DESIGN AND EVALUATION OF AN ENHANCED SOLAR DRYER USING HEAT STORAGE UNIT FOR TOMATOES DRYING | ||||
| Misr Journal of Agricultural Engineering | ||||
| Article 18, Volume 31, Issue 3, July 2014, Page 1025-1046 PDF (896.77 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/mjae.2014.99112 | ||||
 View on SCiNiTO | ||||
| Authors | ||||
| E. Y. Ghoniem1; G.R. Gamea2 | ||||
| 1Professor of Agricultural Engineering, Higher institute of Agricultural cooperative , Egypt. | ||||
| 2Associate Professor, Department of Agricultural Engineering, Faculty of Agriculture, Minoufiya University, Egypt. | ||||
| Abstract | ||||
| Mixed-solar dryer with heat storage unit improve the process of solar drying Roma tomatoes. This paper presents a performance comparison between two mixed-mode solar dryers. The dryers were identically designed and constructed,, however one of dryers utilized mobile and easily adjustable flat solar storage unit attached to the drying chamber during night hours to improve the drying rates after sundown(enhanced). The dryers were tested under both day and night hours. Solar insolation, Air temperature changes of ambient and drying chamber, as well as relative humidity were measured during the drying process. Rehydratation ratio, color and sensory properties were used as a parameter for the dried sample quality. Temperatures inside the dryer that utilized the heat storage unit were approximately 5 15℃"> higher than those in the normal dryer during night hours. The enhanced dryer overall showed a considerable increase in drying rate with a 33.3 and 36 % decrease in total drying time for tomatoes quarters and discs respectively as compared to the normal dryer to reach the final moisture content. Newtonian equation fitted very well the experimental data and it is possible to accurately simulate the thin layer drying behavior of tomatoes drying by enhanced dryer. Two well-defined falling rate periods and a very short constant rate period were observed. Drying constant ( k ) was greatly affected by drying air temperature and shape of tomatoes . Drying of tomatoes discs and quarters by enhanced dryer revealed good color, taste and appearance, meanwhile tomatoes halves gave unacceptable color. So, drying of halves is generally not recommended Heat storage unit permits drying to continue even after sunset or when the environmental conditions such as rainfall and high relative humidity make it difficult for normal solar drying to take place | ||||
| References | ||||
|
Abdellatif, S. M. (1985). "Solar energy collection, storage and utilization in protected cropping". Ph.D. Wye College, University of London, UK.
AOAC (1995). "Association of Official Analytical Chemists" 15th d., Published by AOAC, 2200 Wilson Boulevard Arlington, Virginia 22201 U.S.A.
Bal, M.L.; S. Satya and S.N. Naik (2010)."Solar dryer with thermal energy storage systems for drying agricultural food products: A review". Renewable and Sustainable Energy Reviews, 14.; 2298–2314.
CAPMS. (2011). "Annual year book for general statistics. Central Agency for public Mobilization and Statistics of A.R.E"., Egypt.
Dincer, I. and S. Dost (1996)."A perspective on thermal energy storage systems for solar energy applications". International journal of energy research, vol. 20, 547-557.
Dincer, I. and A. M. Rosen (2010)."Thermal energy storage systems and applications", John Wiley & Sons, Ltd. United Kingdom.
Doymaz, I. and M. Pala (2002). "The effects of dipping pretreatments on air-drying rates of the seedless grapes". Journal of Food Engineering, 52(4), 413–417.
Duffie, J. A. and W. R. Beckman (2006). "Solar Engineering for Thermal Processes". 3rd Ed., pp. 907. John Wiley and Sons. New York: USA.
Gamea, G. R.; A. T. Taha and M. H. Keshek (2012). "Thermal performance of solar energy storage in some solid materials". Misr J. Ag. Eng. Vol. 29 (1):429 – 350.
Gustavsson. J.; C. Cederberg; U. Sonesson; R. V. Otterdijk and A. Meybeck (2011). "Global Food Losses and Food Waste". Food and Agricultural Organization.
Hasturk, F.; T. Aktas; H. Orak and P. Ulger (2011). "Influence of Pretreatment and different drying methods on color parameters and lycopene content of dried tomato". Bulgarian journal of Agricultural science, 17 (6): 867 – 883.
Johnson, R. W. (1992). "Analytical results for specific system Passive solar buildings". The MIT Pres, Cambridge, Massachusets, London.
Joshi, C.; M. Gewali and R. Bhandari (2004). "Performance of solar drying systems: a case study of Nepal". Inst. Eng. (India), (7): 53 - 85.
Mohamed M. A., G. R. Gamea and M. H. Keshek (2010)."Drying characteristics of okra by different solar dryers". Misr J. Ag. Eng. Vol. 27 (1): 294 – 312.
Simate, I. (2001). "Simulation of the mixed-mode natural-convection solar drying of maize". Drying Technology; 19 (6): 1137–55.
Vlachos, N.A.; T. D. Karapantsios; A. I. Balouktsis and D. Chassapis (2002) "Design and testing of a new solar tray dryer". Drying Technol; 20 (6): 1243–71.
Duffie, J. A. and W. R. Beckman (2006). "Solar engineering for thermal processes". 3rd ed., pp. 907. John Wiley and Sons. New York: USA.
Mohamed, M. A.; G. R. Gamea and M. H. Keshek (2010)."Drying characteristics of okra by different solar dryers". Misr J. Ag. Eng. Vol. 27(1): 294 – 312.
Ozturk, H. H. and A. Bascetincelik (2003). "Energy and energy efficiency of a packed bed heat storage unit for greenhouse heating". Biosyst Eng; 86 (2): 231 – 245.
Sander, A.; S. Tomas and D. Skansi (1998). The influence of air temperature on effective diffusion coefficient of moisture in the falling rate period. Drying Technology, 16 (7): 1487–1499.
Skansi, D. and S. Tomas (1995). Microwave drying kinetics of a clay plate. Ceramics International, 21, 207–211.
Somerton, H. W. (1992). "Thermal properties and temperature-related behavior of rock/fluid systems". Elsevier Publishing Company.
Tomas, S. and D. Skansi (1996). "Numerical interpretation of drying curve of food products". Journal of Chemical Engineering of Japan, 29 (2): 367–370.
Workneh, T. S.; V. Raghavan and Y. Gariepy (2011). "Microwave assisted hot air ventilation drying of tomato slices". International conference on food engineering biotechnology. Singapoor. IPCBEV, Vol. 9, 150-162. | ||||
|
Statistics Article View: 120 PDF Download: 174 |
||||
