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| dc.contributor.author | Semahagn, Yematawu Desta | |
| dc.date.accessioned | 2024-06-05T06:24:23Z | |
| dc.date.available | 2024-06-05T06:24:23Z | |
| dc.date.issued | 2023-03-07 | |
| dc.identifier.uri | http://ir.bdu.edu.et/handle/123456789/15867 | |
| dc.description.abstract | Several researchers have attempted to enhance the performance of solar dryers by adding different features to the air heating system. Besides, developing a solar dryer supposed to sustain the drying operation even in non-shining times is necessarily important. This research is aimed to develop a reliable solar dryer system to vegetables and fruits. Thus, this work is going to develop a solar dryer system that employs an evacuated tube collector (ETC) for shining hours by integrating an independent rock bed as thermal storage in a way as able to discharge heat during the non-shining time. Here, the rock bed has to be built from a thermally insulated tank with transparent double glassed top coverage to absorb and store the solar flux during sunny hours. This system had been designed to dry potato slice weighting 7.5kg sample from its wet base initial moisture content of 80.1% to the optimum (7-13%) within eight hours at an average temperature of 65℃. Then, the drying chamber having size of 85cm x 61cm x 62cm, 1.3m 2 area of evacuated tube collector, 0.137m 3 volume of rock bed (with a solar absorbing area of 0.52m 2 and depth of 0.26m) have been designed with the blower requiring 330W electrical power. Finally, the solar dryer system prototype developed from locally available materials, and tested with loading slices at different air flow rates (i.e., at 0.016 m 3 /s, 0.008 m 3 /s and 0.024 m 3 /s) and open sun. Here, the more moisture reduction (9.3% within eight hours), higher efficiency of the collector (62.02%), more drying temperature (60℃), as well as higher efficiency of the dryer (23.87%) was occurred at 0.016m 3 /s compared to lower and higher airflow rates. Finally, 20% of drying time was saved compared to open sun drying (takes ten hours). Besides that, the significance of the rock bed as well as the reflectors was also studied by conducting tests using ETC having extended reflectors and using ETC only at the best air flow rate of the first test (0.016m 3 /s). Finally, integration of the rock bed is significant for reliable heat supply (due to it increased by 9.56%), more moisture reduction (due drying rate increased by 3.6% compared to the case of using ETC only); and the presence of reflectors also results for increment of heat production from the collector (increased by 5.1% -16.9%) and from the total thermal system (8.6% average increment), which results for higher drying rate (increased by 15.5%) and saved 12.5% of drying time relative to using ETC only and with the assistance of rock bed, and 30 % relative to open sun. Keywords: Solar collector, Evacuated tube, Thermal Storage, Rock bed, Reflector & performance. | en_US |
| dc.language.iso | en_US | en_US |
| dc.subject | Mechanical and Industrial Engineering | en_US |
| dc.title | DEVELOPMENT AND EXPERIMENTAL TESTING OF THE PERFORMANCE OF SOLAR DRYER EQUIPPED TO EVACUATED TUBE COLLECTOR WITH INTEGRATION OF ROCK BED AND REFLECTORS: (CASE OF POTATO SLICE DRYING) | en_US |
| dc.type | Thesis | en_US |
