Fire - Ethanol potato cooker

I was thinking about my Murray River epic adventure, and thought I might need a small emergency stove for when I find myself in a storm, or otherwise unable to make a fire. The difference between being miserable and content often boils down to a hot meal.

So I thought I'd make a ethanol stove. There are a few on the market, and they work by boiling the ethanol within a small chamber with holes around the top. The ethanol turns to a gas, exits at the holes, and burns like a nice gas stove. Lots of heat, light weight, and perfect for what I need.

There are quite a few examples of home made versions on the net, so after quite a bit of research, I thought I'd have a go.

I failed.

I found it impossible to squeeze two halves of a drink can that were the same diameter over each other.

Stupid physics.

So I thought I'd convert my failed project into a potato cooker.

It looked a little something like this...

I started with a can.

I poked some holes around the near top of it with a drawing pin.

I cut the top off with a box knife.

The best way to do this is to lightly score it, round and around, until you gently wear through.

I didn't do that, and I nearly cut all my fingers off one after the other in a series of ever more lucky near misadventures.

Lucky.

To cut the next bit, I originally set the can upright with the blade held at the correct height by placing it in page 321 of Stephen Hawking's book "God created the integers" which was exciting, because I finally found a use for it.

It didn't work as well as youtube told me it would.

Neither did the box knife without Steven Hawkings' help.

Eventually I used scissors. 

This pic is me cutting the planed base that the top was meant to firmly slide over.

I threw that bit away in the end, and used a potato instead.

I cut a strip from the can, and made a cut first half way through one end, and then half way through the other side of the other end.

Then used the opposing slots to make this inner sleeve.

I also cut a little v in it to allow the flow of fuel.

I sat the inner sleeve inside the outer, top bit with the holes in it.

I sliced a potato top and bottom to make a nice stable base, rested it over the top, and gently pressed it down onto the device until it was firmly stuck in place.

It looked like this and appeared to make a pretty good seal.

I added fuel up to the holes, and lit it.

At first the inner section burns and heats up the fuel between the sleeve and the outer section.

At this stage you just leave it alone for a few seconds until it warms up.

Quite suddenly and with a pleasant pop reminiscent of lighting a gas stove, the fuel turns to steam and the burner ignites at the holes.

Total surprise. 

The thing actually works. 

I quickly found a pot, and put one metric cup (250ml) of cold tap water on the heat.

As soon as you do this it snuffs the centre section, but because the holes are down a bit from the top, they continue on perfectly. 

I had a proper boil at around 5 minutes, and a slight simmer at just shy of four minutes.

Much better than I expected. This was a total success.

The entire project from the time I looked at the soft drink can to the time I could make a cup of tea was around an hour and a half, but most of that was attempting to make it without the potato. I think I could knock one of these up and have water boiled in 10 minutes with nothing but a drawing pin and pair of scissors.

Way cool. Thanks to everyone on the net that did stuff like this and gave me all your tips. My only contribution was the potato.

120 Things in 20 years - Ethanol stove - Potato cooker. Boiling water! Yum!

Solar hot water - Aquaponics - interesting consistency

I've only put half the measures I have in mind to put, but it seems I'm winning.

I planed on trying a few different things in an attempt to stabilise my grow house temperatures. One was adding thermal mass, another was shifting heat from the top where it was hottest, to the bottom where my thermal mass is, and where it is coolest.

So far I've added around 45L of water as additional thermal mass, and have a coil of black 4mm poly pipe at head height (mine not yours), with water flowing through and into the fish tank, gathering some heat as it does. I also have a 12 volt computer cooling fan blowing some air down from the top.

I turn the fan off at night so it isn't blowing cold air around, and stop the flow of water through the coil of polly pipe, so it doesn't act as a fishtank cooler at night. I'll figure out some what to control both of these automatically at some stage.

This morning was my first real test of the hothouse in the last week, as its the first cold rainy, overcast, and generally wintery day. The last few days have all been sunny even when they have been cold.

The fish tank temperature, and the grow house air temperature were both 17c this morning, and gradually lost heat over the day. It's sundown, and they fish tank and air temp are both 16c.

That's an amazing result as far as I can tell. Even though the world was trying to cool the system, it did quite a good job of hanging on to whatever gains it had saved from past days.

I think this is going to work.

I hope we get a few miserable days in a row so I can see how long it's heat reserves last.

Solar hot water - Poly pipe collector

It was a chilly and windy day in the hills today. But the sun was out for a while in the morning.

The ambient temperature was around 11°C as I added the rest of the T junctions to my new poly pipe collector, and I was almost confident that I'd sooner or later, be making some solar hot water. 

The water temperatere was around 10°C from my rainwater tank.

It was interesting to note the temperature of the collector was very close to the temperature of the storage tank, and the air temperature in the collector stayed low. (digital thermometer is testing water temperature and the glass one is testing air temp in the collector) 
No doubt this means that the heat exchange area of the black poly pipe is sufficient. This came as a bit of a surprise to me, although in hindsight it would appear that the transfer rate is self governing to some degree. The hotter the water gets, the faster it will flow and thus the more heat exchange will occur.




Final temp before it started raining and I went inside was only 22°C, and it didn't get any higher in the overcast, windy and rainy conditions, even when I went outside hours later. But, I think it was actually a success. I doubled the temperature of the water and it only took an hour and a half. 


Given I only used two sheets of corflute for insulation, and the insulation for the top, bottom, and sides was just tape, which isn't really insulation it's really just tape, It did about as well as I hoped.


The experiment served its purpose in that I learnt a few things and didn't cost anything as I'll be pulling it apart and using all the bits in the real thing.


Lessons learnt ...

• Air bubbles are not your friend. Don't let them collect.
• You don't need a lot of tubing to shift a lot of heat from a collector.
• Insulation is amazingly important. (tape leaks heat so that you can feel it leaking)
• A tube based solar siphon regulates itself, so there wont be any issues with the collector overheating.
• Even at the rate this poorly constructed solar collector collected heat, it would still be worth using it as a bathroom heater or something*. On a bigger scale without changing anything except scale I could heat my house by building a wall out of water tank and simply circulating the water to my collector.
• Collecting free energy is a worthwhile pastime.
• I'm not very skilled at gluing.
• there was a reason I collected all that 19mm poly pipe for all those years, even though it had holes in it every few metres, and kinks in the sections between the holes.

*Hmmm towel heater...

Aquaponics - Success

Success! I've actually managed to out-smart my fish. This last thwarter was made from a plastic mesh designed to keep leaves out of your gutters.

It's a good thing I'm learning on my small blue barrel system. I'd hate to be making all these adjustments on, and drilling holes in, my big system.

I just spent an hour trying to get my auto siphon to work again.

In order to prevent my fish tank from getting too cold overnight, I tried turning off the pump during the hours of darkness (I now have a small air pump for oxygenation). The downside to this was an increase in ammonia and nitrite levels.

- The nitrates values are divided by 100 so they fit on the graph. (I'm told nitrates can safely be over a thousand, so nitrates are not a concern)

I think my nitrite and ammonia levels are still within safe limits, and it was only for one night, but I've decided to go back to running the pump overnight.

Solar hot water - My first solar collector

Its done. Or at least its as done as its ever going to be. Now all I have to do is sit back with a tea bag at the ready and wait for all my hot water to collect.

I have a recommendation.

Paint stuff.

I've never really been into painting things. I'm more of a "just let it rust" kind-a-guy. But now I'm not so sure. Very small sections of this thing actually look as if it were made by someone who could make stuff. And all it took was some black paint, and a camera that cant deal with contrast.

Now all those people who say things like "If a jobs worth doing its worth doing properly." don't seem quite as insane as they did in the past. It occurs to me that when this thing springs a leak, even though its just an experiment, I'm really going to regret that decision to use that old tube of silicone I had lying around. A piece of junk left behind your garden shed is just junk, but paint it, and you leave that same piece of junk in plain sight where it belongs.

I should put this to the test by painting pieces of litter I find in the street.

Tomorrow I test my painted junk to see if I can collect some heat.

Solar hot water - Lukewarm response

My first test of my experimental solar hot water system ended in disappointment.

There are two pipes attached to the storage tank, one drawing cold water from the bottom, and one carring hot water to the top. Due to my overly hopeful construction technique, there was no way to remove the inevitable bubbles. The result was, as soon as the system started working, it would stop.

I managed to get from 12 deg C to 23 deg C but I had to remove the bubbles. That meant losing water and adding cold water to replace it. So I was back to square one again. I did that a few times and each time it would rise rapidly to 23 and then bubbles would collect again.

The other issue (actually there were many) was the flow was too low. If the system is working properly we should see the collector box being cooled by the water flowing through. Cooling one place means shifting heat to another. I was still getting readings around 70 deg C and I'm pretty sure they should have been more like 55 deg C.

I changed the top pipe entry point so that it no longer traps air bubbles. I'll test it again tomorrow. And I've just discovered I have a leak.

Solar hot water - Hot water system

If we create the bottom half of a thermosiphon by putting a black hose into a foam box and cover it with a sheet of glass, we will see the beginnings of a (hopefully) slightly efficient (albeit temporary and largely useless) solar collector.

If we use a large insulated drink bottle to concentrate collected hot water as the top half of the thermosiphon, we will see the beginnings of a temporary and largely useless solar hot water system.

Its night time.

Its not collecting much heat.

It's not very well designed. There are bits where the tubes form loops, and all tubes go down in through the top. My head says it should work a bit. The rest of me is not so sure.

We shall see when the sun next shines.

Solar hot water - Greenhouse

Anyone who has left a hose out in the sun on a hot day will know how much heat its possible to collect. Collecting heat on a hot day is easy. What we need to be able to do is collect heat when there isn't much around. One way to do that is to flatten out your hose to increase the surface exposed to the heat. The downside to that is you also increase the hose's ability to radiate or lose heat.

What we need is a flat, large surfaced hose that's insulated to prevent heat loss. Unfortunately what we also need is a big flat hose that's exposed to the sun and isn't insulated in any way. In fact what we need is a big flat hose that's both, a conductor of heat, and well insulated.

Some years ago in Rome, someone accidentally mixed a flux of some kind into their beach party's fire. The same thing probably happened in China as well. Some time after that, people started making glass. Others may have a slightly different or more complex  history of glass, but I'll leave it to the reader to decide on their preferred history.

Normally when the sun's radiation hits something it gets warm. If the object becomes warmer than the surrounding environment, the object starts to radiate energy to share the warmth. Heat and light (and microwaves, and for what it's worth, puppies and beer) are all basically the same stuff. There is a very cool characteristic that glass has. Light, unlike puppies and beer, to a large degree can pass through glass. Once it hits something that it cant pass through it is either reflected away or is absorbed. If it's absorbed it is absorbed as heat. Normally when something outside is heated, the heat radiates away and warms up the air or whatever else is around it. This air then rises and disperses away. But you can use glass to stop that hot air escaping, or at least to slow it down. If you used glass in this way you will have built a greenhouse.

It seems to me, in order to make a solar collector, what we need here is some kind of big flat matt black greenhouse hose.

I think I understand the main principles involved here so It's time to do some experiments.

Solar hot water - Heat exchange

Some things allow heat to move from them to other things really well and some things don't.

The rate of heat exchange between one item and another makes us say words like insulation, and conductor. The reason people selling you insulation can claim that it keeps you warm in winter and cool in summer is because it does. Insulation achieves this by denying heat exchange between the sun and your house, or your house and winter. A perfectly insulated house would always be the average yearly temperature of your region.(unless you add or remove heat (Actually a perfectly insulated house would always be whatever temperature it happened to be on the day it was built.))

Heat conductors, on the other hand, love passing heat around and sharing it with anything that also conducts heat. An example of a good conductor of heat would be an aluminium cooking pot. Or in my house, copper based stainless steel cooking pots. The reason the copper is on the bottom of the pot is because it conducts heat well and the stainless steel doesn't. The reason the stainless steel is there is due to a scandalous error from within the scientific community, and some ill-informed law. A poor heat exchanger makes for a poor pot. When you heat a pure stainless steel pot the heat doesn't spread evenly and your food burns because all the heat is in just a few spots where the flame or electric element touches it.

If you want to collect heat, it turns out another thing to do is to stop reflecting it. Those silver things people put up against the inside of car windscreens work quite well at reflecting heat, as do white things. Black things on the other hand absorb heat. Matt black is even better.

For 10 years or so, from when I was about 5 years old, we had a black and white cat. Once, when it had been lying in the sun for a few hours one hot summer's day, I remember patting it. It tore strips of flesh off my arms. It was a starving stray when we took it in and it simply hated humans.

If you want to collect heat from the environment, it's best to use something that is good at heat exchange to collect heat, and then its best to use something that isn't good at heat exchange to store it and stop it escaping. If you want to collect heat from a nuclear reactor,  its best to use someone else's country.

I wont be exercising the nuclear hot water option at my house. Although at first glance it seems safe enough, I'm told it's prohibitively complicated and expensive, and could take longer than the two months I've allotted to each project to gain local council approval.

Solar hot water - Heat

There's really no such thing as cold.

Unlike politics, just because it can make you miserable, numb, or even dead, cold doesn't actually exist.
What you are feeling when you feel cold is actually heat moving away from you and toward something else. Things lose heat or gain heat but don't lose or gain cold. Heat is so generous that it simply wants to share itself evenly everywhere. Unfortunately for you, that means if you are warmer then the winter around you, all that generous warmth you make is going to try to spread out to everywhere else.

"My air-conditioner makes cold" I would sometimes hear myself say. "But it doesn't" I might reply. It turns out an air-conditioner is what is known as a heat pump. All it does is finds some heat and shifts it to somewhere else. In the case of cooling, it takes the heat out of your room, and throws it outside where it belongs. In the case of heating it grabs heat from outside and sticks it in your room. That bit is most amazing as far as I'm concerned. Its incredible to think that there is so much heat out there in chilly winter, that an air-conditioner or a solar hot water system can pick up great wads of the stuff and jam it into my house to make me warm.

Thanks science.

Another important and useful thing about heat is that it rises. That's because when stuff is hot the little stuff that stuff is made of move about a lot. This means the stuff expands a bit. When an amount of stuff is bigger than the same amount of the same stuff, it weighs less. Which is to say it displaces more of some other stuff. I'm glad we cleared that stuff up.

Hot stuff rises above its neighbouring less hot stuff. That means we can move heat for free. If hot air rises and we need to move it up, all we have to do is let it move there. If we need to move it up and to the side, all we need to do is put it in a pipe.