Does the type of reflective lining in a box solar cooker matter?

by Josh
(Maryland)

My name is Josh. For our 6th grade science fair project, we are investigating, "The effect of type of lining on maximum temperature reached." To make our introduction for our project, we have to answer, "Have others tried to answer this question in the past? If so, what research have they found to answer the question?" So I was wondering, has anybody ever investigated this kind of thing before?



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Thank you for your question Josh,
I hope it is not too late to help with your answer.

Dark or shiny solar oven interior?

Yes, many people ask this same question.

And, we and many others have found that it can work both ways when it comes to the interior lining of a solar box cooker.
You can get good results using a dark solar oven interior only, and also by using a shiny reflective interior.
The greatest factor in both would be to make sure that your cookware (pots/pans) are dark in color.
This way your pot/pan is sure to absorb the heat (energy) so that you food will cook.

If your interior is dark also then it will absorb heat as well and transfer (conduct) heat to the pot that is sitting on the floor of your cooker interior and if your solar oven interior is shiny it will help to reflect (direct) the suns rays onto your dark cooking pot which will then absorb the heat (energy) from the sun, allowing you to cook.

That is the explanation in a nutshell ;)

Here is some more information given by a colleague of mine:

"This is probably one of the most asked questions from beginners.

There are people who believe that heat is generated inside a box cooker when
solar radiation strikes the walls of the cooker. This is very likely the best
way to get the best AIR temperatures.

However, its very likely that the best way to heat the FOOD is to make the walls
a continuation of the external reflector panels, so that as much radiation as
possible gets focused on the container holding the food. To understand this
principle, consider the CooKit and other panel cookers, which have NO box and
yet manage to cook food.

One of the reasons that the issue will never be resolved is because people use a
variety of cooking vessels. If you're using a cooking pan that covers most of
the interior of the box, it hardly matters what color the inside of the box is.
So the SPORT, which accepts a 3 qt graniteware vessel perfectly, is painted
black. But an almost identical unit made in South Africa is left shiny on the
inside.

Over the years I've come to realize that the AIR temperature inside a box cooker
is mostly irrelevant. The thermometers are always stationed at the top of the
box, but it might be 50 degrees cooler at the bottom! Still the food cooks,
because light is being reflected down onto it from the external reflectors.

My take is that; the best overall way to make a cooker is with reflective sides
and a black bottom. The bottom is black so that light doesn't get bounced
straight back out the window ... and into your eyes. The sides are reflective to
help focus the light onto the food. It probably helps to put a slight slant on
the inner box sides."