Friday, June 13, 2014

IDEA - Kelly Kettle, plus some musings on efficiencies & enviROIs

One of the joys (of many) of this lark is what you can stumble across. 

And, of course, who. Which can always lead on to all sorts more fun stuff.

The other day on twitter I shared a link to an electric 'eco-kettle' (I'll save detail on this for another day, as this thread is set to head off on enough tangents already).

Suffice to say it was... is... claimed as a very green way to boil water.

I was convinced enough to be tempted, and shared this intention on said twitter, FaceBook, etc. I believe I added a caveat on its claimed values until bought and tried.

What followed was a most interesting serious of exchanges on what it takes to boil water, as you do, with an impressively credentialed gentleman who goes under the name of Roger Tallbloke. On many matters, but especially science and even more so that of climate, well worth a follow:

With that too often over-used and abused (esp. by our glorious 4th estate) term, I think he'll allow me to also confer upon him the accolade of on occasion erring on the 'controversial', but then who worth their salt is not?

But he and I do share a love of science, engineering and, crucially, second-use design (which we will get to soon, promise).

However reductions of waste and promotions of efficiencies do also score high with us.

So let me simply share what he did with me to my apparently incorrect notion that an electric kettle was the most eco (we shall suspend such as health & safety, speed, style & convenience factors for now) way to get water hot:

RT: Electric is a lot less energy efficient than gas for domestic water boiling.
JM: Really? Presumed an element within water was much more efficient than what first needs to heat pan & gets lost around edges.

RT: A lot of energy wasted heating air in bubbles forming on element which then rise to surface and lost to atmosphere. Well designed gas kettle loses little heat because turbulence makes heat cling to sides and be absorbed through to the water

RT: Other forgotten factor in elec vs gas is transmission losses for elec. Mad use of high grade energy for instant gratification.

He then topped the lesson with a lovely design example, including data:

RT: My 2oz kelly ketttle design boils a pint in 4 mins with 16g denatured alcohol. around 56% efficiency.

(Tangent - Interestingly enough, I just took delivery of a 'Junkk' Stirling Engine kit (sadly half the parts missing) that looks just like this. It will be subject of another post once finished, so watch this space. Clearly aluminium beer cans also have their re-uses.)

He has offered to expand when he has a moment, which may happen here, or on the 'Idea Page' on the site I have created in complement.

Roger has kindly amplified in significant detail:

For those who don't know what a kelly kettle is, look at this cross section:

Usually made from 16 gauge aluminium (old ones in copper), they are too heavy for solo backpackers but great for windy campsites.

So I made this lightweight version using UK and USA beer cans (they do the big in america). Rather than using wood for fuel I keep it clean using ethylated spirit (denatured alcohol). The stove at the bottom has two sets of flame-jet holes which heat both the inside and outside of the kettle. A simple aluminium windshield made from an extra large beer can opened out is used as necessary.

The kettle sits on the stove and uses a large american Fosters can with an internal chimney made from a UK beer can of smaller diameter. They are jointed with aluminium solder (and a lot of patience and swearing).

The chimney has flutes folded into it so it tapers from a wide circular base to a narrow 5 pointed star at the top. This raises the velocity of the combusted gases, creating the 'draw' to make the boil happen quickly. The 'hat' in the photo is a section of UK beer can with exhaust holes in and it conducts exhaust gas heat back into the water.

Updates posted - 16/05/14:

If you take care with drying times, you can use superglue for jointing and it'll last 20-30 boils.

I also make smaller versions with pint UK beer can + 2x red bull cans for chimney. Tricky jointing. Just enough for a cuppa. 1oz

The UK version uses a 4g stove made from a lip balm tin - 'internal' jets only. In use here on Red Pike


Finally comes the tricky bit as I need to refer to the blog there and the site page here, but to cut and copy across I need to publish both, go back and then re-edit. Or something.