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2KW low temp Rankine cycle electricity and cooling
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Tim, I want to follow up a little on my first post (notice that Minto started with a compressor and went to a turbine...).

The reason a turbine works better than a reciprocating (or even rotary) compressor that's been re-purposed as a prime mover is because you can add stages to it to extract more energy from the expanding gas

That energy doesn't manifest as pressure alone, but also as heat. The reason it's good to dump heat is that it requires less work to achieve the requisite change of state back to liquid after the gas exits the turbine.

So you have 3 things to consider:
maximum work extraction (prime mover)
which yields:
maximum pressure drop
which yields:
maximum heat loss
which yeilds:
easier change of state
which results in:
best efficiency.

That means the heat source can be smaller (collectors, waste heat, etc.) and the condenser area and temperature requirements are not as stringent.

So, yeah, turbines are better than re-purposed compressors but small ones are hard to come by.

And as was mentioned in one of the posts above, a turbo-charger off a (big) diesel might be a possibility, but it still wouldn't have the stages to use an expanding refrigerant efficiently - turbos just don't have the surface area, are designed to move air, not be moved -by- air.

Anyway, I'd sure like to find a source for Minto's turbines, they were actually designed specifically just for this purpose.

Tony
 
Location: Morongo Valley, California | Registered: March 14, 2009Reply With QuoteReport This Post
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Thanks for the info, I will do some searching for the past info.

The current R 134 refrigerant is pretty close to what you describe for R11, it condenses at about the same temp, much better than using propane as I had originally thought, pressures/temps of the R134 system run a lot less than if using propane. It is not all that expensive either and I don't think a small system will use more than a gallon or so, it is also available over the counter without a frig tech liscence, this makes up a lot for any shortcomings it might have in the temp/pressure area.

Yes, I found references to other folks with working systems, mostly in the tropics, one place in Balize has a system set up using solar for heat and radiators under shade for the cooling/condensing, another island has a large system making electricity using the heat from shallow sea water and the cold from much deaper sea water. This technology is also used in most commercial electrical power plants using the heat from the spent steam that has already passed through the main power generating turbines but there systems are huge in comparison to what I hope to build.

I think the main claim of the Matteran folks is there way of moving the cooled condensed liquid back into the boiler without the need of a power eating high pressure liquid feed pump, it makes the entire system a few percent more efficient. I am willing to use a bit of the electricity to turn a normal mechanical feed pump rather than needing to use the tall tower to produce enough gravity pressure to push the liqued back into the boiler. The small 2K MIT African system proves that a small 2-3 k setup can make adequate power so that a mechanical pump can be used and still have a reasonable amount of electricity left for other uses.

Screw compressor -- I pulled an automotive screw compressor out of a junk yard just to see how they work, sure seems like a lot of loss in the large contact surfaces of the sliding cross bars, I just don't see it working all that well but I have read a web page where they used a converted commercial screw frig compressor just fine to turn an external generator so it can work, just don't seem right to me though. They had to do a good bit of modifying and converting to get it to seal internally and also to not leak refrigerant to the outside world. The York piston compressors are well sealed to begin with and have a sealed crancase to lube the moving parts, by making up a simple flat aluminum plate cylinder head and using a sealed spool type hydraulic cylinder reversing valve you have an engine/expander that is fully sealed and designed to work with the fluid being used, and has a proven operation period of thousands of hours without failure, and it costs almost nothing from a salvage yard, plus it sounds neat running.

I still have never found a price listed for any of the micro-turbins I read about being tested in these systems, I sure have not found one in my local salvage yard.

Another approach I have been wondering about is to power the piston expander using the "flash steam" technique rather than using pressurized vapor. In a normal steam engine you use pressurized vapor to push the piston, this works, but the amount of expansion is not all that great and you must use large supply piping to move an adequate amount of vapor, the large volume of vapor also requires large valve openings to control it, large valves can't move as fast as small valves, if I use the pressurized LIQUID from the bottom of the boiler rather than the pressurized VAPOR from the top of the boiler I get two improvements, first - I only need to inject a tiny amount of hot pressurized liquid into the cylinder to get a LOT of expanding vapor, second - the expanding vapor absorbes a LOT OF HEAT, just as you pointed out, this should reduce the amount of external cooling needed to condense the vapor back into a liquid (somewhat concerned about this, the expander engine may get too cool, normal water steam engines want to conserve the heat loss through the engine, still thinking about this). This would also let me rework the valving of the piston expander away from a 4-cycle type system that uses a restrictive exhaust flow that routs the exhaust vapor back out of the top of the cylinder, through restrictive passages, then through a moving exhaust valve. By injecting pressurized LIQUID directly into the top of the cylinder I can convert the expander engine over to a "uniflow" type exhaust system where the exhaust exits through the side of the cylinder at the bottom of the piston stroke, much like a 2-cycle gasoline engine exhaust. This completely eliminates the need for a sliding valve setup and hopefully will allow me to use electrically controlled automotive gasoline of diesel engine fuel injectors to squirt the high pressure LIQUID directly into the top of the cylinders, The liquid would also allow the use of much smaller feed plumbing to the high pressure side of the engine/expander. By electronically controlling the injector timing and pulse width I will only use as much liquid as is needed to do the job as hand controlling the speed and torque of the expander, this should improve the efficiency of the system even more.

Somehow this direct liquid injection scheme seems like perpetual motion, squirt hot high pressure liquid into the cylinder, the liquid expands into vapor and pushes the piston, the vapor is cooled til it condenses back into a liquid, then the liquid is pumped back into the boiler. Seems like it should take the same amount of energy to pressurize the cooled liquid enough to push it back into the boiler as the amount of energy you extracted in pushing the piston, I know there is heat added to the liquid in the boiler but I just don't have my head wrapped around this yet. There is no differance in the amount of energy used when flashing the liquid into vapor inside the cylinder as there there is in boiling the liquid into vapor and using the vapor to push the piston, I know a system that is pushing the piston with vapor works because there are systems doing it, squirting liquid directly into the cylinder should work even better than vapor, puzzling.

Your referance to turbines being able to add sections to take advantage of the lower energy in the expanding vapor, compound piston steam engines do the same thing by passing the lower pressure vapor through progressivly larger diameter pistons on the same crankshaft, the larger area of the bigger piston produces additional power from the lower pressure vapor.
 
Location: fisher,illinois,usa | Registered: June 03, 2003Reply With QuoteReport This Post
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I did a bit of web searching for info about the Wally Minto freon engine used to power a vehicle and found a nice 6 page PDF story that was in the October 1970 issue of Popular Science magazine. This must be describing his early setup that uses the commercial spiral screw compressor as the expander engine, sure looks better than a turbine to me, and the screw compressor is an off-the-shelf item that should be almost affordable. This system is simple and made mostly from off-the-shelf parts. He did not actually use a turbine as the motor, he sayed he wanted the engine to produce max torque at "0" rpm like a piston steam engine, but have the efficiency approaching a high speed turbine, his solution was to use an off-the-shelf spiral rotary air compressor in reverse, ingenious, this is a fairly small positive displacment air compressor pump so it runs at any speed with max torque. The engine/rotary pump/expander is only about the size of a basket ball. The article says he did not actually use this compressor as his test engine in a VW van, he did the testing powering the VW using a salvaged piston engine from an old stanley steamer vehicle, it may be that the screw compressor didn't actually work as well as an engine as he had expected, I will keep looking for the more recent Popular Mechanics articles.

During the search I also ran across a patent from someone else that showed the almost exact piston expander setup that I described in my above post, the system discription explained why I was having problems understanding how my idea could actually work, my problem was in thinking that the freon would be vaporized in an external boiler to pressurize the liquid freon, then the liquid freon would vaporize after being injected into the engine's cylinder, that won't work, but what the patent explained is that you use the engine's cylinder itself as the boiler by applying external heat directly to the outside of the engine cylinder rather than using an external boiler, this makes the system even simpler by eliminating the seperate boiler comletely. As the cooled condensed liquid freon is injected into the engine cylinder the heat around the cylinder is what causes the liquid to vaporize and drive the piston. The description of the engine in the patent is basically the same idea that I described except they use a mechanical liquid freon injection valve that is moved mechanically by a cam lobe rather than the valve being opened electronically.

The York frig compressor coincidentally already has a chamber surrounding the cylinders that can be flooded with hot water or oil to add the vaporization heat to the cylinders, this is looking simpler and more doable all the time.

The patent is here.
 
Location: fisher,illinois,usa | Registered: June 03, 2003Reply With QuoteReport This Post
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Tim, that's cool that you found that stuff. The 1970 PS was the start of the 3 or 4 year Minto saga.

As PS followed Minto's progress, he developed more advanced freon engines.

After the rotary-screw (sullair) and piston compressors, he contracted with a private shop to build an optimized turbine (because small, off the shelf turbines were non existent).

Minto based his designs on the enthalpy and adiabatic properties of the refrigerant he proposed using, R-11 for the earlier experiments and R-12 for the later developments.

The chief thing to overcome was the efficient change of state back to liquid after the expansion process.

He had more than one corporation in his name, Sun Power Systems of Sarasota being the latest and probably the last.

After the development of his custom turbine (in 2 sizes), he offered turn-key home generators for sale with various methods of condenser configuration possibilities.

One novel configuration was to run a serpentine coil under the 'sod' of lawns using the blades of grass to radiate the excess heat (it worked).

With gas prices stabilizing in the late seventies and the fact that only the SW and SE US states actually had the required solar-days to effect a reasonable pay-back time on his system, he never got the sales figures necessary to continue selling his system.

But please note, the turbine freon engine was his most successful and the prime-mover he based his commercial home power system on.

(P.S. R-123 is about as close to R-11 as we can get with today's 'legal' refrigerants, this has been used recently with scroll-compressors used as the expansion engine in industrial waste-heat reclamation systems)

Tony
 
Location: Morongo Valley, California | Registered: March 14, 2009Reply With QuoteReport This Post
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I suspected that condensing the hot vapor would be the most challenging portion of the system unless there is a large quantity of cold water available. I have been collecting salvage yard condensor radiators from scrapped whole house air conditioners so I will have a quantity on hand if it takes several? Hopefully my idea of using a swamp cooler to cool both air-to-freon and water-to-freon condensors will be succesfull as part of the system. It will take maybe 500 watts to 1KW of power to turn the fan in the swamp cooler and run the coolers water supply pump and the liquid freon feed pump but that should still leave at least 1KW for battery charging.

The PS article was an accidental find, it is stored on someones website, don't really know how I got to it. The popsci.com website does not seem to have archived articles that go back to the 70's, I will keep looking.
 
Location: fisher,illinois,usa | Registered: June 03, 2003Reply With QuoteReport This Post
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Found this very informative MIT engineering student 65 page PDF paper describes a 1KW solar powered ORC electrical generator system using available parts. It uses a Gast sliding vane air motor as the expander motor and a truck radiator sprayed with water for the condenser (very much like to a swamp cooler). There are calculations to figure the size and the efficiency for the various components in the system. They say the efficiency of the system is low due to using components that are designed for other purposes, so what, Arizona has a LOT of sun power available. They referance other research papers that I will try to find.
 
Location: fisher,illinois,usa | Registered: June 03, 2003Reply With QuoteReport This Post
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quote:
Originally posted by Tim c cook:
I have been collecting salvage yard condensor radiators from scrapped whole house air conditioners so I will have a quantity on hand if it takes several?


You know, I've had three brand new 26x18 2-row and one 24x12 2-row (slab) reheat coils, with 1/2" copper cores left-over from a science-lab construction project at UC Riverside laying around the house for about 7 years now, always thought they'd be just the thing for the condensers in an expander-loop.

What I'd like to do is cobble together some software that would let a guy 'model' the fluid-dynamics in an expander system even if it just got us into the right 'ballpark' before committing to a lot of hardware configuration that might be less than optimum (or maybe just 'wrong').

I'll sniff around and see what's out there.

Virtual Modeling kinda goes along with the old adage 'Measure twice, Cut once': get it close with the model before committing to the prototype.

Anyway, the cool thing about that is that you can plug in different coil sizes and air volumes/velocities and freon temps/pressures to see what it takes to deliver a liquid side that will keep up with expander requirements at different rpms and different boiler/evap temps (probably you'd want a decent receiver to handle flow discrepancies - stick a sight-glass in appropriate areas of the liquid-side to see how you're doing and monitor state-change).

That way the finished prototype will be close enough to tweak with valves, velocities and temperature differentials to get something actually working without a major rebuild due to 'gotchas'.

Seems like it would help the 'predictability' factor, might be kinda fun.

Tony
 
Location: Morongo Valley, California | Registered: March 14, 2009Reply With QuoteReport This Post
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Interesting PDF, Tim.

They mentioned that Gast modified the pump to work for this application. (it's in the forward aknowledgements)

I wonder how extreme the mods were?
 
Registered: September 26, 2005Reply With QuoteReport This Post
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Originally posted by welder:
quote:
I wonder how extreme the mods were?

Most likely, removal of high-side check valve. He might also have changed seals (he mentions something about that in his paper).
 
Location: Morongo Valley, California | Registered: March 14, 2009Reply With QuoteReport This Post
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Tim , I went to the link , " the patent is here " , saw about 6 header lines , the 1st was about making solar panels , this is a bs sales deal , if for no other reason , you can not leave the sight without a direct sales pitch , had to close browser to get out .
Still looking at some of the other info you guys are talking about , but I think that people should know in advance that this type of bull sales garbage , so they can avoid .
 
Location: St.Paul | Registered: March 24, 2005Reply With QuoteReport This Post
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(updated 04/04/09)
@john: Thanks for the heads-up, John (I like your truck!).
@Tim: Here's a bunch of stuff I ran down, mostly good stuff but some pay-for-info too.

A more current example of an ORC cycle experiment is included below.

I've included a list of cars that use the scroll compressor noted below in case you want to try and grab one at a salvage yard.

Defs:
CFD: Computational Fluid Dynamics
ORC: Organic Rankine Cycle

Rankine ORC project and data:
http://www.labothap.ulg.ac.be/...inS/TFE_SQ010607.pdf

Sanden scroll-compressors (TRSA12):
http://www.sanden.com/index.php?id=LZYYCH9G2

Cars that use the Sanden TRSA12 compressor:
https://www.action-ac.com/AC-Part/20-03450.html


Fluid Dynamics modeling software & $databases:
http://www.megawatsoft.com/flu...pxllexcel.asp?cat=17
http://www.nist.gov/data/nist23.htm
http://www.hsc-chemistry.net/
http://www.cfd-online.com/Links/soft.html **open source CFD links!

Whitepapers (some $commercial)
http://www.sciencedirect.com/s...5b55e67fff77fe68b86f
http://www.stormingmedia.us/56/5695/0569517.html
http://www.3me.tudelft.nl/live...90ec11937a6d&lang=en

Explanitory/educational/examples:
http://energy.sdsu.edu/testcen...me/indexrankine.html
http://organicrankine.com
http://journals.mup.man.ac.uk/...MEE/V27I4/270337.pdf
http://iga.igg.cnr.it/pdf/WGC/2005/1303.pdf
http://organicrankine.com/orc_...lar_Desalination.pdf
http://organicrankine.com/orc_...ts/auto/srcosmos.pdf
http://www.airsquared.com/m_expanders.html

Resource Tip: go to scribd.com, open an account(free), search on "organic rankine cycle", download any paper or book at no cost.

There's lots more research data out there, ORC development has been ongoing for at least 40 years...it would be cool to find a spreadsheet/XLS or other fluid modeler that didn't have a $200 price-tag, like maybe free.

Keep your eyes open for such an animal in your travels (I search on 'CFD software').
.

This message has been edited. Last edited by: Tony_Triola,
 
Location: Morongo Valley, California | Registered: March 14, 2009Reply With QuoteReport This Post



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Welder - Page 15 and 16 of the pdf say the only changes they made to the air motor was to reduce the diameter of the rotor to increase the expansion ratio from the stock 2.0 to 2.65, they also modified the inlet and exhaust ports (I assume they increased there area, maybe also slightly shifted the timing, don't know). There consultant also suggested improving the internal surface finish to allow better blade sealing and switching to carbon blades. They estimated doing ALL the changers would bring the motors efficiency up to about 50% rather than the 30% efficiency they calculated for there somewhat modified motor.

JohnTF -- I don't have the link problem you describe, when I click the link it goes directly to the text of the patent on the freepatent.com web site, by registering with that site (free) you can download a PDF of the patent that includes the entire text as well as all the drawings, don't have a clue where your provider of browser sent you when you clicked the link, sorry.

Tony -- I will check your links. I am not a fan of even trying to use a refrigeration scroll compressor as the motor, from reading about folks using scroll refrig compressors backwards they seem to take a lot of fiddeling with to get them to work, seems they don't seal well either internally or to the outside world when the pressure gradient is reversed, also something about having to remove internal check valves, don't remember exactly. After tearing one of the auto air conditioning scroll pumps open and seeing how they convert the orbital motion into rotary motion, and using my hand to shift the scroll around it's orbit, I just feel they have way too much loss in that motion conversion process. The air motor seems much more straight foreward plus I have several gast rotary vane air compressor/vac pumps on hand to play with, never tried pushing air through one to run it as a motor, I have seen this done with steam and a van type power steering pump, worked great and the thing just screamed with no load, not much torque though. The screw compressor (not scroll compressor) looks even better, I have a small one in storage that I need to look at closer, bought it at an auction and never looked it over well, not sure if it uses actual odd-numbered spiral screw lobes or just straight lobes like a simple roots blower, it has a 5HP briggs turning it as the air pump portion of a pickup truck bed mounted mosquito sprayer.

My last link is the first place that I have found actual formulas and info on sizing the verious components, adaptable enough to allow one to at least calculate maybe a rule-of-thumb sizing of each of the sections of the system.

Radiators -- The ones I have are from one brand of home air conditioner that still uses big flat radiators in a rectangular box rather than the ones that wrap the radiator around the outside of the compressor in place of a steel box, these are about 36 inches long by 18 inches wide with 2-3 layers of 3/8 or 1/2 inch copper tubing throughout. I collected these originally to use them to cool cistern water with cool nightime air, I was pumping the cool cistern water through radiators inside the house during the heat of the day.

I am not all that concerned with using the exact size condensor, at least not during development, sizing the condensor too large won't cause any problems, it will just store more condensed liquid and loose a bit more heat than optimum, I can always apply more heat, even if it does reduce the system efficiency calculation a bit. Hopefully I can add enough condensing surface area that I won't need to power a swamp cooler, maybe just a very fine water fogger nozzle (no blower motor), dry daytime Arizona air can easily hit 150 deg f so that may be too hot of a temp to condence the working fluid no matter how much area I have, will depend on what fluid I end up using. The swamp cooler makes a nice compact condensor no larger than a 4 ft cube at its largest, I hope anyway. All sized old swamp coolers are cheap in AZ, free for the hauling off usually.

Spreadsheet calculator -- Someplace on an engineering web site there was a dicussion about just such a calculator, several folks sayed that calculaters, and vapor table info, were contained in there professional engineering software but nobody could point to anything cheap or free.

Just went to the freepatents web site and did a search for "Wallace Minto", it shows 30 patents but only a few relate to this discussion, none say anything about his later small turbine.
 
Location: fisher,illinois,usa | Registered: June 03, 2003Reply With QuoteReport This Post
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I went & checked again , now I see what happened , under the short paragraph , abstract , there are google links , that appear to be , at a quick glance , to be a part of the abstract .
 
Location: St.Paul | Registered: March 24, 2005Reply With QuoteReport This Post
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quote:
I am not a fan of even trying to use a refrigeration scroll compressor as the motor

I petty much agree, I don't see -any- positive displacement mover being an optimum choice for this type of application, but I can understand using available off the shelf components when that's all that's available.

In the case of the example cited above, it was a pretty thorough walkthrough and just happened to be using a scroll expander (making replication somewhat predictable). In a perfect world, my personal choice would still be a turbine.
quote:
The screw compressor (not scroll compressor) looks even better, I have a small one in storage

Maybe so, I guess the thing to do, if you have a number of choices available, would be to test them out with compressed air. Of course you'd have to make allowances for displacement differences, but you could get a reasonable idea of their intrinsic strengths and weaknesses visa vi torque and power, at least.
quote:
My last link is the first place that I have found actual formulas and info on sizing the various components, adaptable enough to allow one to at least calculate maybe a rule-of-thumb sizing of each of the sections of the system.

That's very cool, Tim. I haven't looked that closely at the file yet, still in the process of gathering more info to pick through. What I originally envisioned was the way I used to do HVAC design (I'm retired now), I have software that runs on top of AutoCad that does the fluid-mechanics (air) end of things as you draw. All my stuff is in 3D so it calculates volume, velocity, noise and delivery as you go and handles collision checks with other trades, etc. then spits out the pattern stretch-outs for the plasma cutter.

The difference in what my software does and what's needed for expander modeling is that air is 'steady state', refrigerant is not.

I was looking for something sort of 'interactive', like that, so a person could swap out condensers, change airflow, change refrigerant flow, etc. and get a feel for a finished working system.

If you've ever developed electronic circuits, it would be similar to using SPICE software that lets you swap out components and see the results on the fly - simulation modeling.

There's stuff out there that does it (Fluent/Catia) but it's out of my league.
quote:
Radiators -- The ones I have are from one brand of home air conditioner that still uses big flat radiators in a rectangular box....All sized old swamp coolers are cheap in AZ, free for the hauling off usually

Yeah, I prefer slab-coils too, they're stackable and you can run the headers together in any configuration you need, better modularity. Hey, I thought you were in Illinois? Whereabouts in AZ? I'm about 5 hrs from Phoenix (close to Palm Springs), so, yeah, no shortage of swampers and summer-sun (which will be here again real soon).
quote:
Wallace Minto patents...none say anything about his later small turbine.

I know, I did the same thing a couple of years ago and then again just recently, I can't find anything on the turbine either. I know I'm not dreaming it up, I even called him up in Sarasota back when he was in business and he told me all about it, sent me a lot of stuff in the mail because he wanted to sell me a system, of course I can't find it now after over 30 years have gone by (would've been around '75/'76, or so).
 
Location: Morongo Valley, California | Registered: March 14, 2009Reply With QuoteReport This Post
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After some looking around, this software looked like it might be a candidate for what I had in mind. Most of the universities seem to running this along with Fluent and Ansys. Take a look if you get a chance.

OpenFoam CFD modeler (main site, linux only):
http://www.opencfd.co.uk/openfoam/

OpenFoam features:
http://www.opencfd.co.uk/openfoam/features.html

OpenFoam user-manul:
http://foam.sourceforge.net/do...des-a4/UserGuide.pdf

OpenFoam Windows binary (precompiled, latest version 1.5):
http://sourceforge.net/project....php?group_id=252238


It looks like it has solvers for the kind of thing we're looking for.
http://www.opencfd.co.uk/openf....html#thermophysical

Examp:
Chemical kinetics

OpenFOAM includes a library for gas-phase reactions that can read input data in native OpenFOAM reaction scheme format or, optionally, CHEMKIN® format.

CHEMKIN® is a registered trademark of Reaction Design Corporation.

Thermophysical properties of gaseous species:

perfectGas
Perfect gas equation of state

hConstThermo
Constant specific heat cp model with evaluation of enthalpy and entropy

janafThermo
cp evaluated by a function with coefficients from JANAF thermodynamic tables, from which h , s are evaluated

specieThermo
Thermophysical properties of species, derived from cp , h and/or s

constTransport
Constant transport properties

sutherlandTransport
Sutherland’s formula for temperature-dependent transport properties

Fortunately, this comes ready to run as a Windows binary. It was originally just available as linux source and looked like it would get real ugly to try to port over to Win from linux. I'm pretty much just an old Windows C/C++ guy and limited to a .NET 2003 compiler, don't want to get into cross-compiling a complex *nix source at my tender age, if you know what I mean.

Edit:
Found an easier to use one, SolidWorks w/cosmo FloWorks.

Student edition (2 yr license) $139.00

http://www.creationengine.com/html/p.lasso?p=14127

I don't know if it requires student verification for activation, some forums say no.

One of my kids still has connections at CSU Chico, I'll see if he can score it for me.
 
Location: Morongo Valley, California | Registered: March 14, 2009Reply With QuoteReport This Post
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Arizona - I have a few acres about 40 miles north of Tucson that I had intended to retire to, it used to be nice and remote, unfortunatly there have been over 5000 houses built in the area over the last few years. One of the reasons I bought there was because there was 640 acres across the road that was designated as flood plane and thus was not likely to ever be developed, unfortunatly, a developer bought it cheap and then it somehow magically got it's flood plane designation changed, it is now devided into 500 one-acre lots, they were busy building houses up til credit dried up recently. There has not yet been a wet year there since they subdivides it but I have seen the entire acerage under water 4 times over the last 35 year, should be interesting.

Found a bit of info about another style compressor that is stated to have better chericteristics than the air motor. The general name is "SLIDING ABUTMENT" compressor, very much like an air motor but using only one sliding vane that is in the body of the pump rather than several vanes in the offset rotor. This discussion states that for the best efficiency the expander motor wants to have as large an expansion ratio as is possible, the modified air motor had an expansion ratio of 2.65, the discussion indicates that a sliding abutment compressor can have an expansion ratio as high as 20, just starting reading about this. I have a few other articles about using these compressore as ORG expanders but I forgot to save there web addresses, trying to find them again now.

I intend to spend this coming winter in AZ, there are several used book stores around the U of A in Tucson that have bins full of past issues of Popular Science and other magazines, I will try and find the original PS issues about Wally Minto.

The idea of being able to computationally design the system would be nice but way beyond me, I have done it with SPICE models when developing electronics but I specialize mostly in small control devices and have done it for enough years that I usually know what can be accomplished using mature components, it is quicker for me to cluge up a prototype to tinker with than modeling it, you have to bench test and tweek the circuit anyway.
 
Location: fisher,illinois,usa | Registered: June 03, 2003Reply With QuoteReport This Post
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quote:
over 5000 houses built in the area over the last few years

That's what my daughter said too, she moved back to Phoenix after being away for a few years and said she didn't recognize it. The biggest problem with population increases in the south-western states is that the water resources are being tapped to the max. I'm thinking about Northern California as a good compromise between solar-days and water availability, I want to grow vegetables.

quote:
This discussion..."SLIDING ABUTMENT" compressor

I had actually run across this post several times in my travels but didn't pursue it any further after finding the links to carrier.co.kr were broken.

The guy makes it sound pretty good, though. Definitely worth looking into if for no other reason than curiosity over his overt evangelism concerning the compressor.

Here, he's apparently frustrated by the lack of understanding coming from the newsgroup, bit of a rant, but has some pictures (2nd link):
http://listserv.repp.org/piper...December/003548.html
http://gasifiers.bioenergylist...field/slideabut.html

Application - Carrier/Daewoo Mod: EDB260211A, look at page 19, compressor:
http://www.chlodzenie.pl/lg/doc/2_Window.pdf

Now wait a minute, this looks like a hermetic unit, does this guy propose cannibalizing the case to get at the compressor?

Here's some pics of Daewoo hermetic compressors:
http://www.dreamgreenservices....utions-catalog1.html

Well, I guess testing would tell the tail, but I can see why he states that 'nobody knows about this...'. If you have to open a case to retrieve the actual compressor, most wouldn't consider doing this.

I've seen where some people advocate keeping the case intact with hermetics and running the compressor in reverse, using the induction motor as a generator. I would be pretty leary of this arrangement lasting for any length of time because of heat-failure. The windings would definitely burn because there's no cold gas return to carry heat away in an expander configuration.

Not sure if the above is what he's proposing, but opening up one of these units and checking out the compressor might suggest a more workable way to go.

If it was found these units presented a definite advantage over other compressors when used as an expander (and if they were readily available), several could be ganged together to provide the HP requirements for a range of KW needs (maybe with a serpentine belt, like on autos).
.
 
Location: Morongo Valley, California | Registered: March 14, 2009Reply With QuoteReport This Post
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Looking closer at the info in your Carrier compressor catalog link, the 21's line up from the bottom of each page is the "compressor type" line, almost all are listed as "rotary" with a couple being listed as "scroll" and a couple being listed as "recipro", I don't yet see a way to determine the "type" of "rotary"? may still be some hint in the remainder of the info lines, still looking.

The 19th line up from the bottom of each page is labled "maker", there are 2 "Dawoo carrier" pumps listed as maker on page 12, one on page 13, and one on page 18, as well as the one on page 19. Some list the same oil as the page 19 one?

If you click the "subject" tab on your link to the sliding abutmant discussion it gives you 8 postings about the subject.

I was tracking "scroll" compressors on ebay last month, they all look like the pictures in your link, they are tall round canisters. apparently there is no way to know if the sealed units have the sliding abutment type compressor other than opening them up, my local salvage yard gets these in in old air conditioners all the time, must be a dozen there now, they pull them out and they get passed on down the scrap stream in there huge 40 ft long "applience" dumpster, I may be able to cut some of these but am not too keen on the idea, they are full of thin oil so it will be a bit messy, may be able to burn the oil though, or use it as heat transfer medium in a solar collecter, HHMMM.. it should be simple mineral oil these days, it used to be laced with dioxen but that has not been used for many years. The compressor catalog does list the oil type so I will try and look up just what the trade names and numbers of the oil actually means.

Retirement -- I have friends and relatives in Idaho and Montana, I have them keeping an eye out for an old remote played-out 20 acre underground gold claim, grow hudroponic veggies, mushrooms and whatever underground all year long using a wood chip gasifier to make heat and electricity, UV florescent grow bulbs don't use all that much electricity.

Thanks for the links, those were the other pages that I had saved but I forgot to save there links.

Yes, he is talking about a sealed frig compressor unit that he opened up. In his text he talks of using this expander directly connected to a small diameter alternator and sealing the entire assembly inside a salvaged high pressure oxygen cylinder, his idea was to fill the tank with oil so everything was submerged, then apply heat to the bottom of the sealed cylinder to make a completely sealed generator setup along the lines of the commercial units that have been manufactured by the ORMAT CORP. for many years. These are relatively small (for industrial units anyway)sealed 4KW ORC electricity generating units with few moving parts, they use an actual turbine and alternator along with everything else needed, everything is inside a sealed tank and heat is applied to the bottom of the unit, Ormat has been running these in remote locations throughout the world for generations, just VERY expensive.

From one referance in the sliding abutment discussion, and the fact that it is on a discussion board about wood gasification, it think the original idea was to use the waste geat from the gasifier to vaporize the refrigerant, sounds like a good idea to me, our gasifier is located at the shop of a local steam power hobbiest, he has been consideing using the excess heat to produce steam and drive the 2-cylinder converted york frig compressor steam engine/12 volt alternator unit that he already has made up but an ORC system would more correctly match the amount of heat that is available from the gasifier.
 
Location: fisher,illinois,usa | Registered: June 03, 2003Reply With QuoteReport This Post
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Japanese compressor that looks similar:
https://publications.european-...=EP&pn=1612425&ki=A1

Listing of Carrier-Daewoo rotory compressors:
http://www.xpedio.carrier.com/...rr_hermetic-2003.pdf

Looks like the EDB292211A is the largest (still only <2-1/2 ton capacity) but it's listed as rotary. If sliding-abutment is the Daewoo rotory method of choice, it wouldn't make sense for the manufcturer to change-up between sliding-abutment, vane and scroll for a capacity range as small as what's listed in this pdf. If they manufacture in-house, I'd think they're all sliding-abutment rotories. If they sub-out components though, they could be anything.

From the sizes published on this list, I'd suspect that their chief application would be in window/wall AC units and those get junked all the time.

Click on the image to zoom-in:
http://www.carrierland.co.kr/g...pid=49189&uid=289511

I don't translate Korean or I'd email them for a model-number cross reference for their ED******** compressor listings, similar to this one from Carrier:
http://www.brainerdcompressor.com/06D_Mod_No.htm
 
Location: Morongo Valley, California | Registered: March 14, 2009Reply With QuoteReport This Post
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Tim, Tony - fascinating discussion -- much information condensed -- many thanks.

There's a reference in the ORC modeling paper (posting from alaindeloin, "Experimental Study and Model of a Low Temperature Rankine Cycle..." from the University of Liege) to a paper written by [now] Dr. Malick Kane. Dr. Kane has gone on to found EnefTech (Energy Efficient Technology) that, apparently, uses off-the-shelf components for small-scale power generation.

quote
4) Generate on site power from low cost solar collectors, or low temperature geothermal sources.

The company's main technology is based on Organic Rankine Cycles and on mass-produced components which ensures a high reliability and low initial capital cost.
unquote

From http://www.eneftech.com/engineering/technology.html

I am looking to do exactly the same thing.
 
Location: Newark, Delaware | Registered: May 10, 2009Reply With QuoteReport This Post
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