steam turbines

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This topic contains 15 replies, has 6 voices, and was last updated by  Ken4g64 4 years, 3 months ago.

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• #1269

Altaica
Participant

Steam seems to be the ideal power source for a independent Seastead. you can make a combined electricity/heat/desalination plant. They also run off anything that can boil water. But I can’t find any steam turbines for sell. So I guess will have to go straight to making our own. Looks like Tesla turbine is the way to go as they are the easiest to make and repair.

A treatise on screw propellers and their steam-engines: with practical rules and examples how to calculate and construct the same for any description of vessels.
and
A new treatise on steam engineering, physical properties of permanent gases, and of different kinds of vapor.
both by John William Nystrom

seem to be a good start. Anyone have anything more up to date?

#10341

Anonymous

Steam isn’t a source of energy. How do you intend to boil the water? If with solar concentrators, then a turbine might be the way to go. Or a stirling engine.

If you use diesel or fuel oil you might be better off with a diesel engine (genset).

Automotive turbochargers perhaps could be used to make a DIY steam turbine.

#10351

J.L.-Frusha
Participant

One big problem with steam turbines is RPM. They don’t gear-down well. Large turbine generators are in use at all ot the Nuclear Power Plants. A DIY Peltier wheel could work, for smaller systems. Power it with a solar steam generator and store it in batteries.

Later,

J.L.F.

If you can’t swim with the big fish, stick to the reef

#10377

Altaica
Participant

Carl wrote:

Steam isn’t a source of energy.

Electricity isn’t a source of energy ether.

Since the main energy uses in my seastead will be heating, desalination and Propulsion.

since halophytes don’t like frost and my seastead will have heavy use of bio(civil)engineering it’s important I don’t let them get to cold.

Altaica wrote:
They also run off anything that can boil water.

I planing on solar/wood/compressed tumbleweed(same energy density as coal)

Carl wrote:
How do you intend to boil the water?

I planing on solar/wood/compressed tumbleweed(same energy density as coal)

Carl wrote:
If with solar concentrators, then a turbine might be the way to go. Or a stirling engine.

I’ll have to look into making stirling engines.

Carl wrote:
Automotive turbochargers perhaps could be used to make a DIY steam turbine.

ouk emou alla tou logou akousantas homologein sophon estin hen

#10378

Altaica
Participant

J.L. wrote:

One big problem with steam turbines is RPM. They don’t gear-down well.

then use a steam engine for thous applications.

A DIY Peltier wheel could work, for smaller systems.

What’s a peltier wheel? Google didn’t turn up anything. you mean a Pelton Wheel?

Power it with a solar steam generator and store it in batteries.

Last time I checked Batteries had low efficiny for storing eletricity. most of the loss being the charging.

ouk emou alla tou logou akousantas homologein sophon estin hen

#10383

J.L.-Frusha
Participant

Pelton/Peltier… I was close. Been exhausted lately… Watching an EotWawKIE unfold, in the Gulf of Mexico. BTW, a Peltier junction converts heat to electricity. 2 of them can move heat, using electricity… AKA thermocouples…

There are different battery technologies… Storing heat and recovering it is even less eficient.

There are attempls at using high speed turbines to produce electricity in autos… Dodge had one, maybe a decade ago?

Later,

J.L.F.

If you can’t swim with the big fish, stick to the reef

#10395

Altaica
Participant

J.L. wrote:
There are different battery technologies…

If you are justs going to be pulling the raw materials out of your ass you can just use a nuclear reactor.

J.L. wrote:
Storing heat and recovering it is even less eficient.

What ‘recovering’?

electricity => heat => electricity => ‘end effect'(heating/motion)

Plant mater => fire => steam => ‘end effect’

ouk emou alla tou logou akousantas homologein sophon estin hen

#10763

Farmer
Participant

Temperature differential
Most of the sea is around 5c, even just 1 km down. The surface is almost always at least 15c. Many ammonia based refrigerants and pentane have a boiling point between those two numbers.
What people have successfully done on is drop a tube to create a loop so that working fluid pumped up to the surface boils and is then pumped back down to reliquefy in the colder water.
Just a low temp turbine.
With a little more work on this technology ( a lot has already been done including long time operational generators on several scales) I don’t imagine seasteaders wanting for energy at all.
#10767

Jack
Participant

I like it Steam, great idea, However What is your thoughts on Stirling engines?

The reason I think Stirling engines would be the best option is because:

• Steam engines thermal efficiency is about 10-25% (thats how much energy it converst from burning fuel to electrical power)
• Diesel engines thermal efficiency is about 20-25%
• Stirling engines thermal efficiency is about 40-50%

Taking it on the basis that, engine cost, thermal efficiency & cheap fuel is the most important factors, that would make the Stirling engine the Logical choice.

& some power stations can actuly run on burning seawead.. soo couple that with the efficiency of the Stirling engine & you could have a realistic winner.

#10777

Farmer
Participant

Stirlings can run off of temprature differentials of less than 1 degree c.

The difference between a dry, black plate of some collector material (ceramics, iron, anything dense) and a shaded spot of seawater just 10 meters below should be much greater than that.

Yes it would have to be larger than a steam turbine but except for maintenance it would be free and run all day and night without attention.

#10778

Jack
Participant

Very good point farmer, & that had not escaped me.

However I did not post a natural thermal difference engine, because of the added size, & many “traditionalists” like to burn things… it makes them feel better.

But your quite right to have pointed this option out.

It should be noted that Steam engines & Liquid fueld engines may generate up to 50% Thermal efficiency, but require alot of complex & exspensive additions to reclaim energy lost from the exhaust pipes.

(sorry i had to add this as i felt a little guilty about not adding it the 1st time, but i did not want to start explaining why the stirling was better because its a simpler system, thats more efficient without all the extra complex energy extractors and so on).

#10837

Ken4g64
Participant

One thing to keep in mind though is carnot’s cycle, The efficiency ratings of these engines are not so clear cut as it would seem.

Carnots cycle basicly says that the hotter the hot side and the colder the cold side the more efficient of a system you CAN have.

$eta=frac{W}{Q_H}=1-frac{T_C}{T_H}

W is the work done by the system (energy exiting the system as work),
QH is the heat put into the system (heat energy entering the system),
TC is the absolute temperature of the cold reservoir, and
TH is the absolute temperature of the hot reservoir.

sooo with this in mind we look at a sterling engine with 1 degree c difference

if the cold side is at 0 degrees kelvin (-459.67 degrees Fahrenheit) and the hot side is at 1 degree kelvin (-457.87 degrees Fahrenheit) then we have 1.00-0/1=100 % maximum efficiency

if the cold side is at 294.261111 kelvin (70 degrees Fahrenheit) and the hot side is at 295.261111 kelvin (71.7999998 degrees Fahrenheit) then we have 1.00-294.3/295.3=1.00-0.996614=0.003386 or 0.3386 % maximum efficiency

http://www.steves.co.za/Engine_Protection_Units.html uses a number of 830 c to 950 c for diesel egt (exhaust gas temperature) (cylinder temps will be much higher but due to the fact that i have no real numbers to work with i am using the egt number, the real maximum efficiency will be higher due to this fact)

if the cold side is at 294.261111 kelvin (70 degrees Fahrenheit) and the hot side is at 1,223.15 kelvin (1742 degrees Fahrenheit) then we have 1.00-294.3/1223.2= 1.00-0.240598=0.759402 or 75.9402 % maximum efficiency

now remember these are all theoretical MAXIMUM efficiencies, the real number cannot go above this number and the real number will be lower due to internal friction, flow restrictions, etc. input your own numbers into the formula to get your own efficiencies and remember they must be an absolute temp aka rankine or kelvin

hope this helps,

Best regards,

Ken

#10843

Jack
Participant

WERE SAVED no joke, so you understand thermodynamics & sientific equations? OMG were saved! HELLO KEN!

As far as i understand the Carnots theory states that we get greater efficiencies from cooling the vacuum chamber than heating the exspansion chamber no?

ok now the only problem is how do you cool the vaccum chamber efficiently?

Possibly a thermoelectric Peltier divice? (any ideas??)

However i think the power draw would mitigate any gains from using the Peltier system before you started seeing results from Carnot’s theory. (it might not be worth while).

But to be honest, unless it somthing we can buy in kit form, or have a member of the TSI produce these things liek some mad scientist, then its not likely were going to see these things in service for a while, & we need them NOW.

I think its most probable that Stirling engines fueld by some bio/hydrocarbon fuel, or Even Steam Engines fueld by cheap coal as generators is the most probable, unless you got alot of money for PV pannels & wave generators. (Wind turbines drive Fish crazy, had to stop fly fishing at a lake because they built those things so close, made the fish not want to bite some how, & they did kill birds, & the noise travels its not so nice).

Thanks for the breakdown of the equation, im not so good at that.

#10846

Ken4g64
Participant

lol, looking up on the thermodynamics and scientific equations is more of a hobby XD

by cooling the cool side might be more efficient too due to the fact that we have all this cold sea water and hot sunlight

http://www.windows2universe.org/earth/Water/images/temperature_depth.jpg

it looks like the water temperature stabilizes at around 4 degrees c (39.2 degrees f) at 1000 feet (any deeper and we dont get the lower temps as quickly, so i suspect it wont be worth while) so with cooling from sea water and heating from gasification of algae and solar collecters i suspect that sterling engines might be one of the better solutions. another thought is to use a mechanical heat pump (aka air conditioning) to cool the cold side, then we might use the same energy as physically pumping the water but reach a slightly lower temp. dunno if it would work, but def food for thought.

the problem with peltier modules as power generators is not only their limited range in temperature but their ineffiency too. peltier modules are made of semi-conducters, the resistance of the module and its temperature are inversely related (when temp goes down, the resistance goes up) so when you get one side too cold eventually they quit working all together (not really a problem cause this is at a very low temperature) but the hot side cant get any higher than 250-300 degrees f or the solder will melt (some can get higher temps, but are expensive) maybe if they were brazed? on the other hand they arent even 1 for 1 as far as heat pumps are concerned.

modern ac units will usually pump well over 10 for 1 (that is put in 1 watt and move 10 watts, at the cold side we get -10 watts we used 1 watt to pump and at the hot side we get 11 watts of heat) (i believe they might get up to 16, but keep in mind that the larger the difference in temperature, the more inefficient the process will become.)

although, i dont feel that we need alot of money to make large amounts of electricity especially next to the equator.

why not use an old v6 from a poniac or buick? the gm 3800 is a reliable engine and everyone and their grandmother has one, if the block was heated (solar collecter used right on the existing cooling system to prevent the steam from cooling down and condensing, although care must be taken to prevent it from getting too hot and cooking the oil) and the cam was redone (not necessary, but will make it more efficient and 2x more powerful) to open intake valves when piston is moving down and exhaust when piston is moving up, then we have a homemade steam engine that’ll get you started till you save for the big high tech sterling that is naturally balanced (same power strokes as a v12) rigged up to the automatic transmission that came with it and set cruise control, then as more power is needed to keep the generator goin at the same speed (aka more demand) then the transmission will automatically gear the engine down and cruise control will open the throttle body more to increase steam flow.

again, this is just a thought for a simple diy generator set although you still need heat for the steam (algae gasification or large solar collecters)

as far as a solar collecter goes just fibreglass up a dish, paint it with reflective paint, and collect the energy at the focus of the dish and you have an efficient cheap thermal “solar panel”

even after using setting up the sterling engine, we can still use the steam as the heat transfer medium and a source of desalinated water.

best regards,

ken

#10847

Jack
Participant

were screwed again OMG were screwed (some one kill kenny!) lol

yep that rather cold, but not nearly enough i think to over come the cost of movig cold water to your unit?

Indeed the standerd freezer Co2 compressor would do the trick nicely, well a few depending on your vacuum chamber size, (thats where your fancy maths comes into play Keny hehe)

well i see your point about the “dry engine”, but the cost of diesel would kill the project in concept i would have thought?

UGH woman naging me, cant finish a good post

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