[Gasification] Solar ORC's -- The scroll compressor as prime mover ORC

Sun Feb 4 03:41:58 CST 2007

peter, it is good to see you back on your war horse and charging at
the ORC windmills.  things have been a bit too quiet around here of
late.  i think you've been outback pressing coconut oil, cooking snake
bones, and generally making every machine within 50 miles of you
powered by a one lung china diesel, with or without its permission.
so good for you . . . ;-)

however, i find one salient fact in this latest round of peter ORC
promotion: you have never actually made one.  not a single one from
what i can tell.  ever. (i admit i might be wrong on this, but all
words point to this conclusion.  apologies ahead of time if i am
wrong).

peter, the guy who can make anything out of nothing, the naysayer of
all high tech solutions to solve what has already been solved and is
laying around the junkyard, the guy who proves all this power stuff is
really old and easy tech, has, in fact, not proved as such with the
ORC issue.

might this be a meaningful omission in the full frontal diy building
assault of peter?

yes peter, we all see the wonderful potential (and real) applications
of the cycle.  as well as all the tempting compressor motors that can
be repurposed as expansion engines.  but so far, despite years and
years of discussion as such, i've yet to see a single good junkyard
obtainium solution to the expansion engine problem.  and if peter
hasn't found it and built it already, i fear it might not exist (but i
have yet to try, so i'm not going to completely declare defeat on this
front quite yet.)

equally interesting, is to note what peter DOES build and hack,
repeatedly, obsessively, exhaustively, ad nauseum: slow speed one lung
diesels.

there are some obvious reasons for this.  we have an already existing
giant installed base and cheap infrasture for such mechanical animals.
 we all understand them.  they have proven deeply flexible and idiot
tolerant.  the guy down the dirt road can likely fix it.  and they
maintain their lead or near lead in practical efficiency, despite
millions of dollars in DOE funding to the potential otherwise.

you know all this peter, of course.  so why are you back on the ORC
problem?  why have you not yet to build a gasifier to run some of one
lungers crowding you out of house and orchard down there?  not a
charcoal maker.  but a proper engine running gasifier.

i admit i was put off from it forever, as it seemed so complicated.  a
black art from the past, with strange terms and processes that are not
currently imparted in a redneck youth of grease and diesel smoke.  but
peter, this should be the last thing that scares you.  really, you are
peter.

so peter, in the name of (insert favorite), please build a gasifier
already!  not a charcoal maker.  just a straight up gasifier to power
one of your beasts.

i just completely shocked myself how easy it is to do.  see here.
http://whatiamupto.com/Gasification/quadrafier/index.html

you can make a working updraft gasifier from any tank with two welded
pipes.  weld one into the bottom for a grateless air feed.  weld one
into the top to fill fuel and cap and tap it for gas extraction.  this
could not be easier really.  but yes, such will have tar.

so then make a stratified downdraft or a crossdraft.  i made each in
about a day, using junk, one even without a single weld.  4 hours of
work.  and they work fine, even before any of the obvious heat
insulation and waste heat recycling that should be applied.
incorporate some other this and that and really, you'll soon not be
bothering with liquid fuels much i think, given what is around you.

for developing world small scale power situations, i believe the small
IC engine is a forgone conclusion.  so let's make some better fuel to
feed it.  it really is not difficult in any way.  especially for the
likes of a peter.

so far in my runnings, i also find the tar problem overstated in its
importance.  yes, low tar is great.  but if you tar up the motor, put
some gasoline or other solvent in it.  turn it a few times and it all
comes out.

it is probably possible to flush most of it before shut down by
running a petro fuel for a bit.  not sure yet.  while the engine is
hot, it seems the tar isn't that big of deal.  or rather, not good,
but not catastrophic.  and easily fixable after the fact if it becomes
an issue.  change out oil and burn it in the fuel when needed.  you
can pour it right in the gasifier slowly and it will burn just fine.

or am i still just naive on the tar problem in engines and will learn
otherwise soon?  so far, it seems vastly overstated to me if you are
willing to do a little thoughtful cleaning around it.

j

On 2/3/07, Peter Singfield <snkm at btl.net> wrote:
>
> Read all about it (in greatest detail) at:
>
> http://www.freepower.co.uk/site-4.htm
>
> Abstract – The commercial feasibility of small scale solar ORC for
> distributed generation and CHP is demonstrated. This has been achieved with
> an energy analysis of over 150 commercially available solar hot water
> collectors, a survey of candidate working fluids and by adapting rotary
> refrigeration compressors to run in reverse direction as
> expanders/asynchronous generators. A computer code combining the results of
> these sub-studies has demonstrated that self-stabilization close to optimum
> conditions for given irradiance may be possible without electronic feedback
> control.
>
> The principle obstacles encountered included oil migration, face and tip
> sealing problems and low expansion ratios.
>
> Electrical Capacity Costs of capacity - at G=1000W/m 2 were estimated. A
> significant improvement on these figures is possible if a large cooling
> reservoir is available.
>
> Construction of a field prototype will involve developing a high volumetric
> ratio, purpose built expander in collaboration with a compressor
> manufacturer and optimising a liquid piston pump which is being developed
> specifically for ORC feed-pumping.
>
> *********************************************
>
> Please take note in regards to that last part -- specifically:
>
> "involve developing a high volumetric ratio, purpose built expander"
>
> As recently mentioned -- the scroll compressor design does not allow for a
> high enough expansion ratio to be used efficiently as an "ORC" prime mover.
>
> Still -- this entire paper is involved with making small solar ORC system
> -- the kind easy to apply for a single house (Well -- a 3rd world house --
> you need a mini nuke power plant for an American style house!!)
>
> Folks -- it is happening -- period.
>
> One day -- if I find time -- I shall pursue further a very simple -- easy
> to make -- design I developed years back -- for a low RPM pelton wheel
> turbine well adapted specifically for an ORC style prime mover application.
>
> And in the 500 to 1500 watt power range ---
>
> Till then -- have a good one -- eh??
>
> Peter / Belize
>
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