1

Function

:

To control the air temperature inside natural convection solar dryer

2

Specifications:

:

Power requirement - Single phase 230 V, Temperature range 0 - 200oC. Temperature band width 1oC to 10oC, Rated load capacity - 100 W, Thermo couple - Stem type Fe:K

3

Design Features

:

The unit consisted of a thermister sensor circuit to detect the hot air temperature having a differential amplification unit, a buffer circuit for impedance matching and a controller circuit to actuate an exhaust fan.The controller module is a simple "on - off" device with independent dead band and centre level adjustments with the output driving a relay. When temperature of the air inside the dryer exceeds the set level, the controller switches on the exhaust fan to quickly draw away hot and humid air from the dryer, reducing the stagnation temperature to the desired level. As soon as the temperature is reduced to a predetermined level, it switches off the fan checking further drop in temperature. The dead band provision prevents hunting of the controller and provides a precise band of temperature control.

4

Performance

:

Accurate control of temperature within the desired range. Energy consumption less than 1 kWh / d

5

Cost  (approx)

:

Rs 3000/-