Storage Aeration and Dehydration

of Almonds

Michael CoatesPhD candidate

Purpose

1) To shorten the current ground drying process and reduce the likely contact with soil and possible contaminates under wet conditions by going directly to storage.

2) To control mould growth and pest infestation by controlling the climate within the stockpile.

Benefits:• Harvesting is not dependant on the weather conditions.• Transmission of soil contaminates can be better controlled.• Prevent the growth of moulds and pest infestation within the

stockpile.• Stockpile life and quality time can be extended.

(commons.wikimedia.org, 2007)

Introduction

• The first 6 months • The PhD project•Current progress

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The First 6 Months

•Literature review•Research proposal•Confirmation of candidature•Data collection•Liaisons for a test bunker

The PhD Project

A CFD coupled DEM computer model for aerating / dehydrating almonds in bulk storage.

Discrete Element Method (DEM)Computational Fluid Dynamics (CFD)

The PhD Project

Discrete Element Method (DEM)

1. The almond is build from spheres to get the closest likeness.2. Properties are applied to that group of spheres.3. A factory of thousands are created to observe the interaction over

time.4. Primarily used in mining and soil modelling

• Customer algorithm for dimensional changes5. Limited consideration for environmental conditions

(Sarnavi et al., 2013)(DEM Solutions, 2013)

The PhD Project

Computational Fluid Dynamics (CFD)

1. A storage medium is devised with known boundary conditions.2. Inlets and vents are specified on the model.3. Conditions are applied to the model such as rate of airflow, pressure and

change in temperature.4. A fluid (air) is introduced and observed over time.5. Limited consideration for dynamic change in geometry

Air velocity (left) and pressure (right) in a silo (Falkner G., 2004)

The PhD Project

DEM coupled CFD• Provides a more realistic model of the

interaction between the storage medium, the almonds and the environment.

• Determine the best storage design and air flow configuration.

• Maximise airflow• Map changes in relative humidity• Predict fungal growth

(DEM Solutions, 2013)

The PhD Project

Material properties from literature and experiment.

• Bulk density• resistance to air flow• Water Activity (Aw)• Mass transfer• Rate of desorption• Rate of diffusion

• Thermal transfer

25° C Nonpareil isothermal (King et al., 1983)

Current Progress

Acquiring the software and hardware

Moisture content test

Air resistance test

Literature highlights (Karaj et al, 2012)

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Hull Shell Kernel

Current Progress

Moisture Content Test TG&P Orchard (March 2013)

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Before hull split Just after hull split Ready to shake

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Before hull split Just after hull split Ready to shake

Moi

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Kernel

Peerless Nonpareil

Each tree ranges between 85% and 20% Moisture Content

Before hullsplit

Just afterhull split

Ready toharvest

Current Progress

Air resistance Test

Final design

Initial design

Current Progress

Literature Highlights• Most literature is focused on the kernel• Requires experiments to be run to capture hull data

• Open loop control systems• 75% of drying happens in the first 2 hrs. due to

convection. • Systems don’t account for the diffusion cycle.

Desorption rate for Nonpareil (Moreira et al., 1989)

Grain moisture gradient after 10 min (Oliveira et al., 2012)

Acknowledgments

Supervisors:Assoc. Professor John Fielke – The University of

South AustraliaDr Chris Saunders – The University of South

Australia

Industry Co-ordinator:Ben Brown – Almond Board of Australia

This project (AL12003) has been funded by HAL using the Almond levy, voluntary contributions from

industry and matched funds from the Australian Government.

References

Commons.wikimedia.org, 2007, http://commons.wikimedia.org/wiki/File:Rain_cloud_swifts_creek_0107.jpg – raincloud, viewed June 2, 2013.

www.Usefulbusiness.co.uk, 2011, http://www.usefulbusiness.co.uk/blog/2011/4/17/is-the-big-new-idea-overrated.html, viewed June 2, 2013.

King, A. D., W. U. Halbrook, G. Fuller and L. C. Whitehand (1983). Almond nutmeat moisture and water activity and its influence on fungal flora and seed composition. Journal of Food Science 48(2): 615-617.

Sarnavi, H. J., A. Noor Mohammadi, A. Modares Motlagh and A. Rahmani Didar (2013). DEM model of wheat grains in storage considering the effect of moisture content in direct shear test. Research Journal of Applied Sciences, Engineering and Technology 5(3): 829-841.

Falkner, G., 2004 , Numerical Investigation Into the Aeration of Grain Silos, http://eprints.usq.edu.au/11/1/GriffithFAULKNER-2004.pdf, viewed June 2, 2013.

DEM Solutions, 2013, http://www.dem-solutions.com/software/edem-software/particle-fluid-interactions/, viewed June 2, 2013.

Karaj, S., K. Meissner and J. Müller (2012). Geometric vs. Aerodynamic diameter for modelling airflow resistance of wood chip. International Conference of Agricultural Engineering CIGR-AgEng2012. Valencia, Spain.

Internetmarketingvolt.com, 2012, http://internetmarketingvolt.com/keyword-research-and-its-benefits, viewed June 2, 2013.

Moreira, R. G. and F. W. Bakker-Arkema (1989). Moisture desorption model for nonpareil almonds. Journal of Agricultural Engineering Research 42(2): 123-133.

Oliveira, V. A. B. d., A. G. B. d. Lima and C. J. e. Silva (2012). Drying of wheat: A numerical study based on the non-equilibrium thermodynamics. International Journal of Food Engineering Failure Analysis 8(3): 19.

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