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2KW low temp Rankine cycle electricity and cooling
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This links to a website developing this equipment. it uses waste heat no hotter than 200 deg f to make electricity or refrigeration, or both. They seem to have made prototypes work and are now building a mobile demonstrator. web searches have turned up other such equipment that is making power, one island community was using the temp differances of shallow and deep ocean water as the temp source, another used solar collectors and shades radiators as the temp source.
I intend to attempt using solar and shade/evaporitive condensors, using Propane as the working fluid, in Arizona once I make my retierment move. I have done successful water steam tested of a converted 2 -piston type york auto air conditioner pump to use as the engine turning the generator, worked great. Searching the web about this pump/engine conversion found that it is used on several small hobby steamboats, similar tiny water-steam units were used in occupied Europe during WW-2 to turn a small generator to power secret radio transmitters used by local resistance units.
 
Location: fisher,illinois,usa | Registered: June 03, 2003Reply With QuoteReport This Post
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I want one.


--There is no Magic Bullet.--

If bigger is safer, buses are safest.
Save yourself, use Transit.
 
Location: Clemson, SC | Registered: March 02, 2006Reply With QuoteReport This Post
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In the same topic, have a look at this location :
Experimental study and modeling of a low temperature Rankine cycle for small scale cogeneration

The documents explains how to convert a scroll compressor into an expander, and how to integrate it into an Organic Rankine Cycle
 
Registered: November 18, 2007Reply With QuoteReport This Post
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I have been web surfing for any updated info on small organic renkine cycle power generation and ran across THIS website, it is a current program that looks like it began as part of the MIT mechanical engineering D-lab class, they apparently have a couple of reasonably small 1 KW solar electrical generator systems that use the left over heat to heat water, set up in tiny remote villages in Africa. There system uses four 5 X 10 ft solar trough concentrators to heat glycole to around 300 deg f, the glycole is then used to heat refrigerant in a small 3 ft cube sized setup that uses salvage car parts to make up the ORC generator, simple heat exchangers from car radiators and small salvageed steel tanks, turbo for the motor that turns an auto 12 volt alternator, power steering pump to return the condensed refrigerant to the evaporator, etc. Unfortunatly, like most of these grant-based research projects, detailed tech info is not published, There is tons of info on the grant structure, business plan to supply the technology to 3rd world locations, impact on local economy type crap, but no hard details, even found a blog by one of the students while they were building one unit in the African village (HERE) but still no tech specifics. It looks to be pretty early in the development, no mention is made of circulating oil through the turbo bearings of how badly the refrigerant leaks etc but it appears they at least have the concept working. No dought the hot water portion of the unit works but I have my doughts as to how long the ORC portion will keep making electricity. I have found info about VERY expensive commercial systems (edit - links were dead) description - ORMAT 4KW ORC renerators (animation of system) that have been running in unmanned locations for up to 35 years with basicly no maintanance so the concept is sound, just implimenting it out of junk is still in question.

The Florida folks in the first post link have built more prototypes and are still saying they are close to having a viable unit if only a few more folks will put up a bit more investment money. I will keep digging.

This message has been edited. Last edited by: Tim c cook,
 
Location: fisher,illinois,usa | Registered: June 03, 2003Reply With QuoteReport This Post
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Looks like there are a few small home co-gen units already available or about to hit the market in other places around the world, I ran in to THIS webpage while searching for organic rankine info, the info is a bit sketchy and I don't understand German (I think it is German anyway) but a couple of these units look to be using some sort of linear piston heat engine to produce electricity (may actually be sterling engines, I have seen a small commercial unit using this sterling concept to make AC power for boats), a couple others are using very small gasoline piston engines to make both electricity and heat. The "BIXI" unit says it is a true organic rankine cycle engine. sort'a neat anyway.
 
Location: fisher,illinois,usa | Registered: June 03, 2003Reply With QuoteReport This Post
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Tim, thanks for the links. A few months ago, Popular Mechanics http://www.popularmechanics.com/science/earth/4245896.html?page=1 had an article http://www.ecogeek.org/content/view/1353/ about a system in Alaska that used ground source heating and cooling with a refrigerant/turbine unit to make hot water and electricity for a remote hotel/resort complex. There was quite a bit of information in the actual magazine article about how it worked. It was quite similar to the concept of this STG project as it used hot springs to heat the refrigerant and turned a turbine for electricity. Then the "condenser" cycle used cold water to cool and create hot water for the buildings heating and cooling. It's a little more high tech, but it has some more info. Coming from an automotive and HVAC background I find this stuff very interesting. Keep us posted Tim.
 
Location: Cincinnatus, NY | Registered: August 12, 2005Reply With QuoteReport This Post
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Hey Tim,

I just moved from AZ and while I was there I tried without success to develop interest in a solar fired absorption chiller for residential cooling. Take a look at www.solarfrost.com

Also, I have my house in AZ for sale. If you have any interest take a look at: www.connectrv.net Smile

Another thought.... While I was looking at the solar chiller idea I ran across an outfit that was working on converting the Robur (formerly servel) absorption A/C to run on waste oil. That my be worth revisiting. As I recall they were located in the Spokane area.
 
Registered: September 10, 2006Reply With QuoteReport This Post
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I want to know how much quantity of injection (refrigerant)is in Organic Rankine cycle power system?? Confused
 
Registered: January 08, 2009Reply With QuoteReport This Post
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The quantity of refrigerant needed will depend on the size of the system. The small 2KW system I intend to build for testing will use a small 2-piston expander as the engine (York style auto air conditioner compresser) belt driving a 12 volt DC car alternator and will likely use something like one or two gallons of refrigerent in a small heat exchanger/boiler and the condensor. The MIT system linked to above probably uses even less based on the size of the boiler and condensor shown in there pictures. The link above to the remote resort 50KW turbine system probably uses a hundred or more gallons, I don't recall that the article about the resort power system ever stated the amount of refrigerent used but the picture of the turbine/generator unit shows a pretty large turbine?

I have reconsidered the design of my system, originally I intended to heat a large 500 gallon volume of propane (standard 500 gallon propane tank painted black) and passing the high pressure propane vapor throughout the system, the pressures could reach well over 400 PSI (popoff valves on propane tanks are set for 425 PSI, I have had them pop off even in Illinois summer heat), this would require schedule 80 steel piping to be safe, EXPENSIVE. I now intend to heat a few hundred gallons of water, or possibly veg, or mineral oil, maybe even used engine lube oil, and passing this hot ambient pressure fluid through a small boiler to vaporize only a small quantity of refrigerant (can also use flames to heat the water over night, even generator engine coolant?), the refrigerant may be propane or R-134A refrigerant, still researching the refrigerant characteristics that will best suite this system, depends on vaporization and condensation temps and pressures, looking more like R-134A will condense at a higher temp than propane. Still researching how to cool the vapor after it passes through the expander, original thought was to use several large salvaged home air conditioner condenser radiators in parallel/series configuration and blowing either ambient temp air, or evaporitively cooled air from a normal Arizona swamp cooler, through the radiators. all the systems I have read about use a water cooled heat exchanger for there condensor, these are much smaller than air-to-vapor condensors. I am now considering using both type of condensor heat exchangers, use the cooled air from a swamp cooler and blow it through air-to-vapor home air conditioner radiator(s), then passing this partially cooled vapor through a water-to-vapor condensor that has the cooled water from the swamp cooler passing through it, don't know, need to get back to AZ during the summer time and do some temp testing on swamp cooler air and water.

I think the same type of setup can be used to directly make refrigeretion but need to research it more. The website linked to in the very first sentence of this discussion recently sent out an email stating they now have a system running that is making direct vapor refrigeration and also producing electricity using a mini-turbine turning a generator.

Two farm type 500 gallon fuel tanks would present something like 4 square yards of surface area to the sun for solar heating, this is about 4 KW of heat, this would allow a 50% loss in efficiency to produce 2KW of electricity, probably too optimistic but it will be easy enough to add more tanks for additional solar heating.

By using a seperate hot fluid for vaporization I can also better control the system efficiency by controlling the hot fluid circulation pump speed, this will allow more or less hot fluid to be passed through the refrigeration boiler depending on the temperature of the hot fluid and the amount of power needed to the expander engine and from the generator. I also intend to control the expander torque by using electric hydraulic solenoid valves to inject the high pressure vapor into the cylinders, less generator load will need less torque, correctly timed shorter or longer vapor injection pulses should control both the torque and RPM of the expander engine and all this control should allow the highest efficiency from the overall system.
 
Location: fisher,illinois,usa | Registered: June 03, 2003Reply With QuoteReport This Post
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Awesome!

Thanx Tim!!!
 
Registered: September 26, 2005Reply With QuoteReport This Post
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thanks for Tim c cook~~you are kindly~ Could you support us the system diagram?or some more pictures? thanks a lot~
 
Registered: January 08, 2009Reply With QuoteReport This Post



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quote:
I have reconsidered the design of my system, originally I intended to heat a large 500 gallon volume of propane (standard 500 gallon propane tank painted black) and passing the high pressure propane vapor throughout the system, the pressures could reach well over 400 PSI (popoff valves on propane tanks are set for 425 PSI, I have had them pop off even in Illinois summer heat), this would require schedule 80 steel piping to be safe, EXPENSIVE



Hi again Tim.

Geez, ya know, I wish we lived in the same area.

You see, I plan to return to tech school to upgrade my welding skills to Welding Level B, which includes a lot of pipe welding & an optional TIG welding component.

I'm in the International Brotherhood of Boilermakers & Iron Ship Builders (Local 359), but I joined up through a structural steel (non-pressure) production shop, so I need to upgrade my skills to reach my full wage potential in The Brotherhood.

International HQ: http://www.boilermakers.org/
My local: http://www.boilermakers359.org/

I will be capping off my level B with P.W.P. tickets, so I can legally weld boilers & other pressure vessels.

I've welded schedule 80 pipe in structural applications and I'd love to live near you so we could build some awesome pressure energy systems. You could engineer the stuff, we could get the drawings approved by a boiler safety engineer, then I could weld it up. That would make bigger/better projects cheaper.

Wanna move to Vancouver, Canada? (just kidding LOL)
 
Registered: September 26, 2005Reply With QuoteReport This Post
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jack - Sorry, I don't have anything that specific yet, still in the "how to approach" stage of development. Do a few general web searches for "organic rankine cycle" or something similar and see what pops up, I haven't done any searching on this subject for several months. The last search found referance to the university of Texas at El Paso using the heat differential from different temps found at different depths of a fairly shallow pond as there heat source, they are making something like 70KW of electricity from there turbine spun organic rankine cycle system since 1986. I had saved links that went directly to there web pages about this system but they are now dead, might try searching for "university of Texas El Paso (utep) solar pond" or similar, there home page is here but I don't find any referances to either "organic rankine cycle' or "solar pond"? I assume they lost funding or something?

This links to a Nasa paper about using waste diesel engine heat to power organic rankine cycle systems. Another system, another PDF paper, a patent, I had more links but most are now dead?

Welder -- The schedule 80 situation is one of the reasons I reconsidered the approach, that and reading about the MIT system that used external hot glycol to vaporize only a small amount of refrigerent, seemed way more practical and allows for several different sources to keep the water hot.

Canada eh, nice place but I am gettin tired of cold winters, heading to Tucson Az. instead, 70 deg f winter days seems much nicer than the low 20 deg f days here in Illinois, also much more practical to use solar as heat for making free refrigeration and electricity.
 
Location: fisher,illinois,usa | Registered: June 03, 2003Reply With QuoteReport This Post
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Info about using electric solenoid operates hydraulic valves in this application --

I have actually tested this concept of supplying controlled bursts of steam to several differant type compressors. A friend here is into steam power, we used 100-125 pound water steam as the working fluid and some VERY crude switching methods for the solenoid valves, as crude as several layers of duct tape stuck in the the fridge compressor pully that pushed the button on a micro switch, worked far better than expected. We have used single and double piston shop air compressors as well as several York style 2-cylinder refrigeration compressors, one style used the solenoid valve to both inject and expell the steam for each cylinder, we were using 1/4 inch I.D. valves so the RPM of the motor was restricted to a few hundred RPM due to the small size of the valve and having to pass the steam through it in both directions. We also modified one of the York compressors to be a "uniflow" engine by drilling holes out the side of the cylinders near the bottom of the piston stroke, the solenoid valve only injected the steam, the spent steam flowed out of the cylinder at the bottom of the piston stroke similar to a 2-cycle gasoline engine, this engine ran much faster, upwards of 900 RPM, due to far less restrictions.

One nice thing about using a refrigeration compressor is that it is designed for roughly the same working fluid as will be running through the system and it has a sealed crancase to keep the rotating parts lubed. It is also fairly small, roughly 6 in X 6 in X 10 inches tall and the pistons are 2 inches in diameter with a 2 inch stroke, a small 4-cycle Briggs type gasoline engine with this same displacement would be able to produce something like 8-10 HP, this compressor motor will be making even more power due to having pressure on the pistons on EVERY stroke rather than EVERY OTHER stroke.

Since this expander motor is fed with externally pressurized vapor it has the same torque at almost all reasonable RPM's so even though it does not turn at high speed it can belt drive an alternator at reasonable speed by simple pully ratio selection.

I just did another quick web search on this subject and found references to several small systems but they all use some type of turbine as there motor, don't quite understand this as it adds a lot of cost and ties you to one source for parts and repairs, a refrigeration compressor expander is junk yard cheap and available about anywhere and does not have to be replaced with an exact copy, one manufactures's compressor is as good as another, although you may have to make up a new flat metal plate to act as the cylinder head due to differant bolt locations, simple enough to do.

Scroll compressor as expander -- There is info on the web about these but from what I have read this style vehicle refrigeration compressor is not designed to operate in this reverse mode, they don't seal well when pressurized backwards and will likely leak refrigerant unless modified with extra sealing, they are also not nearly as available or cheap as used York-type piston compressors. I picked one up from my local salvage yard and from the design I don't see how they would produce nearly the amount of torque as a piston compressor with a 2 inch stroke, I suspect they would turn at a considerably higher rpm though.

The Matteran Energy web site that I linked to at the beginning of this discussion originally used a modified 2-cylinder shop type air compressor for there first test engine, they made up a rotary valve unit to feed the vapor for it, there was a video of it in operation on there website someplace.

This is a picture of a "uniflow" modified York 2-cylinder refrigeration compressor being used as a steam engine and turning a 12 volt vehicle alternator, This model is using mechanical bump valves rather than solenoid valves and dumps the steam overboard because these both allow it to run at higher RPM, the concept works with either type valve.

Imagesteam_generator_2-cyl_-_pully_side-closer.JPG (45 Kb, 127 downloads)
 
Location: fisher,illinois,usa | Registered: June 03, 2003Reply With QuoteReport This Post
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This is a picture of the first "duct tape" solenoid valved test engine.

Imagesolenoid_engine-view_of_microswitch.JPG (22 Kb, 109 downloads)
 
Location: fisher,illinois,usa | Registered: June 03, 2003Reply With QuoteReport This Post
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Canada eh, nice place but I am gettin tired of cold winters, heading to Tucson Az. instead, 70 deg f winter days seems much nicer than the low 20 deg f days here in Illinois, also much more practical to use solar as heat for making free refrigeration and electricity.



I can't argue with that.

I wanna get outa here too!!!
 
Registered: September 26, 2005Reply With QuoteReport This Post
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Tim c cook

hello Tim c cook~
Maybe i trouble you again.
I meet a problem now that is i can't purchase a 1KW about turbine generator in market.So i turn to you .I want know whether some equipment can be modified to be up to the mustard?
Could you give me some suggestion ?
Thank you again
 
Registered: January 08, 2009Reply With QuoteReport This Post
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jack -- No info concerning a small turbin other than the link in a prior post about the MIT project that says they were using some sort of automotive turbocharger as the turbine. I have not found any more detailed information on how this was actually done. This is the reason I will be using the 2-cylinder York type automotive refrigeration compressor rather than trying to find a turbine.

I did pick up the front portion of an automotive scroll type refrigeration compressor but only the actual scroll and the off center shutteling-cross section that converts the wierd slightly off-center scroll section that converts the wierd orbital, but not ratating, scroll device into rotating the compressors shaft. It is very hard to describe the scroll concept, you will have to research the way the scroll moves, the actual scroll does not rotate, the scroll orbits in a small circle that is a bit off center, the back of the scroll has two sliding crossed shafts moving in slots, the part with the slots is what rotates the shaft, think "scotch yoke" type device. playing with the unit I think there is a lot of energy lost using this concept to drive a rotating shaft, I suspect there is a lot of lost torque due to sideways vector forces on the sides of the sliding shafts and shaft slots. The York style piston pumps are a proven device, cheap, and fairly available from junkyards, they also have a true sealed crankcase to lube the crankshaft and rod bearings. As long as you can apply pressurized vapor to the top of the pistons the engine, called an "expander" in this application, will rotate the output shaft, maybe not fast, but it will rotate, it is easy enough to use a belt and pulleys to get whatever rotating speed you need.

There are a few postings on the internet saying that a few companies are now building what they call "microturbines" to use in these systems but I have not found one that can actually be ordered nor do they give even a hint at the price.

I now have a few short videos of the york steam engine generator running and charging a battery, it runs with 80 pounds pressure but is slow enough to hear the individual exhaust pops from the pistons, sounds like a lawnmower engine running a bit above idle, maybe 1/4 throttle, once the steam pressure is up to 120 pounds the engine is turning fast enough to sound like a smooth continuous low humm. The organic rankine boiler should be able to easily put 200 to 300 pounds pressure across the engine. A sun heated propane tank can easily cause the 425 pound safety popoff valve to blead propane so making the pressure is not that difficult (boiling the refrigerant fast enough to keep up with the vapor flow that the expander needs may be a different story though, just means more surface area for the sun to shine on may be needed), you can determine the pressure by looking up temp/pressure (vapor pressure) charts on the net for any of the refrigerants you may consider using, use the name of the refrigerant followed by "vapor pressure chart".

The larger difficulty is in reducing the pressure on the OUTPUT of the "expander" and doing it in a way that allows enough flow of the vapor through the condensor so as not to cause backpressure. The pressure of the vapor is directly proportional to it's temperature so you have to add some type of cooling after the expander to drop the pressure as much as possible to condense the vapor into it's much smaller volume of cooled liquid, you then use a small high pressure liquid pump (hydraulic gear pump or vane type power stearing pump) to push this cooled liquid back into the boiler. The commercial setups use a vapor-to-cold/cool water heat exchanger for this but I don't find any easy way to figure the size of the condensor so this will be trial-n-error for me.

I hope to use salvaged window, or whole house, air conditioner radiators being cooled by an evaporative type swamp cooler, one radiator will have the swamp coolers cooled output air blowing through it, another will be submerged in the cooled water in the bottom of the swamp cooler. These condensors need to flow vapor easily so I may have to connect several in paralell to reduce the flow restrictions. There are whole house air conditioner condensors that are 18 inches X 32 inches or so and use 3/8 inch tubing, hopefully these will work without producing too much restriction to the vapor. I hope to error on the side of too big, don't care if I cool the condensed fluid a bit as long as I get it completely condensed. The propane charts say propane vapor will condense to liquid at around 100 deg f and 100 pounds or so pressure, 400 pounds pressure on the input of the expander and 100 pounds pressure on the output puts 300 pounds pressure across it, that will produce a LOT of torque, the steam engine version runs the alternator just fine with only 120 pounds pressure, 300 pounds should allow a considerably larger wattage generator to be driven?
 
Location: fisher,illinois,usa | Registered: June 03, 2003Reply With QuoteReport This Post
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You might look at the Lithium-Bromide / Water heat exchangers.

http://www.yazakienergy.com/waterfired.htm

This was designed as absorption refrigeration. But, the same technology might work for your power generation, or combining with the power generation.
 
Location: Oregon | Registered: October 17, 2007Reply With QuoteReport This Post
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I checked out Matteran Energy, linked to in the first post in this thread. You know, these guys seem like they are just rehashing technology that was originally published in a series of articles in Popular Science and Popular Mechanics back in the mid '70s.

The guy that actually did the breakthrough work back then (solar powered freon generators) was Wally Minto, who had a company in Sarasota Fla., a contract with Nissan and even an optimized small turbine that he sold to individuals who wanted to use his freon-powered generating plans (6-10 KW).

Don't know what happened to the company, probably folded when Minto died.

Anyway, he started with a rotary screw compressor (not an automotive one, though) and worked up to his own design for a turbine that would work optimally with his fluid or choice, R-11.

Probably ought to search back issues of Popular Science and Popular Mechanics since he appeared in several issues over about a 3 or 4 year period in both those mags.

I only mention this because I see a lot of 'reinventing the wheel' going on all over the place (and not as successfully as the original inventions, I might add).

Minto had it nailed, unfortunately all I see on web searches is that he's remembered for his 'Minto Wheel', which was just a curiosity.

R11 was a good choice, it's characteristics let it develop high pressures with moderate heat input and yet condense back to liquid state around 70 deg F, I wonder if there are any azeotropes around today based on the newer refrigerants that have similar characteristics?

Tony
 
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