Time Hours




Status: experimental Heating mode: combined or hybrid

Type: chamber dryer Air circulation: natural convection or fan-forced air

The solar dryer presented in this study was developed as a prototype and solely for laboratory use. Under a wide range of weather conditions, it dried green pepper and grapes to commercially acceptable moisture levels with good final product quality. An auxiliary heating system was coupled to the dryer for periods of bad weather.

Characteristics :

The drying chamber has translucent east and west walls and a roof consisting of four layers of polyvinyl chloride sheets separated by air gaps. As well as providing good insulation, up to 75% of the incoming radiation is transmitted, permitting full colour development of the drying product. With this design, the exposure of the drying goods to undesirably high direct radiation intensities is prevented as well. Shelves of plastic covered wire mesh were designed for protection against sulphur dioxide (S02) corrosion as this chemical was used in pretreatment of the products.

The collector, with a net collection area of one square meter, consists of a single layer glass cover and a 10 cm thick pillow of steel chips encased in chicken wire. The matrix was painted black and fitted in a wooden frame with insulated side walls and bottom.

The dryer has an auxiliary heating system which is parallel to the solar collector. A gas burner was installed inside the tunnel connecting the collector to the drying chamber.

Materials of Construction; Drying Chamber

Transparent cover: PVC sheet, 4 layers Frames: wood

Insulation: rockwool

Trays: plastic covered wire mesh

Solar Air Heater

Transparent cover: glass, 3 mm thick

Absorber :

Insulation : Frames :

10 cm thick pillow of steel filings encased in chicken wire rockwool wood

Location : Middle East Technical 2,0

University, Ankara»Turkey «1,5

Longitude : 32°E

Climatological Data; Not reported.

Practical Operation:

Number of units used in the past:one Nuntoer of units currently in use:none

Periods of Operation:

(a) On experimental basis: August 1970 - September 1971

Figure 2. weight Loss vs. Time for Sliced Green Bell Peppers

R - Rainy 0 - Overcast C - Clear PC - Partly Cloudy

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