CFD Simulation of Deep-Bed Paddy Drying Process and Performance

Abstract

Computational Fluid Dynamics (CFD) was applied three-dimensionally to simulate the drying behavior of paddy in a deep-bed dryer. The commercial CFD software Fluent 6.3.26 was used. The deep-bed paddy drying process and performance were studied by incorporating user-defined function (UDF) in Fluent written in C language. The predicted drying parameters were compared with experimental data of deep-bed drying of paddy. The values of mean relative deviation (MRD), standard error of prediction (SEP), and maximum error of prediction (MEP) for prediction of grain moisture content, air temperature, and absolute humidity were less than 6, 10, and 9%; 0.33% (d.b), 1.24°C, and 0.06% (kg/kg of dry air); and 2.25% (d.b), 6.8°C, and 0.37% (kg/kg of dry air), respectively, which reflect reasonable accuracy. Moreover, the energetic and exergetic performance of deep-bed paddy drying were simulated and analyzed. The effects of inlet air temperature and mass flow rate on the performance parameters were investigated. It was shown that the application of higher levels of inlet air temperature and lower mass flow rates yielded higher exergy efficiencies of deep-bed paddy drying.

Keywords:

• CFD simulation
• Deep-bed paddy drying
• Energy
• Exergy

ACKNOWLEDGMENTS

The authors would like to acknowledge Ferdowsi University of Mashhad (FUM) for all its support of this work.

Notes

Note that some of the commonly used Fluent data types are as below:.

cell_t, which is a data type for a cell identifier (e.g., cell_t c).

face_t, which is a data type for a face identifier (e.g., face_t f).

Thread, which is a data structure in Fluent (e.g., Thread *t).

Domain, which is the highest-level data structure in Fluent (e.g., Domain *d).

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