Increasing efficiency of a solar dryer using principle component material

Author
Mafetuka, Tadiwanashe
Title
Increasing efficiency of a solar dryer using principle component material
Abstract
Post-harvest losses have appeared to be a persistent problem that haunts smallholder farmers by robbing them of their scarce profits and the troubling effects are observed directly as a community and even governments fear how people are going to survive. Solutions are clear, preservation methods should be put in place. This study expounded such a solution by optimising a conventional
solar drying (𝐢𝑆𝑑) system by designing a solar dryer which uses thermal storage material (π‘‡β„Žπ‘†π‘‘). The theory on which the π‘‡β„Žπ‘†π‘‘ dryer works is based on energy being stored in the material when solar radiation is high and realised when it is low. The design and fabrication of the dryer was done using Pahl and Beitz (2007) conceptual model for designing processing equipment. Using this
model three models were developed and the best of the three was selected using scoring technique devised by Illinois (2017). Evaluation of the dryers’ properties and characteristics was done by collecting data showing changes in drying temperature, 𝑇 in the drying chamber, observing drying time, 𝐷𝑑 taken to reach the recommended final moisture content, Ξ¦ and observing changes in relative humidity, 𝜏𝐻. The data was used to find drying rates ( ), drying efficiency (𝑑𝐸,%), energy (𝑄, MJ) supplied by the dryer, the moisture content removed (𝑀𝐴) by the dryer and to see if it fits with existing drying curves. Both 𝐢𝑆𝑑 and π‘‡β„Žπ‘†π‘‘ dryers were able to remove 92.8 % of the moisture content from the sample. The drying time taken was 8hrs for π‘‡β„Žπ‘†π‘‘ and 20hrs for 𝐢𝑆𝑑. The 𝑑𝐸, 𝑑𝑅, and 𝑄 values for π‘‡β„Žπ‘†π‘‘ were 51.9%, 11.7%moisture/hr and 26.0MJ, respectively, and those for 𝐢𝑆𝑑 were 20.8%, 3.7%moisture/hr and 24.98MJ respectively. All the data obeyed the underline drying curves; hence, they are in line with expected mathematical behaviours. The results showed optimization of the temperature and drying time of the 𝐢𝑆𝑑 by a factor of 2.5, this can improve yield of dried product and possibly quality.
Date
June 2024
Publisher
BUSE
Keywords
Solar drying
Thermal storage materials
Post-harvest preservation
Drying efficiency
Supervisor
Mr Zingwari, O
Item sets
Department of Agricultural Engineering
Media
Mafetuka, Tadiwanashe.pdf

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