Insolation/ Solar Cooking

 

Solar Oven Design

Donghwan Kim

Solar Geometry and Energy Flow, Spring 2018

University of Texas at Austin, School of Architecture

 
 

Solar Oven Design Strategy

I started to design this ‘solar oven’ with two specific strategies. Firstly, gathering the natural sunlight as much as possible for two hours, testing periods. I thought that it would affect to the temperature inside of the solar oven. Secondly, I tried to keep the temperature stable with ‘insulation’ materials. Basically, I made that the solar oven had two parts; a black box and reflective angled wings.

For the first strategy, I made the solar oven have an angle to the Sun. Through tilting the angle by 20 degrees, I intended to get more natural sunlight during testing period (March 19th, 2018, approximately equinox) in Austin (Latitude: 30 degree). For collecting the changing Sunlight effectively, the reflective wings were folded. The Sunlight reflected to the angled wings and went though a transparent acrylic. Inside of the black box, it was made of black panels to observe the heat and light effectively.

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For the second strategy (keeping the heat inside longer), I put the insulation materials inside of the black box. The insulation materials, Styrofoam, play an essential role of keeping the heat inside. The oven cover was made up of acrylic to go through easily. However, because of weakness to the heat, it was affected by the Sun and bended after testing.

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The size of oven box is 9-inch (width) by 9-inch and 7-inch thigh. The reflective wings were 8-inch high. The reflective materials are cooking foil. The angle of the wings are reflective to the Sun’s position during testing time.

 
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Figure 4 represents a perspective view and section drawing. This solar oven comprises of two boxes; outer box and inner box. Between the two boxes, there is the Styrofoam to keep the heat inside as I mentioned above.

 

Results

Test Date: March 19th, 2018

Table 1 shows test records, and the test was conducted from noon to 2 pm on March 19th in 2018, in Austin (Latitude: 30 degree). Figure 5 represents a graph that I made after the test based on the temperature results. At the starting time, the inside temperature was 26.67 degree Celsius. Every 5 minute, the temperature was increased by 17 degree until 15 minutes. It was gradually increased until 110 degree Celsius for one hour. However, at 13:05, the solar oven was broken by wind, and the cover was uncovered. After the parameter, the temperature was decreased by about 23 degree Celsius. After 25 minutes, the temperature reached to 110 Celsius again (at 13:35). The Solar noon was 13:38, after that, its temperature was decreased a little bit by 104.44 degree Celsius, and it continued until 2 pm.

Cooking

I tried to bake one egg using this Solar oven. I found that a baked egg needs the temperature about 200 degree Celsius for 40 minutes. Then, I put one egg inside and waited for 60 minutes under 110 degree Celsius (230 Fahrenheit). Finally, I got baked egg and it was so delicious.

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Conclusion

My Solar oven model made a temperature by 110 degree Celsius (230 degree Fahrenheit). I tried to test more than 90 minutes, but its temperature was not over the 110 degrees. I thought that it was affected by the materials such as insulation quality, gaps between materials, and acrylic’s bending problem. If I made this oven over by using glass, used more reflective materials, and made this model sealed well, the temperature would have reached higher. Furthermore, the hotter period of time would influence on the temperature as well.

 

 

 

 

 

 

 

 

All rights reserved by Donghwan Kim