3 × 800 kW, 2 × 1.200 kW + 1 × 600 kW, serta 2 × 1.600 kW. Evaluasi dilakukan berdasarkan kemampuan mengikuti beban, kondisi air dingin, laju aliran, chiller staging, konsumsi energi, koefisien performa chiller, dan kW/TR. Beban puncak dan beban minimum masing-masing sebesar 2.247,98 kW dan 749,42 kW, dengan faktor beban 58,8% yang menunjukkan dominasi operasi beban parsial. Seluruh dua belas kombinasi mampu memenuhi beban dan menjaga temperatur suplai air dingin sekitar 4,40 °C. Konfigurasi water-cooled menghasilkan konsumsi energi total lebih rendah daripada air-cooled, sedangkan variable primary flow menurunkan energi pompa air dingin. Konfigurasi terbaik adalah water-cooled variable primary flow berkapasitas 2 × 1.200 kW + 1 × 600 kW, dengan konsumsi energi total 6.766,19 kWh, nilai Plant kW/TR sebesar 0,749 kW/TR, dan koefisien performa chiller 5,437. Penelitian ini mendukung pemilihan konfigurasi chiller plant untuk perencanaan district cooling system skala kampus.
EVALUASI KINERJA THERMAL ENERGY STORAGE PADA DISTRICT COOLING SYSTEM DENGAN VARIASI STRATEGI OPERASI DAN MEDIA PENYIMPANAN TERMAL BERDASARKAN PROFIL BEBAN GEDUNG KAMPUS
District Cooling System (DCS) yang diintegrasikan dengan Thermal Energy Storage (TES) merupakan solusi efisiensi pendinginan terpusat yang memungkinkan pergeseran beban dari jam puncak ke non-puncak, namun kinerjanya bergantung pada strategi operasi dan media penyimpanan termal. Penelitian ini mengevaluasi kinerja TES pada DCS melalui simulasi untuk menentukan konfigurasi yang sesuai dengan profil beban pendinginan dinamis gedung kampus, dengan memvariasikan strategi operasi full storage dan load leveling, serta media penyimpanan air dan larutan ethylene glycol 20%. Simulasi dinamis dilakukan menggunakan OpenModelica dengan Modelica Buildings Library, tangki TES dimodelkan dengan pendekatan stratified multi-node, dan profil beban disusun dari skematik empat gedung Labtek ITB. Kinerja dievaluasi menggunakan Half-Cycle Figure of Merit (HCFOM), efisiensi energi, Storage Utilization Ratio (SUR), Peak Load Shaving Factor (PLF), dan rasio ketebalan termoklin terhadap tinggi tangki (WTC/H). Uji konvergensi numerik menunjukkan parameter energi tidak sensitif terhadap jumlah segmen tangki, sedangkan parameter stratifikasi sangat sensitif. Hasil menunjukkan media penyimpanan berpengaruh kecil pada performa energi tetapi signifikan pada stratifikasi, dengan ethylene glycol menghasilkan termoklin lebih tebal. Strategi operasi lebih dominan: load leveling menghasilkan SUR, HCFOM, dan PLF lebih tinggi, sedangkan full storage menghasilkan efisiensi energi lebih tinggi karena chiller tidak terbagi. Tidak ada strategi yang mutlak superior; pemilihan perlu disesuaikan prioritas operasional. Penelitian ini berkontribusi berupa kerangka evaluasi TES dan rekomendasi desain operasional pada konteks beban kampus dinamis.
PEMODELAN SISTEM DETEKSI KEBOCORAN PADA PIPA MENGGUNAKAN SIMULATOR TRANSIEN DINAMIS
Pipelines are crucial tools in transporting fluids to designated locations. It is almost impossible that a pipeline does not face any problems. One of the most common problems is a leak. Leak can be caused by corrosion, wax, and third-party damage (illegal tapping). In field X, located in South Sumatra, 54 cases of illegal tapping were found from 2014 to 2023. This condition cannot be left unresolved any longer because even a minor leak may lead to environmental damage, risk to human safety, and economic loss. This raises the urgency of detecting a leak for preventive actions to be implemented before a leak happens and fluid loss can be minimized. This study develops a dynamic transient simulator-based model to address pipeline leak detection by simulating transient flow behavior under both shipping and stop shipping conditions. The methodology of this study includes three parts: preliminary study, simulation, and interpretation. A literature review was conducted to define the study objectives. Data from field drain tests, including pressure, flow rate, and temperature, were collected from a pipeline in South Sumatra under both shipping and stop shipping conditions. These data were input into a dynamic transient simulator to build the model. Sensitivity analyses were performed, and model predictions were compared to real leak data to assess accuracy. The results were interpreted to refine the model and improve leak detection in pipeline systems. A Leak was intentionally introduced with specific leak rates, releasing 300 liters of condensate followed by a 30-minute standby, then 600 liters with another 30-minute standby. Data was collected on October 24, 26, and 28 2024 under both shipping and stop shipping conditions. In shipping, fluid flow was driven by the pump, while in stop shipping, the pump off and residual pressure caused minimal fluid movement. At the end of this study, the model was successfully developed and validated with field drain test data, showing accurate replication of pipeline behavior. The model achieved a pressure error of 1.92% under shipping conditions and 11% under stop shipping conditions. Pressure trends during a leak showed distinct drops and ripple. The model accurately predicted leak size and location with a maximum error of 5%, offering an effective tool for pipeline leak detection. Keywords: leakage, illegal tapping, shipping, stop shipping, simulator-based model
PEMODELAN SISTEM DETEKSI KEBOCORAN PADA PIPA MENGGUNAKAN SIMULATOR TRANSIEN DINAMIS
Pipelines are crucial tools in transporting fluids to designated locations. It is almost impossible that a pipeline does not face any problems. One of the most common problems is a leak. Leak can be caused by corrosion, wax, and third-party damage (illegal tapping). In field X, located in South Sumatra, 54 cases of illegal tapping were found from 2014 to 2023. This condition cannot be left unresolved any longer because even a minor leak may lead to environmental damage, risk to human safety, and economic loss. This raises the urgency of detecting a leak for preventive actions to be implemented before a leak happens and fluid loss can be minimized. This study develops a dynamic transient simulator-based model to address pipeline leak detection by simulating transient flow behavior under both shipping and stop shipping conditions. The methodology of this study includes three parts: preliminary study, simulation, and interpretation. A literature review was conducted to define the study objectives. Data from field drain tests, including pressure, flow rate, and temperature, were collected from a pipeline in South Sumatra under both shipping and stop shipping conditions. These data were input into a dynamic transient simulator to build the model. Sensitivity analyses were performed, and model predictions were compared to real leak data to assess accuracy. The results were interpreted to refine the model and improve leak detection in pipeline systems. A Leak was intentionally introduced with specific leak rates, releasing 300 liters of condensate followed by a 30-minute standby, then 600 liters with another 30-minute standby. Data was collected on October 24, 26, and 28 2024 under both shipping and stop shipping conditions. In shipping, fluid flow was driven by the pump, while in stop shipping, the pump off and residual pressure caused minimal fluid movement. At the end of this study, the model was successfully developed and validated with field drain test data, showing accurate replication of pipeline behavior. The model achieved a pressure error of 1.92% under shipping conditions and 11% under stop shipping conditions. Pressure trends during a leak showed distinct drops and ripple. The model accurately predicted leak size and location with a maximum error of 5%, offering an effective tool for pipeline leak detection. Keywords: leakage, illegal tapping, shipping, stop shipping, simulator-based model