A SOLAR DRYER PERFORMANCE OF ONION SLICES UNDER FAYOUM CLIMATIC CONDITIONS | ||||
| Misr Journal of Agricultural Engineering | ||||
| Article 23, Volume 26, Issue 2, April 2009, Page 953-976 PDF (460.03 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/mjae.2009.109762 | ||||
 View on SCiNiTO | ||||
| Authors | ||||
| H. S. Abdel-Galil1; R. I. A. Mourad2 | ||||
| 1Lect. - Faculty of Agriculture - Fayoum University - Egypt | ||||
| 2Assoc. Prof. - Faculty of Agriculture - Fayoum University - Egypt | ||||
| Abstract | ||||
| A solar drying unit was developed and constructed for drying onion slices under Fayoum conditions. The drying unit consists of a 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 onion slice thicknesses (3, 6 and 10 mm) and airflow rate (2.4 and 1.6 m3.min-1) on the onion slices drying rate. The obtained results indicated that the daily average total solar radiation flux incident on the tilted solar collector surface (7.32kWh.m-2.day-1) was greater than that incident on the horizontal surface (6.13kWh.m-2.day-1) by 19.41%. The higher air temperatures were obtained at the lower airflow rate (1.6 m3.min.-1) whereas; the amount of heat 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 higher efficiency of the solar collector was obtained at the higher airflow rate. The solar collector with the higher airflow rate increased the overall thermal efficiency by 12.56% as compared to the lower airflow rate. The moisture content of dried onion slices was strongly affected by the onion slices thickness and the airflow rate. The final moisture content of dried onion slices ranged from (6.8% to 7.7% dry-basis) depending on the drying temperature cycle. Effect of the individual variables (airflow rate, onion slice thickness, moisture removed, and their interactions) on the drying rate was statistically analyzed. A forward step-wise regression technique was applied to arrive at a reasonable good best set of independent variables. The coefficient of determination (R2) was above 0.97 when comparing observed and predicted drying rate. | ||||
| References | ||||
|
Agricultural Statistics (2006). Arab Republic of Ministry of agriculture and land reclamation. Economic Affairs Sector. (1): 57-62.
ASHRAE, (1993). Methods of testing to determine the thermal performance of solar collectors, American Society of Heating, Refrigerating, and Air-Conditing Engineers, Inc., New York, NY.
Al-Katary, H. S. (2000). Exhaust-air properties of onion drying. Misr J. Agric. Eng., 17(1): 173 - 184.
Duffie, J. A., and Beckman, W. A. (1991). Solar Engineering of Thermal Processes. The 2nd Edition. 605 Third Avenue, New York, N.Y., Wiley-Interscience.
Essa, A. H. and Gamea, G. R. (2003). Physical and mechanical properties of bulb onions. Misr J. Agric. Eng., 20(3): 661 - 676.
Hall, C. W. (1980). Drying and storage of agricultural crops. The AVIPublishingInc., Westport, Connecticut, U.S.A.: 291-308.
Lewicki, P. P.; Witrowa, R. D. and Nowak, D. (1998-a). Effect of drying mode on drying kinetics of onion. Drying Technology. WarsawPoland. 16(1): 59 -81.
Lewicki, P. P.; Witrowa, R. D. and Nowak, D. (1998-b). Effect of pretreatment on kinetics of convection drying of onion. Drying Technology. WarsawPoland. 16(1): 83 -100.
Pierce, R. O. and Thompson, T. L. (1980). Management of solar and low temperature grain drying systems. Part II: Layer drying and solution to the over-drying problem. Transaction of the ASAE, 23(4): 1020-1023.
Sharma, P. K. and Nath, N. (1991). Dehydration characteristics ten onion cultivars. Lentensmittel-Wissenchaft-und-Technologies. 28(6): 348-351.
Sharma, G, P.; Verma, R. C. and Pathare, P. B. (2005). Thin-layer infrared radiation drying of onion slices. J. of Food Engineering, 67(3): 361-366.
Yaldiz, O and Ertekin, C. (2001). Thin layer solar drying of some vegetables. Drying Technology, 19(3&4): 583-597. | ||||
|
Statistics Article View: 100 PDF Download: 157 |
||||
