STEP TYPE SOLAR DRYER

1.

Function

:

Drying of fruits,  vegetables and agricultural commodities

2.

Specification

:

i. Collector area

:

2.4 x 1.8 m

ii. Type and Model

:

Step type, TNAU

iii. Number of trays

:

10 in five steps

iv. Insulation (Bottom)

:

Glass wool, 10 cm. thick

v. Motive power      

:

Natural convection

3.

General Information

:

Step type solar dryer has a collector area of about 4.32 m².  This multi track step type dryer can hold 10 aluminium trays at a time.  The absorber is 20 gauge GI sheet, black painted at the top with bottom insulation.  The drier is covered at the top with 2 layers of 3 mm thick plain glass kept at an air gap of 2.5 cm.  At the rear side of the collector, two chimneys of 120 cm height are provided.  Chimneys are provided with butterfly valves to control the movement of air.  Holes provided at the bottom of the collector just below the first step for the entry of atmospheric air into the dryer.

4.

Cost of the unit

:

Rs.15000/-

5.

Cost of operation

:

Rs.3.75/h.

6.

Salient features

:

• Solar drier takes 39.30 hours for drying papaya leather, while conventional sun drying takes 60.8 hours.  Thus there is a saving of 21.5 hours which is 35.36% when compared to conventional drying.

• The drier handles 10 kg of cocoon per batch and each batch takes 30-40 minutes for completion of stifling form 08.00 h to 14.00 h, 8 batches can be conveniently stifled in a day.