Solar Desalination: Taking the Salt Out of the Sea

Overview

Objectives/Goals I investigated whether a container's shape affects how much desalinated water ("D/W") is produced through solar desalination under set conditions. My hypothesis was that a broad/shallow bowl ("Broad Bowl") would produce more D/W than a narrow/deep bowl ("Narrow Bowl") because the sun will heat the larger, shallower water surface more quickly. Methods/Materials METHODS: Placed 1 cup (236.5ml) of sea water in 40 containers: 20 Broad Bowls (13cm water surface area ("WSA")) and 20 Narrow Bowls (9cm WSA) along with a metric measuring cup (the "Cup") to collect D/W. Added 3 drops of red coloring dye to distinguish between the sea water and D/W. Containers were covered with plastic wrap and a weight to make the plastic wrap sag so that D/W driped into the Cup. The 40 containers were exposed to the sun a set period of time and the D/W and environmental conditions were recorded every 2 hours. The total quantity of D/W in each container was recorded and the salinity of the sea water and D/W was measured by both an EC Meter and commercial laboratory. MATERIALS: 5 gallons of sea water; 20 Broad and Narrow Bowls; 40 Cups, fishing weights, and rubber bands; water and air thermometers, EC Meter, aluminum foil, dye, paint.(See, detailed methods and materials list on Science Board and log book.) Results Sample One (3-day test) and Sample Two (2-day test) confirmed that the difference in WSA between the Broad and Narrow Bowls affected the quantity of D/W produced. The results for Sample Two were significantly different and more representative because I modified this experiment to make the slope of the weighted plastic wrap constant for both sized containers. Final measurements: Sample One: 1) Avg. Total Production ("ATP"): Broad Bowls 10.18ml, Narrow Bowls: 8.17ml; 2) Avg. Daily Production ("ADP"): Broad Bowls 3.393ml/day, Narrow Bowls 2.723ml/day. Sample Two (modified method): 1) ATP: Broad Bowls 15.35ml, Narrow Bowls 6.25ml; 2)ADP: Broad Bowls 7.675ml/day, Narrow Bowls 3.125ml/day. Conclusions/Discussion The container's shape and WSA affected how much D/W was produced with the Broad Bowls producing significantly more D/W than the Narrow Bowls.

Awards (1)

• Honorable Mention

Competition history

• CSEF 2011 Physics & Astronomy · Entry J1811

Resources

• CSEF project summary ↗

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