# How far does a propeller push water ?

Discussion in 'Props' started by Stream T, Dec 27, 2017.

1. Joined: Dec 2017
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### Stream TNew Member

Hi !
I hope I am in the right forum and get an answer to my query.
We operate a pumping station which pumps sea water to petrochemical plants and a refinery in the Arabian Gulf. Our sea water intake is jutting ~ 500 m into the sea. However, over the last few years sea water temperature is going up which is affecting our customers.
Alternative 1 is to push the water intake further out into the sea but this is a very expensive option.
Alternative 2 is an outrageous suggestion to push colder water towards the water intake from out in the sea using propellers.
Is this an idiotic suggestion ?
If not, can someone share ballpark numbers on how far does a propeller push water ?
If it is a very large propeller, what is a ballpark volume pushed and the cost of the propeller ?
Cheers,
ST

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### pistnbrokeI try

Extend the pipe

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### rwatsonSenior Member

Pistnborke - has supplied an effective answer, but its much more complicated than that.

If you were an engineer, you would be aware that the surrounding underwater topology ( channel size, direction. ground slope ) is part of a complex calculation that affects the impulse from water movement machinery. Water from a prop will go as far as the pipe takes it, BUT that only applies when the power/pitch/speed combination has been properly calculated, and the outlet size, direction, shape has been optimised.

Looking for solutions for this problems on a public internet forum is a waste of time. Get a qualified Hydro Engineer to do the numbers.

fallguy likes this.
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### Sparky568Junior Member

This really needs to be hydro engineered. The obviois problem with pushing water to your pipe inlet is currents and tides. Another option might be to install a mobile chiller plant, especially if we're talking only a few degrees. I know Kuwait recently upped thier electric rates, but do they subsidize solar?

Looking at this from an investment point of view could be a cheaper and easier to maintain in the long run.

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### gonzoSenior Member

Can you add an email or activate PM? I would like to contact you privately.

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### fallguySenior Member

One of my favorite lakes in the USA has an anomaly in that despite its shallowness; the lake supports a fish that only lives in deep, cold water lakes. They don’t just barely survive, but thrive.

The secret of that lake is that the coolest thing is not the surface water or springs or rivers, but the deep bedrock layers and the stable temperatures of the earth below. The lake is covered with bedrock shorelines.

If you need to change your systems; do not disconsider the subsurface temperature of the earth below which would probably be more stable than the water above.

Your solution might require the two in conjunction.

I believe there has been some research done on this subject specific to Kuwait and the intake for you would be relatively simple. That is to verify whether I am wrong or right. In a place where drilling is second nature; don’t discount the potential of the earth to pull the last few degrees you might need.

It is all well out of my precision, but rather than pushing all the water through the earth; pumping cool, subsurface air into your water would be relatively inexpensive; and done correctly; you could also get another engineering advantage with the air in the system and/or its removal. By the way; the air you send down into the earth could be precooled by the oceanwater.

If you use my concept; probably owe me a boat, wink wink .

Kind regards from the USA.

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### gonzoSenior Member

There is no advantage to use air instead of water for exchanging heat. Also, it doesn't seem to make any sense the reference to subsurface air. Are you claiming there is an atmosphere under the bottom of the sea?

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### fallguySenior Member

Oh no.

If the subsurface temperature is moderated vs the ocean surface temperatures; simple shallow well geothermal could be used. It is used all the time here to moderate temperatures of environments; albeit a different scale, although my original response was going to be have you not heard of Fallguy’s 20,000 Leagues Under the Sea?

In that fictional tale, we get a big giant propeller and force cool ocean water towards our unsustainably designed ocean heating operation. That way we can avoid running costly pipe?

I could be wrong, but someone needs to go back to the drawing board and scale their unsustainable system properly.

If you support creating a man made ocean current with propellers; let me know.

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### gonzoSenior Member

Geothermal wells are usually employed to heat not cool. Also, they are used on dry land. If by "here" you mean the USA, can you point me to any offshore installation using the system you describe? I would be interested to read on it.

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### fallguySenior Member

I understand the normal use of deepwell geothermal. Deepwell meaning thousands of feet.

There are a few systems doing similar things, but probably scaled better than this Kuwait system. Deep water/air source cooling is on wikipedia. I don’t know if they employed the use of wells in these systems, but they are probably either very deep or employing wells or some combination. And actually, geothermal shallow wells are used in smaller applications all the time in places where the earth is a cool 50F (in precooling). These wells are hundreds of feet down; not thousands and some much shallower where possible.

The USA does not face the climate extremes of Kuwait. I would expect Kuwait’s challenges to be great. And they probably have underscaled due to cost. But in all likelihood; they are driving the heat changes to some degree, all puns and all guess. Where does all the warmed water go would be the huge question, notwithstanding the fact that cool water is leaving for the warm surface water with spurious or possibly predictable results. The idea that the ocean is an endless source of cool water is false and they are simply reaching scale, or perhaps facing environmental anomaly-both a problem of scale.

Can you imagine a company in the US selling cooling based on warming the ocean? It won’t pass the simplest environmental testing. Powerplants must; so it is allowed to a degree <-. The Cornell thing is a study or able to sell as one.

My original point is much simpler; potentially flawed and I said so. The earth can be used as a heat sink and the effect of the earth can be great. It may not be possible for Kuwait, but heating the ocean is easy. You pump millions of gallons of water onto the surface and back again! And in all likelihood; they have already done so.

Had they considered the scaling problems; their solution might have been more robust; probably not without EIS.

Kind regards to all.

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### gonzoSenior Member

I am not sure where your information comes from. However, I am still interested in an example of how that is used in the USA as you claim. Also, the weather in Kuwait has less variation than most places in the USA. For example, Wisconsin has an average temperature difference between seasons of 92F (33C), while Kuwait has 79F(26C).

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### fallguySenior Member

Geothermal well cooling is used in small scale all the time and needs no citation. Large scale water source cooling doesn’t use geothermal because it generally has been designed sustainably, or farther from the equator, or even where lakes freeze. In Toronto; the system is 3 miles out into the lake and 285 feet down and they don’t return it I believe.

I presented a concept, but in all likelihood; they are gonna be laying pipe on the ocean floor and deeper.

However, drilling a well might be easier. The problem of sustainability does not go away though. You can end up heating the heat sink. And I already qualified that I don’t know the subterranean temperature; so could be wrong.

But that shallow lake example I gave is interesting because the earth is what is cool; not the water. The water, without the earth heat sinks of bedrock, would warm to temperatures unsustainable for that fish if the lake bottom were clay, for example, or ifbthere were no cooling season.

As for climate extremes, I meant the fact they get nearly no cooling season in Kuwait. If you have shallow geothermal wells; in the summer; they warm and in the winter they cool. So there is moderation of the system.

In Kuwait, things get warm.

But if the earth below the ocean intake is ten degrees cooler; it could be used if it were sustainable and the earth wouldn’t just heat up. And if they only need a few degrees of additional cooling; it might work. Introducing air might allow an evaporative effect in the system as well. All a concept.

I have a boat to build!

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### gonzoSenior Member

I can't really understand what you are claiming. For example, that the city of Toronto takes water from Lake Ontario (which you call a small lake lol) and doesn't return it. Where does all that accumulated water is kept?

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### fallguySenior Member

well, I THINK Toronto uses it for all their water supply and some commercial cooling as well, but I can't recall for sure; it has been awhile since I read about it --- obviously, not an option for Kuwait....small lake was my reference to the lake in Minnesota, not Lake Ontario. Toronto probably has an excess of water from Lake Ontario; I don't know where it goes, but I doubt it is returned to the Lake as the discussions seemed to forbid it. Some river or exiting watershed is probably getting it?

But Toronto does it; it is all public information.

If the surface waters at the intake for Kuwait are 60F, and the water is 100 feet deep there; if they run a mile of pipe to get to waters that are say 300 feet and 50F, what do you think the subterranean temperature of the earth is 200 feet under their existing intake, or even on the shore back the 500m they are out now and 300 feet down? Flatter me with a guess.

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### gonzoSenior Member

You are dealing with engineers in this forum. Any claim is expected to be justified by facts. Subterranean temperature increases with depth as you get closer to the magma. You have your geology wrong.

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