Performance evaluation of small scale energy efficient mixed flow dryer for drying of high moisture paddy

Abstract

Suitable drying technique and energy efficient dryer are important concerns for drying of high moisture paddy. In this study, a small scale mixed flow dryer (MFD), with presenting systematic design approach, was developed and tested for paddy drying. Performance evaluation of the developed dryer in terms of specific energy consumption, instantaneous drying and energy efficiencies, and quality of the milled rice were investigated. A comparative performance analysis between the developed MFD and industrial Louisiana State University (LSU) dryer, which is widely used for paddy drying in Bangladesh, was also studied. In addition, drying kinetics for high moisture paddy was evaluated thorough analyzing outlet air relative humidity. Energy analysis revealed that specific electrical (in terms of primary energy) and thermal energy consumption were 0.97 and 3.17 MJ kg−1 water removed, respectively in reducing paddy moisture content (mc) from initial 25 to 12%, the final mc wet basis. Calculation indicated that 33.1% specific electrical and 21% specific thermal energy consumption can be saved by MFD in contrast to the industrial LSU dryer. The energy and drying efficiency values were found to be varied from 0.85 to 0.90 and from 0.10 to 0.17, respectively. Statistical analysis revealed that paddy samples dried by the MFD yielded 16.01% higher head rice yield than sun drying method. The energy analysis tactics presented in this paper can readily be applied in performance evaluation for heated air drying of different products.