Model Steam engine use make free power for you shop

[Propforward]

Well, I look forward to seeing it in operation, but you'll excuse me if I don't hold my breath.

 

[gus]

Do not attempt to build this engine.


It will not work.


Think conceptually: The boiler is high pressure, the condenser is low pressure. The resultant differential pressure between the boiler and condenser “forces” the stem through the engine. Unlike compressed air, the high heat capacity of steam maintains elevated pressures during work extraction.


Without a differential pressure, you simply cannot extract mechanical power from steam. Consider a traditional boiler design, where a 150 psig boiler feeds a vented condenser. The boiler creates a differential pressure across the steam engine of 150 psig. Again, the pressure is the driving force of work extraction. The high heat capacity of steam slows the drop in pressure during work extraction – which is why water is the medium of choice for power plants, and not air. In the proposed design, you don’t begin to make steam until you draw vacuum on the boiler, which means that the boiler and condenser are operating at nearly the same pressure. The differential pressure across the steam engine will be practically nonexistent, and so will the power extraction.


There is another critical design flaw, which Tin Falcon pointed out – specifically:


Saturated water (212 degrees F, atmospheric pressure) contains 180.12 BTU of energy per pound mass. If you port the saturated water into an evaporation chamber, and draw a vacuum on it equal to 5 psia, here’s what will happen: Approximately 27.7% of each pound of water that enters the evaporation chamber will flash into steam. The steam will have a temperature of 162.18 degrees F, and a specific volume of 73.525 cubic feet per pound-mass.


The remaining 72.3% of each pound of liquid water that enters the evaporation chamber will reduce in temperature to 162.18 degrees F, and will remain inside the chamber. This water must go somewhere, or you’ll fill up the chamber. As designed, the liquid water will be drawn through the steam engine, with no work output.


If you port the saturated water into an evaporation chamber, and draw a vacuum on it equal to 1 psia, here’s what will happen: Approximately 61.3% of each pound of water that enters the evaporation chamber will flash into steam. The steam will have a temperature of 101.69 degrees F, and aspecific volume of 333.49 cubic feet per pound-mass.


The remaining 38.7% of each pound of liquid water that enters the evaporation chamber will reduce in temperature to 101.69 degrees F, and will remain inside the chamber. Again, this water must go somewhere, or you’ll fill up the chamber. As designed, the liquid water will be drawn through the steam engine, with no work output.


Smithdoor, whoever told you that this engine “has been in use for over 100 years” told you a lie.


Additional design consideration: the available solar flux from the sun is about 1-kw per square meter (this is for a bright sunny day). If you assume a reasonable thermodynamic efficiency for the solar panel of 40%, and a reasonable 5% thermodynamic efficiency for a piston-steam engine operating at low temperatures, you’ll require just over 37 square meters of solar panels per one mechanical horsepower out (again, that's assuming a bright sunny day). Point being - there is a reason the solar industry is failing in a disastrous fashion. :fan:

You make good sense. Am doubtful solar heaters will raise enough BTU to get reasonable steam pressure/volume to spin a small recip steam engine.

 

[SmithDoor]

The heat from the sun is 600 to over 800 watts per square yard or just under square meter. On a 2000 square foot home roof will be around 133,333 watts to 177,777 watts. source is from http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/atlas/

Dave

You make good sense. Am doubtful solar heaters will raise enough BTU to get reasonable steam pressure/volume to spin a small recip steam engine.

 

[Entropy455]

The solar industry is very successful, where countries have wholeheartedly promoted it.

The 90-billion in taxpayer dollars spent on US solar R&D was wholeheartedly invested – however the vast majority of the funds proofed into oblivion.

Solar cannot replace coal, oil, and/or nuclear - there’s simply ins't enough energy density in solar power.

Consider a hypothetical 70-horsepower all solar-powered electric car. The energy losses within the motor windings will be about 25%, and the motor’s solid-state controller (power inverter and pulse-width modulation) will suck another 7%. Thus the actual electrical power required to put 70 horsepower to the road, will be about 100 horsepower. At 746 watts per horsepower, this equates to a power requirement of about 75,000 watts to move a 70-horsepower car down the road.

Currently the most efficient mass-produced solar panels have an energy density output of approximately 140 watts per square meter (on a bright sunny day). Thus to drive a 70 horsepower car under “sun” power, you’ll need a solar panel sized 536 square meters. On a car, that would be a rectangle panel six feet wide, and 107 feet long (not possible). You’ll also need to double the cell area for driving on overcast days. And you can’t drive at night. Thus a battery system “could” be used, however now the cell area really needs to be increased in order to charge the battery while also driving the car.

The 70 horsepower number is valid. Most automobiles have much higher horsepower engines under the hood, however for steady-state driving down the road, 70-horsepower is a reasonable “average” power requirement to overcome drag forces on the freeway. When accelerating hard, a vechile can easily require several hundred horsepower.

To really drive home the point on how "not-good" solar is, let’s look at the energy requirements needed to get US cars off of gasoline (which is the ultimate goal of the green movement). There are approximately 250 million registered cars in the United States. Of those 250 million, about half are daily driven. Assume the total minutes driven each day for daily-driven cars is 40 minutes (some drive more, and some drive less – however 40 minutes is a rough, yet reasonable average approximation).

Powering half the daily driven cars (assuming they're running 70 horsepower electric motors) is equal to a power requirement of 2.6042 × 10^11 watts. On a bright sunny day, assuming a solar panel output of 140 watts per square meter, you’d need a solar panel sized 2,155 square miles – which is about 1000 square miles larger than the entire state of Rhode Island. . .

What about going nuclear to get cars off gasoline? You would have to build 261 one-thousand-mega-watt nuclear power plants to produce 2.6042 × 10^11 watts. Even if we could build 261 of these one-thousand-mega-watt reactors, the electric grid cannot route the power, nor can we produce enough batteries to store the charge.

There’s a reactor fuel supply issue also. One kilogram of U-235 will produce about 1000 mega-watts of thermal power, for 24 hours - as it undergoes nuclear fission. A typical thermodynamic efficiency for a commercial nuclear power plant, is about 25 percent - thus a 1000 mega-watt reactor plant will consume 4 kilograms of U-235 per day in producing the required thermal power for the electricity production. This means 261 reactors would consume 2297 pounds of U-235 per day, or 419.2 tons of U-235 per year, to get cars off of gasoline.

The “real” inconvenient truth is that even if we were able to build 261 new 1000 mega-watt reactor plants (which would never happen after the Japan meltdowns), we simply cannot supply the required 419.2 tons of fissionable fuel per year. Just as we cannot cover 2,155 square miles of Earth with solar cells.

Yes Germany is investing heavily in solar and wind. Yet with all their investments, coal-power continues to be their prime source of electricity. Now that Germany has killed their nuclear industry, they are importing electricity to meet their energy demands.

I studied power plant design in college. My mechanical engineering degree was heavily based on thermodynamics and machine design. I can tell you with a high degree of confidence, that there’s no such thing as a free lunch. Humans are gross energy consumers. The only viable way to reduce our current energy dependence on fossil fuels and nuclear power (without significant cuts to our current rate of energy consumption) is through undiscovered breakthroughs in fusion power - or perhaps tapping into and somehow converting gravity into electrical power - perhaps through some futuristic string-theory reactor.

My recommendation to any folks who are considering investing within solar or wind, is don’t do it. As soon as the government subsidies dry up, so will the industries. Instead I would invest in theoretical energy research. Or perhaps within companies that are perfecting technologies to scrub coal combustion byproducts.

Sunworksco, I know you don’t like reading what I posted. Nonetheless, please check my numbers, and tell me where I'm wrong. . . . ?

 

[Robsmith]

what about helium 3 ha ha ha ha

 

[tups]

Solar cannot replace coal, oil, and/or nuclear - there’s simply isn't enough energy density in solar power.

Entropy455 - I have no beef with you or your assertions, but I felt I needed to react because what you write is intellectually unfairly presented. Of course there is enough energy density in solar power to do something useful. All fossil fuel was once biomass, and solar-energy derived. That we are too lazy to extract it directly does not mean the energy is not there.

Consider a hypothetical 70-horsepower all solar-powered electric car. <snip> Thus to drive a 70 horsepower car under “sun” power, you’ll need a solar panel sized 536 square meters. On a car, that would be a rectangle panel six feet wide, and 107 feet long (not possible). You’ll also need to double the cell area for driving on overcast days. And you can’t drive at night. Thus a battery system “could” be used, however now the cell area really needs to be increased in order to charge the battery while also driving the car.

No-one asserted that you need to extract the solar power from the roof of the car while you are driving - there is no reason not to use a dedicated facility to turn solar power into electricity, and use that to charge your car ...when you're not driving it. Electricity storage, that is where the real bottleneck is, and that is what the research needs to go towards. What else is gasoline than conveniently stored (fossil) solar energy ?

To really drive home the point on how "not-good" solar is, let’s look at the energy requirements needed to get US cars off of gasoline (which is the ultimate goal of the green movement). <snip> On a bright sunny day, assuming a solar panel output of 140 watts per square meter, you’d need a solar panel sized 2,155 square miles – which is about 1000 square miles larger than the entire state of Rhode Island. . .

Have you looked at a map of the US ? Have you checked what the size of the state of Rhode Island is ? It would be feasible to put a setup approximately 10 times as big as that in the Utah/Arizona/Texas/New Mexico desert without having to disown anyone's house. Have you checked how much land agriculture uses in the US (and worldwide)? Would you classify that as unfeasible too?

I could use the exact same argument about the feasibility of driving cars in the US on gasoline - you need approximately 3 billion barrels of oil for that annually. That is, according to my back of the envelope calculation, an oil bath the size of the state of Rhode Island about 7 inches deep. Somehow that does not seem to constitute a problem at present.

nor can we produce enough batteries to store the charge.

...and *this* is what the problem is.

So what do you suggest exactly? Sit back, do nothing and sulk until someone invents a string theory reactor ? Investing in fusion on earth is a bit silly when you have a practically inexhaustible 6500K source of fission energy up in the sky from between 6 and 18 hours every day, wouldn't you say ?

Sunworksco, I know you don’t like reading what I posted. Nonetheless, please check my numbers, and tell me where I'm wrong. . . . ?

For me, the main issue is that posts such as yours, however well-intentioned and however well documented with fact, carry a constant undertone of "it can not be done", even if the figures themselves do not seem to state this so clearly as you imply. Whenever someone passionately states that something cannot be done, usually he is wrong.
The "it can not be done" undertone, or more perhaps exactly the statement "at present we do not have a solution", very often is misinterpreted as "then we do not have a problem" and used as an excuse to go for another year, or two, or ten, or twenty, with an uninsulated house and a 12 mpg car.
That is what ticks me off.

Rant over. I need to go teach now. Thermodynamics.

Cris

 

[dman]

as far as solving the energy crisis we could invest in good old steam power (created by nuclear reactors) and do what we can with solar with grid tie in inverters. if nothing else it'll ease the load in peak hours and reduce summer blackouts.

i think solar steam could work but maybe not in a low pressure system. with parabolic reflectors you can create quite high temperatures and could maybe run a turbine. as cool as a piston steam engine would be chugging away in the corner of the shop even if you got high pressure steam from sunlight lets be honest the noise would eventually get to you.

 

[SmithDoor]

Low pressure turbines was built over 100 year ago to run on the steam from the Triple expansion reciprocation engines use in power plant and ships. Before 1900 there was few quadruple reciprocation engines.

* Yes if was building a power plant that was selling the power from I would use the high pressure steam
* BUT I would not use this type in most homes as this is live steam

Keeping the temperature below 212F deg. safer than 350 F deg for home use.
I have even work on using 260 F deg. (24 psi) but still not safe for home use but would work in shops where they working 7 to 6. This cost less to keep up on the solar panels over the higher temperature systems.

I have found it hard to fine any data on the low temperature side. All the data in on oil/coal fire and how to get the most out the oil/coal

FYI try this for turbine was designed to develop about 16,000 shaft horsepower using a water temperature of only 188F deg This was build in 1914 and work for 30 years.

Dave

as far as solving the energy crisis we could invest in good old steam power (created by nuclear reactors) and do what we can with solar with grid tie in inverters. if nothing else it'll ease the load in peak hours and reduce summer blackouts.

i think solar steam could work but maybe not in a low pressure system. with parabolic reflectors you can create quite high temperatures and could maybe run a turbine. as cool as a piston steam engine would be chugging away in the corner of the shop even if you got high pressure steam from sunlight lets be honest the noise would eventually get to you.

 

[Propforward]

Hi Dave SmithDoor,

Out of interest, how big do you think your low pressure steam engine will need to be, and what will it cost to make, for you to power your shop with it?

You did say the power would be "free", of course that's only after you've shelled out the cash to make it - so what will it cost? I'm interested to see the economics and payback on it.

 

[SmithDoor]

The cost in 2009 was under $4,500 and the time build this was less than 160 hours Note this include Fab, machining all parts, piping and wiring For 5 to 10 kw use 50 gal storage tanks. This does not include disign and drafting time.

The drawing that show is after 2009 using large amounts of water for year around use. This can also be use for heating a home. This not hard where I live but on the East cost and North of CA Ever one need heat.

Try figuring how must it would cost to heat a 30,000 gal pool of water for 100 F. deg to 212 F deg. Now think of heating your home with this pool of water. What make this work is two pools of water one hot and one cold each pool would hold 30,000 gal but you pump from hot pool use the heat and returning to cold pool.

Dave

Hi Dave SmithDoor,

Out of interest, how big do you think your low pressure steam engine will need to be, and what will it cost to make, for you to power your shop with it?

You did say the power would be "free", of course that's only after you've shelled out the cash to make it - so what will it cost? I'm interested to see the economics and payback on it.

 

[Philjoe5]

Gentlemen,
I think we have come to some realization of what the word "free" may mean to some individuals.

I suggest this thread be continued at one of the many solar forums on the internet

Your friendly Moderator,
Phil

 

[Entropy455]

Getting back on topic &#8211;

The Titanic&#8217;s low pressure turbine was a great innovation. Low pressure turbines add appreciable thermodynamic efficiency to a power plant &#8211; even more so when re-heat stages are utilized.

That being said - the Titanic used 210 psi boilers which drove the first stage piston. The second stage piston saw 78 psi. The third stage piston saw 24 psi. The steam exiting the third stage piston (which was the energy source to the titanic&#8217;s low pressure turbine) was at 9 psia.

One KEY point that is being overlooked in this discussion, is that the steam source to the Titanic&#8217;s low pressure turbine (while sitting at 5.7 pounds less than atmospheric pressure), was still at a higher pressure than the condenser. Reason: the Titanic&#8217;s condenser was air-ejected, and operated at 1 psia &#8211; resulting in an 8 psig differential pressure across the low pressure turbine for work extraction.

In contrast - you cannot boil warm water from drawing a vacuum on it, and then extract mechanical power from the steam - because there&#8217;s no differential pressure driving the engine.

Respectfully, you are taking one aspect of the Titanic&#8217;s propulsion system WAY out of engineering context.

 

[Philjoe5]

Cost and Engineering covered. Good work folks!

Phil

 

[Herbiev]

I agree with Phil