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Post by rmc on May 31, 2014 3:22:55 GMT
I'm trying to decide if an effective pump for pumping or sucking water out of a nearby creek can be accomplished by letting highly heated steam vent off a bit from a tank, then seal off the tank, letting the remaining steam cool in the closed-off tank, then opening an inlet valve, such that a supply line of water is already primed with water from a nearby creek. This way, the pressure difference created by the steam shrinking inside the cooling tank draws in water, and the tank fills until an equilibrium is made. (no air allowed to be sucked up from the creek or elsewhere)
Basically, the way I am envisioning it, it is a little like that famous video of the large train tank car that implodes inward on itself due to highly heated steam being allowed to cool within a sealed-off tank. Or, perhaps another way of looking at the forces potentially at work here would be to think of the Sterling Engine: one where heated-air cools, then the shrinking, cooling air draws up a piston. The difference here would be that an inlet line would be opened manually once steam cools and shrinks enough, letting water fill the tank, further cooling the interior but also tending toward an equilibrium. My hope is that the suction produced could fill the tank to at least half way. Once filled effectively, one would shut off the supply line from the creek and reopen the vent line when desired, for emptying the tank. I'd like to say that it could be heated via solar power, but I'm thinking some sort of gas heat or wood heat would be more conducive to small scale/ introductory attempts.
I'm wondering how full it would get, or if cooling steam in a tank would produce enough inward draw to lift water out of the creek through a hose?
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Post by the light works on May 31, 2014 3:32:32 GMT
I'm trying to decide if an effective pump for pumping or sucking water out of a nearby creek can be accomplished by letting highly heated steam vent off a bit from a tank, then seal off the tank, letting the remaining steam cool in the closed-off tank, then opening an inlet valve, such that a supply line of water is already primed with water from a nearby creek. This way, the pressure difference created by the steam shrinking inside the cooling tank draws in water, and the tank fills until an equilibrium is made. (no air allowed to be sucked up from the creek or elsewhere) Basically, the way I am envisioning it, it is a little like that famous video of the large train tank car that implodes inward on itself due to highly heated steam being allowed to cool within a sealed-off tank. Or, perhaps another way of looking at the forces potentially at work here would be to think of the Sterling Engine: one where heated-air cools, then the shrinking, cooling air draws up a piston. The difference here would be that an inlet line would be opened manually once steam cools and shrinks enough, letting water fill the tank, further cooling the interior but also tending toward an equilibrium. My hope is that the suction produced could fill the tank to at least half way. Once filled effectively, one would shut off the supply line from the creek and reopen the vent line when desired, for emptying the tank. I'd like to say that it could be heated via solar power, but I'm thinking some sort of gas heat or wood heat would be more conducive to small scale/ introductory attempts. I'm wondering how full it would get, or if cooling steam in a tank would produce enough inward draw to lift water out of the creek through a hose? basic rule of drafting would seem to apply. I would be inclined to use a one way checkvalve for the inlet valve, just to reduce the amount of valve twidding you would be doing. so you start with the tank primed, heat it for the steam, blow off the steam through the manual vent valve, then let the tank cool. as it cools it produces a partial vacuum , which draws the water (I know the in depth, just don't feel like reciting it) into the tank. your lift would probably be limited, and I'm not sure how much air the steam would displace in the charging portion of the experiment. overall, I would think there would be more efficient ways to draw water into a tank, but it should function. |
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Post by rmc on May 31, 2014 3:39:57 GMT
Maybe, using your one-way valve idea, it could have a few iterations? In other words, if it isn't full enough after cooling once, heat it up again, partial blow off, and then let it cool again? Of course, now, there's a larger body of water to be heated in order to produce the needed steam.
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Post by GTCGreg on May 31, 2014 4:01:24 GMT
I'm not sure how much vacuum you can get by condensing the steam. Don't forget that as the pressure in the tank goes down, so does the boiling point of any liquid water in the tank. That water would boil at a lower temperature producing more steam. Even if you could get a perfect vacuum, you can only "suck" water 32 feet in elevation. The overall efficiency of such a system would be pretty low. Seems like all the energy it's going to take to boil all that water would be much better put to use driving a pump.
Also, don't forget what happened to that rail tank car. Most tanks are not designed to support much of a vacuum.
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Post by the light works on May 31, 2014 5:21:50 GMT
Right. I think it would be more efficient to drain off all but a token amount of water between cycles. more water to convert to steam means more heat required to convert it, slower cooldown time, and thus a slower cycle.
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Post by rmc on May 31, 2014 14:21:48 GMT
Thanks, the light works and GTCGreg. I have to admit I am very dubious about the effectiveness of such a heated/cooled 'vacuum' system. The only thing going for it so far is the relative ease of constructing such a device as compared to other constructible, and inexpensive-to-operate systems.
One that I found is called the Williamson Ram Pump, involves a below-water-level compartment where a column of incoming water compresses another column of air, forming a kind of water/air piston to drive a couple of valves and somehow achieve an outgoing cycle of water that can rise above the waterline. Not too sure I actually believe that one works, though. It sounds sort of perpetual-motion-like to me.
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Post by GTCGreg on May 31, 2014 14:39:32 GMT
Ram pumps do work and are effective but only under just the right conditions. You have to have a pretty good drop in your stream level. The system works by running a lot of water through the pump and getting a little water pumped to a higher level. It's the water flowing through the pump that makes it work so it won't work with standing water as in a lake or pond.
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Post by rmc on May 31, 2014 15:12:35 GMT
Here's one of the videos I saw about the DIY Ram Pump:
It looks as though you can dam up the water supply or otherwise siphon down to a required below-waterline level of the pump to have the necessary incoming water pressure.
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Post by GTCGreg on May 31, 2014 15:24:18 GMT
Here's one of the videos I saw about the DIY Ram Pump: It looks as though you can dam up the water supply or otherwise siphon down to a required below-waterline level of the pump to have the necessary incoming water pressure. As long as you have the topography to do that. |
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Post by rmc on May 31, 2014 15:58:41 GMT
Right. It looks to me that if you have to set up below the waterline for effective pressure, your check valves could end up filling up whatever pit you've constructed (if you have had to do that).
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Post by the light works on May 31, 2014 16:36:02 GMT
so it looks like it basically works by water hammer. it looks like a fun thing to try, except for the 100' of head I already have on my irrigation system. hard to justify spending money an a pump, no matter how ingenious, when you have all the running water you can use, already.
but yes, definitely getting a very large waste to use ratio out of the system - so your applications are limited to locations where your water source is plentiful.
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Post by Cybermortis on May 31, 2014 20:09:50 GMT
Disclaimer; I am NOT an engineer by any stretch of the imagination. The design in the OP sounds similar to the worlds first steam engine invented and patented by Thomas Savery; en.wikipedia.org/wiki/Thomas_Savery#First_steam_engine_mechanismBased on what I'm reading on Wilki (and from what little I recall about Newcomen steam engine designs from elsewhere) this is not a very efficient design, nor a very powerful one. |
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Post by chriso on Jun 1, 2014 7:43:55 GMT
It would work, but as cyber pointed out it will be inefficient. Working on vacuum puts a few inherent limits on the system, and in addition to water boiling, stealing energy, you are wasting a large amount of energy warming and cooling the tanks walls as well. Ideally, you would want that energy to be going into moving the water instead.
Strangely, this thread popped up right as I am going through the Thermodynamics unit. I could try to run the numbers, but looking at it I don't think I know enough yet to model it.
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Post by the light works on Jun 1, 2014 15:14:26 GMT
it leaves me wondering, though, if you could make a semi-passive water pump with the thermal expansion concept - using a solar boiler and checkvalves, so it would send steam up the pipe in the daytime, and draw water from a shallow well when it cooled off at night.
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Post by the light works on Jun 1, 2014 15:17:08 GMT
Disclaimer; I am NOT an engineer by any stretch of the imagination. The design in the OP sounds similar to the worlds first steam engine invented and patented by Thomas Savery; en.wikipedia.org/wiki/Thomas_Savery#First_steam_engine_mechanismBased on what I'm reading on Wilki (and from what little I recall about Newcomen steam engine designs from elsewhere) this is not a very efficient design, nor a very powerful one. It looks like the draw stage is the same; though it looks like Savery's has a discharge stage as well, where the steam pressure blows the water further up while recharging the vacuum chamber. |
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Post by rmc on Jun 1, 2014 17:42:24 GMT
it leaves me wondering, though, if you could make a semi-passive water pump with the thermal expansion concept - using a solar boiler and checkvalves, so it would send steam up the pipe in the daytime, and draw water from a shallow well when it cooled off at night. That is a good question. The problem with the Ram Pump for me is that the available water supply is basically a stagnant pond of sorts (usually). Otherwise, the runoff there is a torrent once a year. Anyway, the ram pump requires that I somehow get below the water level for the ram pump action to work. But, with a steam-driven system like what you are talking about, it could all be above the waterline, I'd think. And, the creek water supply is only about 5 feet below the current tank altitude. Though, we want to raise that up at some point another 4 feet to get a better supply of water, having more water pressure. So, the work involved is in the neighborhood of about 10 feet of lift overall. For vacuum, there is the known limitation of 32 feet. So, we are in the ballpark of possibility. And, if it is some sort of passive system that runs all the time, (as in on solar of some kind), then, even if it is merely a trickle, it stands the chance of filling the garden water supply as we occasionally use it. If it gets too full, the runoff can always be redirected back to the creek or another tank. Basically, even if the heated steam vacuum system is weak, it really only has to do so much to make us happy. However, specifically just what that entails? I am still working on that. |
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Post by Cybermortis on Jun 1, 2014 20:15:13 GMT
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Post by rmc on Jun 1, 2014 20:58:47 GMT
Maybe something like this pump, but the compressed air, or in our case steam, is supplied via solar (or geothermal) techniques?
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Post by Cybermortis on Jun 1, 2014 22:57:21 GMT
Possibly. I know that both solar and geothermal heating systems have limitations, and which would be most practical for you would depend in a lot of factors starting with where you happen to live - solar pumps naturally work best in places that get a lot of sun.
You'd need FAR better advice than I am capable of giving - see the above disclaimers - to work out what might work best for you and be most practical. It is, for example, possible that such systems might not be capable of producing steam but *might* be capable of producing enough electricity to run a compressor(?) assuming you don't need the pump to be running at top speed. (It is also possible that there are incentives in place in your area for installing 'green' energy sources such as solar panels. So that might be something to look into.)
*Muses*
What about going even more 'old school' and using a windmill to power the pump?
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Post by GTCGreg on Jun 1, 2014 23:22:03 GMT
If it was me, I'd just go with a couple of solar panels and a small DC pump. You could even add a Gel Cell battery if you needed nighttime operation.
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