Exhaust Heat Recovery - Steam Power

[NiHaoMike]

What about modifying lawnmower engines into steam engines?

[Patrick]

Originally Posted by NiHaoMike

What about modifying lawnmower engines into steam engines?

Well it's been done before and it's pretty easy. All you have to do is take the camshaft out and weld an additional intake and exhaust lobe on it 180 degrees out from the original lobes. Put the camshaft back in and pipe the steam into the intake port. You may have to give it a push to get it started.

[user removed]

Running about 2k RPM on 120 PSI shop air supply.

Also self starting.

http://www.youtube.com/user/Ride122609



regards
Mech

[Bicycle Bob]

I have some old reference books around, with a large selection of boiler styles for steam engines. They all specify either ten or twelve square feet of boiling area per HP. That's with ideal temperatures. Heat recovery schemes would need even larger hardware. To run a nicely refined, efficient steam engine you need most of the bits used in the Doble steam car. It was able to compete with the gas buggies in refinement and ease of use, but was very expensive. It is hardly worth the price of another complex engine for a few percent savings.

[user removed]

Spiral wound tube boiler inside a pipe just after the cat.

Insulated spherical reservoir that can handle high pressure.

Engine like the previous link attached to the alternator like a pulley, with an electric clutch to engage a belt if you did not generate enough steam.

Use available heat from condenser to heat passenger compartment.

A small air grinder can spin a wheel up to 100 MPH so you might want to use the die grinder to spin up a flywheel then engage the field to place a load, and pulse and generate the system.

Get rid of cooling system operated heater core and hoses.

I doubt you can do it cheap with off the shelf parts, but if so a rotary vane pump would be your best bet. You would need at least 3 cylinders and pistons for it to be self starting.

regards
Mech

[bschloop]

I used a compressor off of a plymouth breeze. I didn't take it apart, just blew air into each side. it turned with no load, but had very low startup torque. a cluch would be necesary, but it has a clutch on it, I believe.

[LeakyIdeas]

What about taking a diesel RC motor, welding it to the exhaust manifold (insulate the outside of it), and when it gets hot enough dripping water into the injector port (instead of fuel)?

(and collecting the steam from the exhaust and recycling it so the water is already hot and add a little oil)

i.e. skip the whole storing and heating large amounts of water part.

an alternator from a motorcycle may be better in this case (if underpowered), as i think they spin slower. if it worked then you could put one between the exhausts so getting 3 on an inline 4.

or is that just too simple to work?

[jdgFirefly]

Originally Posted by Bicycle Bob

I have some old reference books around, with a large selection of boiler styles for steam engines. They all specify either ten or twelve square feet of boiling area per HP. That's with ideal temperatures. Heat recovery schemes would need even larger hardware. To run a nicely refined, efficient steam engine you need most of the bits used in the Doble steam car. It was able to compete with the gas buggies in refinement and ease of use, but was very expensive. It is hardly worth the price of another complex engine for a few percent savings.

12sqft/hp good rule of thumb number to know. If we only want to run an alternator, 1hp should be good enough. So a simple single tube in tube boiler will be 30' long. Guess we need to think up a different heat exchanger setup.

Multiple tube's like in a classic boiler.
Maybe a heater core in the exhaust stream, however soot and corrosion would be a problem.
Small OD copper tubing coiled in the exhaust stream would be easy, however as mentioned earlier it would need to be coiled vertically to prevent the steam from getting trapped.

Yes the Idea of heat recovery adds the complexity of a second engine and at this point we are only looking for a few % return. But this Idea has huge potential for the future, it is definitely worth investigating and experimenting with. As I mentioned before an a/c system has all the major components of a Rankin cycle, in other words all the complexity of a second heat engine and the auto manufacturers have been able to economically add these system. So I don't think that it's unreasonable to make a heat recovery engine.

[bschloop]

update on the AC compressor idea. I set it up again, and engaged the clutch while it was spinning. It has so little torque that I could hold it stationary with my hand. (Gloved of course) this was at 90psi, so it seems it will not work. Bummer

[bschloop]

Originally Posted by jdgFirefly

Small OD copper tubing coiled in the exhaust stream would be easy, however as mentioned earlier it would need to be coiled vertically to prevent the steam from getting trapped.

Instead of coiling the tubing you could arrange multiple tubes along the inside wall of a larger diameter exhaust pipe ( ie. if your exhaust were 2in then you would use 3in pipe) and having them all connected at both ends for inlet and outlet. Choose the longest straight section in your exhaust and replace it with this slightly larger pipe. Or if you are really into fabrication and welding you could replace everything behind the cat and have multiple inlets and outlets. There ought to be plenty of room for the larger pipe, and if you use small enough tubing it shouldn't need all that much water.