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ISSN Online: 2377-424X

ISBN Print: 1-56032-797-9

International Heat Transfer Conference 11
August, 23-28, 1998, Kyongju, Korea

THERMAL DRYING OF HERBS AND GREEN LEAVES USING A BED-TYPE SOLAR DRYER

Get access (open in a dialog) DOI: 10.1615/IHTC11.290
pages 169-174

Résumé

Results of investigation on the solar drying of herbs such as spearmint, parsley and jew-mallow are reported. These herbs are dried as green leaves without stems and their drying characteristics have been evaluated. The experiments are carried out at average drying air temperature and relative humidity of about 47°C and 30%, respectively. The effects of surface loading and drying air velocity on the drying process are investigated for surface loads of 1.75, 3.5 and 7.0 kg/m2 and air velocities of 1.0, 1.5 and 2.0 m/s. The results indicated that the effect of increasing the surface load or decreasing the air velocity is to increase the drying time and consequently reducing the drying rate. The effect of herbs type has been investigated for a constant load of 3.5 kg/ m2 at drying air velocity of 2.0 m/s. It is found that parsley yielded maximum drying rate (minimum drying time) followed by jew-mallow and spearmint. In addition two drying mathematical models available in the literature were fitted to the experimental data with the Page model predicts better results than the exponential model. Moreover, the drying characteristics have been correlated in terms of the operating conditions.