Numerical Simulation of Corn Drying in a Hybrid Fluidized Bed‐Infrared Dryer

Abstract

This study deals with numerical modeling and experimental validation of hybrid fluidized bed-infrared drying of bulk grain. A mathematical model of simultaneous heat and mass transfer for the aforementioned dryer was developed: first single phase model was used to establish heat and mass transfer equations over the fluidized bed, then the effect of infrared heating was incorporated into the single phase model as a source term to develop the model for a hybrid fluidized bedinfrared dryer. The model is capable of predicting the moisture content of bulk corn as well as the drying air parameters (i.e., out let air temperature and out let air absolute humidity) during drying. The model was validated by comparison with experimentally obtained drying kinetics for different combinations of inlet air temperature, infrared power density and bed height. The results of verification test for all drying conditions indicated that the mean relative deviation for prediction of grain moisture content, out let air temperature and absolute humidity were less than 8, 11 and 7%, respectively, which reflects an acceptable accuracy (<15%). Other results showed that the application of infrared power in conjunction with fluidized bed drying to reduce corn moisture content from 0.23 to 0.12 kg H 2 O/kg dry solid led to a 45-87% saving in drying time and 36-68% saving in specific energy consumption compared to conventional fluidized bed configurations. The model indicated acceptable performance and hence the model could be suggested as a mathematical tool providing precise prognostications dealing with fluidized bed drying equipped with infrared heat source. PRACTICAL APPLICATIONSThe suggested model is an efficient method to simulate drying process of bulk grain in infrared-fluidized bed dryers. This model provides precise prognostications regarding the variations in grain moisture content, gas temperature and gas absolute humidity. Additionally the features of the model introduced in the present study might qualify it for use in automatic control of fluidized bed dryers and online prediction of drying time to reach a desired value of moisture content.

Parboiled Paddy Drying with Different Dryers: Thermodynamic and Quality Properties, Mathematical Modeling Using ANNs Assessment

“…The hybrid infrared-convective drying produces a synergistic effect, and is therefore considered to be more efficient than individual IR or convection drying methods [5]. It has been extensively applied on different products, including sweet potato [6] and kiwifruit [7].…”

Optimization design of cane sugar evaporative crystallizer based on orthogonal test and computational fluid dynamics

“…CFD simulation has become a useful tool for solving modern fluid engineering problems (Villermaux, 2019). For example, Nejadi and Nikbakht (2017) established a CFD model of simultaneous heat and mass transfer for the hybrid fluidized bed-infrared drying of bulk grain, which indicated acceptable performance and hence the CFD model could be a scientific tool providing precise prognostications dealing with fluidized bed drying. Ramachandran, Akbarzadeh, Paliwal, and Cenkowski (2017) conducted CFD modeling for superheated steam drying of spent grain pellet.…”

Low temperature plasma pretreatment enhances hot‐air drying kinetics of corn kernels

“…However, chemical pretreatments hold the problems of chemical additives residue (Bai, Sun, Xiao, Mujumdar, & Gao, 2013). Several nonchemical treatment methods for drying have been devised over the past decade, such as the infrared, ultrasound, microwave, superheated steam, and their combinations (Lv, Zhang, Wang, & Adhikari, 2018;Momenzadeh, Zomorodian, & Mowla, 2011;Moraitis & Akriridis, 1998;Nejadi & Nikbakht, 2017). Nejadi and Nikbakht (2017) reported that hybrid fluidized bed-infrared drying of corn led to a 45 -87% saving in drying time.…”

“…Several nonchemical treatment methods for drying have been devised over the past decade, such as the infrared, ultrasound, microwave, superheated steam, and their combinations (Lv, Zhang, Wang, & Adhikari, 2018;Momenzadeh, Zomorodian, & Mowla, 2011;Moraitis & Akriridis, 1998;Nejadi & Nikbakht, 2017). Nejadi and Nikbakht (2017) reported that hybrid fluidized bed-infrared drying of corn led to a 45 -87% saving in drying time. Abdoli, Zare, Jafari, and Chen (2018) showed that ultrasound frequency of 25 kHz and power density 14.6 kW m −3 on fluidized bed drying of corn caused 43% reduction in drying time.…”