Effect of Filling Height on Bulk Density of Wheat in a Test Weight Cup

Transcription

1 Effect of Filling Height on Bulk Density of Wheat in a Test Weight Cup Presented by: Marvin C. Petingco PhD Student, Biological & Agricultural Engineering Kansas State University

2 Packing Definition the increase in grain bulk density due to the compressibility of grain when subjected to the cumulative weight of overlying material in a storage unit. Related terms packing factor, compaction, pack Use as an adjustment factor to accurately determine the mass of the grain stored in a bin Different impacts on operations Grain elevators inventory, auditing On-Farm bins insurance

3 WPACKING Description: A computer program for predicting packing and mass of stored grain in a bin How it works? Use Jannsen s equation and the relationship between overbearing pressure, moisture content and bulk density D x = weighted average of D i s D 0 = initial uncompressed bulk density D i s Packing is dependent on the initial or uncompressed bulk density (D o ) In practice, test weight is used as input for D o Q: Is the uncompressed in-bin bulk density = test weight? dy D n D 2 D 1 Bulk density gradient Source: Thompson et al., 1987; Ross et al., 1979

4 A: They are NOT Equal. Bulk Density is NOT an intrinsic property Test weight and hectoliter weight o Both standard measure of bulk density o Use different setups o Give two different values Conversion factor was developed Test weight Device (Seedburo) Australia Chondrometer (Graintec) Q: How much does the uncompressed in-bin bulk density varies with the test weight? We want to determine the in-bin bulk density before overbearing pressure is applied Improve WPACKING prediction Source: Greenaway, 1977,

5 Factors Affecting Bulk Density Manner of filling: filling method, filling height, filling rate Size and type of confining space Grain properties kernel density, moisture content, friction coefficients size of the particles, size distribution, composition amount of fines, broken, and foreign materials, dockage particle shape Source: Stephens & Foster, 1978; Chang et al., 1983; Mosey, 1984; Molenda et al., 1993; Zhong et al., 2001; Montross & McNeill, 2005; Yang & Williams,

6 Objectives of the Study Determine the effect of filling height on wheat bulk density in a test weight cup Use Discrete Element Method (DEM) simulation to predict the wheat bulk density for different filling heights DEM models the true physics of every single particle

7 Materials and Methods Sample hard red winter wheat (Varieties: Garrison, KanMark, 1863) Grain Properties Garrison KanMark 1863 Test Weight, lb/bu (0.14) (0.09) (0.07) MC, % wb 11.1 (0.1) 11.5 (0.1) 12.4 (0.1) Kernel Apparent Density (kg/m 3 ) (3) 1378 (4) Mean Kernel Length (mm) (0.5) 5.6 (0.5) Mean Kernel Width (mm) (0.6) 2.7 (0.5) Mean Kernel Thickness (mm) (0.4) 2.5 (0.4) Mean Equivalent Sphere Diameter (mm) (0.5) 3.4 (0.5) % Retained in Sieve Variety #6 #7 #8 #10 Pan Total Garrison KanMark

8 Materials and Methods Setup Winchester bushel test with some modifications Filling heights: 1h, 2h, 4h, 8h, 16h, 32h

9 Materials and Methods DEM Simulation Particle models Schemes Single-Sphere Seven-Sphere Without Striking With Striking

10 Materials and Methods DEM Simulation Particle and Material Properties Input Particle Wheat Particle Properties Measured/ Published* Poisson s ratio 0.2 * Solid Density (kg/m 3 ) KM, Shear Modulus (Pa) 7.65 x 10 7* 7.65 x x 10 7 Coefficient of Restitution (wh-wh) 0.33 * Coefficient of Static Friction (wh-wh) 0.30*, 0.38 * Coefficient of Rolling Friction (wh-wh) 0.20*, 0.18 * Coefficient of Restitution (wh-b) 0.6* Coefficient of Static Friction (wh-b) 0.37* Coefficient of Rolling Friction (wh-b) 0.1 * Coefficient of Restitution (wh-w) Coefficient of Static Friction (wh-w) Coefficient of Rolling Friction (wh-w) s 7s Properties Input Values (1s,7s) Size Distribution Mean KM, (3.3 mm) Std Dev KM, (0.5 mm) Scale by Radius Material Properties Input Values (1s,7s) Material-Brass Poisson s ratio 0.31* Solid Density (kg/m 3 ) 8490* Shear Modulus (Pa) 3.70 x 10 10* Material-Wood Poisson s ratio 0.4* Solid Density (kg/m 3 ) 5000* Shear Modulus (Pa) 1.00 x 10 7*

11 Results and Discussion Laboratory Test: Filling Height Vs Bulk Density Bulk Density (kg/m3) Interval Plot of Bulk Density vs Filling Height 95% CI for the Mean 16h 1h 32h Variety Bulk Density (kg/m3) at Different Filling Heights 1h 16h 32h KanMark (1.3) (0.5) (0.3) (1.0) (0.3) (0.6) Garrison (1.8) (4.3) (4.0) Filling Height (in) Individual standard deviations are used to calculate the intervals Increase in bulk density as filling height is increased

12 Results and Discussion DEM simulation is done at particle level

13 Results and Discussion Time to Fill the Test Cup: DEM Simulation Vs Laboratory Results Filling Height Time to Fill (s) % Difference from Actual Actual 1s 7s 1s 7s 1h 5.4 (0.2) h 5.4 (0.1) h 5.4 (0.2) Simulation time ~ % difference with the actual Time for mass to stabilize after overflowing in the test cup takes a lot of time in simulation as compared with laboratory experiment

14 Results and Discussion DEM Simulation: Filling Height Vs Heap Profile 1h 16h 32h 1h 16h 32h Z Y Z Z X Single-Sphere Particle Model X Seven-Sphere Particle Model Importance of shape of particle model Similarity of heap profile in ellipsoidal particle model with laboratory experiment

15 Results and Discussion Bulk Density: DEM Simulation Vs Laboratory Results DEM simulation without striking Filling Height Bulk Density, (kg/m3) % Difference from Actual Actual 1s 7s 1s 7s 1h h h DEM simulation with striking Filling Height Bulk Density, kg/m3) % Difference from Actual Actual 1s 7s 1s 7s 1h h h Simulated and actual bulk densities are in good agreement for both schemes

16 Conclusion Bulk density of wheat increases with filling height DEM simulation can predict the bulk density of wheat (KanMark, 1863) at different filling heights Single-sphere particle model o Without striking predicted with lower percentage error (-0.5% to +0.7%) compared with striking (-1.0 % to -1.5%) Seven-sphere particle model o With striking predicted with lower percentage difference (-0.7% to +0.1%) compared with without striking (+0.5 % to +1.4 %) Actual particle shape is critical to get accurate surface or heap profile

17 What we want to do Example: Filling Height and Bin Diameter H H h H h h d d d' d, h, H d, h, H d', h, H Initial Bulk Density or Test Weight BD Bulk Density as affected by filling height BD(H ) Bulk Density as affected by filling height and bin diameter BD(H, d ) H* h d* d*, h, H* Uncompressed In-Bin bulk density BD 0 H* h d* d*, h, H*, y Average In-Bin Bulk Density at depth y using WPACKING y Laboratory Experiment and DEM Simulation DEM Simulation DEM-ANSYS Simulation and WPACKING

18 Acknowledgements The Andersons Grant Funding Program Team Competition USDA and Kansas Ag Experiment Station Dan Brabec, Jonathan Zeller, Alex King, Elizabeth Maghirang, Dennis Tilley, Austin Ebert, Josephine Boac, Fei Xyza Asuncion

19 THANK YOU! Funding Source: The Andersons Grant Funding Program Team Competition Project Title: Determining Time, Aeration, and Loading Cycle Effects on Grain Packing Project objective being addressed: Effect of secondary crop quality parameters on packing Team Members: Mark Casada - USDA Ronaldo Maghirang Kansas State University Marvin Petingco Kansas State University Sidney Thompson University of Georgia Michael Montross University of Kentucky Samuel McNeill University of Kentucky Aaron Turner University of Kentucky Rumela Bhadra Kansas Department of Health & Environment