Rapid Drying of High-Moisture Paddy Using a Pneumatic Dryer with Corrugated-Surface Drying Column

Chatchai Nimmol,Anucha Hirunwat,Aswin Yodrux,M Sriariyanun,K Rattanaporn,P Yasurin,W Rodiahwati,Y.S Cheng

doi:10.1051/e3sconf/202014101006

Chatchai Nimmol, Anucha Hirunwat + Show 6 more

Open Access

https://doi.org/10.1051/e3sconf/202014101006

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Abstract

Combination of corrugated-surface drying column and multipass drying concept (first-pass and second-pass drying) was made to increase the performance of a pneumatic dryer for high-moisture paddy. In this study, different characteristics of the drying column, which could be characterized by the ratio between the corrugated-surface length (C) and the total length (L) of the drying column (or C/L), were proposed. The influences of drying temperature (120oC, 150oC, and 180oC) and value of C/L (0, 0.5 and 1.0) on the dryer performance and energy utilization of the drying process were disscussed. The drying column with a higher value of C/L had higher potential for increasing dryer performance. For the first-pass drying, the drying system using the drying column with corrugated surface could reduce the energy consumption by 14% to 44% compared with the drying system using the drying column without corrugated surface. For the second-pass drying, the drying system using the drying column with corrugated surface consumed more energy, however. The moisture reduction of paddy could also be significantly increased after the second-pass drying.

Highlights

Because the moisture content of freshly harvested paddy obtained from the field is rather high, it must be reduced to the safe level to avoid the damage of paddy during storage
Application of surface roughness, which is an effective method for heat transfer augmentation [9,10], on the drying column of the pneumatic dryer is needed to improve the dryer performance
This was because a higher degree of turbulence was created in the drying column at a higher value of C/L, leading to a higher rate of heat and mass transfer [9,10]

Summary

Introduction

Because the moisture content of freshly harvested paddy obtained from the field is rather high, it must be reduced to the safe level to avoid the damage of paddy during storage. Drying is a significant step used to reduce the moisture content of freshly harvested paddy in the rice industry. The freshly harvested paddy may be dried in the first stage to rapidly remove surface moisture from the paddy, and it is subsequently dried in the stage by the slow drying process. The pneumatic dryer is a traditional means that can be adopt as a first-stage dryer to quickly remove surface moisture from a particulate material including paddy. The pneumatic dryer has successfully been used to dry various high-moisture materials [1,2,3,4,5,6]. Application of surface roughness, which is an effective method for heat transfer augmentation [9,10], on the drying column of the pneumatic dryer is needed to improve the dryer performance. When surface roughness is applied to the pneumatic dryer, the surface area for heat transfer increases and the turbulent flow pattern of drying medium is promoted, leading to a greater rate of heat and mass transfer

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