Design Improvement Of Static Mixer Geometry To Improve The Selective Catalytic Reduction Performance

Musyaffa, Akhyar (2025) Design Improvement Of Static Mixer Geometry To Improve The Selective Catalytic Reduction Performance. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

This study investigates the impact of static mixer geometry on the uniformity of velocity and ammonia (NH₃), pressure loss, and flow behavior in a Selective Catalytic Reduction (SCR) system using Computational Fluid Dynamics (CFD). The geometry of the mixer was optimized by introducing flow obstructions, which separate the flow into a centralized high-velocity stream and enhance mixing through radial dispersion. These obstructions also generate recirculation zones and increase turbulence intensity, both of which contribute to improved mixing. However, pressure loss must remain within the manufacturer’s maximum allowable limit. Static mixers affect NH₃ distribution through recirculation, centralized velocity dispersion, and turbulence dispersion. Among the evaluated designs, the centralized curved plate mixer produced the highest average NH₃ mole fraction and the best uniformity index (UI) for both velocity and NH₃. This performance is attributed to its ability to maintain a strong centralized flow, resulting in superior radial dispersion compared to more uniformly spread flows. The blade-induced flow blockage promotes flow separation and recirculation behind the blades, directly influencing NH₃ distribution downstream. Modification 1, which involved reducing blade area, led to a faster central flow but lowered the maximum velocity and turbulence, resulting in decreased velocity and NH₃ UI. Additionally, the addition of a fourth blade in this configuration significantly increased pressure loss due to increased flow obstruction. In contrast, Modification 2, which employed smaller blades, successfully reduced pressure loss by 15% (from 836 Pa to 708 Pa) while preserving essential flow features such as separation, centralized velocity, and recirculation zones. Consequently, it achieved UI values close to the centralized curved plate mixer. These findings demonstrate the critical role of flow structures (recirculation, centralized velocity, and turbulence) in optimizing SCR performance and achieving effective NH₃ mixing with manageable pressure losses.
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Penelitian ini menganalisis pengaruh geometri static mixer terhadap keseragaman kecepatan aliran dan ammonia (NH₃), pressure loss, serta perilaku aliran dalam sistem Selective Catalytic Reduction (SCR) menggunakan Computational Fluid Dynamics (CFD). Optimasi geometri dilakukan dengan menambahkan hambatan aliran yang menyebabkan pemisahan aliran menjadi aliran berkecepatan tinggi yang terpusat dan meningkatkan pencampuran melalui dispersi radial. Hambatan ini juga membentuk zona resirkulasi dan meningkatkan intensitas turbulensi, yang berperan penting dalam proses pencampuran. Namun, pressure loss yang ditimbulkan tetap harus berada di bawah batas maksimum yang ditentukan oleh produsen. Static mixer memengaruhi distribusi NH₃ melalui zona resirkulasi, aliran terpusat, dan dispersi turbulen. Dari hasil simulasi, model centralized curved plate menghasilkan nilai rata-rata fraksi mol NH₃ dan indeks keseragaman (UI) tertinggi untuk kecepatan maupun NH₃. Hal ini disebabkan kemampuannya mempertahankan aliran kecepatan tinggi yang terpusat sehingga menghasilkan dispersi radial yang lebih baik dibandingkan aliran yang tersebar merata. Keberadaan bilah juga mendorong pemisahan aliran dan membentuk zona resirkulasi di belakang bilah, yang secara langsung memengaruhi distribusi NH₃ di hilir. Modifikasi 1, yang mengurangi luas bilah, menyebabkan peningkatan kecepatan di area pusat namun menurunkan kecepatan maksimum aliran terpusat, sehingga intensitas turbulensi menurun dan menyebabkan penurunan nilai UI baik untuk kecepatan maupun NH₃. Penambahan bilah keempat pada modifikasi ini secara signifikan meningkatkan pressure loss akibat peningkatan hambatan aliran dan zona resirkulasi. Sementara itu, Modifikasi 2 dengan ukuran bilah lebih kecil mampu menurunkan pressure loss sebesar 15% (dari 836 Pa menjadi 708 Pa), namun tetap mempertahankan karakteristik penting aliran seperti pemisahan, aliran terpusat, dan zona resirkulasi, sehingga menghasilkan nilai UI yang mendekati mixer terbaik. Temuan ini menunjukkan bahwa struktur aliran seperti resirkulasi, aliran terpusat, dan turbulensi sangat berperan dalam optimalisasi performa SCR dengan pencampuran NH₃ yang efektif dan pressure loss yang terkendali.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Emission, NOx, Selective Catalytic Reduction, Static Mixer, Emisi, NOx, Pengaduk Statis, Reduksi Katalitik Selektif
Subjects:	Q Science > QC Physics > QC151 Fluid dynamics T Technology > T Technology (General) > T57.62 Simulation T Technology > TA Engineering (General). Civil engineering (General) > TA174 Computer-aided design. T Technology > TA Engineering (General). Civil engineering (General) > TA357 Computational fluid dynamics. Fluid Mechanics T Technology > TD Environmental technology. Sanitary engineering > TD883.5 Air--Pollution T Technology > TJ Mechanical engineering and machinery > TJ762.E93 Exhaust systems T Technology > TP Chemical technology > TP155.7 Chemical processes.
Divisions:	Faculty of Marine Technology (MARTECH) > Marine Engineering > 36202-(S1) Undergraduate Thesis
Depositing User:	Akhyar Musyaffa
Date Deposited:	05 Aug 2025 02:48
Last Modified:	05 Aug 2025 02:48
URI:	http://repository.its.ac.id/id/eprint/126829

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