Abstract:
Ethiopia is one of the African countries with a lot of solar potential. The daily solar potential
ranges from 4.5 to 7.5 kWh/m
2
. Solar thermal process heating systems are a promising renewable
fuel replacement technology. With advanced, market-available solar-thermal systems, lowtemperature heat demands up to 100 °C and energy for hot service water can be met. Brewery
factories in Ethiopia use electrical energy or petroleum to produce steam for different purposes.
A well-run brewery would use from 8 to 12 kWh electricity and 150 MJ fuel energy per hector liter
of beer produced. Major low-temperature processes of Dashen brewery factory are bottle washer
and pasteurization. This paper will focus on the delivery of hot water at a temperature of 80
0
c at
a flow rate of 840 liters per hour and evaluate the performance. The parabolic dish concentrator
is designed and developed based on the specification collected from the hosting company and
metrological data of sunshine hours for five years from the Ethiopian metrological agency. The
area of a single solar collector is to be 2.59m
2
with a conical receiver area and focal length of
0.0345m
2
and 1.1m respectively. The prototype is then developed using locally available materials.
Experimental investigation on the performance of parabolic dish concentrator for water heating
carried out at Gondar city for different three months of 6 days starting from 9:30 AM to 4:00 PM.
The flow rate of water varies for each month because of variations in radiation intensity. The flow
rate at February, March and May is 0.00678kg/s, 0.00633kg/s and 0.0074kg/s respectively. The
maximum efficiency that occurred on February 25 is 84.47% and the exergy efficiency of 25.55%.
With useful heat extraction of 1414.19W and exergy gain of 480.7W. On March 14 the recorded
maximum thermal and exergy efficiencies are 72.52% and 21.55%. Useful heat gain of 1283.28W
and exergy gain of 428.51W is achieved on March 14. In May beyond the energy and exergy
analysis, the figure of merit of the parabolic dish is tested. The maximum thermal efficiency of
69.15% with useful heat gain of 1367.19W and exergy efficiency of 19.4% with exergy gain of
430.98W IS recorded. The figure of merit recorded at 1:30 PM is 0.194 which is the maximum
value.
The reduction in carbon dioxide emission is calculated based on the replacement of heavy oil
which is used by Dashen Brewery. So, the carbon dioxide saved in February, March, and April is
114.4kg, 108.35kg, and 111.65kg per day. Finally, the economic analysis was carried out and the
payback period on the collector is 1.94 years.