Analisis Pengaruh Jumlah Bilah pada Static Mixer Tipe Swirl terhadap Ammonia Uniformity dan Pressure Drop di Sistem SCR Menggunakan CFD

Hutagaol, Jorell Chrisel Arnold (2026) Analisis Pengaruh Jumlah Bilah pada Static Mixer Tipe Swirl terhadap Ammonia Uniformity dan Pressure Drop di Sistem SCR Menggunakan CFD. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Sistem Selective Catalytic Reduction (SCR) merupakan teknologi utama untuk menekan emisi NOₓ pada motor diesel kapal guna memenuhi regulasi IMO Tier III. Efektivitas reduksi NOₓ sangat bergantung pada keseragaman distribusi amonia hasil dekomposisi urea sebelum memasuki reaktor katalis, yang dikuantifikasi melalui ammonia uniformity index (UAI). Peningkatan keseragaman umumnya dicapai dengan pemasangan static mixer, namun penambahan komponen ini menimbulkan penalti berupa kenaikan pressure drop yang berdampak pada konsumsi bahan bakar. Penelitian ini bertujuan menganalisis pengaruh variasi jumlah bilah (5, 6, dan 8) pada static mixer tipe swirl terhadap ammonia uniformity index dan pressure drop, serta menganalisis trade-off di antara keduanya. Simulasi dilakukan menggunakan Computational Fluid Dynamics (CFD) dengan pendekatan steady RANS, model turbulensi standard k-ε, species transport, dan model discrete phase (DPM) pressure swirl atomizer pada saluran berdiameter 100 mm, dengan blockage ratio dijaga konstan agar perbedaan kinerja murni disebabkan jumlah bilah. Hasil menunjukkan bahwa UI amonia berperilaku non-monoton terhadap jumlah bilah dengan nilai berturut-turut 0,867 (5 bilah), 0,901 (6 bilah), dan 0,804 (8 bilah), sedangkan pressure drop meningkat secara monoton sebesar 3134,4 Pa, 3206,6 Pa, dan 3462,1 Pa. Konfigurasi 8 bilah menghasilkan swirl paling kuat dan bertahan sehingga memicu segregasi sentrifugal amonia dan menurunkan keseragaman. Analisis trade-off menunjukkan transisi 5 ke 6 bilah meningkatkan UI amonia 3,9% dengan kenaikan pressure drop hanya 2,3%, sementara transisi 6 ke 8 bilah menurunkan UI amonia 10,7% sekaligus menaikkan pressure drop 8,0%. Dengan demikian, konfigurasi 6 bilah ditetapkan sebagai konfigurasi optimum karena memberikan keseragaman amonia tertinggi pada penalti tekanan yang moderat, sehingga paling sesuai untuk aplikasi Marine SCR.
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The Selective Catalytic Reduction (SCR) system is a leading technology for reducing NOₓ emissions from marine diesel engines to comply with IMO Tier III regulations. The effectiveness of NOₓ reduction strongly depends on the uniformity of the ammonia distribution produced from urea decomposition before it enters the catalyst reactor, quantified through the ammonia uniformity index (UAI). This uniformity is commonly improved by installing a static mixer; however, adding such a component introduces a penalty in the form of increased pressure drop, which affects fuel consumption. This study aims to analyze the effect of blade-count variation (5, 6, and 8 blades) of a swirl-type static mixer on the ammonia uniformity index and pressure drop, and to analyze the trade-off between them. The simulations were carried out using Computational Fluid Dynamics (CFD) with a steady RANS approach, the standard k-ε turbulence model, species transport, and a discrete phase model (DPM) pressure-swirl atomizer in a 100 mm diameter duct, with the blockage ratio held constant so that performance differences are attributable solely to blade count. The results show that UI ammonia behaves non-monotonically with blade count, yielding values of 0.867 (5 blades), 0.901 (6 blades), and 0.804 (8 blades), whereas the pressure drop increases monotonically at 3134,4 Pa, 3206.6 Pa, and 3462.1 Pa. The 8-blade configuration generates the strongest and most persistent swirl, inducing centrifugal segregation of ammonia and lowering uniformity. The trade-off analysis reveals that the 5 to 6 blade transition raises UI ammonia by 3.9% with only a 2.3% pressure-drop penalty, whereas the 6 to 8 blade transition lowers UI ammonia by 10.5% while raising pressure drop by 8.0%. Consequently, the 6 blade configuration is determined to be the optimum, providing the highest ammonia uniformity at a moderate pressure penalty, making it most suitable for Marine SCR applications.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	ammonia uniformity index, CFD, pressure drop, SCR, static mixer, swirl
Subjects:	T Technology > TJ Mechanical engineering and machinery > TJ762.E93 Exhaust systems T Technology > TJ Mechanical engineering and machinery > TJ797 Diesel motor--Fuel systems--Testing.
Divisions:	Faculty of Marine Technology (MARTECH) > Marine Engineering > 36202-(S1) Undergraduate Thesis
Depositing User:	Jorell Chrisel Arnold Hutagaol
Date Deposited:	01 Aug 2026 05:52
Last Modified:	01 Aug 2026 05:52
URI:	http://repository.its.ac.id/id/eprint/141598

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