Dryers usually have two types, vertical and horizontal.
This dryer is a vertical type with dimensions of 30 x 30 x 60 cm.
The cold air enters from the bottom and is heated inside the device, then it moves up due to the convection current and exits the chimney along with the moisture of the fruits. The chimney improve the convection current.
The suitable temperature for drying fruits is between 50 and 60 degrees Celsius.
I used a 100 watt incandescent bulb because it produces a lot of heat. The temperature of the lowest tray reaches 60 degrees and the temperature of the highest tray is around 30 degrees.
Using a fan to suck air cools the device. So, if you use a fan, you should use a powerful heat source.
Keep a safe distance between the lamp and the body to avoid possible hazards. The temperature of the glass of the 100 watt lamp is between 90 and 130 degrees Celsius.
Covering the inner chamber of the device with aluminum foil will reflect the radiant energy and prevent the body from getting hot, as a result, more heat will be absorbed by the fruits.
When drying, switch the upper and lower trays every few hours so that they dry evenly.
Please write your questions and ideas in the comments section.