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VOL. 10, ISSUE 5 (2025)
Farmers friendly solar tunnel dryer for vegetables dehydration
Authors
Dr. P G Thenmozhi
Abstract
A solar heating system is used to increase the thermal energy storage
inside the solar drier during the day or to transfer excess heat from inside
the drier to the heat storage area. Dehydration is a common technique for
preservation of agricultural and other products, including fruits and
vegetables Narinesingh and Mohammed (1988) [2]. Depending on weather
conditions, the solar tunnel dryer was found to be more efficient than the open
sun drying and resulted in saving to the extent of about 17.4% of drying time.
Samples dried in the solar tunnel dryer were completely protected from insects,
rain and dusts and the dried samples were high quality in terms of colour and
hygienic. The present new type solar tunnel dryer designed manufactured
consisted of an air collector, drying chamber and an air circulation system.
During the drying period, drying air temperature, relative humidity, solar
radiation, and lose of moisture were measured continuously in different parts
of the dryer. The portable solar tunnel dryer for the drying of fruits &
vegetables, mushroom and greens. The system was designed as a portable system
for decentralized applications at various sites to satisfy the drying
requirements of small farmers. The cross-sectional area of the solar tunnel
dryer was trapezoidal in shape having 0.254 m2 face area, with length and width
of three meters and one meter respectively. It comprises a collector section
1.35 m long and a drying section 1.65 m long and two PV powered DC fans to
provide the required air flow rate over the perishable agricultural products to
be dried. Transparent polythene cover was used to close the dryer on top side
to maintain the steady state air flow within the dryer. It has been observed
that the drying air temperature was easily raised by some 8-14°C above the
ambient temperature at air velocity ranges 0-1 m s-1. The efficiency of the
solar tunnel dryer was found to be 40-45%. Psychrometric analysis was also
carried out within the dryer and the process curves were drawn. The process curves
were found similar to a conventional dryer showing that this dryer can be
successfully utilized for the drying of agricultural products using solar
energy. Now it is possible to design solar dryers by keeping in view the
needs of the farming community and end-users. Industrial and commercial
applications can easily be met by using forced circulation solar drying systems
because these technologies provide good control of temperature and air
distribution system within the dryer unit. These systems also facilitate to
couple with the existing drying systems. Roof space available in small-scale
industries would normally permit installation of systems of one to two tons per
day capacity. This is not only an efficient method of drying but also produces
better quality products (Naween, 2009) [9]. Keeping all facts in
view, the study objectives were to design and fabricate, evaluate the
performance of solar tunnel dryer and to develop psychometric curves for drying
of various agricultural products.
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Pages:60-62
How to cite this article:
Dr. P G Thenmozhi "Farmers friendly solar tunnel dryer for vegetables dehydration". International Journal of Food Science and Nutrition, Vol 10, Issue 5, 2025, Pages 60-62
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