Free source of heating?

Graham_Wright said:
Every time I breath out, I expire quite a dollop of heat.

Such a waste. Now, if I could breathe that down the inside instead of giving it to the world……………

Ideas?
Click to expand...

You need a heat exchanger because you require a fresh source of oxygen with each breath. Fortunately evolution has covered this and built one in as standard : it's called your nose, try breathing through that.

Boo2
 
You are producing about 120 watts of heat. 7 guests plus yourself will give you one kilowatt.

An extra-nasal heat-exchanger will increase your "dead space" and you will accumulate CO2.
 
As I have patently not explained very well, I will use baby talk.

I breathe in a couple of lung-fulls of air (i.e. two lungs, one inspiration) through my nose.

The O2 does its stuff and partially converts to CO2. In the process, heat is transferred from my body resources into the oxygen depleted air ready to be expired.

I expire the air together with the heat.

If I could blow that expired air down the inside of my clothes, the heat could transfer to my skin. Otherwise it goes to atmosphere and heats the world. Just to be clear, I next inspire through my nose from atmosphere (not my stinky body).

Having warmed my body, the heat still ends up in the world anyway so no harm done.

Now, is that clear enough?!
 
You could achieve this by wearing a snorkel and placing the tube into your clothes.

The tricky part would be dehumidifying the expired air so you don't get all clammy.
 
Graham_Wright said:
If I could blow that expired air down the inside of my clothes, the heat could transfer to my skin.
Click to expand...

And the moisture in it would transfer to your clothes. This may not be ideal.

Furthermore, since your breath is at body temperature and your skin, under your clothes, is only slightly cooler, very little heat will transfer from one to the other.

Furtherfurthermore, how much heat is there in the first place? Average tidal volume of air is about 1/2 litre, and 20 breaths per minute is the high end of normal. So that's 10 litres per minute, which is about 10g/minute of air. Assume that it comes out your mouth at 37C and that you arrange for it to leave your clothing at 0C on a cold day, and, neglecting water vapour effects, that the specific heat capacity of air is about 1J/gK, that gives you 370J/minute, or 6W.
 
JumbleDuck said:
And the moisture in it would transfer to your clothes. This may not be ideal.

Furthermore, since your breath is at body temperature and your skin, under your clothes, is only slightly cooler, very little heat will transfer from one to the other.

Furtherfurthermore, how much heat is there in the first place? Average tidal volume of air is about 1/2 litre, and 20 breaths per minute is the high end of normal. So that's 10 litres per minute, which is about 10g/minute of air. Assume that it comes out your mouth at 37C and that you arrange for it to leave your clothing at 0C on a cold day, and, neglecting water vapour effects, that the specific heat capacity of air is about 1J/gK, that gives you 370J/minute, or 6W.
Click to expand...

Don't forget, that the 'heat of condensation', will add to the heat available.
Bit wet though.
 
alant said:
Don't forget, that the 'heat of condensation', will add to the heat available.
Bit wet though.
Click to expand...

Yeah, I though of that. However, I don't think it will be much, and if I could find my steam tables amidst the chaos under which lurks my desk[1] I'd work it out ...

[1] Allegedly. It may just be a pile of paperwork.
 
Graham_Wright said:
As I have patently not explained very well, I will use baby talk.

I breathe in a couple of lung-fulls of air (i.e. two lungs, one inspiration) through my nose.

The O2 does its stuff and partially converts to CO2. In the process, heat is transferred from my body resources into the oxygen depleted air ready to be expired.

I expire the air together with the heat.

If I could blow that expired air down the inside of my clothes, the heat could transfer to my skin. Otherwise it goes to atmosphere and heats the world. Just to be clear, I next inspire through my nose from atmosphere (not my stinky body).

Having warmed my body, the heat still ends up in the world anyway so no harm done.

Now, is that clear enough?!
Click to expand...

You're in good company. Nernst, the Prussian scientist who formulated the Third Law of Thermodynamics [broadly, it is impossible to reach the absolute zero temperature], had inherited a farm growing grain but with a herd of cows and a carp pond. Entering the cow shed on a cold day he enquired of a worker why it was so warm inside. He was told it was the metabolic heat from the cows.

Some time later, he was showing a guest around who asked him why there were no cows. He replied: 'I had to get rid of them, it's not my job to heat up the universe'.
 
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