what's the difference between all solar cooker.
Food temperatures
I've just changed the sentence that said no food can go above 100 C as it's not strictly true. Pure water boils at 100 C but as soom as you put something in it it boils at a very slightly higher temperature, for example jam can boil at 104 C . There is some food that can get much hotter if it contains sufficiently little water. Toffee for the extreme example needs a temperature of 150 C / 300 F. Obviously at altitude these boiling temperatures drop. 84.51.146.100 09:12, 15 April 2007 (UTC)
- That is quite right. Thanks for that edit. I might add that I lived at at 9200 ft (2800 m) for awhile. At that elevation, water boils at 90°C. Beans are difficult to cook in an unpressurized container. Walter Siegmund 18:16, 15 April 2007 (UTC)
If a major source of heat lost is the window then it would be wise to use double windows? Like seperated by a half inch air gap. Oh just made my first solar box cooker (just need to get the window). I may try it with one window first then a second one. I guess it will also reduce light input so it may have trade offs. 70.254.38.215|70.254.38.215]]
- About
4%12% of power input is blocked by adding a second layer of glazing, but heat loss through the window is more than halved (from 4 to 1.7 W/m2°C). Please see Forum:Why doesn't my solar cooker work? for more. Walter Siegmund 09:33, 1 May 2007 (UTC)
- Uh, ahem. An ordinary single pane of 3 mm window glass, when clean, actually reduces the light intensity by around 12%, not 4%. This is due (roughly) to 4% reflection at the front surface, 4% absorption, and 4% reflection at the back surface. If the glass is dirty, or if the sun's rays go through the glass at an angle, the total reduction of light intensity is probably as high as 15% or even 17%. —the preceding unsigned comment is by Elocn (talk • contribs) 02:57, 21 May 2007
- I agree. For float glass, the dielectric reflection is 4% per surface (n=1.52).[1][2][3] For 1 mm thickness, the transmission is above 90%.[4] For a more robust 3 mm thickness, 88% sounds reasonable.
- However, for the second layer of a window, it may be better to use a polymeric film. Such a film absorbs and reflects less and is partially protected from UV degradation by the first layer.[5]
- My point above is unchanged despite what material is used. A second window layer reduces heat loss more than transmission. Walter Siegmund (talk) 15:58, 21 May 2007 (UTC)
- By the way, how does one assume or know when to assume that food won't burn in a box cooker? I designed a box-type cooker contraption which got to around 166oC (330oF). Seeing that this was within the temperature range recommended by standard cookbooks for caramelizing sugar, I tried placing a small jar containing sugar inside it the next day. After several hours, the sugar actually turned dark brown! Surely if sugar can turn brown then food can burn, as it's basically the same reaction. —the preceding unsigned comment is by Elocn (talk • contribs) 02:57, 21 May 2007