DESIGN, CONSTRUCTION AND PERFORMANCE EVALUATION OF A SOLAR DRYING UNIT OF BASIL LEAVES | ||||
| Misr Journal of Agricultural Engineering | ||||
| Article 6, Volume 33, Issue 1, January 2016, Page 75-100 PDF (807.83 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/mjae.2016.98159 | ||||
 View on SCiNiTO | ||||
| Authors | ||||
| A. T. Imbabi1; H. S. Abdel-Galil2; T. KH. Abdel-Kader3 | ||||
| 1Prof., Agric. Eng.; Fac. of Agric. Fayoum Univ., Egypt. | ||||
| 2Assist. Prof. ; Agric. Eng.; Fac. of Agric. Fayoum Univ., Egypt. | ||||
| 3Post Graduate Student of Agric. Eng.; Fac. of Ag. Fayoum Univ., Egypt. | ||||
| Abstract | ||||
| Two similar solar drying units were designed, constructed and evaluated for drying basil leaves (Ocimum basilicum L.) as a medicinal and aromatic plant at initial moisture content of 590.73% (d.b) or 85.52% (w.b) under Fayoum conditions by using heated air. Each drying unit consists of a flat-plate solar collector, which oriented and tilted with an optimum tilt angle and attached with drying chamber. The drying experiments were carried out to examine the effect of basil leaves thicknesses (2, 4 and 6 cm) and airflow rate (0.015 and 0.025 m3.sec-1) on the basil leaves drying rate. The obtained results indicated that the daily average total solar radiation flux incident on the tilted solar collector surface (29.30 MJ. m-2.day-1) was greater than that incident on the horizontal surface (24.30 MJ.m-2.day-1) by 24.58%. The output higher air temperatures were obtained at the lower airflow rate whereas; the energy gained to the air from the solar collector was relatively higher at the higher airflow rate as compared with the lower airflow rate. Consequently, the solar collector with the higher airflow rate increased the overall thermal efficiency by 5.46% as compared to the lower airflow rate. The moisture content of dried basil leaves was strongly affected by the basil leaves thickness and the airflow rate. The final moisture content of dried basil leaves ranged from (11.52% to 14.58% d.b) depending on the drying temperature cycle. Very small changes were observed in the colour and shape of heated-air dried basil leaves as compared to that dried at direct sun rays. The essential oil contents of dried basil leaves were slightly higher for the drying unit with the higher airflow rate as compared with the corresponding values obtained from the drying unit with the lower airflow at all basil leaves thicknesses. While on Contrast, total chlorophylls contents were slightly higher for the drying unit with the lower airflow rate as compared with the corresponding values obtained from the drying unit with the higher airflow at all basil leaves thicknesses. Effect of the individual variables (airflow rate, basil leaves thickness, moisture removed, and their interactions) on the drying rate was statistically analyzed. Under the conditions of this study, the optimum depth to dry basil leaves by using heated air is 4 cm. | ||||
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