ABSTRACT
This study developed model parameters and optimized the performance of a maize dehusker sheller developed at the Institute for Agricultural Research (IAR), Ahmadu Bello University, Zaria.
To facilitate this, a study on some physical properties of ACR, QPM, and TZPB maize varieties in relation to moisture content was conducted. Three mathematical models for shelling, grain damage, and scatter loss were developed based on analysis.
All model development and were enhanced through performance evaluation experiments conducted with speed, feed rate, moisture content, and cylinder concave clearance variables each at three levels in a completely randomized block design.
The indices of model evaluation used were coefficient of determination, bias, root mean square error, index of agreement, slope, and intercept of plots between the predicted values obtained from the developed models and the measured values obtained from experiments.
Differential sensitivity coefficients were used to variables according to their order of importance in the developed models. SAS package was used for the statistical analysis of variance. Optimization based on a genetic algorithm in MATLAB R2008a toolbox was used.
Seven (7) functional parameters (input variables) under upper and lower constraints and three (3) performance criteria multi-objective output parameters were considered in the decision process in search of the solutions.
TABLE OF CONTENTS
Title page ………………………………………………………………………………….. i
Declaration ….……………………………………………………………………………. iv
Certification……………………………………………………………………………….. v
Dedication………………………………………………………………………………….vi
Acknowledgment…………………………………………………………………………vii
Abstract……………………………………………………………………………………viii
Table of Contents……………………………………………………………………………x
List of Tables……………………………………………………………………………..xiv
List of Figures……………………………………………………………………………xviii
List of Plates ……………………………………………………………………………..xix
List of Appendices ………………………………………………………………………..xx
List of Symbols…………………………………………………………………………..xxi
CHAPTER ONE: INTRODUCTION
1.1 Background ………………………………………………………………………1
1.2 The Existing IAR maize Dehusker Sheller………………………………………5
1.3 Statement of the Problem………………………………………………………….7
1.4 Justification…………………………………………………………………………8
1.5 Objectives…………………………………………………………………………..9
1.6 Scope and Limitations of the Study……………………………………………..10
CHAPTER TWO: LITERATURE REVIEW
2.1 Introduction………………………………………………………… ……………11
2.2 Development of Power Threshers ……………………………………………. ..11
2.3 Maize Processing …………………………………………………………………12
2.4 Criteria for Evaluating Threshing Performance……………………………… 16
2.5 Effects of Crop and Machine Parameters on Shelling Performance………….16
2.6 The Modeling Process……………………………………………………………21
2.6.1 General threshing models………………………………………………………….21
2.6.2 Models for stationary grain threshers ……………………………………………..30
2.7 Dimensional Analysis in Modeling ……………………………………………..33
2.7.1 Determination of pi terms…………………………………………………………33
2.7.2. Product Function of Component Equation………………………………………..34
2.7.3 Summation function of component equation ……………………………………..38
2.8. Model Performance Evaluation ……………………………………………..40
2.8.1 Model verification…………………………………………………………………42
2.8.2 Model validation…………………………………………………………………..43
2.8.3 Sensitivity analysis………………………………………………………………..44
2.9. Optimization-……………………………………………………………………45
2.9.1. Use of genetic optimization toolbox of MATLAB ……………………………….46
CHAPTER THREE: MATERIALS AND METHOD
3.1 Materials/Instrumentation ………………………………………………………48
3.2 Determination of Some Physical Properties of selected varieties of Maize …48
3.2.1 Dimensions ……………………………………………………………………..48
3.2.2 A thousand kernel mass, M1000 …………………………………………………….48
3.2.3 Moisture content …………………………………………………………………..49
3.2.4 Bulk density…………………………………………………………………………49
3.3 Performance Indices …………………………………………………………… 49
3.4 Experimental Layout and Design……………………………………………….50
3.5 Data Analysis ……………………………………………………………………..51
3.6 Theoretical Development of Prediction Equations ……………………………51
3.6.1 Description of the dehusking-shelling process ……………………………………51
3.6.2 Modeling assumptions ……………………………………………………………53
3.6.3 Shelling efficiency ………………………………………………………………. .54
3.6.4 Grain damage dimensionless groups ……………………………………………..58
3.6.5 Grain loss dimensionless groups ……………………………………………………..59
3.7 Model performance evaluation …………………………………………………59
3.8 Optimization …………………………………………………………………….60
CHAPTER FOUR: RESULTS AND DISCUSSION
4.1 Some Physical Properties of Selected Varieties of Maize (Zea mays L)………62
4.2 Model Development Experiments ……………………………………………..65
4.2.1 Effect of cylinder speed on performance indices…………………………………66
4.2.2 Effect of crop feed rate on performance indices………………………………….72
4.2.3 Effect of the cylinder – concave clearance on performance indices……………………73
4.2.4 Effect of grain moisture content on performance indices ………………………..75
4.3 Model Validation Experiments………………………………………………….76
4.3.1 Effect of cylinder speed on performance indices …………………………………76
4.3.2 Effect of Crop feed rate on performance indices…………………………………82
4.3.3 Effect of the cylinder – concave clearance on performance indices…………………..83
4.3.4 Effect of grain moisture content on performance indices…………………………85
4.4 Shelling Efficiency Model …………………………………………………….86
4.4.1 Shelling efficiency model evaluation ……………………………………………..88
4.5 Grain Damage Model……………………………………………………………90
4.5.1 Grain damage model evaluation …………………………………………………..93
4.6 Grain Loss Model ……………………………………………………………….94
4.6.1 Grain loss model evaluation ………………………………………………………98
4.7 Optimization Results …………………………………………………………..100
CHAPTER FIVE: SUMMARY CONCLUSION AND RECOMMENDATIONS
5.1 Summary ……………………………………………………………………….102
5.2 Conclusion ………………………………………………………………………103
5.3 Recommendations ………………………………………………………………104
REFERENCES …………………………………………………………………106
INTRODUCTION
Less than a dozen plant species provide over 80 % of mankind’s diet, and among these plants, the cereal crops are in the first place (Kim and Gregory, 1989a, b).
Maize is cropper excellence for food, feed, and industrial utilization (plate I). Maize is the third most important crop in the world after wheat and rice (Adebayo et al., 2010).
Worldwide production of maize as of 2008 was 785 million tons with Africa producing 6.5 % and the largest producer in Nigeria with nearly 8 million tons (IITA, 2009). World cereal production in 2014 is anticipated to reach 2, 523 million tons, some 65 million tons higher than FAO’s initial forecast published.
Continued upgrading of coarse grain harvests, maize, in particular, has been the main underlying factor (FAO, 2014).
Maize is presently the most important cereal crop in West and Central Africa because of its high yield potential, increasing role in the human diet, its use for animal feed, and in agro-allied industries (Baffour et al., 2014).
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StudentsandScholarship Team.
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