Solar-powered water desalination science project m gastrocnemius medialis


Nicholas Kinsman is interested in inventing is there a gas station near me solar-powered devices to reduce our dependence on other energy sources. He is also a winner of a Science Buddies Clever Scientist award for his 2007 California State Science Fair project (Kinsman, 2007). Nicholas set out to build a simple, inexpensive device to desalinate seawater, using readily available materials and easy construction methods.

Typical seawater contains dissolved salts at concentrations between 32 and 37.5 parts per thousand. That means that if you started with one kilogram of seawater (which is approximately one liter of seawater) and then you allowed all of the water to evaporate, you would be left with between 32 and 37.5 grams of salts (also called total dissolved solids).

With all of that salt, seawater is not suitable for drinking nor for watering most plants. The fluid circulating in your body (blood plasma) contains much less salt than seawater (on the order of 9 grams of total dissolved solids). If you were to drink seawater, your body would actually lose water, because the high salt concentration of the seawater causes an osmotic pressure gradient which drives water out of your cells. Desalination is the process of removing the dissolved salts from water, making it pure enough for drinking or irrigation.

Nicholas’s first design for a desalination device is shown in Figure 1 below. There are eight small bottles surrounding the large collection jug. Each of the small bottles is filled with seawater. The small bottles have holes in their caps. One end of a flexible straw is inserted into the hole, and the other connects electricity voltage in paris to the large collection jug at the center. When the entire device is set out in the sunlight, the seawater in the small bottles heats up, which causes the water to evaporate and fill the small bottles with water vapor. The idea was that as the water vapor increased, it would condense in the straws and flow down into the collection jug. Unfortunately, the idea did not work. You can see in the picture that there is condensation on the inside of the top of the bottles, but there was very little condensation in the straws.

Figure 2. Here are two examples of Nicholas’s second design for a solar-powered desalination device. The large jug, laying on its side, holds the seawater. The top side of the jug has been cut out with a utility knife. Plastic cling wrap seals the top side, and a quarter is used as a weight to make a low point in the center. Beneath that low point, Nicholas placed a collector, made from the top of a small water bottle with a flexible straw inserted into a hole in the cap. The other end of the straw passes through the side of the large jug, and then to a plastic cup where the condensate collects. The device on the left has an aluminum foil reflector covering the back side and bottom of the large jug while the device on the right has no reflector.

Why is it important that in the improved design a large jug is used to hold the saltwater? The jug, which is laid on one side, lets the saltwater cover a relatively large area. Because water molecules can only evaporate from the surface of water, a body of water with a large surface area will have a greater rate of evaporation than a body of water with a smaller surface i electricity bill com area (assuming all other conditions are the same). The top side of the jug is cut out, using a utility knife, and covered tightly with plastic cling wrap. The cling wrap covering the large opening provides a large surface area on which condensation can form, which is another reason why using a larger container is an important change in this design. A quarter is used as a weight to make a low point at the center of the cling wrap. When the device is heated up in the sunlight, the condensation that forms on the cling wrap eventually flows down to this low point and drips into a funnel electricity news in nigeria. In Nicholas’s design, the funnel is simply the cut-off top of a small water bottle, which has a flexible straw inserted into a hole cut in the cap. The other end of the straw passes through a small hole in the large jug, and then to a plastic cup (tightly covered with cling wrap using a rubber band to prevent evaporation).

For his science fair project, Nicholas tested the desalination devices based on his second, improved design with and without aluminum foil reflectors (you can see examples of each type in Figure 2 above). For each device, he made several measurements so that he could compare the performance, including the amount of condensate collected, or his condensate yield, and the conductivity of the saltwater and condensate. The yield measurements told him how efficient his devices were at heating the saltwater and producing desalinated water. The conductivity measurements (which can be taken using a handheld meter) told him how well the condensed water had been purified of dissolved salt because water that contains dissolved salt can conduct electricity, and the more salt that is dissolved in the water, the higher the conductivity of the water.

In this environmental engineering science project, you will build desalination devices similar to Nicholas’s second design and see how the design can be improved even more. Specifically, you will investigate how the color of the bottom of the device affects its efficiency. You will compare a device with a white-colored bottom to a device with a black-colored bottom electricity sources in canada. Something that is light-colored reflects more light than something that is dark-colored, which absorbs a lot of the light that hits it. Light is a form of energy and energy can be transferred to nearby objects (such as a body of water) in the form of heat, in a process known as heat transfer. Which colored bottom do you think will result in a more efficient desalination device? Terms and Concepts

• In this science project you compared the performance of desalination devices with a black-colored bottom and a white-colored bottom. What do you think would happen if you used an aluminum foil reflector, as Nicholas Kinsman did (as discussed in the Background)? How do you think you could set up such a reflector so that it heats up the water in the device as much as possible? Hint: research parabolic reflectors.

• Surface area is a factor that affects the rate of evaporation. Think of a way to modify one of your desalination devices so that the same volume of saltwater takes up only half of the surface area of the bottom of the jug or container, such as by attaching a plastic divider to the bottom. Test the two desalination devices again, using the same volume of saltwater in each. Does the change in surface area correlate with a change in condensate yield?

• Saltwater has a higher boiling point than freshwater. Does this mean that electricity prices by state you would get a higher condensation yield using freshwater than you did using saltwater? To find out, you can try this science project again but this time use saltwater in one desalination device and freshwater in the other. To make sure you are collecting pure water, you can add some food coloring to the initial water in each device. Are the condensate yields very different between the two devices? If you try even saltier saltwater than was used in this science project, is there a greater difference?

• Make sure there are no large wrinkles in the plastic cling wrap, as this can trap condensation. To get rid of a large wrinkle, try taping up a little more cling wrap in that area. Also make sure that the corners and sides of the jug or container are taped to the cling wrap. The cling wrap should allow condensation to roll smoothly down to the collection gas in back point, below the washer or quarter.

• You can try filling the jug or container with less salt water. You should fill it with enough to just barely completely cover the bottom of the jug or container, but do not add any extra salt water. All of the water needs to be heated up enough for water to start evaporating, so if you use more water then more energy will be required to heat it up.

• If you are not using the Science Buddies kit, selecting the right jug or container is important. Use a jug or container with a large surface area, since water molecules can only evaporate from the surface of water. It is recommended to use a jug or container with at least 1500 cm² of flat surface area on the bottom. Make sure the jug or container has straight sides that do not lean inwards and has no overhangs, as these features can trap condensation.