CFD simulation of fixed bed dryer by using porous media concepts: Unpeeled longan case
DOI:
https://doi.org/10.25165/ijabe.v6i1.677Keywords:
deep-bed dryer, longan, velocity and temperature distribution, Computational Fluid Dynamic (CFD), ANSYSAbstract
Quality of dried product depends on the temperature and velocity at each position in the dryer. Simultaneous microscopic and macroscopic simulation on Computational Fluid Dynamic (CFD) is a general problem of fixed bed dryer consisting of water transportation in porous media and dynamic flow of hot air in the dryer. Simplifying the dryer by assuming the packed bed as porous volume, viscous and inertial resistances (1/? and C2) are necessary for calculating the pressure drop and velocity change in the bulk. Comparing the ?P/L of the standard packing with experimental results, the porosity and resistance parameters can be estimated. Simulation of unmodified, adding false floor and invest mesh, and insulating the dryer wall are used for validation with previous results. Adding the round holed sieve as false floor and invert mesh can produce better profile but cannot obtain uniform distribution. Air velocity distribution shows similar but the calculating temperature is higher than that from the experiment. By analysis of thermal efficiency of dryer without insulator, the heat loss rates with flue gas and heat flux at wall are in the range 14%-17% and 5.5%-7.3%. Integrating with single fruit or thin layer drying kinetic in the future, the CFD simulation can be used for optimal design of fixed bed dryer.References
Norton T, Sun D W. Computational fluid dynamics (CFD)-an effective and efficient design and analysis tool for the food industry: A review. Trends in Food Science & Technology, 2006; 17(11): 600-620.
Xia B, Sun D W. Applications of computational fluid dynamics (CFD) in the food industry: A review. Computers and Electronics in Agriculture, 2002; 34(1-3): 5-24.
Lawrence J, Maier D E. Three-dimensional airflow distribution in a maize silo with peaked, levelled and cored grain mass configurations. Biosystems Engineering, 2011; 110(3): 321-329.
Molenda M, Montross M D, McNeill S G, Horabik J. Airflow resistance of seeds at diferent bulk density using Ergun's equation. Transactions of the ASAE, 2005; 48(3): 1137-1145.
McCabe W L, Smith J C, Harriott P. Unit Operations of Chemical Engineering. 6th Ed. New York: McGraw-Hill Higher Education; 2001.
Phaphuangwittayakul W, Alikhani Z, limpiti S. A batch dryer for un-peeled longan drying. Agricultural Mechanization in Asia, Africa and Latin America, 2004; 35(1): 41-44.
Henz L C. Thermal efficiency investigation of a longan dryer in Chiang Mai, Thailand. Project report, Stuttgart, Germany: University of Hohenheim; 2005.
Azcárraga J C G. Performance investigation of a Taiwan type flatbed dryer currently used for longan (Dimocarpus longan Lour.) in Chiang Mai, Thailand. Master Thesis, Stuttgart, Germany: University of Hohenheim; 2006.
Nagle M, Azcárraga J C G, Phupaichitkun S,
Mahayothee B, Haewsungcharern M, Janjai S, et al. Effects of operating practices on performance of a fixed-bed convection dryer and quality of dried longan. International Journal of Food Science & Technology, 2008; 43(11): 1979-87.
Nagle M, 1Azcárraga J C G, Mahayothee B, Haewsungcharern M, Janjai S, Müller J. Improved quality and energy performance of a fixed-bed longan dryer by thermodynamic modifications. Journal of Food Engineering, 2010; 99(3): 392-399.
ANSYS. Ansys Fluent Theory Guide. Canonsburg, PA: ANSYS Inc., 2011; 786 p.
Molenda M, Montross M D, McNeill S G, Horabik J. Airflow resistance of seeds at different bulk density using Ergun’s equation. Transactions of the ASAE, 2005; 48(3): 1137-45.
Thompson S A, McNeill S G, Ross IJ, Bridges T C. Packing factors of whole grains in storage structures. Applied Engineering in Agriculture, 1997; 3(2): 215-221
ANSYS. ANSYS FLUNT 13.0 user’s guide. Canonsburg, PA: ANSYS, Inc.; 2009.
Perry R H. Perry’s chemical engineer's handbook. New York, USA: McGraw-Hill Companies, Inc., 1999.
Ouchiyama N, Tanaka T. Porosity Estimation for Random Packings of Spherical Particles. Industrial and Engineering Chemistry Research Fundamentals, 1984; 23(4): 490-493.
Downloads
Published
How to Cite
Issue
Section
License
IJABE is an international peer reviewed, open access journal, adopting Creative Commons Copyright Notices as follows.
Authors who publish with this journal agree to the following terms:
- Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
- Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
- Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access).
