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Problem Statement
Lakshitha Selvamani and Penelope O'Meara need to build a parabolic solar cooker, primarily made up of recycled materials, that has the ability to heat up 100ml of a liquid at Northern High School from 12:00 pm-2:30 pm.
Constraints
Constraints
The primary building material must be used/recycled/reclaimed cardboard.
The final product must be able to be stored in a 16”x16”x16” space. It may expand to a larger size while in use.
Wood glue will be provided.
Students may use recycled mirrors, glass or plexiglass.
Students may not spend more than $15.00 on the materials that go into the production of their solar cooker.
Students must be ready to cook on 09.07.2021.
a. The students will be allowed to cook on Northern’s grounds between 11:04 am and 2:25 pm.
Students must be able to demonstrate connected math and chemistry concepts related to their solar cooker.
Parabolic Solar Cooker Process
References
Chen, A. (2009). The Critical Angle and Percent Efficiency of Parabolic Solar Cookers. National Science Foundation. http://www.geometryexpressions.com/downloads/Investigating%20Parabolic%20Solar%20Cookers.pdf
PBS. (2007). Saved By the Sun. https://www.pbs.org/wgbh/nova/teachers/activities/pdf/3406_solar_03.pdf
Rojas, D. (2018, February 11). Mylar Blanket Parabolic Solar Array 3 Kilowatt solar power Death Ray. Www.youtube.com; Green Power Science. https://www.youtube.com/watch?v=-1GV3FIOR6E
Brainstorming process:
Possible solutions were created by Penelope O'Meara, Emma Vantongeren, and Kirsten Neubauer-Pons. Solution 9 from the top right image was selected.
Procedures
Building Procedure:
Gather materials (used umbrella, solar blanket, 4 pieces of scrap wood equal length, wood glue, spray adhesive, clear plastic CD case, hot glue, cardboard, cylindrical microwave splatter cover (or any other wide cylindrical-shaped piece of scrap), 3 stakes, 3 1ft long pieces of string, and a saw or grinder)
Construct main reflective piece
Lay fully opened umbrella down, inside up.
Cut out triangle sections that fit in each of the triangles that make up the inside of the umbrella.
Spray one side of a triangle and the corresponding triangle inside the umbrella with spray adhesive.
Set the triangle down onto the sprayed umbrella part.
Press firmly for 2 minutes.
Repeat this process for the remaining sections on the umbrella.
Use a saw (or a grinder) to remove the upper part of the umbrella handle. The full end length of the handle (after cutting it down) should be the height of the focus point.
Construct platform for the beaker
Split clear plastic CD case in two.
Use the hot glue to horizontally glue the flat side of the clear plastic CD case onto the umbrella handle attached to the umbrella.
Construct the base stand for the umbrella
Cut out two 16"*16" flat pieces of cardboard.
Mark four corners on one flat piece of 16"*16" cardboard
Use wood glue or hot glue to glue the four equal-length scrap wood pieces onto the marks as legs.
Glue cardboard 16"*16" on top of legs
Put down the cylindrical microwave splatter cover upsidedown (open side up) on top of the 16"*16" cardboard platform/table
Place assembled umbrella onto upsidedown cylindrical microwave splatter cover.
Connect 3 pieces of string to stakes
Connect other ends of strings to the umbrella to keep it stable.
Experiment Procedure:
Day One Procedure (Water)-
Gather materials needed (100mL beaker, water, solar cooker, thermometer, scale)
Measure the weight of the 100mL beaker alone
Put 60mL of water into the beaker after recording the mass of the beaker
Weigh the beaker with the water and record the mass
Measure the temperature of the beaker with water (in Celsius) and record it
Bring the solar cooker outside and stake it into the ground
Place the beaker of water on the focal point (plexiglass platform)
Record the temperature of the water every 30 minutes from 12:00 pm to 2:30 pm (also record weather, humidity, and the temperature outside)
Bring the solar cooker inside after recording the final temperature
Day Two Procedure (Soybean Oil)-
Gather materials needed (100mL beaker, oil, solar cooker, thermometer, scale)
Measure the weight of the 100mL beaker alone
Put 60mL of oil into the beaker after recording the mass of the beaker
Weigh the beaker with the oil and record the mass
Measure the temperature of the beaker with water (in Celsius) and record it
Bring the solar cooker outside and stake it into the ground
Place the beaker of oil on the focal point (plexiglass platform)
Record the temperature of the water every 30 minutes from 12:00 pm to 2:30 pm(also record weather, humidity, and the temperature outside)
Bring the solar cooker inside after recording the final temperature
Building Process:
Umbrella covered with solar blanket via spray adhesive.
First base on top of umbrella pole (pole was cut using a grinder).
Base stand in progress. Using wood glue to attach wooden slabs we cut to make a platform.
First "platform" for beaker that goes on base on umbrella pole. This ends up breaking and being replaced with an improved version.
Legs completed for stand.
Stakes were used to hold down the umbrella in the wind.
Final base design. There was an addition made: a cardboard circular cut out below a microwave splatter guard. This keeps the umbrella in one place and at a comfortable length to adjust the beaker.
Final Product
Final Product
The solar cooker worked; a change of 21.6°C for the water and a change of 15.2°C for the soybean oil. The soybean oil's temperature did not increase as much due to the weather on the day of testing (cloudy).
The stand could have been refined, but it worked efficiently and held the contraption stable throughout both days (day 2 was very windy). The number of wrinkles in the solar blanket also could have caused the decline in heat; however, the reflective quality of the solar blanket was still good enough to heat both substances at least 15°C.
Data Analysis
The change in the temperature of the water was 21.6 degrees celsius and the change in the temperature of the soybean oil was 15.2 degrees celsius. Day one of testing (water) has a greater change in temperature due to the hot and sunny day. In contrast, day two has a low change in temperature due to the cold and windy day.
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