Investigation of Parabolic Dish Solar Concentrator for Local Areke Distillation
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Date
2015-03
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Addis Ababa University
Abstract
Areke is Ethiopian’s locally produced traditional fermented alcoholic liquor which is produced
from difedif- mixture of milled gesho (Rhamnus Prinoides), finely ground and cooked/baked
cereals, and water left for fermentation for nine to ten days, by the of process distillation.
The heat required for the distillation process is obtained from burning firewood on inefficient
three stone stoves. Energy inefficiency, greenhouse gas emission to the environment, human
respiratory system diseases and deteriorating household economy are the major negative impacts
that resulted from using biomass as energy source for local areke distillation.
This thesis work presents the design and manufacturing of parabolic dish solar collector system
for local areke distillation process as a substitute energy source instead of burning biomass and
reports the test results of the system. In order to show design procedure; parabolic dish solar
collector system with aperture diameter of 1.6m, depth of 0.4m and focal length of 0.4m was
designed in full scale. The parabolic dish is designed for distillation of 24 liters of difedif to
obtain 3 liters of areke with alcohol content of 44% per day (i.e. from 8:00AM to 5:00PM). One
cycle of distillation takes on average 3 hours to obtain 1 liter of areke from 8 liters of difedif.
However, the parabolic dish frame of aperture diameter of 1.2m, depth of 0.3m and focal length
of 0.3m, which already exists in AAIT Mechanical workshop, with a little maintenance and
modification was used for the test purpose. Aluminum foil laminated galvanized sheet is used as
reflective surface for dish concentrator. The parabolic dish tracks the sun ray manually based on
the shadow of pin on the edge of dish aperture. Especially made clay pot with capacity of 4 liters,
and having effective surface area of 0.071m2 was used as absorber. 2.5 liters of difedif was used
to conduct the test in three different days.
The test result showed it was possible to obtain from 2.5 liters of difedif 0.25liters of areke with
alcohol content of 44% and on the average it took 3 hours. And on average it took 1 hour and
15minutes to reach temperature of 70.4oC which is the boiling point temperature of alcohol in
Addis Ababa at atmospheric pressure of 0.746atm, where the test was conducted. So, with
appropriate design of solar energy distiller system for local areke distillation as an alternative
source of energy showed promising results and has the potential to mitigate the negative impacts
related to traditional areke distillation method.
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Thermal Engineering Stream