Small Scale CHP Steam Engine System

Kevin Olson wrote:You've clearly considered this more than have I.  For what reasons do you think that reciprocating steam is a poor choice for an automotive prime mover?  Is it mostly the difficulty of coping with the widely variable load (and the turn down ratio of the burner that entails, though I might have a useful idea on that count, too), on grounds of achievable thermal efficiency, or due to something else (perhaps in addition to these) which I haven't yet properly considered?...

I think I've sufficiently derailed your CHP thread for now!  Thanks for your indulgence of my ignorance.

Hey Kevin. The main problem I see is superior alternatives exist. The main reason to favor steam power is to make use of a fuel that the alternatives cannot use. Well, a wood or charcoal gasifier can fuel automotive gas engines fairly well. And as you noted, some Diesel engines can use all kinds of fuel oils - and they can even be partly fueled with a gasifier. The only application for a steam engine system I see as promising is off grid combined heat and power (especially in a cold climate). And this is precisely what I'm working on. I want a bullet proof and compact system fueled by wood and/or waste oil with minimal processing, reasonably efficient electricity generation, highly efficient heat recovery, and easy to repair.

Everyone is more or less ignorant of small-scale steam. It truly is a lost art. The reason it interests me is it's counterintuitive in many ways.  I've found the vast majority (even engineers) who think they have a good understanding actually have a lot of misconceptions. It took a long time to piece meal my current understanding - which remains limited. Good information is scant. I recommend www.kimmelsteam.com. He has a lot of great resources (check out the old books from the early 1900's). But Tom Kimmel is particularly interesting for digging up resources on modern steam projects conducted after the age of steam power (like the Jay Carter engine and the White Cliffs engine, and smaller projects pursued by John Wetz and Jim Tangeman that I consider even more interesting).

NOTE: BTW, I only started this project fairly recently. But the designs were considered on the order of 10-15 years back. I waited mainly because it's hard to justify such a project financially. Indeed, I still can't really justify it. So, I have to keep my budget extraordinarily tight and proceed at a snail's pace. So far, it's been gratifying to see all the designs prove out (so far). That noted, I have no illusions about the difficulties of the next stages of the project.

M Buenijo wrote:I haven't considered this. Just off the cuff, one possibility is to place something akin to a blast damper (i.e. fast-acting valve) in the steam exhaust line before the condenser. A steam relief in the system can made to lift at a fairly high pressure like say 100 psi. This would fairly quickly increase the exhaust pressure on the steam expanders leading to very high cylinder compression. Additional lines installed in the cylinder heads might include steam relief valves that connect back to the steam exhaust. Again, this is just off the cuff. The idea is the high pressure settings would be significantly less than peak steam operating pressure - so they would not normally lift during normal operation (only braking).

I happened to read this again. I doubt this would work. The recompression would not exceed steam admission pressure. To work, this might require admitting steam at a medium pressure to the exhaust after the fast-acting valve shuts. In any case, I think it's way too much trouble. The steam admission valve should work as a check forcing the recompressed steam back into the steam generating tubing. A steam relief in that system might be activated by the process thereby eliminating the need for a second relief valve. Just speculating here.

M Buenijo wrote:

M Buenijo wrote:I haven't considered this. Just off the cuff, one possibility is to place something akin to a blast damper (i.e. fast-acting valve) in the steam exhaust line before the condenser. A steam relief in the system can made to lift at a fairly high pressure like say 100 psi. This would fairly quickly increase the exhaust pressure on the steam expanders leading to very high cylinder compression. Additional lines installed in the cylinder heads might include steam relief valves that connect back to the steam exhaust. Again, this is just off the cuff. The idea is the high pressure settings would be significantly less than peak steam operating pressure - so they would not normally lift during normal operation (only braking).

I happened to read this again. I doubt this would work. The recompression would not exceed steam admission pressure. To work, this might require admitting steam at a medium pressure to the exhaust after the fast-acting valve shuts. In any case, I think it's way too much trouble. The steam admission valve should work as a check forcing the recompressed steam back into the steam generating tubing. A steam relief in that system might be activated by the process thereby eliminating the need for a second relief valve. Just speculating here.

Yeah, I'd need to look at a P-V diagram and think about it.  I'm sure there's a way to do this, but I haven't had my head in reciprocating steam for almost 30 years, and even then I was an amateur.  My intuition about the Rankine steam cycle isn't very well-informed, these days.  Whether it's worth the fuss, I don't know.  The main attraction I see for this (reciprocating steam for mobile power, generally) is the flexible fueling and the more robust or lower stressed components.  Whether this is sufficient justification probably mostly depends on the circumstances in which one finds oneself.

I'll check out Kimmel's website, and track down some more of the references you've mentioned.  As I said, another rabbit hole to fall down (as if I needed another!).

Thanks again for your insights and references, and my apologies for derailing your CHP thread somewhat.

I do appreciate the wisdom you've shared.  And, I'll be cogitating on monotube boilers for process and space heating, now...

Solar steam engine in process..


Tesla steam engine.




Myself, I want to get ahold of a cyrogenic stirling engine so I can make my own heat pump...

Mart, I went to the Testur Energy website. A shame they don't have turbines that can handle steam. I was somewhat interested to try it. A good piston steam engine will be more efficient. But you can't beat the simplicity of the Tesla turbine! I note he claims significant torque at surprisingly low RPM. That's very interesting.

M Buenijo wrote:Mart, I went to the Testur Energy website. A shame they don't have turbines that can handle steam. I was somewhat interested to try it. A good piston steam engine will be more efficient. But you can't beat the simplicity of the Tesla turbine!

Hmm...  Did you watch the video?    

I was impressed with how much wattage  the demonstration in the video, but that was a powerful air compressor they were powering the turbine with.      

Myself even with air I was impressed with what the turbine shown in the video could do.      

I was surprised that they were getting so many watts out at the RPM shown.      I want to know how it does over a longer time period...

https://www.testurenergy.com/solar-cryophorus-turbine-system

This page states that they plan to use steam....

It could be the present systems they have are too new for them to be selling product.


Oh on another design  of Tesla...

https://youtu.be/aDZdSZirJHA design for water...

Mart Hale wrote:https://www.testurenergy.com/solar-cryophorus-turbine-system

This page states that they plan to use steam....

It could be the present systems they have are too new for them to be selling product.

I'm going to contact them this week. I'll get back to you. I need to feel them out and see if they're legit. I need specs.

M Buenijo wrote:

Mart Hale wrote:https://www.testurenergy.com/solar-cryophorus-turbine-system

This page states that they plan to use steam....

It could be the present systems they have are too new for them to be selling product.

I'm going to contact them this week. I'll get back to you. I need to feel them out and see if they're legit. I need specs.

Always best to get 3rd party verification.....

And hold on to your pocket book ;-)

larry kidd wrote:Back in 2010 - 12 I built a working low pressure steam generator also using an alternator to make electricity. It was also made from repurposed parts. A twin cyl air compressor made by Emglo IIRC.  My steam valve was a log splitter valve which worked brilliantly.  100psi supplied about 40 amps at 14 volts. I built it and posted a couple short clips on youtube and then gave it up as to dangerous to let unknowing people copy it, as was my original purpose. To share the knowledge is what I was after and then decided most people didn't have the sense to be safe! So I packed it away. I could get it going again in a day or three if ever needed.

My point is be CAREFUL with what you share so anyone who doesn't understand gets maimed or killed!

Hi Larry. If you are willing to share some of the details of your project, then I would be very interested. I'm sure others would be interested as well. BTW, I am aware of hydraulic valves being use as steam valves with success. It's a very good idea for an engine using saturated steam at modest pressure. I wonder, did you use a more traditional boiler (pressure vessel with a fairly large mass of saturated water under pressure)? If so, then do you personally believe a small steam engine system can be made safe with a monotube boiler with safety systems like steam relief and high temperature shutdown?

M Buenijo wrote:Jay Carter engine: https://www.steamautomobile.com/wsa/tutorial/index_18.htm

I have attached a PDF of the October 1974 Popular Science article which is linked from this URL (for those who are interested).

I had an interesting conversation with a senior boiler inspector in Texas. It's hard to make sense of boiler codes and other bureaucrat-speak. So, I just called the office. I got shuffled around to higher-ups until I came upon a boiler inspector guru. He told me the primary criteria they use to determine whether to regulate a boiler is size, pressure, and placement. Anything over 15 psig is considered a "power boiler" and subject to inspection, but only if it is placed where members of the general public have access. I explained my system is designed for combined heat and power in remote off the grid settings on private property. He said they don't care about things like this. Furthermore, he expressed personal interest in the system saying he'd love to see it when I'm done! Pretty cool guy I thought.

This is good news. I've have countless people tell me that I shouldn't both developing the system as it is illegal. I course, I wouldn't let this stop me from developing the unit. But it would stop me from selling them. Looks like I don't have to worry about it after all (at least in Texas).

M Buenijo wrote:I had an interesting conversation with a senior boiler inspector in Texas. It's hard to make sense of boiler codes and other bureaucrat-speak. So, I just called the office. I got shuffled around to higher-ups until I came upon a boiler inspector guru. He told me the primary criteria they use to determine whether to regulate a boiler is size, pressure, and placement. Anything over 15 psig is considered a "power boiler" and subject to inspection, but only if it is placed where members of the general public have access. I explained my system is designed for combined heat and power in remote off the grid settings on private property. He said they don't care about things like this. Furthermore, he expressed personal interest in the system saying he'd love to see it when I'm done! Pretty cool guy I thought.

This is good news. I've have countless people tell me that I shouldn't both developing the system as it is illegal. I course, I wouldn't let this stop me from developing the unit. But it would stop me from selling them. Looks like I don't have to worry about it after all (at least in Texas).

It all depends on location. Here would be the limits in force in Ontario where I live.
https://www.ontario.ca/laws/regulation/r01220

David Baillie wrote:[ It all depends on location. Here would be the limits in force in Ontario where I live.
https://www.ontario.ca/laws/regulation/r01220

I can't make sense of bureaucrat-speak. Besides, how the laws are enforced is more important than what the law actually states. Hell, there are so many laws around today that just about everything is technically illegal. My system will be very safe. But the problem with bureaucrats is they don't care about such things. They just apply the codes.

Kevin Olson wrote:

M Buenijo wrote:Jay Carter engine: https://www.steamautomobile.com/wsa/tutorial/index_18.htm

I have attached a PDF of the October 1974 Popular Science article which is linked from this URL (for those who are interested).

Kevin, this might interest you. The steam cylinder for my project is to mount on the crankcase with the steam piston connected to the lower crankcase piston via a sealed piston rod. I previously assembled an air pump by welding together ABS plastic with acetone and using flexible plastic reed valves that allowed the crankcase piston to act as an air pump to force air into the furnace. It worked perfectly. However, I later decided a small dc blower fan makes better sense for my application (the fan simplifies starting from cold and shutting down the blower makes it possible to stall the engine quickly for a rapid shutdown - this facilitates automation - but the automotive application has an operator available at all times). But this idea seems good for simplifying an automotive steam engine system based on the Carter configuration. The accelerator pedal linkage could close a spring-loaded damper to direct more air into a wood chip furnace (more heat, more steam, more pressure, more torque). A fairly modest motor might be used to drive a pressure washer pump, and the motor would be powered by a PID controller with steam line temperature feedback. An alternative might be to power the pump off the crankshaft such that excess water is always sent. The steam/condensate mixture would go to the separator column. The condensate would drain out the bottom via a fixed orifice. This works because the mass flow rate of water through the orifice is roughly 10X that of steam all else equal. Therefore, very little steam would escape. The heat that leaves the system via this orifice would be regenerated in a compact feed water heater. Note I came up with this idea long ago. But an engineer actually built a unit more recently, and he verified it works well. The saturated steam from the top of the separator column can be shunted through a superheater in the hottest part of the furnace. Also, since the majority of the steam generator coil is filled with steam/water that never exceeds saturation, the main coil can be made of black iron pipe, carbon steel, or some other relatively low cost alloy. Finally, for the condenser, I suggest a high flow rate water pump (standard automotive unit should work fine) force water from a well cooled hotwell to mix with the steam before it enters a conventional automotive radiator. These don't handle steam well. But most of the steam can be condensed by mixing with water.

M Buenijo wrote:Hell, there are so many laws around today that just about everything is technically illegal. My system will be very safe. But the problem with bureaucrats is they don't care about such things. They just apply the codes.

Yeah, my brother has said nearly this same thing verbatim.  Joel Salatin has a book titled "Everything I Want To Do Is Illegal".  Lots of laws and rules on the books, many of them outdated and/or unenforceable, without question unnecessary.  Most of the rest, selectively enforced.  I've been on the receiving end of this in a minor way, but I know of other people who have been endlessly harassed by this.

M Buenijo wrote:Kevin, this might interest you. The steam cylinder for my project is to mount on the crankcase with the steam piston connected to the lower crankcase piston via a sealed piston rod. I previously assembled an air pump by welding together ABS plastic with acetone and using flexible plastic reed valves that allowed the crankcase piston to act as an air pump to force air into the furnace. It worked perfectly. However, I later decided a small dc blower fan makes better sense for my application (the fan simplifies starting from cold and shutting down the blower makes it possible to stall the engine quickly for a rapid shutdown - this facilitates automation - but the automotive application has an operator available at all times). But this idea seems good for simplifying an automotive steam engine system based on the Carter configuration. The accelerator pedal linkage could close a spring-loaded damper to direct more air into a wood chip furnace (more heat, more steam, more pressure, more torque). A fairly modest motor might be used to drive a pressure washer pump, and the motor would be powered by a PID controller with steam line temperature feedback. An alternative might be to power the pump off the crankshaft such that excess water is always sent. The steam/condensate mixture would go to the separator column. The condensate would drain out the bottom via a fixed orifice. This works because the mass flow rate of water through the orifice is roughly 10X that of steam all else equal. Therefore, very little steam would escape. The heat that leaves the system via this orifice would be regenerated in a compact feed water heater. Note I came up with this idea long ago. But an engineer actually built a unit more recently, and he verified it works well. The saturated steam from the top of the separator column can be shunted through a superheater in the hottest part of the furnace. Also, since the majority of the steam generator coil is filled with steam/water that never exceeds saturation, the main coil can be made of black iron pipe, carbon steel, or some other relatively low cost alloy. Finally, for the condenser, I suggest a high flow rate water pump (standard automotive unit should work fine) force water from a well cooled hotwell to mix with the steam before it enters a conventional automotive radiator. These don't handle steam well. But most of the steam can be condensed by mixing with water.

So, basically, use the stock piston as a cross head, with the power piston connected to it by means of a piston rod, with a packing seal on the rod between the two?  Am I picking up what you're laying down?

I'll have to think about the rest.  I am a little slow on the uptake!

Kevin Olson wrote:
So, basically, use the stock piston as a cross head, with the power piston connected to it by means of a piston rod, with a packing seal on the rod between the two?  Am I picking up what you're laying down?

I'll have to think about the rest.  I am a little slow on the uptake!

Yes, this has been done before. Nothing new. But I also put the crankcase piston (crosshead) to work as an air pump. I installed two plates on the cylinder head one sealed the cylinder (with a single hole for air transfer of course), and the other was to serve as the lower steam cylinder plate. The two plates were separated by standoffs (the steam piston rod packing gland would be between the plates as well). My air pump (the assembly that contained the reed valves) slipped into the gap between the two plates like a cartridge. The hose connected at one end, and an air filter was at the opposite end. Pretty slick actually. At the same RPM, the stock gas engine pistons will provide twice the air mass flow rate because it's not working as a 4 stroke in this case. This will compensate for the lower thermal efficiency of a steam engine as well as providing some excess air for a furnace. If the transmission is retained, then the torque profile would be similar to a gas engine. But much higher low end torque would be available (as the Carter unit showed) because it's possible to jack up steam pressure at (almost) any RPM. Gas engines are very limited here (why they all have gears). On that note, a parallel hybrid configuration could eliminate the transmission altogether while allowing for a smaller steam system (and reducing the condenser requirements has benefits).

M Buenijo wrote:Kevin, this might interest you. The steam cylinder for my project is to mount on the crankcase with the steam piston connected to the lower crankcase piston via a sealed piston rod. I previously assembled an air pump by welding together ABS plastic with acetone and using flexible plastic reed valves that allowed the crankcase piston to act as an air pump to force air into the furnace. It worked perfectly. However, I later decided a small dc blower fan makes better sense for my application (the fan simplifies starting from cold and shutting down the blower makes it possible to stall the engine quickly for a rapid shutdown - this facilitates automation - but the automotive application has an operator available at all times). But this idea seems good for simplifying an automotive steam engine system based on the Carter configuration. The accelerator pedal linkage could close a spring-loaded damper to direct more air into a wood chip furnace (more heat, more steam, more pressure, more torque). A fairly modest motor might be used to drive a pressure washer pump, and the motor would be powered by a PID controller with steam line temperature feedback. An alternative might be to power the pump off the crankshaft such that excess water is always sent. The steam/condensate mixture would go to the separator column. The condensate would drain out the bottom via a fixed orifice. This works because the mass flow rate of water through the orifice is roughly 10X that of steam all else equal. Therefore, very little steam would escape. The heat that leaves the system via this orifice would be regenerated in a compact feed water heater. Note I came up with this idea long ago. But an engineer actually built a unit more recently, and he verified it works well. The saturated steam from the top of the separator column can be shunted through a superheater in the hottest part of the furnace. Also, since the majority of the steam generator coil is filled with steam/water that never exceeds saturation, the main coil can be made of black iron pipe, carbon steel, or some other relatively low cost alloy. Finally, for the condenser, I suggest a high flow rate water pump (standard automotive unit should work fine) force water from a well cooled hotwell to mix with the steam before it enters a conventional automotive radiator. These don't handle steam well. But most of the steam can be condensed by mixing with water.

Still chewing on this, but let's see if I have at least part of the idea:

The reed valve blower actuated by the original piston (now also the cross head)  provides forced draft to increase fueling/firing rate.  This is needed because you have a closed steam loop (give or take some inevitable losses, offset by some makeup water), so you can't use exhaust steam to enhance draft as in locomotive practice to make up for a short stack.  Because of your comment about the accelerator damper, I'm guessing this blower pump is capable of providing excess air under most circumstances.

To boost pressure from the condenser to the boiler coil, you are suggesting using a pressure washer pump, driven by a micro-controller governed small electric motor, or a crank driven pump which is capable of providing excess volumetric flow.

No steam dome, as would be common in locomotive practice, so you use a separator column (still need to look at details of this, I assume some sort of packing is inside), with a drain orifice at the bottom.  Even if the separator column is dry, not much steam can escape through the orifice.  Steam passes through a superheat coil in the boiler assembly, then on to the engine.

I still need to think about the hotwell, but coolish water is injected into the exhaust steam flow to partly condense the steam, before going to the automotive radiator to be cooled/condensed back to liquid water, and sent to the pressure wash pump.

And, subsequent;y, you are suggesting that a "steam Prius", with a "right sized" steam engine for cruise, with electric for surge (acceleration, hills, sprints), would result in a more efficient vehicle.

Is this mostly correct?

Kevin Olson wrote:The reed valve blower actuated by the original piston (now also the cross head)  provides forced draft to increase fueling/firing rate.  This is needed because you have a closed steam loop (give or take some inevitable losses, offset by some makeup water), so you can't use exhaust steam to enhance draft as in locomotive practice to make up for a short stack.  Because of your comment about the accelerator damper, I'm guessing this blower pump is capable of providing excess air under most circumstances.

To boost pressure from the condenser to the boiler coil, you are suggesting using a pressure washer pump, driven by a micro-controller governed small electric motor, or a crank driven pump which is capable of providing excess volumetric flow.

No steam dome, as would be common in locomotive practice, so you use a separator column (still need to look at details of this, I assume some sort of packing is inside), with a drain orifice at the bottom.  Even if the separator column is dry, not much steam can escape through the orifice.  Steam passes through a superheat coil in the boiler assembly, then on to the engine.

I still need to think about the hotwell, but coolish water is injected into the exhaust steam flow to partly condense the steam, before going to the automotive radiator to be cooled/condensed back to liquid water, and sent to the pressure wash pump.

And, subsequent;y, you are suggesting that a "steam Prius", with a "right sized" steam engine for cruise, with electric for surge (acceleration, hills, sprints), would result in a more efficient vehicle.

Is this mostly correct?

Yeah, it's just a positive displacement piston air pump in lieu of a traditional blower. The benefits include (1) the pistons are already there, so use them (and it's EASY and low-cost to fabricate!), and (2) it can provide a lot more pressure which is useful for pushing air through a recuperator to scavenge otherwise wasted heat. I suggested putting a damper on the discharge in lieu of the intake (like a throttle plate) because pumping losses would be high in the latter case. The crosshead pistons are already working to displace air into and out of the cylinder. The reed valve assembly just directs the air to a discharge plenum. The additional work required to push air through this path at low pressure is minimal. Opening the damper would dump part of the discharge away from the furnace. Whereas, closing down the damper (done by pressing down the accelerator pedal) causes more air to enter the furnace. Starting from cold using this air pump would require a starter motor able to operate for an extended period without overheating. But a modest blower could be provided only for cold starting.

A pressure washer pump is easily the least costly alternative for a water feed pump. A triplex pump is ideal. The separator can be nothing more than a vertical length of pipe a couple inches in diameter. Most of the condensate will collect in the base (might use a needle valve in lieu of a fixed orifice to drain the condensate). The steam taken from the top would be somewhat wet without some kind of packing, baffles, or sieve. But the superheater will dry it out. Besides, a bump valve uniflow can handle wet steam even condensate slugs w/o damage.

If a condenser is used, then a significant portion of the system would have to be dedicated to dumping excess heat. A second radiator dedicated to subcooling the condensate that leaves the primary radiator is a very good idea. The cooler water will more effectively condense the steam before it moves into the primary radiator (called "direct" steam condensing vs "indirect"). Yeah, you don't NEED a condenser. But you'll go through tons of water w/o it.

Yeah, a parallel hybrid is just one possibility that can have advantages. But everything is a trade-off. Benefits include a much smaller steam system and higher voltage and higher capacity battery system available to power auxiliaries.

 scheming on a sort of CHP system

Can you explain what this CHP system is please?

John C Daley wrote:Can you explain what this CHP system is please?

John, "CHP" means Combined Heat and Power. It refers to a system designed to provide electricity while also harvesting otherwise wasted heat for useful purposes (i.e. water heating, space heating, etc.).

M Buenijo wrote:http://kimmelsteam.com/smith-petersen-work.html

If you reference this page and scroll down a bit, you will see some data on testing a Mercury outboard two-stroke engine converted to a steam engine using bump valves. The data provided is as follows:

“Merc” 4 cylinder Engine on
cradle type E, Fan Brake for test,
Pressure: ~200 psig
Temp:     ~390° F.
RPM:     ~200
Exhaust Pressure – Atmospheric: (14.7)
Water Rate this test: 23.7 lbs/H.P. HR
—R.Smith

Assuming the data is accurate (and based on Smith's work I imagine it's reasonable), this puts the cycle efficiency at around 10.5% which is approximately 75% of theoretical maximum Rankine cycle efficiency. The reader may not likely appreciate this, but I'll just say this is pretty nuts for a small steam engine. A typical double-acting slide valve steam engine expander would show around 50-55% of theoretical maximum under these conditions. So, a good single-acting uniflow can provide 50% MORE work from the exact same steam source. Furthermore, the uniflow design is simpler mechanically.

The White Cliffs engine using saturated steam at around 550 psig (about 480F) and exhausting to a partial vacuum at around 5 psia showed around 73% of theoretical maximum (actual cycle efficiency was 16%). The cycle efficiency increases as the steam temperature increases (i.e. more superheat). However, the % of theoretical maximum tends to fall mostly due to clearance volume losses. For example, the White Cliffs engine showed about 65% of theoretical maximum efficiency when the steam temperature increased to 780F (cycle efficiency was measured at 21.9%). Furthermore, the efficiency gains start to flatline after about 150F superheat.

The lesson I got from this is don't bother trying to use crazy hot steam. You get diminishing returns and the additional thermal stress on the engine isn't worth it. I plan to operate at about 500 psig and no higher than 700F. This can yield a cycle efficiency of 20%.

DISCLAIMER: The "theoretical" efficiency figures I listed here were, shall I say, grossly estimated (sort of a thumb rule estimate - calculating a precise figure is a real PITA). Any engineers, please don't bother with a rebuttal (I know it is flawed). That noted, the cycle efficiencies reported by the two uniflow engines considered here were MEASURED.

Just making an update for anyone who might be interested in this project of mine.

I tested the steam generator again yesterday. No problems. I'm confident it's working as designed. So, I will advance to the next step. I just purchased the alternator that will load the crankshaft. It will directly couple to the crankshaft, and I will load the alternator with a heating element installed in my pot still. You can check the unit here if you're interested: http://www.motenergy.com/mepmge.html . I will mount it using an adapter plate. A small oil pump will mount to the plate and get driven by the camshaft via a rod extension that penetrates the crankcase cover. I'll start assembling steam expanders after this is done. I'm going to try a design that does not require oil lubrication. But other designs call for oil (hence the oil pump).

M Buenijo wrote:

I'm going to contact them this week. I'll get back to you. I need to feel them out and see if they're legit. I need specs.

I called several times on different days and left email. No reply.

M Buenijo wrote:Just making an update for anyone who might be interested in this project of mine.

I tested the steam generator again yesterday. No problems. I'm confident it's working as designed. So, I will advance to the next step. I just purchased the alternator that will load the crankshaft. It will directly couple to the crankshaft, and I will load the alternator with a heating element installed in my pot still. You can check the unit here if you're interested: http://www.motenergy.com/mepmge.html . I will mount it using an adapter plate. A small oil pump will mount to the plate and get driven by the camshaft via a rod extension that penetrates the crankcase cover. I'll start assembling steam expanders after this is done. I'm going to try a design that does not require oil lubrication. But other designs call for oil (hence the oil pump).

My alternator arrived today! That was fast! I was expecting a couple weeks. Anyway, I need to do some basic machine work including cutting down the shafts (both the alternator and the crankshaft PTO). I'm going to use a clamping coupling to avoid having to cut a new keyway. This will take a minute as my tools are primitive.

We are building small chp for retrofitting biochar kilns. So farmers and communities can make biochar, electricity and purified water

It is very low cost and any mechanic can build it. If you are interested in building it our NGOs will reimburse you for  the materials if you publish step by step instructions and test results. Wastefree23.org

Start with your heat source - tlud, wood stove whatever,  take 40 meters of ss or aluminum tube.  Put tube in sand/clay that blankets heat source. Connect a Tesla steam turbine you built to one end with a pulley system to get the rpm right for your generator,  a valve and a pressure relief set at 150psi

On the water inlet side another valve and a pressure tank filled with water and a little air maintained at 100 psi or a 100 psi auto switch water pump

M Buenijo wrote:

Mart Hale wrote:https://www.testurenergy.com/solar-cryophorus-turbine-system

This page states that they plan to use steam....

It could be the present systems they have are too new for them to be selling product.

I'm going to contact them this week. I'll get back to you. I need to feel them out and see if they're legit. I need specs.

I bought the 4 inch 500 watt turbine of eBay for $120. So far it is working great with our flash boiler. Good torque and rpm this weekend hooking up to a 300 watt generator. Will post photos and updates.

D Fujito wrote:

I bought the 4 inch 500 watt turbine of eBay for $120. So far it is working great with our flash boiler. Good torque and rpm this weekend hooking up to a 300 watt generator. Will post photos and updates.

I sent you a mooseage that included my cell number. Feel free to call anytime. I'm interested in whatever data you are able to collect from testing this turbine. Note I am primarily interested to direct steam exhausted from my piston expander through a small Tesla turbine to power auxiliary systems.

NOTE: I had independently considered that much household "waste" can be used as a fuel source in my system. Shredded paper waste and plastics can be supplemented to a wood chip gasification furnace along with dry shredded biomass products other than wood (provided wood remains as the majority of the fuel).

1 we are currently using saturated wet steam to power our turbine , steam quality can fall all the way to saturated liquid and our turbine is still expected to run

2 we are testing , will get back to you on that

3 also under testing but we have an idea . Its turbine specific and dependa upon blade configuration.


If you can identify the required toqrue requirements of your fan,  i can help you size an appropriate turbine

D Fujito wrote:1 we are currently using saturated wet steam to power our turbine , steam quality can fall all the way to saturated liquid and our turbine is still expected to run

2 we are testing , will get back to you on that

3 also under testing but we have an idea . Its turbine specific and dependa upon blade configuration.


If you can identify the required toqrue requirements of your fan,  i can help you size an appropriate turbine

A big problem with these Tesla turbines is the dearth of rigorous test data. Also, it's frustrating to see so many testing these units on compressed air. This is simply not useful. Steam is really the only practical working fluid for such a system (because low grade heat and water are cheap). I imagine quite a few folks are interested in your test results.

NOTE your steam generator must have temperature control to ensure the vapor is fully saturated as a wet steam will be less useful for thermal efficiency measurements. Preferably, the steam should be slightly superheated to ensure there is no condensate. What I would like to see is a "water rate" measurement where steam flows through the turbine to a condenser. Once the turbine output stabilizes, then the power will be recorded and the condensate from the steam that flows through the unit during the test period is collected and weighed. This is the simplest way to measure the quantity of heat used during the test with thermal efficiency as shaft work / heat input.

I am interested to power a typical whole house fan normally 100-300 watts mechanical. Ideally, the turbine could provide enough torque at low speeds to directly couple to the fan (around 3000 rpm). However, this is a tall order. I could gear down with a pulley/belt. But the lower the turbine speed the better. If the thermal efficiency were shown to be optimal at a significantly higher speed, then it would be better to just power a small generator directly. In such a case, I would be interested to direct steam engine exhaust through the unit to boost overall generator efficiency.

M Buenijo wrote:
DISCLAIMER: The "theoretical" efficiency figures I listed here were, shall I say, grossly estimated (sort of a thumb rule estimate - calculating a precise figure is a real PITA). Any engineers, please don't bother with a rebuttal (I know it is flawed). That noted, the cycle efficiencies reported by the two uniflow engines considered here were MEASURED.

I decided to check these figures more closely comparing the measured efficiency with the theoretical maximum "Rankine" cycle efficiency. All the data points for the White Cliffs engine showed 70-75% of Rankine cycle efficiency. Whereas, the Richard Smith engine I mentioned came in at around 57% of maximum. This is fantastic considering the best engineered large piston steam engines of the early 1900's were a bit over 80% and while using lower pressure and lower temperature steam.

In my opinion, the main reason Smith's engine came in lower is because there was no condenser and the steam supply pressure was relatively low. You have to expand the steam to get high efficiency. But the uniflow exhausts the steam through ports in the cylinder wall like a two stroke gas engine. Well, when the steam supply pressure is relatively low, and the steam exhaust pressure is relatively high (i.e. no condenser), then expansion must be more limited - otherwise, there will be not enough pressure to exhaust enough steam on each cycle. If this engine were to add a vacuum condenser, then getting 15%+ cycle efficiency would be possible - and without having to take pressure beyond 200 psig. In fact, I had considered previously to install a larger steam cylinder and operate at a lower pressure and lower rpm. But it would be difficult to get the power I want under this condition. Besided, my design can handle high pressure - and it's a CHP engine, so the condenser pressure can't get too low or the temperature gets too low to be useful.  

I am corresponding with the folks at gyroscope.com. They make a fairly large Tesla turbine with an integrated PMA that is rated for 1400 watts. The turbine is supposedly designed for saturated or slightly superheated steam up to 150 psig. They DO NOT have testing data on steam which I consider a red flag. So, I declined to purchase. But I offered to test the unit if they send me a unit. Note they are in the UK. I'm skeptical. But I will test it thoroughly if they send me a unit. My steam generator is almost perfectly sized for this unit.