Performance investigation of parabolic trough solar collector for desalination: A case of Diguna Fango Dimtu water

Abstract

Solar energy employing desalination is basically fast growing field of the research now a time. Solar thermal energy employing water desalination is most sustainable solution for dry region like Dimtu where there is the shortage of drinking water. This region also has high potential of solar energy .This thesis aim to study experimental chemical composition of Diguna Fango Dimtu water and desalination of this water by using parabolic trough solar collector for drinking purpose. Chemical analysis of both raw saline water of the region and desalinated water were analyzed by using different instruments like TDS meter or conductivity meter,photo meter ( model 7100).PH,turbidity tube at ASTU chemistry department laboratory. The total dissolved solid before the desalination plant is 3690 mg/l and after desalination the TDS of the average of nine day is 911.5 mg/l and according to the WHO standard it is possible for drinking purpose. Desalination experiments were performed by manufacturing parabolic trough solar collector composed of solar energy receiver system, reflective mirror,heat exchanger and desalination assisted by PTC and horizontal north-south orientation tracking system operated manualy. Firstly,the amount of solar radiation incident up on the Earth is estimated using sunshine hour of Dimtu meteorological conditions and compared with Adama solar radiation. For small scale PTC the length of 3 m, width of 0.88 m and Aperture area of 2.64 2 can be used for manufacturing purpose to fulfill daily water requirement for small family as per WHO guideline and the assembly drawing done in CATIA software. The experimental test was carried out between January 9 to 17, and the temperature values were measured by using thermocouple. The result shows that the maximum desalinated water was 3.2 lit/ 6 hr (from 9:00am to 3:00pm).This water production was achieved at the feed water flow rate of 0.000583 kg/s and also the maximum heat transfer fluid temperature was 118℃ the maximum efficiency obtained during the experiment is 41% but, the efficiency values is less than the expected due to tracking error, alignment of the receiver error, the alignment of mirror error. Besides, the mass flow rate is the most important parameter to control the outlet temperature of HTF in parabolic trough collector.