I don't know how many of you caught this, but today Harvard released the results of an invention that they've been sitting on for ten years, a discovery that will incre)ase the power of a solar cell 100-500 times.
The reason for sitting on it for so long was legal, there were too many questions on how to patent it, etc.
If this is true, solar cell technology might become affordable for almost everyone.
Well, meanwhile, I emailed Ener-g-rotor about buying a 5 kw compressor, no answer. If you read their web page, they sound like they want to come to your business and install one of their systems, so I don't expect much.
I'm trying that Stirlin? (something) place next
There are three "sterlimg" companies in the solar heat engine business that I know of, one is STERLINGSOLAR.COM this web address actually goes to the "matteran" website that I linked to in the very first post of this discussion. The website no longer completely loads on my computer and when I tried to download there latest "updades" the attempt crashed. These are the Florida folks supposidly developing a small ORC system that runs on swampwater heat, looks like they may be out of business. The second 'STERLING" company is the huge one making integrated commercial 25KW engine/generator packages being tested at the "NREL" federal lab (see below), I don't find them with a web search so must go by some other name, they don't make anything nearly usable in out back yard. the third company is http://www.stirlingengine.com/, they make toy sterling engines.
I thought I had posted this link earlier in this discussion but don't find it now, the web page has been around for years and has links to all sorts of home built "heat engine" projects. It has a good bit of information about using SCROLL compressors as expanders and it lists lots of scroll compressor part numbers for both home and car air conditioning systems, lots of interesting info here - http://www.redrok.com/engine.htm
I also thought I had put up a link to the "National Renewable Energy Lab - NREL" division of the U.S. Department of Energy but I don't find it now either. http://www.nrel.gov/solar/, this is a HUGE HUGE website with all sorts of gov funded testing of all things solar, they have been testing BIG 25 kw Sterling engine parabolic concentrator solar electrical generating plants for a few years, mostly on remote Indian reservations. I don't think I found anything about ORC systems there but I have not looked for a couple years. Unfortunately, all the stuff they play with is in partnership with big commercial companies and is not easily adaptable to our back yard, still good reading though.
Well, I typed "ORC" in the NREL search box and got back THESE 4 pages of articles, all look to be about big commercial systems, it will take a while to check over these.This message has been edited. Last edited by: Tim c cook,
I missed it, do you have a link?
The latest from Harvard I could find was this 04/10/2010 article in Technology Review:
Here's an archive of Harvard's news releases:
Maybe it's too recent to be listed.
Well, if they don't answer, here's a company that will sell you a whole system or just the turbine but the smallest they make is 10kw, the turbine by itself goes for $15K.
Since ORC recovery systems are pretty much specific to each client's circumstances, they aren't an off-the-shelf proposition. Because of costs involved with 'one at a time' engineering/manufacture and the fact that these costs can be offset by state and federal subsidies for large power consumers, they are really only cost-effective for commercial plants.
Personally, for $15K, I'd rather put the bucks into a CNC mill/lathe, fire up Autocad and 'roll my own'.
The harvard story is no problem, just google it. It was on yahoo news yesterday.
for the sad story of the day,
my company has an excellent machine shop and an excellent machinest, but I could never use it or him. I'll bet my buddy could churn out a nice gerotor to my specifications in way less than a day, but we'd both get fired.
Unless someone has a way to pour some composite material into a mold, or something.
Other than that, I guess we'll have to experiment with existing pumps, etc.
If you're a little short on experience around the machine shop, the next best thing might be trying some prototyping with one of these. Since you still have to generate a CAD file to make the parts anyway, you could take the dwg/dxf to a machine shop for the final build once you had all the wrinkles ironed out.
If you wanted to get into machining yourself, here's a relatively inexpensive CNC mill:
But yes, the most expedient (and least expensive) route is to use something that's already available.
New in/out port placement for the Mallory gearotor expander test - I was thinking about this while looking at the drawing of the Minto gearotor motor shown in the PS article when I realized the drawing actually showed the port locations and shapes. I tweaked the picture a bit to better see the dotted outlines as well as the actual port shapes. The exhaust port placement and shape seems to make sense but the input port is a bit puzzling, The odd shape of the port actually divides it over two gear tooth opening if you mentally rotate the gears clockwise in your mind. Just wondering if any of you engineering folks here might have an explanation for the divided input port shape.
This pic shows the dotted outlines for the ports.
minto_gearotor_pic_1_-_shows_port_outlines_-_tweeked_for_net.jpg (40 Kb, 28 downloads)
I shifted the contrast and brightness of this pic to highlight the shape of the ports against the dark portions of the other picture. The port openings show up in black here but not all black is an actual opening, have to mentally superimpose the dotted lines over this pic to get the full port shapes.
minto_gearotor_pic_2_-_hi_con_-_port_shapes_-_resized_for_net.jpg (20 Kb, 23 downloads)
Yes, that's what we need to know, how to apply the working fluid in the gerotor and where. Needs a lot of study.
Meanwhile, the 'Sterling' I was talking about several posts ago was Sterling Allan, a person, a journalist.
Reading his stuff led me to star rotor. Probably the only other company besides ener-g-rotor that uses gerotors with working fluid.
Mark Holtzapple is the president, he's also a chemistry professor at the u. of Houston.
He's trying to develop a car using the brayton cycle, uses a compressor and an expander, both of them are gerotors, and it looks almost exactly like the techniques we're talking about. He calls the drive unit a turbine, but its still a gerotor. He's also talking about trying to combine the compressor and the expander together somehow.
Anyway, I emailed him, told him our difficulties and our conserns, he replied, and said that they are developing a waste heat management system using the Organic Rankine cycle, it should be available this fall.
No prices yet.
The representation in the jpg is probably more of a 'diagrammatic' view, simplified to convey the concept.
This might be helpful. Scroll down a bit to download the PDF:
Now keep in mind, Minto has several patents listed with uspto, hunt through them to find what you're looking for. Also remember that, during this period, he had funding from Nissan, so he could have had anything machined he wanted, and I'm sure he took advantage of this funding to do just that.
It's doubtful any of his expanders, at this point, were 'off-the-shelf' or repurposed units.
OK, read through the patent and it explained the porting shown in the gearotor diagram pretty well. I suspect the diagram shown of the gearotor is NOT the prime mover gearotor but is the AUXILIARY gearotor motor used to power the accessories on the vehicle. I think the porting in there diagram is what the auxiliary motor would have been ported like, this gearotor motor is not designed to be reversed, it runs clockwise only. The input port design applies vapor pressure to the first two lobe spaces after the space has been completely closed at the top of the rotor's position, the patent indicates that by applying vapor pressure to both the first two spaces of the gears the motor will produce higher torque, applying the vapor pressure to only the first smaller opening will create less torque but a higher expansion ratio, thus is more efficient (start out with less vapor but let it expand to a larger volume before exhausting it from the motor).
Since I don't need to reverse the Mallory gearotor motor/generator I think something close to the porting shown in the PS diagram is what I will start with, I won't know if I need all the available torque to drive the permanent magnet DC motor-turned-generator til I get it built, if not I can make another valve plate and only apply pressure to the first opening, this would reduce the vapor flow rate and thus increase efficiency.
Had a thought about "compounding". The Mallory pumps are available in several flow rates as pumps, from what I have so far observed the only difference is that the gearset portion of the pump is taller so the gears have a larger volume (Mallory seems to use 2 different sized motors too but all the higher flow pumps than the 70 G/H one (1070 model) seem to use the same larger motor?). Adding one of the larger flow rate Mallory pumps after a first smaller flow rate one, such that the larger surface area of the second units taller gears would produce about the same amount of torque (thus electricity) as the first unit even though the pressure of the vapor from the first unit has already been reduced by expanding through the first set of gears?
Evaporative cooling swamp cooler test -- Just started setting the test up today and ran the swamp cooler for an hour or so just to get the pads wet. The ambient air temp was close to 100 deg f today with around 10% humidity, the outlet air was noticably cooler than 100 deg but not extrely cold, just plesant, cool enough to stop me sweating, so around 80 deg f by guestimate - BUT- the water in the bottom of the swamp cooler was surprisingly CHILLY, stuck my fingers in the water and it was far colder than I expected. The amount of water evaporated over the hour was more than I had hoped, lost about 2 inches of water depth from the sump of the cooler, have yet to figure the actual amount evaporated today but it will be part of the testing. Hope to get the temp sensors added tomorrow and run some temp measurements over time.
I have to get to town and pick up a couple cheap hot water heater elements to use to add a few kilowatts of heat into the coolers sump water to simulate a hot condensing radiator being submerged in it, it will be interesting to see if hot water evaporates faster than the cool water, probably will.
O.K. gang, check this out,
Look up u.s. patent 4741681.
Its basically a gerotor inside a gerotor. My idea is to use something very similar to this patent in order to turn the input shaft to the inside gerotor with a d.c. motor. Then rig the outside gerotor to take the working fluid pressure of the refrigerant.
The idea being that the two forces would augment, or add to each other. Which would in turn, turn the output shaft to the generator.
The patent itself might need a little 'tweaking'.
If this concept is possible, it might be an idea that would be 'more bang for the buck'. Namely a much higher kw output power than we're contemplating presently.
Please tell me where I'm wrong.
I sincerly doubt that anyone has ever made such a device. The patent was approved in 1988.
I sent this idea to professor Holtzapple. We'll see what he thinks.
The one thing he does have is the resources and facilities to create such a thing, if it really is a good idea.
Interesting proposition. Would you hog-out the port-side of the pump-case and use some AL blanks to come up with the best port-config? I guess that way you could try different port setups to see which worked best.
How would you handle shaft-speed or torque differences if the units are ganged-together on a common belt, you know, so one isn't 'dragging' the other one along or one doesn't act like a 'brake' on the other? Maybe there's a way to do it other than a belt?
A 15-20 deg-F TD is pretty much best-case for a swamper (even refrigeration-ACs are only designed for 20 deg-F TDs across their evap-coils ).
As the humidity rises, the evaporation will diminish and the output temp will go up...BUT, you can 'force' more evaporation at higher humidity by increasing the air-flow across the pads (speed up the fan).
However, a fan's air-moving capacity is limited by it's design, they operate on a bell-curve that falls off on both sides of it's optimum speed-range (so there's a limit as to how much you can just 'turn it up').
No hogging-out needed, the Mallory electric fuel pumps already come that way.
A bit of background and a few pictures about these pumps. The pumps are small, they will fit in your hand. they are made up of 4 parts, on top is the 12 volt DC electric motor, it's shaft goes through a seal and a ball bearing that are located in the aluminum housing just below the motor that also holds the gear set, then there is the port plate, this is 3/16 inch thick from the manufacturer but can be about any thickness required if making up a replacement, below that is the aluminum in/out assembly that consists of two large sump openings that connect to the outside world through 3/8 pipe threaded in/out openings.
This pic shows the complete smallest 70 g/h Mallory pump/motor assembly, it measures 5 1/4 inches top-to-bottom.This message has been edited. Last edited by: Tim c cook,
complete_pump_assembly_-_70_G-H_-_resized.JPG (28 Kb, 20 downloads)
This pic shows the two screws that hold the entire pump portion together.
bottom_-_shows_screws_resized.JPG (22 Kb, 11 downloads)
This shows the pump disassembled into it's three sections.
disassembled_70_G-H_pump-_resized.JPG (41 Kb, 17 downloads)
This shows the relationship of the existing in/out port plate to the in/out sump section.
relationship_of_port_plate_to_in-out_sump_section_-_resized.JPG (14 Kb, 10 downloads)
This shows the gearset diameter.
gear_set_measurment.JPG (21 Kb, 11 downloads)
This pic shows the size comparison between the 70 G/H pump on the left to the 110 G/H one on the right. From looking at Mallory pump advertisment pictures it looks like all the pumps 110 G/H or larger are all the same size but it may be that they use the same general icture in all there advertising but it may be that they use larger gears, don't know as I have not yet seen anything but the pictures in sales of used pumps on Ebay, they all look the same no matter what flow rate they indicate?
The larger 110 G/H flow rate pump uses the same diameter gears as the smaller pump except that they are longer (taller), the motor is also larger and turns a bit slower than the small pump, the larger motor will be able to produce more amps when used as a generator as well as being able to handle more heat.
mallory_pump_size_comparison_-_L_4070_-_R_4110.JPG (24 Kb, 12 downloads)
"Compounding" more than one pump/expander/generators - "shaft-speed or torque differences" - NOT A PROBLEM, the vapor output of the first pump/expander is simply plumbed into the vapor input of the next larger pump/expander etc., since each pump/expander has it's own independent electrical generator there is no mechanical link between them, each generator will output whatever volts and amps it is capable of depending on vapor input power and load. Each generator could charge it's own 12 volt battery by simply placing a diode between the generator positive output lead and the battery, since each generator has isolated plus and minus leads out the batteries can even be part of a series wired group, each generator would simply charge it's own battery. OR - there could be a bit of electronics connected to each generator that would take in whatever power the generator creates and convert it into a standard voltage and then would add the amps from each generator together and use the total to charge the battery.
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