Author Topic: Fascination with flywheel discussion  (Read 3076 times)

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Peter-

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Fascination with flywheel discussion
« on: June 09, 2010, 01:39:00 PM »
I probably shouldn't do this, but I'm gonna anyway. I was fascinated by the recent "flywheel" discussion. I felt the need to clarify my viewpoint instead of simply giving up on it.

Here is what I have so far to work with: an older Tecumseh 5-horse in good condition, and collecting mags at the moment. Rather powerful, I already got a blood blister from 2 mags. Also some decent electonic equipment incl. a expensive DMM and a surplus scope which I had for years. I still want a scale to measure fuel weight and a non-contact (IR) thermometer.

For the most part I'm stuck with accepting a range of values from most engineering manuals, such as BTU's per gallon, etc.

I have to offer my real-world experience and commentary about this, though.
In the steel and welding shop where I worked, there was a very antique machine which basically ran on flywheel power. It would punch holes, cut and notch steel plate, etc. It was built in the late 1800's or early 1900's.

It would punch a 1 inch hole through 1/2 inch plate as fast as you could feed it. It has a cast iron flywheel 9 inches thick by 4 feet in diameter, driven by a 3-horse electric motor. It was geared down so the wheel was only at a few hundred RPM. The manufacturer advertised an 80-ton force through a 2-inch stroke length.

Nobody cared how fast it accelerated; you only had to start the machine once, in the morning. Every hole punched became cheaper to do after that. It lost perhaps less than a dozen RPM after each hole. The electric motor only had to supply enough power to keep the RPM within working range.

I apply the same idea to a stationary genset. Regardless if it's diesel or gas, I assume you want a fairly constant RPM, to be achieved with both governors and flywheels. Constant RPM for years on end equals money saved. Especially for AC. The savings are gained by not having to accelerate much except when there are peak demands. Also less "wear and tear" and not having to re-start.
This doesn't even get into re-using the "waste heat" from water jackets and exhaust.

I view it as the mechanical equivalent of large capacitors and inductors. Sure you are going to lose some due to friction or resistance. But the losses are tiny compared to what is available through something over-sized, in order to over-ride both the internal losses and the actual surges in demand. The wind and solar guys have exactly the right idea in this regard, using batteries.

A car alt on a mower engine is a whole different ball of wax: there isn't much concern for efficiency there, but rather dump a bunch of power ASAP.

Overall, I do not deny that it's gonna cost you and energy isn't free; rather I argue that such things could be *way* more efficient, and IMHO a heavy flywheel and engine governor is the way to go for constant-speed applications.

TomW

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Re: Fascination with flywheel discussion
« Reply #1 on: June 09, 2010, 04:50:13 PM »
Well, you are right. You shouldn't do this.Why split the thread?

It just makes following it hard for future interested parties.

Please go there to discuss this.

Thread is locked.

Tom