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Papasan Chair Solar Cooker

581 bytes added, 00:04, 8 July 2012
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[[Image:PCSC_-_low_setting_front.jpg|frame|center|Ready to cook!]]
[[Image:new_gimble.jpg|frame|center|Close up of pot holding gimble made from small bike rim and coat hanger wire. Is baking cookies in a small pot on a black dish. Photo Credit:Bart Orlando ]]
{{TOCright}}==Concept==
The word "Synergy" comes from the Greek words for “to work together”. This project combines the existing parabolic shape and comfortable sitting cushion of the Papasan chair with the natural-source energy utilization of the [[solar cooker]]. My hope was that, in the spirit of synergy, the whole would be greater than the sum of the parts and that people may find the idea of owning a solar cooker more practical if they can also sit and read a book in it when its not in use. Compared to the traditional mono-functional [[Parabolic Solar Cooker]], this project serves as a chair when not in use, which saves space and is less of a fire hazard than the traditional [[Parabolic Solar Cooker]]. It is built mostly from salvaged materials as to not contribute to consumption.
===Bart Orlando===
[[Image:PCSC - Bart.jpg|thumb|left|Bart with 8' dish.]]
Local Solar Cooking expert and Appropriate Technology innovator Bart Orlando inspired and co-created this project. Bart offered his vision of the papasan chair solar cooker as a class project when he came to speak in front of the class at the beginning of the semester. Bart has been working with students in the Humboldt area for more than 15 years, building and designing pedal powered and solar powered technologiesprototypical educational displays. Working with Bart means that this project had the benefit of the innovative design that comes from years of experience. For more information on Bart's projects, visit these [http://wwwfriends.humboldtccathsu.educom/%7Eccatbart/pedalpower/inventions/frames_final_htm..htm pedal power], [http://wwwfriends.humboldtccathsu.educom/~ccatbart/solarcooking/parabolic/paraboliccookerwebsection-pg1.htm parabolic solar cooker], and [[parabolic_Basket_Solar_Cookerparabolic_Basket_Solar_Cooker_-_Engineering_305| Parabolic basket solar cooker]] web pages.Bart Orlando's main web page students wishing to start a project with him is entitled               ==Literature Review==[[Projects With Bart]].
== Literature Review ==
*Daniels, Farrington. ''Direct use of the Suns Energy.'' New Haven and London: Yale University Press, 1964.
Though it was heartening to see that there was literature on [[solar power]], the books I found were not very helpful for this project. What was helpful was these links:
* http://solarcooking.wikia.com/wiki/Compendium_of_solar_cooker_designs - A massive list of different solar projects. Lots of pictures. Good wikia, tons of info.
*http://www.fsec.ucf.edu/en/research/solarthermal/solar_cooker/documents/reflectivematerialsreport.pdf - An exhaustive, though somewhat disorganized list of reflective materials. The chart in the [http://www.appropedia.org/[Papasan_Chair_Solar_Cooker#Reflector |reflector]] section is based on this. ==Criteria==
== Criteria ==
This project was designed with the following Criteria in mind:
'''Ease of use''' - If multiple parts are to be used, then they should be safe, employ intuitive design, and not require the use of tools for operation.
==Design== 
===Solar Cooker Background===
A solar cooker is used to concentrate sunlight onto a pot or dish. It can be used to bake, fry, make popcorn, cook rice, light fire, sterilize and boil water. This has potentially important applications in sun soaked areas where fuel for cooking is scarce, or where women must travel farther and farther from their villages to gather wood as fuel becomes more scarce. If solar cooking catches on it, it would become a new style of outdoor recreation similar to the barbecue, but one that is directly connected to the world at large (ie the sun) and has no carbon footprint (if people reused their plates and silverware).
*'''Stable''' enough to face moderate winds without the risk of spilling hot/boiling food/liquid on the ground and people
*'''Light''' enough to allow frequent adjustments to track the sun.
The frame can be constructed in a variety of ways; it can be cast from a mold, built from salvaged materials, such as satellite dishes, and even [http://www.appropedia.org/[Parabolic_Basket_Solar_Cooker_-_Engineering_305 |blackberry bushes]], or be fabricated with new materials especially for the cooker. It can also utilize a pre-existing paraboloid (as in this case). [[Image:PCSC_CHAIR_NAKED.JPG|thumb|right|Papasan chair with cushion removed.]]
*In this design, a used Papasan Chair provides a sturdy, lightweight, somewhat-stable backbone without the requisite of purchasing new materials. This design method is not available in all areas of the world, but[http://en.wikipedia.org/wiki/Rattan Rattan], the material this papasan chair's frame is made from is widespread throughout Asia, Africa, and Australia.
We went with a tripod constructed of bamboo and a bike inner tube, with a 1/2" width chain for suspension. The bamboo should be a least 1" thick for durability and strength. In addition to being a fascinating organism, [http://en.wikipedia.org/wiki/Bamboo Bamboo] is a choice building material for sustainability.
==Fun Math stuff==* In math, a parabola is a conic section with the graph (y=x²) on a Cartesian plane. If that 2 dimensional image were to be "spun" around the origin in the 3rd dimensiony-axis, the resulting shape would be a paraboloid, the shape used by this cooker. Both parabolas and paraboloids have the effect of concentrating energy waves to a single point (or sphere, in the case of a paraboloid) known as the focus. There are numerous [http://en.wikipedia.org/wiki/Parabola#Parabolas_in_the_physical_world examples of parabolas in the natural world.]
*A deep focused parabola is one that contains the focus within the form. A shallow focus parabola projects the focus outside of the form. For this reason, deep focused parabolic cookers are much safer than shallow because they don't project balls of incendiary light outside of the rim plane and accidentally burn things or people.
* Area of circle in m<sup>2</sup> * 1000 watts/m<sup>2</sup> = Ideal power output in W (m<sup>2</sup> cancel out)
1530 1.53 m<sup>2</sup> * 1000 W/m2 m<sup>2</sup> = 1530W
* Ideal power output in W * Reflectivity coefficient of anodized aluminum = Reality-adjusted power output in W
*Diffusion of light from scratched/dirty facets (Bart estimates that the reflectivity for this project is more along the lines of 90%)
==Implementation==
Since we were designing this project as we built it, our time frame was on the order of weeks and months, but this could feasibly be built in one to two days once all materials have been acquired.
*one piece of paper, black
Materials for the food holding device are not included, because there are several options. To view these, [http://www.appropedia.org/[Papasan_Chair_Solar_Cooker#Food_holding_device|click here]].
*Now it is time to spread out the facets and tie them down to the outer rim of the chair with the hemp twine. Be sure that they are flexed to shape of the chair before tying them down so that you can get an accurate parabolic focus later on. [[Image:PCSC - aim no shadow.jpg|thumb|right|Note how the facets are tied down to the rim.]]
NOTE: It may be advisable to drill an additional hole 2/3 down the length of each mirror corresponding to where the frame lies under it, so that the mirrors can be tied close to the fameframe. This may facilitate a tighter focus. However, the chair we used was not a perfect parabola and it turned out that '''not''' having the additional ties allowed for a better focus.
===Suspension===
*Besides posing a threat to the stability of your setup, Wind also has the potential to greatly reduce the temperature of your cooking pot. If this is an issue, try finding a wind-shaded area or using a dead-air-space design for your cooking pot, like the HotPot mentioned [http://www.appropedia.org/Papasan_Chair_Solar_Cooker#Food_holding_device|here].
==Safety== 
*As with any type of concentrated energy this has the potential to be dangerous and must be respected. Solar cookers can easily reach temperatures above 450 degrees Fahrenheit. Care must be taken around small children and animals, especially when hot food or liquid is suspended from a tripod.
*Be sure to ''''ALWAYS USE SUNGLASSES WITH UV PROTECTION when cooking/testing/adjusting your cooker!''' Concentrated sunlight is even more damaging to the eyes than the regular kind... And if you are wearing cheap sunglasses that only protect against visible light, you will be more comfortable than usual when staring at concentrated UltraViolet radiation that you can't see. This radiation is even more damaging to the eyes than visible light. UV protection!!
==Cost==
{| border="1" cellspacing="0" cellpadding="2" align="center"
! Quantity !! Material !! Source !! Cost ($) !! Total ($)
|}
==Discussion==
*The Bamboo + bike tube makes an awesome adjustable tripod. Bart mentioned that if we were to use 2" X 10' or bigger poles, the tripod could also function as a tee-pee.
*The chair we used is not a perfect parabola. This means that the focal area is more of a cylinder than a ball, but this may vary from chair to chair. Its possible to graph a parabola and then overlay the graph on a photograph of the chair to see if they line up. However, one would have to guess the coefficient of the parabola. However, this project was a success anyway as the concentrator gets hot enough to to cook with.
Ease of use - Yes. People can be taught the basics in under an hour by somebody who knows what they are doing. Learning curve of a few cooking sessions.
==Picture Gallery==
<gallery>
Image:PCSC CHAIR NAKED.JPG|The frame of the chair pre-mirror
</gallery>
==External LinksSee also==http://solarcooking.wikia.com/wiki/Compendium_of_solar_cooker_designs An Excellent Overv* [[Compound parabolic concentrators]]* [[Compound parabolic reflectors for solar cookers]]* [[Parabolic solar cookers]]
== External links ==
[http://solarcooking.wikia.com/wiki/Compendium_of_solar_cooker_designs An Excellent Overview]
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[[Category:Engr305Appropriate Technology]][[Category:Parabolic solar cookercookers]][[Category:Solar cooking]]
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