Insulation

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Sunday evening, after Surreal Life, I went out for another check.

Sunday night numbers:

Insulation Material

Remaining ice chunk size
(approx. cubic cm)

Balloons      0
Aluminum foil       0
Diapers 300
rice crispies 378
goose down 715
cardboard  1200
Styrofoam 2376

The diaper's ice had been reduced to a little ice floating in a couple cups of water, it looked like it was going to be the next victim.

The goose down ice had also been significantly reduced. It was much less impressive at just 715 cubic centimeters.

The Styrofoam-protected ice was doing very well. It appeared to be the huge obvious winner. 

In four more hours, just after midnight, I checked the boxes again.

The diaper box ice had succumbed to the heat. All that remained were tiny chips of ice floating in water. The goose down  ice had also melted completely. Now only the rice crispies, cardboard and styrofoam boxes had ice remaining.

Sunday midnight numbers:

Insulation Material

Remaining ice chunk size
(approx. cubic cm)

Balloons 0
Aluminum foil 0
Diapers 0
goose down 0
rice crispies 140
cardboard  798
Styrofoam 2200

The neighbor's dog started barking when I checked the styrofoam box.  I suddenly realized that I didn't want to have to explain this circus train of ice boxes to a disgruntled neighbor. I slid inside the house and went to bed.

I was pretty sure the boxes would all be melted by Monday night.

 

 

 

There are three types of heat transfer, and all three were at work on my back porch.

Radiation

Radiant Energy - All hot objects emit infrared electromagnetic waves. They don't need air, or anything to travel through, so the only way to keep them from escaping is to reflect the waves back towards the hot object.

An example is the sun's rays traveling through the vacuum of space.

Speaking of space, I've read that astronauts have 17 layers of reflective material to stop heat transfer in and out of their space suits.

 

Conduction

Conduction is heat transfer through a solid. This transfer takes place as the speedy motion of hotter molecules bump into and share fast free electrons with colder molecules. Solids with a bunch of free electrons, such as metal, conduct heat quickly, whereas solids with few free electrons, such as rubber and wood, are poor heat conductors.

The aluminum foil balls were definitely the best conductor, and one of the worst insulators in my experiment.

Convection

Convection is the transfer of heat by the motion of or within a fluid. The fan in your computer cools the processor and power supply by pulling fresh air over and around the inside of your computer.

Convection ovens use a fan to encourage heat transfer into foods and immersion freezers use a pump to encourage heat transfer out of foods.

The simple rule for limiting convection heat transfer is to turn off any fans and to compartmentalize areas where convection would occur through air movement.

The pink balloon box in my experiment had not been able to control heat loss through convection. The big balloons left plenty of free-moving air space in between the balloons.

 

 

Please continue reading page 7 of the insulation test.

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Dec 20, 2005  

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