Sains Malaysiana 48(10)(2019): 2093–2101

http://dx.doi.org/10.17576/jsm-2019-4810-04

Experimental Study of Drying Characteristics and Mathematical Modeling for Air Drying of Germinated Brown Rice

(Kajian Eksperimen Ciri Pengeringan dan Model Matematik untuk Pengeringan Udara Beras Perang)

ZHENWEI YU, KHURRAM YOUSAF, YU WANG & KUNJIE CHEN*

Department of Agricultural Engineering, College of Engineering, Nanjing Agricultural University, Nanjing, Jiangsu 210031, P.R. China

Received: 3 June 2019/Accepted: 21 August 2019

ABSTRACT

In view of existing problems in the drying process of germinated brown rice (GBR), the self-made hot air drying test system was utilized. The drying medium temperature and wind speed were selected as the drying parameters, and different constraints were set for the test. The effects of the drying medium temperature and wind speed on the drying rate and unit energy consumption were examined, and the drying mathematical models of GBR were established. The results perceived that as the temperature rose, and the wind speed increased, the drying rate increased accordingly. When the temperature was above 95°C, wind speed exceeded 3.6 m/s; the drying rate would not change deliberately. When the temperature of the drying medium rose, the change rate during the drying preheating stage and the deceleration stage increased sharply, whereas the drying rate in the constant-speed drying stage increased, and the drying time was greatly shortened. Unit energy consumption decreased with the increase of temperature and increased with increasing wind speed. Furthermore, when the drying temperature was ranged between 50°C and 80°C, the unit energy consumption changed meaningfully; when the medium temperature was between 80°C and 110°C, the unit heat consumption turned slowly. Wang and Singh’s model could best simulate the drying process of GBR within the experimental settings. And then comparing the RMSE and under the various dry conditions, the data of Wang and Singh model were between 1.6% - 2.8% and 2.5×10-4 - 5×10-4. The R2 values of the model were higher than 0.98.

Keywords: Drying characteristics; energy consumption; germinated brown rice; mathematical model; moisture content

ABSTRAK

Disebabkan masalah sedia ada dalam proses pengeringan percambahan beras perang (GBR), sistem ujian pengeringan udara panas buatan sendiri telah digunakan. Pengeringan suhu sederhana dan kelajuan angin dipilih sebagai parameter pengeringan dan kekangan berbeza ditetapkan untuk ujian. Kesan daripada pengeringan suhu sederhana dan kelajuan angin pada kadar pengeringan dan penggunaan tenaga unit disemak dan pengeringan model matematik GBR telah ditubuhkan. Keputusan menunjukkan apabila suhu meningkat dan kelajuan angin bertambah, kadar pengeringan meningkat dengan sewajarnya. Apabila suhu melebihi 95°C, kelajuan angin melebihi 3.6 m/s; kadar pengeringan tidak akan berubah secara terancang. Apabila suhu pengeringan itu meningkat, kadar perubahan pada peringkat pra-pemanasan pengeringan dan peringkat nyahpecutan meningkat secara mendadak, sedangkan kadar pengeringan pada peringkat pengeringan laju meningkat dan masa pengeringan telah banyak dipendekkan. Penggunaan tenaga unit menurun dengan peningkatan suhu dan meningkat dengan kelajuan angin. Tambahan pula, apabila suhu pengeringan berada dalam lingkungan 50°C hingga 80°C, penggunaan tenaga unit juga turut berubah; apabila suhu sederhana adalah antara 80°C dan 110°C, penggunaan haba unit bertukar menjadi perlahan. Model Wang dan Singh adalah stimulasi terbaik bagi proses pengeringan GBR dalam tetapan uji kaji. Apabila perbandingan RMSE dijalankan pada pelbagai keadaan pengeringan, data bagi model Wang dan Singh adalah antara 1.6%-2.8% dan 2.5 × 10-4-5 × 10-4. Nilai model R2 ini lebih tinggi daripada 0.98.

Kata kunci: Ciri pengeringan; kandungan lembapan; model matematik; penggunaan tenaga; percambahan beras perang

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*Corresponding author; email: kunjiechen@njau.edu.cn