This document presents a mini project on a solar tunnel dryer. It includes an introduction to solar drying and conventional drying methods. The objectives are to design, fabricate, and test a solar tunnel dryer. The methodology involves using the dryer from 9am to 5pm to dry foods and agriculture products. Results found the dryer was capable of drying chili and garlic hygienically. Drying rates varied with temperature and moisture was removed faster inside than outside the chamber.
2. CONTENTS:
1. Introduction
2. Literature Survey & Review of the literature
3. Objectives
4. Methodology
5. Block Diagram / Experimental Set up
6. Advantages, Disadvantages
7. Applications
8. Possible Outcomes
9.Results
10.References
3. INTRODUCTION :
1. The conventional drying system to preserve fruits, vegetables, grains, fish,
meat, wood and other agricultural products is sun drying which is free and
renewable source of energy.
2. The heat from the sun couple with the wind has been use to dry food for
preservation for several years.
3. Drying of agricultural products using renewable energy such as solar energy is
environmental friendly and has less environmental impact.
4. Dryers are devices that use solar energy to dry substances especially food, solar
energy are used to remove the moisture, soils from crops and vegetables therefore
increases the life of crops and vegetables.
4. LITERATURE SURVEY:
1. Agrawal, A. et.al (2014). A review of research and development work on solar dryers
with heat storage.
2. Ayensu, A. (1997). Dehydration of food crops using a solar dryer with convective
heat flow. Solar Energy, 59, 121-126.
3. Diamante, L. M. Mathematical Modeling of the thin layer solar drying of sweet
potato slices.
4. Karathanos, V. T. (1999). Determination of water content of dried fruits by drying
Kinetics.
5. OBJECTIVES:
1. To design and fabricate of the solar tunnel dryer .
2. To carry out a comparative study of the performance of the solar box
type tray dryer with and without latent heat storage material .
3. To study drying behavior of treated and untreated black pepper dried in
a box type solar dryer with and without latent heat storage device (LHS).
4. To develop a solar dryer in which the grains are dried .
7. EXPERIMENTAL SETUP:
1. A natural convection solar tunnel dryer comprising three major units, a solar collector
unit, a drying unit, and a vertical bare flat-plate chimney, is constructed.
2. Solar collector unit : It is a flat plate type with airflow above the absorber plate while
the cover was a transparent 200 micro meters polythin sheet .
3. The reason for using this type of collector unit is because of its low thermal losses.
4. Drying unit and collector unit is made up of same material and configured in series.
5. The base and side of drying unit where also clad with 20mm sheets to minimize its
heat losses to the ambient air .
6. Chimney unit : It is a bare flat plat type collector constructed from a 0.3mm thick flat
GI sheet with a channel depth of 0.1 meters.
7. The solar radiation receiving surface of the chimney was painted matte black to absorb
as much of the incident solar radiation as possible.
8. METHODOLOGY:
1. The solar tunnel dryer keep outside for drying from morning 9am to evening
5pm.
2. Solar tunnel dryer collect solar energy i.e. energy from the Sun rays and air
from atmosphere to dry food product, color agriculture material like tomato,
onion, waste leaves and grapes etc.
3. The material to be dried is spread in an even layer of trays on the racks inside
the tunnel.
4. The air below the semi transparent collector is heated by the Sun and spreads
throughout the tunnel.
5. It increases the temperature inside the tunnel.
6. The increased temperature inside the tunnel dryer decreases the relative
humidity of the air, there by allowing the air to more efficiently dry the material
inside.
9. ADVANTAGES:
1. Food enclosed in the dryer and therefore protected from dust, insects, birds and
animals.
2. The dryers are water proof .
3. The dryers can be constructed from locally available materials .
4. Solar dryer are last longer .
5. Easy to maintenance.
6. The food dry faster compared to traditional air drying.
7. It is economically friendly.
11. APPLICATIONS:
1. Solar dryers can be utilized for various domestic purposes.
2. They also find numerous applications in industries such as textiles , wood , food and fruit
processing , paper and pharmacy .
3. Natural convection walk-in type dryer for bulk dry of agriculture and agro industrial
products at moderate air temperature.
12. POSSIBLE OUTCOMES:
1. Natural convection solar tunnel dryer was capable of drying garlic and chilli .
2. Products dried in solar tunnel dryer were hygienic and they are of good quality .
3. So, solar tunnel dryer can be utilized for drying highly perishable vegetables
and fruits which could increase the income of farmers with little maintenance.
4. For the drying of grapes , and drying should be done from morning 9am to
evening 5pm.
16. DRYER RATE:
The above graph represents total moisture % removed per every hour inside and
the outside of the chamber. The lower most and the middle graphical line represent
moisture content removed in % at inside the chamber. Lower most graphical lines
represent the MC removed in % outside the drying chamber. The following represents
the MC removed in % with respect to time and the temperature at that point. Since the
solar drying does not given constant temperature because of climatic condition; so the
moisture % removed varies un-uniformly with time and the varied temperature.
17. REFERENCES:
1. Agrawal, A. & Sarviya, R.M. (2014). A review of research and development work on
solar dryers with heat storage. International Journal of Sustainable Energy, 35, 583-605.
2. Ayensu, A. (1997). Dehydration of food crops using a solar dryer with convective heat
flow. Solar Energy, 59, 121-126.
3. Diamante, L. M. & Munro, P. A. (1993). Mathematical Modeling of the thin layer
solar drying of sweet potato slices. Solar Energy, 51, 271-276.
4. Karathanos, V. T. (1999). Determination of water content of dried fruits by drying
Kinetics. Journal of Food Engineering, 39, 337-344.
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