Making Steam

January 10th, 2011

I’m taking advantage of being snowed in by working on a project. Specifically, I had an idea for a tankless steam engine. Instead of boiling the water in the reservoir, I want to boil the water in the tube on the way out of the tank. The idea is that it would have a faster startup and response to heat changes.

So, I got a 5-gallon bucket, some soft copper tubing, fittings, and a single-burner propane stove intended for camping use. I bent the tube into a coil and plumbed it into the bottom of the bucket via a needle valve for flow control.

What I thought would happen is: the coil gets heated above the boiling point of water. Then, when the water flows, it converts to steam and blows out the other end of the tube.

What actually happens depends on whether the water is flowing when the burner is lit. If the water is flowing, then it never converts to steam no matter what the pipe temperature is. If the water is not flowing, then when I do open the valve, it spits steam but never establishes a solid flow.

Okay, the flow-first problem is probably that residence time isn’t long enough to boil the water. Which means I need a longer tube and/or lower flow.

The no-flow problem must be that the first bit of water flashes to steam and the resulting back-pressure keeps more water from entering. But I would expect a continuous flow of steam even in that event.

Dang, I was hoping I’d figure out how to make it work by the time I got done explaining the trouble.

UPDATE:  Gravity plays rather a larger role in the process than I had originally assumed.  By orienting the water coil such that the outlet  is higher than the inlet, I have been able to generate steam at the outlet, as desired.  At this point, I was also able to determine that ambient-pressure steam is less energetic than I had hoped.   This must be why pressurized boilers were all the rage in their heyday.  Obviously, by allowing the steam to escape to the atmosphere, I am giving up any expansion work I might hope to extract from it.  If I could measure the pressure within the outlet tube, I could determine whether this line of inquiry is worthy of further pursuit, or a more standard boiler is in my interest.

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This Is Me Thinking

December 1st, 2010

I’m writing a computer game (no big surprise) which requires a detailed and naturalistic landscape. I like to make these sorts of things randomly generated. An important aspect of the terrain is where the water is.
I’m using a fractal heightmap generator, which works great. It produces, as is quite reasonable, local minima. In other words, there are lots of spots on the map that are lower than every point surrounding it. Which is great, until I start pouring water over the map.
It goes like this: put a drop of water on a point on the map. Find which adjacent point has the lowest height, and move the drop of water to that point. Repeat until you hit sea level. Then do the next point.
The first problem is obvious: if the water rolls into a local minimum, it’s going to stay there and never reach sea level. My fix was equally obvious: in this case, find the lowest adjacent point surrounding the minimum, drop its height to slightly less than the minimum, and move the water there.
The resulting problem took a little longer for me to understand. Sometimes, after reducing the point’s height, that point becomes a local minimum. So, it looks around as described above, and winds up picking the point that the water came from in the first place. So it goes back to there, and digs a little deeper into the ground. And back and forth, drilling straight down to sea level.
Okay, so don’t allow it to pick a point that’s already been used. But then there’s a problem when Drop 2 finds its way to the path previously cut by Drop 1. Eventually, enough paths are laid down that no step is possible without intersecting a previous path. Which would be a great place to stop moving Drop 2 except that it might also intersect its own path.
Okay, so instead of digging out the adjacent point, fill in the minimum until it’s higher than something else. That runs the risk of invalidating its selection in the first place.
Okay, adjust the terrain map so there are no local minima before running the water. That’s cheating.
Okay, fill in the minimum with water, making a little pond, spreading out until you find a spot or spots where it over flows, and proceed from there. That has the merit of being something I haven’t tried yet. Or, finding the rim of the “bowl” (local maxima) and cutting a path to the lowest of those. Or, go over the rim to find a spot naturally lower than the current point, and dig a path to there. The problem with all these ideas is that it breaks the “from Point A to Point A+Delta” system I already have developed by dealing with a whole batch of points in one go.
This isn’t even the complex part of the game.

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Math Is Angrifying

October 6th, 2010

I’m trying to figure out these things called quaternions. It’s a mathematical structure that, in a nutshell, allows unfettered rotation calculations to be done in 3D space. If you want to turn to your left, you put in “Turn left” and quaternions figure out that you’re already upside down and sideways and so it needs to rotate you along axis Blah so that, as far as you’re concerned, you turn left.

I’ve taken a lot of math classes in my life. I’ve done matrix math by hand and written programs to do them by computer. The concepts are not beyond me.

I’m relying on the internet for my research, because all my books are in the other room. I’ve read the theory, I’ve gone over all the math described in Wikipedia, I’ve found Java data structures to hold all these numbers.

The one thing I can’t find is simple. Given rotations around the x, y, and z axes, how do I convert those angles into a quaternion thingy? Every single explanation I find seems to gloss over that step, or talks about a set of three angles relative to the object being rotated (as in, once you turn it on the x, y and z aren’t pointing the same direction anymore).

It’s all very frustrating and makes me feel stupid. Me!

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Herr Doktor’s Journal

April 12th, 2010

In my continued efforts to develop an alternative method of flight, I recently ran into a setback involving my inability to construct an appropriate air-moving device using my go-to materials of foam-core and balsa wood. I created a spreadsheet to perform a sort of finite element analysis-slash-faux integration of my intended propulsion mechanism, the result of which indicated a frankly ridiculous amount of lift on a particular moving surface, enough lift that I must assume I made an error in my calculations, or perhaps the underlying assumptions, despite my inability to locate such an error.

These two events led me to pursue a different line of inquiry, using, rather than moving air, a moving surface. Construction is much simpler. However, I think my materials are still too heavy and my motor too weak.

Which leads me to another thing I don’t believe. I went to the local RC hobby store with a mind to finding both a better power to weight ratio and a hands-off control scheme. The man there told me that the little airplane motor he was bouncing in one hand was a 1 horsepower motor. To my mind, a 1 HP motor is about the size of my head and several times as heavy. I know it’s a neodymium motor, which needs much less magnet mass, but that just seems unreal.

Also, I have finally been able to define a psychological block within myself when it comes to the pursuit of cool things. The less sure I am that it’ll work, the more reluctant I am to spend money on it. This one factor explains much of the stress I feel and my desire to plan and/or calculate everything before I start anything. Maybe not a grand revelation, but personally quite interesting.

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An Open Letter

April 7th, 2010

Nephew,

I understand you’ve been thinking about the nature of reality and purpose of existence, and thought you might find it helpful to read my opinions on the matter.

There are three main schools of thought regarding the basis of reality and how and why everything happens. They are: magic, science, and religion.

Magic we can dispose of quickly. If the universe operated based on magic, there would be no consistency. Reality would bend to the will of whomever wanted it the most. Everyone would get everything they want all the time, unless someone is actively opposing them. Or, magic is so difficult, and its results so minimal and unpredictable, that it could almost never be considered to work at all. Which leaves us trying to explain everything that magic doesn’t.

That leaves us with science and religion. The basic idea of science is that we can observe the world around us, notice causes and effects, and predict future effects based on those observations. Science tests ideas, and accepts only those that can be proven true. It can be very unsatisfying, because it can be very slow to determine and accept new facts, and even those facts are known to be, at best, approximations that can be disproven tomorrow if some new discovery invalidates it. There’s a lot of arguing and disagreement, and no one accepts anyone else’s word for anything. At any given moment, the sum total of scientific knowledge can be considered humanity’s best guess as to how the universe works, which makes it really discouraging when you want to know the reason and purpose of everything. No one knows how to test for it yet.

Religions of all sorts boil down to one basic idea: God did it. Or, a god did it, or a bunch of gods did it. In any case, it’s the easy answer to all questions. Why is the sky blue? God did it. Why did this rotten thing happen? God has a plan. What happens after we die? God takes care of it. I’m not saying it’s the right answer, or even a good answer, but it does cover a lot of territory. Except it isn’t really an answer; it’s what logicians call an “appeal to authority.” This omniscient, omnipotent thing that loves you is taking care of it, so don’t worry about it. It also stops all questions. God did it. How? He’s God; he can do that. If you can honestly accept “God did it” as the answer that makes everything okay, it’ll make you feel good, but it doesn’t tend to lead to further investigation. It’s like knowing your Dad is there to take care of you, except Dad lives in the sky and makes lightning. It’s comfortable.

Obviously, I come down on the side of science. I can’t honestly say we’re here for any particular purpose. We exist; that’s all I need. I can’t say there’s anything after death. In fact, I seriously doubt it. But I am willing to be wrong, and must admit there are times I kind of like the idea. But I’m not willing to base my life on the hope that I’ll get a prize when it’s over. It doesn’t mean I’m not moral; it does mean my morality is not based on the fear of eternal punishment, but rather on the idea of minimizing the pain I cause others here and now, because I want to live in the sort of world where everyone acts like I do.

Did any of that make sense?

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This Is Both Confusing, And Math

April 2nd, 2010

It finally occurred to me to look up the equations for stress in a rotating disk instead of trying to work them out myself, which I’ve obviously been out of college too long to be able to do anymore. Of course I found them, along with evidence that I’d looked for them previously, which is odd but irrelevant.

Short course in mechanics of materials: you apply force to a material, it deforms (bends, stretches, whatever). This leads to internal forces in the material, which we call stress. The amount of stress depends on the cross-sectional area of the material in the direction of the force. Any material can only take a certain amount of stress before it breaks.

So, the general idea is to figure out how much force you want to put on an object, and then figure out how beefy you have to make it so it can survive the resulting stress. That’s called engineering.

Anyhoo. These equations I’ve got have variables for material density, rotational speed, and more radii than you can shake a slide rule at. There’s one for stress in the radial direction, and one for the tangential direction. It all makes prefect sense.

Except there’s no thickness variable. There’s an assumption that thickness is much less than diameter, which means you don’t have to worry about stress on the surface versus stress in the center. But according to these equations, it doesn’t matter how thick the disk is; 1/16″ or 1″, the stress will be the same, if the diameter is relatively huge.

Which makes sense for a rotating disk. If it’s thicker, then the new material is also rotating and having to deal with its own stuff, so it can’t help reduce the overall stress level in the way that making a column thicker would help hold up the building better.

Which means this does me no good in determining how thick I need to make my disks. Or, looked at the other way, I can make them as thin as I want as long as they’re still stiff enough not to flutter in the breeze.

Oh, I never told you why I want rotating disks, did I? Hmm, weird.

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Shouting At My Congressman Is Becoming A Habit

March 14th, 2010

My letter to Parker Griffith:

Under no circumstances are you to allow the Democratic majority to pass the “Slaughter Solution” which would let the House declare a bill passed without your having voted on it. It goes against every principle that representative democracy is founded upon. In fact, it would signal the end of representative democracy within the halls of Congress.

I’m not just asking you to vote against it. Put a stop to it. Be a politician. Persuade people. Make everyone understand that the Republicans will use the same tactic to cram through the bills most offensive to the Democrats when they regain the majority, if that’s what it takes.

Even if I were an ardent supporter of ObamaCare, I would still oppose this attempted coup. The principle is more important than any policy issue.

I can’t promise I will vote for you if you manage to block the Slaughter solution, but if you agree to abandon the legislative process, I can promise that you, and as many of your colleagues as electorially possible, will be out of a job come November. Assuming you don’t “deem” a Constitutional amendment extending your terms indefinitely.

And the aftermath:

I am extremely disappointed in the results of tonight’s vote on ObamaCare.  Congress failed to listen to us, the People.  You acted against our strongly expressed desires to such extent that you can no longer be considered representative of us.

Until ObamaCare is repealed or overturned, the only thing I want you to do is obstruct.  I don’t care if you pass another bill, ever.  Require all bills to be read aloud.  Don’t allow anything to be done by unanimous consent.  Whatever you have to do.

If Congress is not going to act on behalf of the country, I want you to make sure it does as little as possible.

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Programming Note

February 22nd, 2010

The pharmacy gave me lispro insulin instead of my usual 75/25, and I didn’t realize until after I took my shot. So I’ve got about 4 times as much insulin as usual trying to counteract my supper. I’m not sure I have enough sugar in my larder for this circumstance.

If I don’t post an update to this by about noon tomorrow, I’d appreciate it if someone would call 911.

12:52 AM:  So far, so good.  One crisis passed.  Stay tuned.  Rest assured Wal-Mart will hear of this.  I’m kind of afraid to go to sleep.

UPDATE:  The alert is hereby canceled.  I feel like crap, but I’m good.  Thank you for your participation in this really inappropriate use of internet resources.

UPDATE:  And… I am appeased.  The lesson for today, kids, is this: always talk to the manager.  The rank and file have neither the authority nor the inclination to keep you happy.  Also, make sure your doctor writes down the same drugs he actually wants you to take.  Also also, trust no one who cares less than you do.  Or who cares as much as you do about something different.

That last one isn’t really relevant, but I think it’s good advice anyway.

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Success!

February 13th, 2010

I just finished building a working by-God Van de Graaff generator. It produced sparks I could feel, and in darkness see.

Granted, the range of those sparks was maybe 1/32 of an inch, and I only got a half dozen of them before a flaw in my dielectric belt caused the whole thing to freeze up.

But that’s beside the point. I did it. I solved the major design problems and was able to put together a machine that achieved its purpose. And that’s awesome.

Now I need to come up with a way to keep polyester ribbon from fraying itself to oblivion under stress….

UPDATE:  By changing to a latex rubber belt, I managed to correct the self-destructing belt problem.  Woo!  Unfortunately, the belt now has a strong tendency to crawl to the end of the upper roller, up the little flange on the end, and hang out there.  Surprisingly, it still works, with an arc length of maybe 1/4 inch, but not as well as it could.  I need to put either a hump or a divot in the middle of the roller.  A hump would do better at keeping the belt flat, I think.

UPDATE 2:  The hump on the roller worked.  The power is now mine to command.  Mwa ha ha and so forth.

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Eighteen Billion Dollars

January 29th, 2010

That is the entirety of NASA’s 2009 budget. The return-to-the-moon budget was between 1 and 3 billion. By canceling the lunar return program, the feckless fucktard occupying the White House has saved the American taxpayer precisely jack shit.

$3,000,000,000 / 300,000,000 people = $10 / person. 2.7 cents per day, over the course of one year. Or, we could go to the God damned moon.

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