This pic shows the swamp cooler test setup. Today's test was done with the fan on "low".
The ambient temp sensor is measuring the shop temp about 10 feet away from this roll-around swamp cooler that I use as a shop cooler, you can see the cool air sensor dangling from the end of the metal strip in front of the fan, the water sensor temp black wire can be seen running down the left corner of the cooler.
I did one run late today but had a sensor problem, these temp sensors are advertised as being capable of being submerged in liquid, well - the one I chose for that purpose was not sealed well and created a railed reading of 999, I swapped it with one of the others that did work submerged but the leaky one must have still had a bit of water internally as it read about 12 deg cooler than it should.
The cooler temps took about 45 minutes to stabilize, the water temp was about 12-13 deg cooler than the ambient air temp and the output air was about 12-13 degrees cooler than that, 100 deg f ambient created about 88 degree water and 76 deg f cool air.
The water supply sump holds just a bit less than 4.5 gallons and It ran out of water after two hours 25 minutes so even with the fan on low it evaporates a good bit of water. The starting ambient temp in the shop was 102 deg f with about 7% humidity, at the end of the test the ambient temp in the shop was 98 degrees f, some of this drop probably was caused by the cooler but probably more because the sun had set so was not adding heat to the uninsulated tin roof of the shop.
I will try it with the fan on "HI" tomorrow.
swamp_cooler_test_setup.JPG (30 Kb, 30 downloads)
Tim, I like that idea, it solves a lot of problems, has a lot of merit both in practicality of application and from an engineering standpoint.
I also like the possibility to handle additive differences through controlling the generated-power side rather than the mechanical side, it takes all the major efficiency-loss areas and consolidates them 'under one roof' (i.e. electrical & control), not to mention that any mechanical disparities are obviated.
As for the expansion side, it would seem that it allows for modular extraction of the majority of energy available by staging successive expanders, as necessary, so would be suitable for a wider variety of expansion-media since condensation parameters could be controlled more easily.
Although Carnot/Rankine efficiency may or may not be impacted to any substantial degree, any impact that may have is offset by the lower cost, availability and relative ease of application this method would afford.
So, now that the idea looks sound, all that remains is designing the test protocols, gathering the data, doing the math, extrapolating for a range of requirements, generating the diagrams, designing the controllers, writing the control-software, testing various configurations, etc. etc. etc.
Good show, Tim!
Yes, although you can force more evaporation to occur at higher fan speeds (and perhaps 'because' you can force more evaporation to occur...), you have to balance this with the amount of cooled-water left over after being evaporated over the pads that trickles down into the sump, which is what lowers the sump temperature.
In dry conditions, you may evaporate 'too much' of the water as it passes over the pads, which could 'starve' the sump, requiring the float valve to admit more make-up water from the mains, which would have the effect of increasing the sump temperature and, thus, increasing the air temperature you notice coming out of the cooler.
As the humidity rises, less water will be evaporated at any given air-delivery, so the sump will have less of a requirement for make-up water (which is usually at a higher temp than sump water).
It's a bit of a 'balancing act' since the ambient humidity, which is a dynamic component, is the determining factor in fan speed selection (water delivery across the pads is a 'fixed' constant due to the trough openings at the top of the pad frames).
Anyway, don't be surprised if the temperature doesn't cool down more when you kick the speed up under low-humidity conditions.
Now that I've read through this again, I see you have a manually filled sump that doesn't use a float valve for make-up, so you won't have the effect I mentioned above, you'll just run out of water sooner.
O.K., I'm sorry,
My last proposal wasn't too bright.
But now I've got it. I'll bet you'll all like this one.
Only thing, I can't post it now, I want to look at the swamp cooler video first. I can't do that until I get home, which won't be until tomorrow, at the earliest.
Do you think which one more efficient?
Microturbine or scroll expander?
Does anybody know the manufacturers of microturbine and scroll expander?
Does anybody know about Organic Rankine cycle (ORC) for power and cooling (CHP)?
Does it use heat pump to absorb the heat from building and transfer it to refrigerant fluid?
Thanks so much..
tondang, what size load (building, plant, etc.)? What is your excess heat source?
Have you read through the previously posted links?
The term 'turbine' is used generically by several commercial heat/power reclamation concerns, it doesn't necessarily define the physical configuration of the expander. It is more often a positive displacement arrangement of some sort rather than a true 'turbine', mainly due to manufacturing costs.
A staged, conventional turbine matched to the expansion medium in use is more efficient than any of the positive displacement alternatives we've been talking about in this thread, turbines of the size we're interested in are not available because there isn't a substantial market for them.
Truly, positive displacement expanders, whether scroll, vane, gerotor or reciprocating have very similar efficiencies. Although there may be marginal differences, they all share about the same efficiency-range.
The advantage is that positive displacement units are available as standard items rather than being 'proprietary', as is the case for expanders in commercial reclamation units, so they are 'affordable' for personal experimentation.
Here's a few commercial sites:
I've been experimenting with different types of impellers, it seems like there is little difference in the output from any of them. One style is only slightly more effective than the other. And that 'compounding' idea is sort of what I was thinking about, basically to hit the turbines with more than one nossle simuntaneously. Which is the mystery element that no one seems to have experimented with, the nozzle. appearently, different shaped nozzles handle the steam better than other shapes. I had a paper on that, but I can't find it right now. I'll report back when I get it.
I still can't find the nozzle article, I probably deleted it. I'll find it. Here's something a little different, using pelton impellers for turbines. There are also pelton hooped impellers, you might google.
For anyone that missed that harvard study on a solar cell advancement, you might find it under 'black silicon'. Now they're only saying it will be about twice as effective as present technology, which will still be too expensive, and it'll be a while before its available
What happened, guys ?? This was getting VERY interesting, then, stopped ??
I have done some searching, and read an article about someone rigging up an Air Motor. Said it would be ideal, and, some other guy, agreed. Said ebay can have some good deals on this particular set up.
I can go find that article and post a link, if that would help ??
I have several farmers here that could use the ORC generating-cooling system, for keeping their cheese cooled until the buyer shows up, so, I am very interested in how y'all are getting along ??
Don't know if Y'all have seen this article ?? have to PURCHASE from the Feds, but, it is from 1972-73.
Supposed to explain about how to build a 3KW system ???
Actually, info from an outfit in Mass. ??
Searched the DTIC website (here) and found a bit more info in an abstract.
Unfortunately, small turbines are still not available at a reasonable price. I will do a bit of research on the working fluid they indicated to determine it's properties, availability, and cost but The 530 deg f vapor temp pretty much eliminates this fluid for use in a home-built solar system.
I'm still having trouble grasping where the RPM's originate from. I know it's a Turbine, but, where does that high pressure come from ??
Solar Concentrator, like a Fresnel lens would do nothing for this type system ?? Making fast-plentiful "steam" is pretty easy with a Fresnel ??
I'm just trying to excite the brain cells of whoever is really understanding this system, so I can learn about it as well.
The high volume, high pressure vapor used to power the expander comes from applying heat to the liquid working fluid, the basic process is the same as when using water in a water steam engine but rather than water some other fluid is used, the process is the same but the temperature ranges will shift up/down compared to water, depending on just what fluid is being used.
A heat source, could be solar or any type of heat, is used to boil a liquid, the boiling creates a much larger volume of high pressure (thus high temperature) vapors, these high pressure vapors are fed to an expander/motor to convert the vapor flow into a mechanical motion that is used to do work of some type. As the vapor flows out of the expander/motor it's temperature and pressure are lower than when it went into the expander, but for re-use the vapor needs to be cooled even more until it condenses back into a liquid, once it is again a liquid a smaller high pressure pump is used to push the cooled and condensed liquid back into the boiler where it is again heated and turned back into a vapor with a much larger volume than when in it's liquid form - round-n-round it goes. The usable work comes from the vapor flow created due to the difference in pressure and volume between the smaller volume of the condensed liquid and the much larger volume of the heated vapor. The usable energy comes from the external heat used to boil the liquid into a vapor.
This links to the "how it works" page of what started out as the MIT Solar Turbine Group ORC system. It also shows the type of trough solar collectors they are using with the system.
This links to an animation of the process, this is from the Matteran Energy ORC website, it is a bit more complicated due to the way Matteran condensed the spent vapors back into the boiler, they don't use a mechanical pump but instead use valves to control the flow of the cooled and condensed liquid, the liquid is first cooled and condensed, then moved into a separate tank by gravity, they then heat that tank and use the high pressure vapor that collects above the liquid, plus gravity, to force the liquid back into the boiler. This boiler feed concept is the basis of there patent, they say it adds a few percent (3-4?) more efficiency to the system over using a much simpler method of using a mechanical pump to push the condensed liquid back into the boiler.
This links to some info on small Fresnel water boilers being worked on by Charles Shults, the concept is to use several small boilers heated with salvaged Fresnel lenses ganged together as a water steam source to power some sort of steam engine. I have heard conversations with him over the radio, he sounds good but the idea seems to have gone dead. There are some videos of there testing someplace on the net, only shows the lens/boiler array, never did see them connected to any sort of engine.
Got sidetracked with other projects this year but have collected some parts (York compressor, air conditioner radiators, 500 gallon tanks for heat storage etc.), hope to do some actual testing over next summer.
Thanks for this latest info. I wish my search efforts were as rewarding as yours.
This gives me several ways to explore what I intend to achieve.
Anything I manage to develop, with success, will be posted to this thread.
Have you seen this set up ??
ALASKA & GEOTHERMAL ENERGY 101
check it out........
the fisrt electric power generation at Chena Hot Springs Resort in Alaska using a 74°C, 165.2F geothermal using a refrigerant.
resource (Lund, 2006).
Deadheader -- Interesting link, my old computer did not download the videos that well but from what I saw the power generation is intermittent, a couple seconds of making power then a couple seconds resetting, would work for battery charging but not direct use, maybe if there flywheel was a lot heavier, It appears that they at least have something actually producing power, not enough details given to know efficiency or how much problem they have condensing the frig fluid?
Dennis - I have followed the China Springs setup on and off, the last thing I read was that they had changed there frig fluid to R134a recently. the short article did not go in to the details as to why.
I will be hauling a couple used round steel 500 gallon farm fuel tanks, along with several large flat home air conditioner radiators, back to Arizona after the first of the year, hope to be able to at least do some solar water heating tests using the radiators mounted in some sort of glass/plastic covered insulated box and a 12 volt shurflo RV water pump as the circulator.
check it out
Evacuated Heat Pipe Solar Hot Water System
The development of the heat pipe originally started with Angier March Perkins who worked initially with the concept of the working fluid only in one phase (he took out a patent in 1839 on the hermetic tube boiler which works on this principle). Jacob Perkins (descendant of Angier March) patented the Perkins Tube in 1936 and they became widespread for use in locomotive boilers and baking ovens. The Perkins Tube was a system in which a long and twisted tube passed over an evaporator and a condenser, which caused the water within the tube to operate in two phases. Although these early designs for heat transfer systems relied on gravity to return the liquid to the evaporator (later called a thermosyphon), the Perkins Tube was the jumping off point for the development of the modern heat pipe.
Another application of low-temperature ORC systems is through the use of Solar Ponds. In large lakes with high salt content, much of the salt sinks to the bottom. “The upper layers of [fresh]water act as an insulating blanket and the temperature at the bottom of the pond can reach 90 degrees C. This is a high enough temperature to run an organic rankine cycle (ORC) engine or Stirling engine,” as described on SolarThermalMagazine.com, The first solar pond ORC system in the United States was a 100-kW system that supplied process heat to a commercial manufacturer. It was installed in Texas in 1986 and produced at 85°C [185°F], according to Ormat Technologies, which supplied the unit.
Chena Hot Springs, Alaska, is the site of the lowest temperature commercial geothermal plant to date, though test units of 1-4 kW have run on lower temperatures. Two 210-kW units using 73.3°C [165°F] geothermal fluid as the heat source were installed at Chena in 2006 by United Technologies Corp. The systems replaced on-site diesel generation systems, resulting in substantial cost savings.
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