Numerical Simulation of Conventional and Porch Patterns for Air Inlet Channel in Paddy Dryer

Document Type : Research Article

Authors

• H. R. Gazor ¹
• O. R. Roustapour ²
• R. Jahanian ³

¹ Agricultural Engineering Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran

² Department of Agricultural Engineering Rresearch, Agricultural Engineering Research Center of Fars Province, Agricultural Research, Education and Extension Organization (AREEO), Shiraz, Iran

³ Graduated Student of Mechanic engineering (M.Sc.), Islamic Azad university, Bafgh, Iran

https://doi.org/10.22067/jam.v9i1.63603

Abstract

Introduction
Long drying time and high energy consumption are the big problems in paddy drying using conventional batch type dryer. Besides, non-uniformity occurs in paddy rice dried and low milling quality. Paddy is over dried in lower layers and broken kernel chance increased in milling process. Using of a new pattern for warm air causes to better air passing through the paddy bulk and uniformity of drying. Computational fluid dynamics (CFD) is a good method for modeling of air passing in dryers in order to find better air condition in paddy drying process. The aim of this research was investigation on common and porch patterns applied for air entrance to paddy bulk in a dryer in order to optimize air channel conditions in a conventional paddy dryer.
Materials and Methods
In this study, optimization of air flow was investigated in a batch type paddy dryer using computational fluid dynamics (CFD). Two patterns as conventional and porch (reverse V type) patterns were applied for air entrance to paddy bulk in the dryer as conventional and porch (reverse V type) patterns. Experimental examination were done using a laboratory batch type dryer with chargeable air flow pattern in 50 °C for drying paddy (Tarom-Hashmei Var.). Numerical simulation of air velocity and pressure drop in porous media of paddy in the dryer was achieved by employing computational fluid dynamics method and Fluent software. Air velocity pattern and temperature changes in bulk of paddy were investigated in different time of solution including 20, 100, 1000, 1800, 3600 and 7200 seconds for both patterns.
Results and Discussion
Considering air flow and temperature as constant, the results showed the porch type pattern has better performance than the conventional pattern for air passing in the dryer. The velocity vortex was higher in all parts of the channel in the porch scheme. Air velocity uniformed decreased from beginning to end area in the conventional pattern, but in the porch type pattern, air velocity was more in the end of the duct than beginning area. Pressure drop was about 10 percent in the conventional pattern than porch pattern. At the end of the air channel, this variation inversed due to contact of the air with the end wall and pressure drop in this part of the chamber of porch scheme was higher than the conventional one. Improvement of air flow in paddy occurred in low and middle layers in the porch type pattern and there was no difference between two air passing patterns in top layers. Validation of modeling showed that temperature disturbance of the porch model was more uniform than the conventional model and difference between temperatures of model and experiments was about 2 to 3 °C.
Conclusion
The research concluded that using of the porch type pattern had better performance than the conventional pattern for air passing in the dryer but it is needs to more supplementary research to find the best height and angle in the paddy dryer. Porch type pattern causes to more speed and uniformity of air among of paddy than the conventional pattern. This improvement observed in low and middle layers of the paddy bulk. Validation of temperature data showed that the difference between experimental and modeled data was 4 to 6 percent and this difference was higher in the conventional pattern than the porch pattern. According to the results of this research, Porch pattern can be recommended to use in the conventional batch type dryer.  

Keywords

• Computational fluid dynamics
• Modeling
• Paddy dryer
• Porous media

20.1001.1.22286829.1398.9.1.4.3

References

1. Achenbach, E. 1995. Heat and flow characteristics in packed beds. Experimental Thermal and Fluid Science 10:17-21.

2. Amanlou, Y., and A. Zomorodian. 2010. Applying CFD for designing a new fruit cabinet dryer. Journal of Food Engineering 101: 8-15.

3. Azimi, O. 2016. Computational Fluid Dynamics Analysis in a Corn Air Flow Paddy Dryer with Two Types of Passing Air Flow of Lateral and Central. Faculty of graduate. Islamic Azad University, Bafgh Branch. (In Farsi).

4. Cakmak, G., and C. Yildiz. 2009. Design of a new solar dryer system with swirling flow for drying seeded grape. International Communications in Heat and Mass Transfer 36: 984-990.

5. Esmaeilzadeh, A. 1994. Numerical heat transfer and fluid flow. Tabriz University Publisher. Tabriz (In Farsi).

6. Fadaie, D., and Y. Amanlou. 2010. Analysis of air temperature and speed profiles in Hybrid cabinet dryer using Computational Fluid Dynamics (CFD). National congress on Agricultural Machinery and Mechanization, Karaj, Iran. (In Farsi).

7. Kazemi, F. 2016. Numerical Modeling of Airflow in a Cabinet Dryer and Determination the Effect of Using Air Deflector Plates on Airflow Pattern and Drying Rate in the Dryer Chamber. Faculty of graduate. Faculty of graduate. Islamic Azad University, Bafgh Branch. (In Farsi).

8. Mirade, P. S. 2006. Prediction of the air velocity field in modern meat dryers using unsteady computational fluid dynamics (CFD) models. Journal of Food Engineering 60: 41-48.

9. Mohsenin, N. 1980. Thermal properties of foods and agricultural materials. Gordon and Breach Science Publishers Ins. New York.

10. Motamedzadegan, A., Sh. Hosseinee and M. Poormoghdam. 2013. Effect of parboiling on physical properties of Tarom Hashemi cultivates. National congress on Agricultural Machinery and Mechanization, Mashhad, Iran. (In Farsi).

11. Mousavi, S. F., M. H. Abbaspour-Fard, and M. Khojastehpour. 2015. The effect of fan speed control system on the inlet air temperature uniformity in a solar dryer. Journal of Agricultural Machinery 5 (2): 491-501.

12. Mozaffari, K. 2013. Numerical modeling of air flow in the chamber of an active solar dryer in order to flow optimization by using some elements in the dryer chamber. Faculty of graduate. Islamic Azad University, Shiraz Branch. (In Farsi).

13. Rafati-Saleh, A., and M. Zivdar. 2010. Study on turbulence models in simulation of dry pressure drop for structured packings using CFD analysis. Students Conference of Chemistry Engineering. Kermanshah, Iran. (In Farsi).

14. Rezk, K., and J. Forsberg. 2011. Geometry development of the internal duct system of a heat pump tumble dryer based on fluid mechanic parameters from CFD software. Applied Energy 88: 1596-1605.

15. Rigit, A., and P. Low. 2010. Heat and mass transfer in a solar dryer with biomass backup burner. World Academy of Science Engineering and Technology 38: 105-108.

16. Roustapour, O. R., K. Mozaffari, and A. R. Tahhavor. 2014. Optimization of energy consumption in a solar dryer by numerical modeling of flow in the chamber with air deflectors. Journal of Agricultural Machinery Science 10: 43-47.