RE: Dry Ice

Thought I'd throw my 2cents in here. The chemistry degree is a bit dated, and switching from chem to computer science, the practical is a bit old. But I do seem to recall..... Cold air shouldn't 'flow' out of the system. It will change the temp of the surrounding molecules. Since the drain, theoretically, has no insulation around it, unlike the ice box itself, you will lose cold air to it. Which, in reality, is the warmer air energizing those molecules. Putting a bend in the pipe just gives more surface area to lose the cold through, but shouldn't 'trap' it. It will take *alot* of CO2 to kill you. Remember, that's what you exhale. And, yes, in a closed compartment, you can theoretically run the O2 level down below what's healthy. But I'm guessing most people have a cabin that's not airtight. So there should be enough exchange to avoid a problem. CO is a problem because it 'pretends' to be O2 for your blood cells, so they get starved with oxygen. That doesn't happen w/CO2.

am… [at] verizon.net wrote: > > > > Cold air shouldn't 'flow' out of the system. It will change the temp > of the surrounding molecules. > It flows by convection--hot air is less dense and rises; cold air is more dense and falls. There's also the heat transfer effect that you describe. The convection issue is one that's often overlooked in insulating houses. You can pack all the insulation you want in an attic, but if you have pathways for heated air to flow upward, it will. I learned this when I was in the attic of a rented house once. I was looking for something in a box in the winter and happened to place my face above a hole drilled for electric wires. There was a constant stream of heated air drafting upward. This is why chest freezers are more efficient than front-door models--when you open a front door model, cold air flows down and out. In the chest freezer, it just sits there in a puddle. Chris Campbell