Thermo-electric generators?

[Neb]

Mrpete has a playlist on sterling engines.




I haven't watched them YET.

Ben

 

[Neb]

https://www.youtube.com/results?search_query=water+heater+explosion

Thanks!

It failed at 335 psi which is 5x what I think I would need for a steam engine.

Ben

 

[Biggkidd]

Thanks!

It failed at 335 psi which is 5x what I think I would need for a steam engine.

Ben

Ben Have you looked at the difference of power made in steam engines with regular steam versus super heated / high pressure steam? IIRC the difference is quite large.

 

[Neb]

Ben Have you looked at the difference of power made in steam engines with regular steam versus super heated / high pressure steam? IIRC the difference is quite large.

Only as far as seeing multiple expansion engines where the high pressure steam drives s small diameter cylinder then the existed steam feeds a larger diameter cylinder. The theory goes that a steam engine works more efficiently if the temperature is kept constant. By expanding the steam in multiple stages the temperature of each cylinder stays in a more narrow range.

But that is too complicated for me at this point.

I started my steam engine build adventure by asking myself...

Can I build a steam engine with what I can find in my shop?

The best I could do with what I had in the shop had a ... 1/2 or 3/4 inch bore. Doing the math I figured that would do 1/8 hp max maybe.

So I found a set of castings and plans from Tiny Power for a 2 cylinder 2hp steam engine. That allowed me to learn about machining and revealed what tools I needed. I was able to machine 5he base, split bearings and fit a crankshaft. A5 that point I took the plunge and invested in additional casting set one of which I paid Tiny Power to machine for me so I could use it as an example to learn from.



But that is only a first step.

That engine is intended for steam launches where the shaft is direct coupled to a propeller that always presents a load on the engine. A steam 3nfine with no load will increase speed until it destroys itself. I need to add a governor.

Steam engine running on steam require steam oil which is very viscous and needs an appropriate oiler to inject the oil into the steam.

A steam engine is not an energy source but rather a device that concerts the energy in steam into mechanical energy. I will also need a boiler to covert the chemical energy of the fuel I burn into to steam. Ignoring how to couple the rotational energy to useful work...

A boiler is not just a tea kettle. The water level inside the boiler has to be maintained less the fire melts the sides of the boiler bad bad bad. Sight gauges are required to monitor the water level. But 5hey are not fool proof so test valves mounted at different heights can be used to validates the sight gauges.

As the water is converted into steam the water level drops and has to be replaced with more. Hand pumps can be used to inject more water into the pressurized boiler but require manual operation. Automatic injectors will reduce 5he work of running the boiler.

A boiler has to be serviced to clean out the soot and scale. To deal with the former one has to be able to clean out the fire tubes. For the latter we have to clean out the boiler.

Scale can be controlled via the feed water chemistry. The pH of the water should be kept on the alkaline side because acid will dissolve the metal of the boiler bad bad bad.

Sorry about the long reply but I am in the mode to think out loud.

Ben

 

[Biggkidd]

You've seen video of the steam engine I built out of junk I had laying around. The most it could do with my boiler at the time was about 30 amps @ 12V DC. With a properly matched boiler it could likely have made 60 or so amps at 12 volts. Just not nearly enough to be worthwhile. IMO

 

[Neb]

You've seen video of the steam engine I built out of junk I had laying around. The most it could do with my boiler at the time was about 30 amps @ 12V DC. With a properly matched boiler it could likely have made 60 or so amps at 12 volts. Just not nearly enough to be worthwhile. IMO

That could run my milling machine at 2/3 capacity. A good start.

Ben

 

[Biggkidd]

I

That could run my milling machine at 2/3 capacity. A good start.

Ben

IMO Ben the key is I made one and learned a LOT and now I know I can make another more capable unit out of scrap if need be. I also made the boiler and later made a rocket stove that was supposed to be a water heater but in reality was much better at making steam using a single coil of copper tube. We used that water heater for 8 years and the rocket stove was made from scrap metal. Mostly propane tanks. My original boiler was also made from propane tanks. I never took it much over 100 psi with steam I tested it to 155 with air.

 

[Neb]

I

IMO Ben the key is I made one and learned a LOT and now I know I can make another more capable unit out of scrap if need be. I also made the boiler and later made a rocket stove that was supposed to be a water heater but in reality was much better at making steam using a single coil of copper tube. We used that water heater for 8 years and the rocket stove was made from scrap metal. Mostly propane tanks. My original boiler was also made from propane tanks. I never took it much over 100 psi with steam I tested it to 155 with air.

Nice..

I have worked to improve my stock on hand.

Ben

 

[Biggkidd]

Nice..

I have worked to improve my stock on hand.

Ben

Roger that I too have a lot of stuff on hand to make do with if the time comes. Including pop off valves and sight glasses maybe even a water intake pump to maintain the boiler level among other things.

 

[GaryLa]

What would be wrong with a big Sterling engine instead of steam?
No boiler to worry about exploding.
Apply heat to the cylinder, and rotational power comes out.

I researched and experimented with Stirling engines for about 6 months. It's a beautiful engine.

But it needs to be large to produce the amount of power we need for A/C units, ovens, welders, and other items. Really large.

The most impressive one I've ever seen is the one built by Ford (with prior work by Philips). It was 4-cylinder, used hydrogen at 2000PSI, attained 4500RPM and generated 260HP. Lots of high tech for the time period.

Even Robert Stirling saw that the only way to get decent power out of them was to pressurize the air. In his time, the seals failed often and were a major source of friction. Even today it's difficult to find seals which can withstand the temperatures you'd want to achieve at the hot end. Also, the metal of the hot end failed from heat fatigue. They also use more wood than a boiler for the same power output. Boilers heat water which holds the heat well compared with air.

I think the best use for Stirling engines today is using them to produce refrigeration. I intend to drive one backward from the exhaust steam to produce cooling. The exhaust will still have plenty of energy to accomplish this.

But heat fatigue is a major issue with boilers, too. It would be best to know the exact metal from which the vessel is derived before incorporating it. While it may perform well on test runs, it should be known how it will perform month over month before relying on it.

 

[SheepDog]

NASA has a plan to use Stirling engines on Mars for electrical power but they plan on using U238 to heat the units. I don't believe our government will permit a U238 power system in a back-yard.