Analisis CFD Aliran Udara Panas pada Pengering Tipe Rak dengan Sumber Energi Gas Buang
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Abstract
Abstract
Hot air from residual biomass combustion in biomass power plant can be used for drying process. The objective of this syudy was to analyze the distribution of hot air inside tray dryer using Computational Fluid Dynamic (CFD) and to modify the dryer room for copra drying based on the result of CFD analysis. Result of CFD analysis shows that the distribution of hot air inside dryer room was not homogen among trays. The average temperature at top tray (I) was 90.0±10.8oC and bottom tray (IV) was below 49oC. Modification of dryer room was carried out by adding partition wall in the end of tray to allow the hot air flow through all trays. After modification, the temperature of drying air inside dryer room increased and the temperature distribution was better than that before modification. Form CFD simulation it was resulted the temperature of drying air at tray I, II, III and IV were 114oC, 124oC, 135oC and 119oC respectively. Fruther
modification was carried out to obtain the drying temperature of 75-90oC. This drying temperature was achieved by decreasing the frequency electricity for suction fan from 50 to 25 Hz, 20 Hz and 15 Hz. From CFD simulation was indicated that in order to obtain the temperature inside dryer room of 75-90oC, the frequency of electricity should be decreased to 206.9oC (20 Hz) to 230.7oC (25 Hz).
Keywords : gas from residual biomass combustion, CFD, temperature distribution, tray dryer.
Abstrak
Udara panas sisa pembakaran biomassa pada alat pembangkit listrik tenaga biomassa dapat dimanfaatkan untuk proses pengeringan. Tujuan penelitian ini adalah menganalisis sebaran suhu pada ruang pengering dari alat pengering tipe rak yang memanfaatkan udara panas sisa pembakaran biomass menggunakan Computational Fluid Dynamics (CFD) dan melakukan modifikasi ruang pengering berdasarkan hasil simulasi CFD yang sesuai untuk pengeringan kopra. Hasil analisis CFD untuk sebaran panas di ruang pengering menunjukkan ketidakrataan sebaran udara panas antar rak pengering. Suhu rata-rata pengukuran rak paling atas (I) 90.0±10.8oC, sedangkan rak IV (bawah) 49oC. Modifikasi ruang pengering dilakukan dengan menambahkan dinding pembagi untuk mengarahkan udara pengering yang diletakkan di ujung rak I, II, dan III. Setelah penambahan dinding, udara panas lebih merata dan terjadi kenaikan suhu yang disebabkan karena panas gas buang yang besar yaitu sekitar 294.5oC. Suhu rata- rata simulasi CFD setiap rak I, II, III dan IV masing masing 114oC, 124oC, 135oC dan 119oC. Modifikasi selanjutnya dilakukan untuk mendapatkan suhu pengeringan antara 75-90oC yang sesuai untuk pengeringan kopra dengan menurunkan frekuensi kipas hisap dari 50 Hz menjadi 25 Hz, 20Hz, dan 15 Hz. Penurunan frekuensi kipas hisap menyebabkan penurunan suhu dalam ruang pengering. Dari hasil simulasi CFD menunjukkan bahwa untuk mendapatkan suhu dalam ruang pengering 75-90oC, maka suhu gas buang diturunkan menjadi 206.9oC (20 Hz) hingga 230.7oC (25 Hz).
Kata kunci: gas sisa pembakaran biomassa, CFD, distribusi suhu, pengering tipe rak
Diterima: 22 Oktober 2014; Disetujui: 15 Januari 2015
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