ABSTRACT
This study focused on development and evaluation of an integrated bush mango nut extraction and drying machine. The machine comprises of two processing operations: seed (nut) extracting and drying units. The extracting unit consists of the de-fleshing/de- pulping chamber and the separating chamber. Powered by a single prime mover, the integration was achieved through open, crossed belts and pulley arrangement for synchronized operations. The design capacity of the bush mango hopper was for 60 bush mango fruits. Performance evaluation of the nut extraction efficiency, 𝜂𝑒𝑥(%) was carried out at varied fruit moisture contents (fresh and microwaved fruits) and de- fleshing speed ranging from 51.8% to 91.8% and 27rpm to 67rpm respectively. The result indicated maximum extraction efficiency, of 91.67% at a de-fleshing speed of 27rpm and moisture content of 91.8 % with an average output of 107.84Kg/hr. It was also found that the de-fleshing time varied slightly with fruit mass. The dryer demonstrated a capacity of 2.57Kg of moisture removal in 2 hrs 20 mins, evident from the test conducted. Cost benefit analysis carried out showed that the machine has a benefit-cost ratio of 1.28 which is acceptable for investment. Hence, the machine significantly reduces production time and eliminates drudgery in the production of bush mango dry nuts.
TABLE OF CONTENTS
Title Page i
Declaration ii
Dedication iii
Certification iv
Acknowledgements v
Table of Contents vi
List of Tables ix
List of Figures x
List of Symbols and Abbreviations xii
Abstract xiv
CHAPTER 1: INTRODUCTION
1.1 Background of Study 1
1.2 Statement of Problem 4
1.3 Aim and Objectives of Study 4
1.4 Scope of the Study 4
1.5 Justification for the Study 5
CHAPTER 2: LITERATURE REVIEW
2.1 Overview of the Irvingia Spp 6
2.1.1 Some physical and mechanical properties of Irvingia nuts 7
2.2 Review of Fruit Juice Extractor, Separator and Drying Machines 8
2.2.1 Review of fruit juice extractor 8
2.2.2 Review of separators 9
2.2.3 Review of dryers 11
2.4 Processing Stages Involved in Processing Bush Mango Fruit to Kernel 12
CHAPTER 3: MATERIALS AND METHODS
3.1 Materials 13
3.1.1 Material properties 13
3.1.2 Other considerations in the selection of mild Steel for the machine construction 13
3.2 Method 15
3.2.1. Machine component and descriptions 15
3.2.2 Mode of machine operation 18
3.2.3 Design calculations 19
3.3 Design Analysis of the Bush Mango Seed Extraction and Drying Machine 23
3.3.1 Design of the machine hopper 24
3.3.2 Weight capacity of the de-fleshing unit 25
3.3.3 Weight capacity of the separating unit 27
3.3.4 Weight capacity of the drying unit 28
3.3.5 Selection of pulleys and belts 29
3.3.6 Determination of center distance 30
3.3.7 Determination of length of belt 31
3.3.8 Determination of actual center distance 31
3.3.9 Determination of angle of lap of belts 32
3.3.10 Determination of tensions in the belts 32
3.3.11 Selection of shafts material 34
3.3.12 Simulation for bending moment, shear force, deflection and
ideal diameter of the shafts using INVENTOR CAD software 35
3.3.13 Selection of prime mover 43
3.4 Determination of Heat Required for Drying Wild Mango Seed 43
3.5 Performance and Cost Evaluation Procedure 44
CHAPTER 4: RESULTS AND DISCUSSION
4.1 Performance Analysis of an Integrated Bush Mango Nut Extraction
and Drying Machine 47
4.2 Cost Analysis of the Developed Integrated Bush Mango Nut
Extraction and Drying Machine 51
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion 55
5.1.1 Contribution to knowledge 56
5.2 Recommendations 56
REFERENCES APPENDICE
LIST OF TABLES
2.1 Frictional Properties of Irvingia Nut at different Moisture and Page Contact Surfaces 8
4.1 Processing Time of Various Masses of Bush Mangoes at 27rpm 49
4.2 Bill of Engineering Measurement and Evaluation (BEME) 52
4.3 Payback period of the bush mango nuts processing machine 53
4.4 Benefit-cost analysis of the bush mango nut extraction and drying machine 54
LIST OF FIGURES
1.1 Various Fruit in Both the Ripe and Unripe Stage 2
2.1 Iringa Spp Dry Kernel 7
2.2 Flow Diagram of How Wild Mango Fruit Is Process into Dry Kernel 12
3.1 Isometric View of the Developed Wild Mango Nut Extraction and Drying Machine 15
3.2 Exploded View of Wild Mango Nut Extraction and Drying Machine 16
3.3 Schematic Diagram of the Bush Mango Nut Extraction/Drying Machine 23
3.4 Arrangement of Bush Mango in the Hopper 24
3.5 a Bending Moment Diagram of the Separating Shaft 36
3.5b Shear Force Diagram of the Separating Shaft 36
3.5c Shear Stress Diagram of the Separating Shaft 37
3.5d Deflection Diagram of the Separating Shaft 37
3.5 e Ideal Diameter of the Separating Shaft 37
3.6 a Bending Moment Diagram of the De-Fleshing Shaft 38
3.6b Shear Force Diagram of the De-Fleshing Shaft 39
3.6c Shear Stress Diagram of the De-Fleshing Shaft 39
3.6d Deflection Diagram of the De-Fleshing Shaft 39
3.6 e Ideal Diameter of the De-Fleshing Shaft 40
3.7 a Bending Moment Diagram of the Dryer Shaft 41
3.7b Shear Force Diagram of the Dryer Shaft 41
3.7c Shear Stress Diagram of the Dryer Shaft 42
3.7d Deflection Diagram of the Dryer Shaft 42
3.7e Ideal Diameter of the Dryer Shaft 42
4.1 Effect of Speed on Extraction and De-Fleshing Efficiency 47
4.2 Effect of Mass of De-Fleshed Bush Mango Nut on the Processing Time 50
4.4 Chart of Responses to Moisture at 27rpm of De-Fleshing Chamber Speed 51
LIST OF SYMBOLS AND ABBREVIATIONS
a Cross sectional area
BCR Benefits Cost Ratio
𝐵𝑓 Breadth of bush mango fruit
Bt Benefits in time
C Centre distance between two pulleys
C1 Actual centre distances between the electric motor pulley and the
C2 Actual centre distance between driving pulley of the separating shaft and
𝐶𝑆 Theoretical capacity
Ct Costs in time
𝐶𝑤𝑚𝑠 Specific heat capacity of wild mango seed
d Shaft diameter
D Screw diameter
D1 Diameter of pulley on the driving shaft
D2 Diameter of pulley on the driven shaft
DA Diameter of the pulley fixed on the electric motor
DB Diameter of the pulley on the separating unit
Dc Base diameter of cone
Dc Base diameter of cone
dc Tip diameter of cone
dc Tip diameter of cone
DC Diameter of the driving pulley fixed on the separating shaft
DD Diameter of drying cylinder
DD Diameter of the pulley on the speed reducer
Ddc Base diameter of de-fleshing cylinder
DE Diameter of the pulley fixed on the de-fleshing shaft
𝐷𝑓 Average diameter of bush mango fruit
DF Diameter of the pulley on the drying shaft unit
di Inner diameter of the screw conveyor
Do Outside diameter of the screw conveyor
Dsc Diameter of separating cylinder
Dsc Diameter of separating cylinder
𝐸𝑡 Total energy consumption
g Acceleration due to gravity
hw Latent heat of vapourisation
Kb ,Kt Combined shock and fatigue factor for bending L Length of the screw conveyor
Lb Length of belts
Lb1 length of the belt between the electric motor and the separating shaft Lb2 length of the belt between the separating shaft and the speed reducer shaft pulley
Lb3 length of the belt between the de-fleshing shaft and the dryer shaft pulley
Lc Length of cylinder
Lc Length of the de-fleshing chamber
Lc Length of cylinder
lc Length of de-flesher cone
LD Length of drying cylinder
Ldc Length of the de-fleshing chamber
Lds Length of drier shaft in drying chamber
𝐿𝑓 Length of bush mango fruit
Ls Length of de-flesher shaft in de-fleshing chamber Lsc Length of separating cylinder
Lsc Length of separating cylinder
LSS Length of separating shaft in separating chamber m Mass per unit length
M moisture removed
M1 – M5 Different bush mangoes moisture content
mb Maximum bending moment on the shaft, N-mm Md Mass of dry bush mango nuts
𝑚𝑑 Mass of de-fleshed bush/wild mangoes
𝑚𝑜 Initial moisture content
mt Maximum twisting moment on the shaft, N-mm Mw Mass of fresh bush mangoes
𝑚𝑤𝑚𝑠 Mass of wild/bush mango seed/nut
N Shaft speed
N1 speed in rpm of the driving shaft
N2 Speed in rpm of the driven shaft
NA Rated speed of the electric motor
NB Speed of separating shaft pulley
𝑁𝑏𝑚 Number of fresh bush mangoes
ND Speed of speed reducer pulley
NE Speed of the de-fleshing unit
𝑁𝑒𝑥 Number of extracted bush/wild mango nuts NF Speed of dryer shaft pulley
𝑁𝑖𝑝𝑑 Number of improperly de-fleshed bush mango nuts
𝑁𝑝𝑑 Number of properly de-fleshed bush mango nuts
PdC Power transmitted from the de-fleshing shaft to the drying chamber PDC Power transmitted from the separating shaft to the de-fleshing chamber Pm Power rating required
PSC Power transmitted by the electric motor to the belt at the separating chamber
PT Total power required
PVB Present Value Benefit
PVC Present Value Cost
Q Quantities of heat required
Rc Base radius of cone
rc Tip radius of cone
rds Radius of drier shaft
𝑟𝑖 Interest rate
rs radius of de-flesher shaft
Rsc Radius of separating cylinder
Rsc Radius of separating cylinder
rss Radius of separating shaft separating shaft pulley
t Time taken
T1 Tension on the tight side of belt
T2 Tension on the slack side of belt
Ta Tension on the tight side of the belt driving the separating shaft
Tb Tension on the slack side of the belt driving the separating shaft
Tc Centrifugal tension
Tf Final temperature the pulley of the speed reducer driven pulley of the drying shaft
Tmax maximum tension
To Initial temperature
𝑇𝑝 Throughput capacity
V Volume
V.R Velocity ratio
V60f Volume of 60 pieces of wild mango
V8f Volume occupied by 8 wild mango fruits
VBH Volume of the de-fleshing unit or chamber
VBH1 Actual volume of the de-fleshing chamber
VD Volume of drying chamber
VD1 Actual volume of the drying chamber
Vsc Volume of cylinder in separating chamber
Vsc Volume of cylinder in separating chamber
Vsc1 Actual volume of the separating chamber
Vsc1 Actual volume of separating chamber
W Effective weight capacity
WBG Weight of de-fleshing shaft
WDG Weight of dryer shaft
𝑊𝑏𝑚 Weight of bush mango
WDp Weight of the driven pulley on the separating shaft
Wdp Weight of the driving pulley on the separating shaft
WDP Weight of the drying shaft pulley
WEM Weight of the de-fleshed bush mango
WEM Weight of the separated bush mango
𝑊𝑓 Width of bush mango fruit
WP Weight of the driven pulley on the de-fleshing shaft
WSS Weight of separating shaft
x Truncated length of cone
𝑣 Inlet velocity
θ Angle of lap
θ1 Angle of lap of the belt connecting the electric motor and the separating unit pulley
θ2 Angle of lap of the belt connecting the driving pulley of the separating unit and the speed reducer pulley
θ3 Angle of lap of the belt connecting the de-fleshing shaft pulley and the drying shaft pulley
µ Coefficient of friction between belt and pulley
𝜌 Screw pitch
Θ Filling factor
𝜌𝑏𝑚 Density of bush mango
2β Groove angle
σ Maximum safe stress
α Coefficient of increase of the belt length per unit force
𝑟 Allowable shear stress for steel shaft
𝜂𝑚 Load factor of electric motor
𝜂𝑒𝑥 Extraction efficiency
𝜂𝑑 De-fleshing efficiency
𝜂𝑚 Load factor of electric motor
𝜂𝑒𝑥 Extraction efficiency
𝜂𝑑 De-fleshing efficiency
∆T Change in temperature
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND OF STUDY
Bush Mango (Irvingia gabonesis) commonly known and referred to as Ogbono, African Mango, Iba-tree, wild mango, Dikanut or Odika bread tree are economically important fruit tree, native to moist lowland tropical forest in Central and West Africa, constitutes an important part of rural diet in Nigeria (ICRAF and FAO,2021). The tree is a hard wood and the fruit is a fleshy, fibrous drupe concealing a nut with the seed used for weight loss source. Traditionally, the kernels are dried in the sun, grind to paste or powder and used to thicken certain Nigerian and Cameroonian soups. The bush mango seed extracts used for weight loss is rich in proteins, fiber and antioxidants. Research on bush mango shows beneficial effect for diabetes and obesity as well as analgesic, antimicrobial, antioxidant, and gastrointestinal activity (Gbagbo et al., 2013).
Ethno-medicinal treatments utilize the bark, kernels, leaves or roots for a variety of ailments (Lowe et al., 2000). The bark is mixed with palm oil for treating diarrhea and for reducing the breast feeding period (George and Zhao, 2007). The shavings of the stem declaration bark are consumed by chewing which can be used for the treatment of hernias, yellow fever, and dysentery and to reduce the effect of poison in French Equatorial Africa (George and Zhao, 2007).
The antibiotic properties of the bark help cure scabby skin and the boiled bark relieve tooth pain (Ainge and Brown, 2001). The Mende tribe in Sierra Leone grinds the bark into a paste with water and rubs it as a product to the skin for pain relief (George and Zkao, 2007) in some parts of Africa countries. The bark is ingested to produce analgesic effect while the powdered kernels act as an astringent and are also rubbed on burns (George and Zhao, 2007). The stems of the tree are used as chewing sticks to help clean teeth (Ainge and Brown, 2001).
Fruit maturity of irvingia gabonensis is barely three to four months. Harvesting is done manually by gathering the fallen ripe fruit by the villagers’ processors or mechanically using harvester, which stakes the stem and collects the fallen fruits through its tray collector to avoid bruising of the mesocarp. The fruit is stored in a controlled atmosphere storage system when the temperature is made a little below room temperature but not freezing.
Irvingia gabonensis has its fruiting period on the rainy season, which is ripen, in June and August (Chudnoff, 1980). The fruits are green, which turn pale-yellow at ripening stage as shown in Fig.1.1.
Fig. 1.1: Various fruit in both the ripe and unripe stage.
It is about 3-5cm long in size and spherical or ellipsoidal in shape. The fruit comprises fleshy mesocarp and the nut which is made up of a hard shell and flattened kernel and seed (FAO, 1982). Its seeds have an outer brown testa (hull) and two white cotyledons. Etukudo (2003) gave the optimum temperature for the fruit storage as 25oC. It was further noted that above this temperature, quick fruit ripening leading to spoilage is induced. Also, below this stated temperature, the pulp starts decaying. The fruit can be stored for a period of four to five months provided the atmospheric parameters favoring the storage are maintained (Sedgley and Grafin, 1989).
The fruit is grown for food and foreign exchange purposes. It is used as sauces and thickener in soups to achieve a desirable glutinous consistency. It also serves as a complement to “fufu’ “gari”and “cocoyam”. In processing Irvingiagabonensis fruits to kernel, the fibrous pulp is eaten raw because of its sweetness or used for the production of juice, jelly and jam (Okafor, 1973). The nut can be sundried, drum dried or smoked to aid the extraction of the kernel. The kernel can be extracted from the nut by the use of matched to crack the nut or striking it against stone or using machine to crack the nut open for the kernel extraction.
1.2 STATEMENT OF PROBLEM
From research, Irvingia spp are locally processed which totally has a longer processing time and because of drudgery involved at different processing stages, mass production of this seed and year round market availability is a major problem. So literally, the sector is faced with some problems stemming from long processing time of the seeds which result in low output (difficulty in mass production of the seeds) and difficulty in increasing profit margin for investors because of low production rate. All these were as a result of inadequate mechanisation and integration of the processing operation. Moreover, several operations within the processing line can adequately be integrated thereby making the process cost effective and energy saving in addition to reduction in processing time.
1.3 AIM AND OBJECTIVES OF STUDY
The aim of this work is to design and evaluate Irvingia spp (fruit) nut extraction and drying machine. The specific objectives are:
i. To design and fabricate an integrated Irvingia spp nut extraction and drying machine,
ii. To Evaluate the performance of the developed processing machine,
iii. To perform cost benefits analysis of the developed processing machines.
1.4 SCOPE OF STUDY
This study involves design, fabrication, and performance testing (which include: Best operating Speed, Defleshing efficiency, Extraction efficiency and Throughput capacity) and cost benefits analysis of Irvingia spp. processing machines.
1.5 JUSTIFICATION OF THE STUDY
Development of integrated Irvingia spp, processing machines will be of great relief to producers and marketers of the Irvingia spp kernel product, as it makes for much availability of the product and in large quantity. There is an integrated nut extraction and drying unit and a stand-alone seed cracking unit which would increase production, reduce processing time, create great relief to farmer of Irvingia spp. This innovation is to aid and encourage youths to engage in Irvingia spp cultivation, seed processing into ogbono, being stress free and at the same time have high return on investment
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