Pemodelan dan Validasi Distribusi Temperatur pada Reaktor Pirolisis Sekam Padi Berbasis Computational Fluid Dynamics

M. Irfan Faridh Syahira, Makbul Hajad, S.T.P., M.Eng., Ph.D., IPP.; Prof. Dr. Ir. Bambang Purwantana, M.Agr.

2026 | Skripsi | TEKNIK PERTANIAN

Pirolisis merupakan metode konversi termokimia biomassa yang dipengaruhi oleh distribusi temperatur. Penelitian ini bertujuan memprediksi dan menganalisis distribusi temperatur pada reaktor slow pyrolysis fixed bed sekam padi menggunakan simulasi Computational Fluid Dynamics (CFD), serta mengevaluasi kesesuaiannya terhadap data eksperimen pada variasi massa sekam 10, 15, dan 20 kg. Unggun sekam dimodelkan sebagai porous media, sedangkan panas pembakaran arang direpresentasikan menggunakan Effective Heat-Release Decay Model. Hasil simulasi menunjukkan temperatur puncak sebesar 481,11°C, 449,74°C, dan 400,96°C masing-masing pada massa sekam 10, 15, dan 20 kg. Peningkatan massa sekam menurunkan temperatur puncak dan memperlambat perambatan panas menuju bagian atas unggun. Validasi menghasilkan nilai RMSE sebesar 46,12°C; 93,49°C; dan 112,27°C, korelasi Pearson sebesar 0,956; 0,933; dan 0,858, serta R² sebesar 0,914; 0,871; dan 0,736 untuk masing-masing variasi. Distribusi temperatur bersifat tidak seragam, dengan temperatur tertinggi di dekat zona arang dan menurun menuju bagian atas unggun serta dinding reaktor. Model CFD mampu merepresentasikan karakteristik distribusi temperatur dengan tingkat kesesuaian yang baik terhadap data eksperimen.

Pyrolysis is a thermochemical conversion process influenced by temperature distribution. This study aimed to predict and analyze the temperature distribution in a rice husk slow pyrolysis fixed-bed reactor using Computational Fluid Dynamics (CFD) simulation and to evaluate its agreement with experimental data for rice husk masses of 10, 15, and 20 kg. The rice husk bed was modeled as a porous medium, while heat from char combustion was represented using an Effective Heat-Release Decay Model. The simulation results showed peak temperatures of 481.11°C, 449.74°C, and 400.96°C for rice husk masses of 10, 15, and 20 kg, respectively. Increasing the rice husk mass reduced the peak temperature and slowed heat propagation toward the upper section of the bed. Validation yielded RMSE values of 46.12°C, 93.49°C, and 112.27°C; Pearson correlation coefficients of 0.956, 0.933, and 0.858; and R² values of 0.914, 0.871, and 0.736 for the respective variations. The temperature distribution was non-uniform, with the highest temperatures occurring near the char zone and decreasing toward the upper section of the bed and the reactor wall. The developed CFD model was able to represent the temperature distribution characteristics with good agreement with the experimental data.

Kata Kunci : Computational Fluid Dynamics, pirolisis sekam padi, slow pyrolysis fixed bed, porous media, distribusi temperatur.