Drying Air Properties Investigation and Simulation Study of a Commercial Mixed-Flow Batch Type Paddy Seed Drying System

Publication Date : 20/06/2019


Author(s) :

Azmi. M., Z., Rukunudin. I., H., Ismail. H., A., Dahuli. K..


Volume/Issue :
Volume 2
,
Issue 1
(06 - 2019)



Abstract :

In Malaysia, numerous extensive research to gauge the performance and efficiency of paddy dryers were conducted by past researchers. These studies gave valuable insights into paddy drying and promoted further research oppurtunities, especially in engineering and technical studies. However, the study of commercial grain dryers performance for paddy seed drying still lacks in Malaysia. The absence of fundamental information, such as the static pressure requirement, the right volume of air (volumetric flow rate) and the drying air temperature profile requisite in regard to paddy seeds drying leads to illinformed judgements and poor decision-making which can be detrimental, especially in regars to the design and plant installation. This study was therefore undertaken to investigate the three pertinent parameters i.e. static pressure, volumetric flow rate and the temperature profile of the drying air of a commercial, mixed-flow, batch type seed dryer at Loji Pemprosesan Benih Padi Sah (A) at Telok Chengai, Kedah using both field experimentation and computational fluid dynamics (CFD) simulations. Results from experimentation investigation suggested that in current operating condition and configuration, the drying system is producing 460 Pa (46.90 mmH2O) of static pressure per 300 mm of grain bed depth which is lower than the recommended value of 500 Pa (51.00 mmH2O) and 4 times lower than the actual required value due to higher grain bed depth (1,200 mm) at the top of the dryer. The volumetric flow rate of 15,699 m³/h (9,240 cfm or 577 cfm/mt) produced by the blower fan also indicated that it lacks volume of air to facilitate efficient drying rate as recommended value are as high as 1,589 cfm/mt. Thermal imaging of the drying system revealed that 8.88% losses in temperature occured from the blower fan (45°C) to the drying plenum (41°C). Computational Fluid Dynamics (CFD) simulations was performed through ANSYS-Fluent commercial software indicated that these results were acceptable as the disparity between the actual experimentation results and the simulated results were 10.0% and 7.3% for the static pressure and temperature profile respectively.


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