Powere sources for a stirling

[John Hill]

Bogs, there are a number of chemical reactions you might consider for your heat source. 

For example, it was my dubious pleasure some years ago to exist for a couple of weeks in Baghdad on American "MRE"s, military field rations that include food packs that self heat when water is added.  Maybe not those exact chemicals as the reaction appeared to give of hydrogen.  Maybe slaked lime and vinegar?

[Bogstandard]

John,

These items would need to be run continuously for say six hours, non stop for say three consecutive days. Methinks chemical reactions would a little off putting to be running for that length of time, plus maybe rather costly in the long run, and of course, I would have to supply reams of documentation as to what is actually happening in that chemical reaction.

That is why I am looking for the safest, cheapest and easiest methods possible, where they have to be safe for everyone, as they would be being displayed in public places. That is why I am trying to get low pressure gas accepted as a safe medium to use at certain venues, in a totally rigid setup using mini bunsens, in a contained cage, rather than methylated spirits in a moveable tank, for running engines like flame lickers and other types of Stirlings.

I want to get back onto the display circuit, but now things have all changed regarding safety and public display. As long as I can get my modelling insurance to cover it, then there should be no problems from the display organisers, and for the insurance to accept it, it has to be proved that no one should get hurt by having the safest means possible to achieve the goal.


John

[arnoldb]

Bogs, another idea that might be worth looking at if the mat does not work...

With Heat Sink Mountable resistors - here's a sample - (I didn't search for the cheapest though)

If you get some of these heat sink mountable resistors, you could make up a base from wood or plastic with smallish aluminium pads in it, and mount these resistors from below on the pads and wire them up to a variable power supply to control the amount of heat generated.

While you would lose random placement, a layout like this will allow you to maximise efficiency, as well as control how fast the LTDs run - even in different ambient temperatures.
I didn't do any calculations on best values to use or anything; If you'd like that I'll be happy to work it out for you.

Unfortunately I have not yet built any LTDs to test such a scheme, but I do think it will work.  I do have a USB coffee cup warmer for when I build that first LTD though, seeing as these new flat screens don't have space on top to pit it on like old CRTs had :-)

Kind regards, Arnold

[John Hill]

John,

These items would need to be run continuously for say six hours, non stop for say three consecutive days. Methinks chemical reactions would a little off putting to be running for that length of time, plus maybe rather costly in the long run, and of course, I would have to supply reams of documentation as to what is actually happening in that chemical reaction.

That is why I am looking for the safest, cheapest and easiest methods possible, where they have to be safe for everyone, as they would be being displayed in public places. That is why I am trying to get low pressure gas accepted as a safe medium to use at certain venues, in a totally rigid setup using mini bunsens, in a contained cage, rather than methylated spirits in a moveable tank, for running engines like flame lickers and other types of Stirlings.


John

Hmmmmm....... I see what you mean John, those organisers might not believe your engines are running on just the plain water that you pour into those plastic bags. Just a wild idea but how about taking the heat in with you as hot water in thermos flasks?  I know you live in England so obviously a cup of tea must be permitted!

[Bogstandard]

John,

That is the way a lot of the low temp ones are run, sitting on top of thermos flasks, but always behind screens where kiddies can't scald themselves with hot water.
The stirling society are starting to get the right idea, they have small incandescent bulbs hidden in what looks like blocks of wood and in the wooden bases as the heat sources.

This is a very bad vid of them I took a couple of years ago at the Harrogate show

John

[NickG]

I wish more engines could be seen running at the shows too. I think we were allowed meths at the last Harrowgate show, obviously it needs 100% supervision though.

I guess putting a light underneath it demonstrates the principals but there's something about doing that that just doesn't please me in the same way, for instance, even a tea light under it would, or a flame licker with a burner, an i.c. engine or steam engine would. Suppose the majority of steam engines are run from a compressor so it's the same sort of thing.

Nick