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Re-starting the Steam Engine Project
  • Vote Up0Vote Down
    November 2011
    As many of you know, I put quite a bit of work into developing a steam engine design earlier this year.  That design has problems in it that will need further research and experimentation.  Marcin has indicated that he's not interested in exploratory or experimental work, but rather wants a design that can be fabricated and built.  I would like to re-start the project, but rather than having it be a pure-OSE project, I have created an
    independent set of Google sites where we can discuss and document
    the project.  I have sent out some invitations, but if you didn't
    get one and are interested in joining, please go to and request
    to join.

    Documentation will be collected at  At the moment, this
    site is empty.  I will be granting serious contributors write
    permissions to this site once there is information to be added.  I
    will curate the site and moderate the forums.

    Here is the invitation I sent out:

    I am starting up a project to research, design, and build an open
    source steam engine and eventually other steam related technologies. While
    there are many useful steam engines for sale (do a quick Google search), I
    have yet to find a solid set of plans and building instructions that are fully
    open source and free. There are some great organizations that support steam
    engine development (like SACA), but these tend to rely on personal
    relationships and local events to guild people new to steam technology. This
    is not a bad thing at all, but not everyone can attend such events.

    What we need is a repository of information on steam technology. It should
    include different approaches to steam engine development (both historical and
    new). It should include information on safety, tools needed, skill development,
    etc. If you are interested in participating, please join the Google group
    I've created.

    While I will lead this project, I fully intend to delegate aspects of it to
    capable and willing people. I believe in a collaborative approach to
    development. While it can be slow at times, it leverages the diversity of the
    individual contributors. All of us have something to contribute to projects
    like this, even if it's tracking down some piece of needed information.

    - Mark Norton
    OS Steam Project

    There is room for contributors of all sorts:  researchers,
    designers, CAD artists, engineers, fabricators, etc.  Steam devices that come out of this project will be made available to OSE to be included in the GVCS, if deemed appropriate.

    - Mark Norton

  • 7 Comments sorted by
  • Vote Up0Vote Down
    November 2011
    Very interesting project, hope it works out.   I would suggest though that instead of keeping less serious contributors out by permission you instead do things by allowing everyone, but then having another section that is write only to the serious contributors.  More welcoming for people who may become serious contributors.  Or more welcoming yet allow anyone to edit anything and then filter the additions into the right places, as wikipedia does.

    Anyway, I am skeptical about the idea of a "scalable" design.  Of course most such designs can be scaled a bit, but I think a better approach, which may also be easier since it breaks the problem down some, would be to produce a set of designs.  Because scaling or customizing such a machine will ultimately require some of what is, in fact, redesign.  If anyone, even people who have no expertise are to make the machines that are safe and will work as well as they followed the build instructions, then they have to be able to use the design as-is.  We need a library of designs, not these hypothetical "scalable" designs.

    If this sort of thing caught on, sets of approved designs would probably be what evolved anyway, as the tested designs were copied by people who were hesitant to try to scale things.

    Anyway, I have a suggestion to drop on an expander which, after having looked at a lot of different expander types (claw compressor, screw compressor, roots blower and gear pumps, gearrotor, globoid expander, gear pump, there was one very clever one from a pump of the type which is for pumping sewage and concrete but I forget what it is called, it uses a universal joint and a sort of helical shaped mass moving within another mass that is almost the negative shape but not quite, the various turbine systems, diaphragms, piston engines of various types like the normal crankshaft and nutating disk types flexible shaft kind ("the green steam engine") and totally linear kind, wankel/rotary, and various cockamamie schemes that I thought up from scratch, etc.),  I think there are two expanders that really stand out:

    It you want electricity only, the entirely linear one combined with a linear alternator looks interesting.  Easy to make, very few moving parts, can have a very high expansion ratio, etc.

    The other one is the modified claw compressor kind.  For clarification see the wikipedia article for claw compressor.  Anyway modifying it for use as an expander for high temperature steam:  Instead of a claw, it can be a circular mass at the end of the male rotor tips.  So it is more of a club than a claw.  A cylindrical prism basically attached at the end of a rod of square or rectangular cross section.  The only purpose of this is to increase the expansion ratio - the claw shape implies a dead space at top dead center otherwise.

      Have external gears that synchronize the two rotors so they never touch.  This is done on oilfree compressors and gearrotor expanders already.   The gears are lubricated with normal lubricant because they are cold.  The hot expander requires no lube because there is not metal to metal contact.  This eliminates the oil. (BTW the return pump could operate in a similar way but a rearrotor pump might be more appropriate.)

    Okay, so you see the point is that the club part (rather than claw) is acting as the piston head, with the cylinder replaced by the other rotor.  Then you need a way to inject and exhaust the steam, obviously.  It could be injected/exhausted through a hole in the face of the casing, as with a compressor.   The interesting things about this sort of expander being the smaller number of parts, the inertia required to reverse the piston motion is not a problem so it can operate at higher RPMs, potentially much lower wear and therefore maintenance because the cold synchronizing gears and the rotor bearings are the only part where there is any contact, and they can be at low temperatures last a very long time when appropriately lubricated (and consume a lot less lubricant).  There is only 2 surfaces that bear high loads, the rotor bearings.  No piston rings needed since there is no wear in that area.

    It looks a lot simpler to make than a reciprocating piston type, less alignment and little fiddly bits to make maybe. 
  • Vote Up0Vote Down
    November 2011
    Why not make these kinds of suggestions on the OSteam forum, Gregor.  They become part of the conversation stream that way.  Thanks for the suggestions, BTW.

    - Mark
  • Hi Mark and folks,

    Will there be any OSEcology / OpenSourceSteam associates in attendance at the SACA meeting this coming weekend, Jan 13-15, 2012 in Sacramento, CA?  I've only discovered OSE/SACA recently, so this is last minute to me.  I'm assessing the personal feasibility and group need for attendance. It'd be great if there were a host of video documenters to record the technical discussions.  I haven't been in contact directly with SACA to see if video recordings are already planned.

  • Vote Up0Vote Down
    January 2012
    I'm not planning on attending, TriSimon.  If you are going, perhaps you could capture some of it for the rest of us?

    - Mark
  • Hi Mark,

    I attended the steam meet.  Following are two video playlists from the event.

  • Vote Up0Vote Down
    February 2012
    Nice stuff, TriSimon.  Thanks for taking the time.

    - Mark
  • Vote Up0Vote Down
    February 2013
    NOTE: I had posted this elsewhere, but reposted it here as it might be relevant to some concerns here.

    As I understand it, OSE is still working on a piston steam engine
    design. I tend to agree that a piston expander is the way to go for its
    relative ease in fabrication. Unfortunately (at least from my
    perspective) the OSE guys seem to be emphasizing high thermal
    efficiency, and things start to get really complicated when one tries to
    get high thermal efficiency in a small steam system. So, I'm just
    throwing out my concerns for anyone who might find interest.

    biomass is the fuel source, and the system is used on a residential
    scale or any setting where the waste heat can be put to use, then it
    seems preferable to sacrifice high thermal efficiency for higher
    condenser temperature in order to make the most of the heat available
    from the system. There are so many ways to use this heat that can
    displace electricity otherwise used. A few examples beyond the obvious
    like space heating and water heating include water pasteurization, space
    cooling, biomass fuel drying, air circulation in the home by
    convection, clothes drying, and food drying. In particular, I think
    there is promise in a desiccant evaporative cooling system. Here the
    heat from a high temperature steam condenser can be used to boil the
    water out of the desiccant for regeneration, and the steam generated
    from this process can be used again in other heating applications. The
    distilled water that results is used for evaporative cooling. There are
    many other possibilities. Basically, I think an emphasis on high thermal
    efficiency could be counterproductive for some settings. Actually, I
    prefer a configuration where electricity use is minimized to the point
    where a micro heat engine is really unnecessary. Let photovoltaics and
    wind turbines do this. A micro heat engine might be useful as a backup
    only. However, a biomass furnace can provide the bulk of energy required
    for a home as a source of heat for the aforementioned applications.

    respect to a remote solar heat engine where putting waste heat to full
    use might be impractical, then I can understand a focus on higher
    thermal efficiency. However, even here it can be impractical. After all,
    since the solar "fuel" is free, then the efficiency of a solar power
    system is a four letter word: cost. Sacrificing some thermal efficiency
    is justified if it can get the overall costs down. I have yet to see a
    mention of the following configuration on the OSE forums, so I will
    mention it here. I wonder if using conventional double acting, two
    cylinder compound, piston steam engines (with slide valves) will yield
    good results by integrating a heat transfer fluid (such as a thermal
    oil) and a bottoming cycling using an organic working fluid. In this
    configuration steam could be generated with thermal oil at a temperature
    that allows for circulating lubricating oil with the steam/condensate.
    The exhaust from the first compound engine can be kept at a high
    saturation temperature to transfer its heat to an organic working fluid
    selected to keep the same pressures as the steam engine at these lower
    temperatures (NOTE: see saturation conditions for butane - it might be a
    good candidate). Sure, there are some disadvantages here, but the
    advantages include not having to maintain a high vacuum in a steam
    condenser, and being able to use conventional steam engine systems with
    little modification. There would be additional pumping losses required
    for an ORC, but perhaps the higher pressure and smaller cylinders can
    reduce friction and thermal losses for this to be a wash. There would
    also be losses involved in the transfer of heat from the steam
    to the organic fluid, but my research suggests that surprisingly small
    copper heat exchangers can see very high heat transfer rates when
    saturated vapor/condensate compounds with high density are used, and with little temperature difference. Anyway, if the
    OSE guys are having difficulties in developing a piston steam engine
    with high thermal efficiency, then just toss this idea around.

    NOTE: This configuration would also show minimal superheat on the steam
    side, and the pressures could be limited to 500 psig or so. This would
    be a lot safer than many other approaches... especially in a DIY

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