Examples of Results in 2012
In the Winter Sciece Camp 2012, we made two concentrator type, four box type and four panel type solar cookers. I would like to introduce you some interesting results and facts clarified through the analyses. These knowledge are new to me and I enjoyed them a lot. Do not try to mimic the successful ones but try a new improvement. I'm not expecting an old success but new findings by you!
The above panel type has two sets of V shaped mirrors. One is made by side panels and the other by top and bottom mirrors. A V-shaped mirror can concentrate the light near the corner and this characteristics is clear when the angle is sharp. One of the demerits for this kind of arrangement for the mirrors is low robustness.
The above one is similar to the Solar CookKit by SCI. To meet the low sun elevation in Japanese winter, it has a top-and-bottom reversible rear panel. Still it needs an improvement to meet the sun elevation in spring (or fall).こ
They improved the concentration by raising the position of the pot about an inch using a wireworks.
The last panel type is quite similar to our Educooker002. The analysis is for 002 but the above cooker has additional front panels to increase the light directed to the pot and therefore, the compression is definitely higher than 002.
This one is a very standard type of box cooker with a shallow iner box and a black aluminum bottom. Unfortunately wrongly added second booster mirror blocks the sun light as the sun moves in the northern hemisphere.
The angle of the walls of the inner box is too shallow and it cannot direct the light to the pot. If you want to use the walls in the inner box as reflectors, you need to carefully design the shape of the inner box. Again, one of the additional booster mirrors is not only useless but blocks the light, so it is declined.
Same mistake with the previous one.
This one has a small opening contrally to the ordinary design. It can reduce the volume of the inner box but at the same time, it reduces the incomming light. To increase the light introduced into the box, it employs a curved booster mirror. Through the experiment, it proved its effectiveness.
This one is probablly the largest concentrator type solar cooker made in our science camp history. It has a diameter of 1.2m and boiled the 400cc of water in 30 min. 64 plane mirrors forms the parabola with the focal length of 20cm. The size of the pot is too small (16cm) and makes the compression as small as 12.
The compression is 45 if the reflector is perfect parabola. Because we employed polyhedral shape for the reflector and the pot is too small, The compression is only 12.
Tow of the TA's made a conical reflector with the same diameter. Just like the V-shaped mirrors, it can concentrate the light inside the cone. It boiled the same amount of water in 40 min. By the analysis we found the compression of this cooker is more than 14, but it is very difficult to find a precise position which makes the compression maximum.
I hope everyone enjoyed the stay at AIT for three days.
|