ABSTRACT
The modification of a single-rotor cassava grater was undertaken. The singlerotor grater was modified into a double-rotor self-action grater and its performances evaluated by determining its throughput capacity and efficiency. The throughput capacity was determined by grating known quantities of cassava roots in three respective runs and the time taken to grate them measured from a stop watch. The efficiency of the machine was calculated from the quantity of roots grated and quantity of roots not recovered as dough. The percentage improvement of the measured parameters of the improved machine over the single-rotor was also determined. t-test was used to determine if there was any significant difference in the performance of the single-rotor and double-rotor machine at P ≤ 0.05. Performance test-run of the machines showed that of the 10kg mean value of cassava root used for the test, 8.88kg was recovered as dough and 1.12kg not recovered for the single-rotor machine while 9.95kg was recovered and 0.55kg not recovered for the double-rotor type. The result obtained showed that the throughput capacity of the double-rotor and single-rotor were 1152kg/h and 684kg/h respectively. The corresponding efficiencies were 89% and 95% respectively. This showed an improvement of 72% and 7% of the double-rotor over the single-rotor. The t-test analysis showed that the throughput capacity of the improved machine was significantly different from that of the single-rotor grater at P ≤ 0.05. However, the machines efficiencies were not significantly different. The modification of the single-rotor grater into a double-rotor self-action machine showed great improvement in the throughput capacity of the machine. Thus, it was established that power rating of prime-mover of existing motorized grater can also be used to run the modified grater to result in much greater throughput capacity without any significant difference in their efficiencies.
TABLE OF CONTENTS
Certification and Approval i
Dedication ii
Acknowledgement iii
Abstract iv
Table of contents v
List of Tables ix
List of Figures x
List of Plates xi
CHAPTER ONE: INTRODUCTION
1.1 Background of the Study 1
1.2 Statements of the Problem 2
1.3 Objectives of the Study 2
1.4 Significance of the Study 3
1.5 Limitations of the Study 3
1.6 Scope of the Study 4
CHAPTER TWO: LITERATURE REVIEW
2.1 Origin of Cassava 5
2.2.0 Types and Classification of cassava 6
2.2.1 Scientific Classification of Cassava 6
2.2.2 Sweet/Bitter Cassava 7
2.2.3 Cultivars/Clones of Cassava 8
2.3.0 Uses/Processing of Cassava 9
2.3.1 Uses of Cassava 9
2.3.2 Processing of Cassava 10
2.4.0 Grater/ Cassava Grater 13
2.4.1 Grater 13
2.4.2 Cassava Grater 13
2.5.0 Types of Cassava Grater 13
2.5.1 Manual Grater/Traditional Method 13
2.5.2 Pedal Grater 15
2.5.3 Motorized Grater 15
2.6 Appraisal of Existing Manual and Motorized Graters 17
CHAPTER THREE: MATERIALS AND METHODS
3.1 Description of Grater 19
3.1.1 Description of Single-Rotor Grater 19
3.1.2 Description of Double-Rotor Grater 21
3.2 Design Analysis of Double-rotor Grater 23
3.2.1 Design Considerations 23
3.2.2 Shaft Design 28
3.2.3 Design of Grating Rotor 40
3.2.4 Design of Gears 42
3.2.5 Design of Machine Frame 50
3.2.6 Design of Pulley 50
3.2.7 Selection of Bearing 54
3.2.8 Selection of Belt 56
3.2.9 Design of Hopper 59
3.2.10 Design of Outlet Chute 59
3.3 Performance Evaluation 59
3.3.1 Evaluation Procedure 59
3.3.2 Determination of Throughput Capacity 60
3.3.3 Estimation of Efficiency 61
3.4 Analysis 63
CHAPTER FOUR: RESULTS AND DISCUSSION
4.1 Results 64
4.2 Discussion 66
CHAPTER FIVE: CONCLUSION AND RECOMMENDATIONS
5.1 Conclusions 67
5.2 Recommendations 68
References 69
APPENDICES
1. Calculation of Shaft Diameter of Rotor 1 73
2. Calculation of Shaft Diameter of Rotor 2 74
3. T-test Analysis for Throughput Capacity 75
4. T- test Analysis for Efficiency 78
5. Bill of Engineering Measurement and Evaluation (BEME) 81