ABSTRACT
A 1.05 cubic metre capacity storage facility which is to increase the shelf life of stored vegetables as designed fabricated and tested. The equipment operates on the principle of evaporative cooling and increasing the relative humidity of the interior of the equipment. The door and the back wall were of particle board of 12mm thickness while the two sides are made of jute bag through which water flows on a trough at the top flows with the influence of gravity. The facility designed was able to contain tomatoes and Celosia spp. for nine (9) days without appreciable deterioration while the control vegetables were totally spoilt .The cooling efficiency was found to be 85.5% and the average cooler temperature was 20.5°C while the average outside temperature was found to be 28°C. The material cost of the facility was 90,000 naria
TABLE OF CONTENTS
TITLE
CERTIFICATION
ABSTRACT
ACKNOWLEDGEMENTS
DEDICATION
TABLE OF CONTENTS
LIST OF TABLES
LIST OF FIGURES
LIST OF PLATES
CHAPTER ONE:
INTRODUCTION
1.1 GENERAL BACKGROUND
1.2 STATEMENT OF PROBLEM
1.3 JUSTIFICATION
1.4 OBJECTIVE OF STUDY
1.4.1 SPECIFIC OBJECTIVES
CHAPTER TWO:
LITERATURE REVIEW
2.1 HISTORY OF EVAPORATIVE COOLERS
2.2 ADVANCES IN EVAPORATIVE COOLING TECHNOLOGY
2.3 FACTORS AFFECTING SHELF LIFE OF FRUITS AND VEGETABLES
2.3.1 Ambient conditions
2.3.1.1 Temperature
2.3.1.2 Relative humidity
2.3.2 Variety and stage ripening
2.4 FACTORS ACCOUNTABLE FOR DETERIORATION IN FRUITS AND VEGETABLES
2.4.1 Physiological activity
2.4.2 Pathological infection
2.4.3 Mechanical injury
2.4.4 Water evaporation
2.5 POST-HARVEST CHANGES IN THE QUALITY OF FRUITS AND VEGETABLES
2.5.1 Colour change
2.5.2 Loss of weight
2.5.3 Fruit firmness
2.5.4 Change in total soluble solid
2.6 PRINCIPLES OF EVAPORATIVE COOLING
2.6.1 Evaporative cooling and the Psychrometric chart
2.6.2 Factors affecting evaporative cooling
2.7 METHODS OF EVAPORATIVE COOLING
2.7.1 Direct evaporative cooling
2.7.2 Indirect evaporative cooling
2.8 FORMS OF DIRECT EVAPORATIVE COOLING
2.8.1 Passive-direct evaporative cooling
2.8.2 Non-passive direct evaporative cooling
2.9 ENERGY CHANGES DURING EVAPORATIVE COOLING
2.9.1 Vapour transmission through materials
2.9.2 Heat and mass balance for pad-end
2.10 COOLING PAD MATERIAL
CHAPTER THREE:
MATERIALS AND METHODS
3.1 DESIGN OF THE EXPERIMENTAL COOLING DEVICE
3.1.1 Design principles
3.2 MATERIALS OF CONSTRUCTION
3.3 FEATURES OF THE COOLER
3.3.1 Pad-end
3.3.2 Water distribution system
3.3.3 Storage cabin
3.3.4 Fan position
3.4 PAD MATERIALS SELECTION
3.5 EXPERIMENTAL METHOD AND PROCEDURE
3.5.1 No-load test of the evaporative cooling system
3.5.1.1 Temperature and relative humidity measurement
3.5.2 Heat load of the evaporative cooler
3.5.3 Load test of the evaporative cooling system
3.5.3.1 Physiological weight loss
3.5.3.2 Colour Changes
3.5.3.3 Fruit Firmness
CHAPTER FOUR:
RESULTS AND DISCUSSIONS
4.1 Physical Properties of Pad materials
4.2 No-Load Test of the Evaporative Cooler with Jute Bag
4.2.1 Temperature Readings
4.2.2 Relative Humidity Readings
4.2.3 Cooling Efficiency
4.3 ASSESSMENT OF THE QUALITY OF STORED PRODUCTS
4.3.1 Physiological weight loss
4.3.2 Colour changes
4.3.3 Firmness
CHAPTER FIVE:
CONCLUSIONS AND RECOMMENDATIONS
REFERENCES
APPENDICES