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No Such Thing As A Free Lunch

Started by Dualfuel, September 30, 2013, 09:51:25 AM

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Jens

Quote from: mobile_bob on October 01, 2013, 09:37:50 AM
Sorry Jens, my point was not to ruffle feathers, or come off harsh
its just been a really bad few weeks for me

my dad had been sick for the last 2.5 weeks leading up to his sudden death last wednesday morning
then we got word the very next day that my wife's dad passed away barely 30 hours later! 

Bob, I am sorry to hear of your family situation, my sympathies!
I didn't take your comments as feather ruffling or harsh, I took it more as you working yourself up and I didn't want my casual inquiry to be the cause of that.

quinnf

Not presuming to speak for Bob, but if I know Bob, I wouldn't worry about it if I were you.  Bob likes a good scrap, and ever since GuyFawkes disappeared, he hasn't had a really formidable adversary to keep his rapier-like with finely honed. 

q.

Dualfuel

Hey Bob, I am glad you came here to get away for a bit...sorry to hear about your family. I too like to get away and sort of Ivory Tower Cogitate.

I started this thread because I realized people who get took by the geet and orgone guys, are the ones who don't know enough thermo and Mech E stuff to tell the BS from the real deal.

Why did I pick out 47% because I have a quotable source for the calculations...I am not depending on my own feeble maths skills to prove anything. If someone reading this realizes that an old flat head engine peaking out at 450psi during ignition has a theoretical upper limit of 47%, then they should be able to realize that there is no way that some Internet Salesman will be able to offer Unity or 100%.

I was really hoping to discuss how the limit was arrived at. As Jens explained, he just doesn't have the knowledge base to understand the theory behind the number. Breaking this theory down to simple terms is important, almost as important as going back to the very beginning of Internal Combustion to understand how we got where we are. Why? Because there are a lot of other ways of doing this, and for 100 years the IC engine has been adapted for road engine use, when its really best off as a stationary engine running at a constant speed. These engines now are mutated away from being efficient generator engines.  But how would anybody know, unless they had some experience with the engines that came before?
Anyhow, I'll bring some more back to this a bit later...supper is calling me...

Jens

Quote from: Dualfuel on October 01, 2013, 03:11:28 PM
I was really hoping to discuss how the limit was arrived at. As Jens explained, he just doesn't have the knowledge base to understand the theory behind the number. Breaking this theory down to simple terms is important, almost as important as going back to the very beginning of Internal Combustion to understand how we got where we are. Why? Because there are a lot of other ways of doing this, and for 100 years the IC engine has been adapted for road engine use, when its really best off as a stationary engine running at a constant speed. These engines now are mutated away from being efficient generator engines.  But how would anybody know, unless they had some experience with the engines that came before?
Anyhow, I'll bring some more back to this a bit later...supper is calling me...

Waiting in total anticipation !!!!!!!!!!!

SteveU.

#19
Well BobG my condolences.
For my Dad it was in 1987 after a two year cancer battle with me admin'ing the final meds and being the final bedsider.
Wifes Father it was a sunny September day in 2005 filing chainsaw chains for me sitting out under his front yard apple tree. Very unexpected for all. We both walked up on him thinking he was chair sleeping. Hurts for a long time either way.
Then you realize after a time, that now: TAG! You'er IT from now on. Now expected to be the family instant oldest, Wisest.

Hey BrucePJ be very interested to hear your presentation.

IC piston four stroke Ottos haven't completly all gone zillion RPM unrecognizable.
GE/Jenbachers . . . Warsila . . . . Arrow . . . . Prakash . . . . Guascor . . . . along with even Honda and a few other manufactures been pushing for the best practical real in this world useable efficiency limits on stationary gasious fueled engines.
My point here is here are named six different countries/manufactueres scattered through out the world beholding to no any one except to produce sellable results.
My no math, no theory needed examples that  IF a woo-woo tech leap forward was possible it will get snapped up and be in actual use now by some manufacturer hungy for an advantage. The practical limits of materials, fuels, heats and energies says we must all play by the same rules, limitations and posibilities.
After a steady 1950's and 60's diet of Popular Mechanics and Popular Science "hope/soap" engine/energy  solutions; and too many 70's desperate try anything and everything attemps now I just want to be Left Behind with my "boring" "conventional" IC piston Otto's engines.

Regards
Steve Unruh

"Use it up. Wear it out. Make do. Or do without."
"Trees are the Answer" to habitat, water, climate moderation, food, shelter, power, heat and light. Plant, grow, and harvest more trees. Then repeat. Trees the ultimate "no till crop". Trees THE BEST solar batteries. Now that is True sustainability.

Tom Reed

Bob, so sorry to hear of your wife and your losses. I hope both of your parents are in a better place.
Ashwamegh 6/1 - ST5 @ just over 4000 hrs
ChangChi NM195
Witte BD Generator

Tom

glort

Quote from: quinnf on October 01, 2013, 11:43:25 AM
Quote from: mobile_bob on October 01, 2013, 09:37:50 AM
[snip]

we buried dad yesterday, and my wife is due to leave for california to settle her dad's affairs this morning.  we sleep around here, but we don't seem to be getting any rest.

when it rains it pours, or so it seems
all this will pass, i am sure, but it doesn't make it any easier while one is going through this sort of thing.

i came in on here to sort of take my mind off the issues here at home and probably should have taken another avenue for escape rather than come off too sharp/harsh for the membership.

sorry guys

bob g


Um . . . shouldn't we be saying something like "sorry to hear that, Bob.  Grouse all you want to.  Considering what you've been going through, and what you ARE going through now, you're entitled."

Here.  I'll start.


Quinn



Totally agree!

I am sorry to hear of the loss of your father Bob.  I do feel for you and your wife.

I did not think you came off harsh or out of place at all! In fact I enjoyed reading your straight to the point post quite a bit.  If you think that was out of place or whatever, I say there should be a lot more of it!

Please come to the forums to let off steam all you want. Hopefully it's therapeutic for you and it's informative and beneficial from a learning POV for us!

Dualfuel

Ha Ha! Steve! a presentation? no, prolly more like a ramble.
I hope you folks reading this care enough call me if I wander off into some BS.
I like to start with pressure. Pressure is what moves the piston. Before the Otto cycle four stroke engines in the 1860s there was the Lenoir. This engine didn't compress the charge before it ignited it.
Here is a Lenoir
http://www.youtube.com/watch?v=NKmGPaUJc0o
Here is the Otto version of the atmospheric engine

http://www.youtube.com/watch?v=KmJy_BsFwcA

what was important about these engines was there was no compression ratio. So it had to move the piston on the downstroke for a bit to suck in a charge, then close the intake valve and fire the charge, building pressure to propel the piston the rest of the way on the stroke. So if you look at the math, the difference in pressure started at below atmospheric and ended up with higher pressure when the exhaust valve opened. Its backwards. The pressures are reversed, compared with what they did next, which was compress the charge before firing it.
What these were, were double acting steam engines converted to internal combustion... they used sliding "D" block valve gear, not poppet valves. Remember this was before the Corliss valve gear came along and revolutionized steam engines.
These Lenoir engines burned illuminating gas, which could have been made in gas producers, or blau gas made in benches. What it wasn't was gasoline.
As Steve or anyone else with a gas producer can tell you, the flame speed of Carbon Monoxide is pretty darn slow, even with turbulent flow.
So the fuel, and the engine together made for a very poor power producer. They just didn't produce enough cylinder pressure to make a lot of power.

Dualfuel

I ended that last post with the word Power.
one horse power is defined as a weight of 33000 lbs being lifted straight up a distance of one foot per minute. This originally came from the coal mines of Great Britain. It wasn't about horses, it was a way for Boultan and Watt to sell different sized steam engines. It was a gauge for measuring how much water could be lifted out of a mine. The original Newcomen atmospheric steam engine was about 5 horse power. Meaning it could lift 33000lbs, 5 feet in one minute. Which is about the length of its stroke.
Anyhow, the point is that horsepower represents several measurements at once, Force (or lbs), Distance, and Time. You can manipulate the units and get something more practical. The common perception of horsepower today is torque (twisting force) times angular speed (revolutions per minute). Because somebody blurts out that their lawn mower is 3 horsepower doesn't make it the same kind of power as that delivered by a 3hp hit an miss engine. The fine print on the lawnmower says it develops that 3hp while turning at 3600 rpm, while the hit an miss engine is turning at 300 rpm. To get the same number, the torque supplied at the crankshaft is roughly ten times greater on hit an miss engine. Also, the lawnmower has a light flywheel and no momentum.
Why care? Three is three right? Well lets say everything else is equal, and you have a 1500 watt belt driven generator hooked to each of these engines. Through the right pulley size you can get a constant speed out to the generator, but when a sudden load is applied to the generator, like striking a welding arc, or starting an electric motor, the high speed engine will stall, while the slow speed engine will have the torque and momentum to turn through the load and not stall. It is an amazing thing to witness, the difference between a Briggs 2 pole generator and a Onan CCK 4 pole generator, or a Kohler 4 pole. All are rated 5000 watts but only the Kohler and the Onan will allow me to mig weld.

Jens

Quote from: Dualfuel on October 01, 2013, 08:26:10 PM
Here is the Otto version of the atmospheric engine
http://www.youtube.com/watch?v=KmJy_BsFwcA

What is the stick that keeps shooting out at the top ??? That would scare the you know what out of me if I wasn't expecting it!

Dualfuel

Dear Jens,
The stick shooting out the top is a perfect example of how differently things started out...the stick is the our equivalent of the connecting rod. Below the stick, and attached to it, is piston. The piston fires its charge, shooting the stick straight up. The stick is actually a rack (from rack and pinion fame). A rack is a gear that isn't circular, but linear or straight. The rack falls down when the pressure under the piston is relieved. When the rack falls, its weight is what drives the pinions (circular gears) on the fly wheels.
I am telling you, this is such a bizarre way of doing things from our lofty perspective 150 years later but....
From where these guys were coming from...they could easily calculate this machine's horsepower....the weight was a known force, and its fall could be timed, as well as the number of times it fell per minute, and the fall was a known distance...F, L, T, all the units for figuring horse power. All they were left with was how to get that darn charge to repeatedly fire. One advantage of this engine, is that the pressure moving the piston could be constant. It was always the same weight over it, so no throttle was needed, it was always the same amount of fuel and air.  Why would this be important? Again refer to any of your lunatic friends who might be operating gas producers...I know that in my case, producer gas has basically a 1:1 ratio of air to gas...so it has a very narrow "sweet" spot, and when you are trying to dial in a new engine, its a PITA to have to continually readjust the mixture...these atmospheric engine guys didn't have to do that, they just set it once so it ran and were done with it. Again that is called Constant Volume, and it is extremely important.

Dualfuel

Constant Volume....I am hammering this because its the very fundamental concept behind IC engines. Constant Volume, Constant Pressure, and the Specific Heat of Air.
If I can prevent the reader's eyes from glazing over long enough to get this concept across, I think Bob and Steve, and all the other OverUnity haters will have a lot less trouble.
Constant Volume refers to a basic chemistry idea. Lets say we have a gallon milk jug with some gasoline and air in it. If you shake that jug hard, you will get the gasoline to vaporize or mix with the air. Premium gasoline will ignite properly at a ratio of 14 parts air to 1 part gasoline...(the ratio can vary greatly, which is why gasoline is a wonderful fuel). The idea here is that at that ratio, 14:1 in a known size container, gives you a known amount of gasoline to burn. This gasoline/air mixture is a Constant Volume. As such, it gives you a constant amount of BTUs or heat when it burns.
IC engines are called heat engines...because they convert heat into mechanical work. They do this by heating air...inside a cylinder. Its important to realize that the exhaust gases present inside a cylinder are what is actually being heated, BUT they have the same properties as air. The ability of the gases inside the cylinder to absorb heat is called Specific heat.
A watched pot never boils, and that is because to a hungry cook, water's Specific Heat is seemingly limitless. Water can absorb heat and absorb heat, it takes forever before something happens. Not so with air. Air has a low Specific Heat, so when heat is applied, it absorbs just a little, then immediately begins to raise its temperature.  When the air temperature goes up, then the movement between air particles becomes more violent, meaning the air pressure goes up. If the pressure goes up enough to overcome the resistance behind the piston, the piston moves.
So at a fundamental level, an IC engine depends on the Specific Heat of Air in order to function. If air absorbed heat like water does, we'd not have IC engines. As the air temp goes up, the specific heat of air changes, it actually can absorb more heat the hotter it gets.
So now we know for a Constant Volume of charge, we would get a known amount of heat out. We also know that the heat from that charge will cause a known pressure to be created in the cylinder. These two ideas are what we can use to understand that there is a limit to what is going to be possible to have happen inside that cylinder.

SteveU.

#27
Morning BrucePJ
Still absorbing. I'll try and be careful not to distract from your building blocks. Waiting for the next installment.

Jen's a current adaptation of this rack and pinion drive system can be seen on the Supersplit wood splitter system. You can search this up and see diagrams and videos. Opposite drive - flywheel energy into the rack ram. Interesting to see the flywheel pick up speed on Duelfuels OTTO video and the flywheel slowing down on the Supersplit. Ahh . . . with a quick 3 second cycle time I'll stick with my slower 11 second hydralic system to give hand clearing time thank you very much!

My earlier reference to the large "squish" area in a Wankle  versus IC piston; and DualFuels refernce to "quench" area is about the phenomena that air/fuels mixes will not combust/burn up next to a surface. Fuel then gets wasted, then not converted into heat, then not into pressure, then not into shaft power. One of the Primary sources of HC pollution emissions. Even this varies a lot with the actual HC fuel type, pressure and average combustion temperature over and above the physical structure of the actual engine.

Yeah. CO, carbon monoxide is a weak engine fuel needing special engine setting up. Lots of ignition advanve timing for it's reletivly slow even when compressed burning speed. And for longest time in cylinder to compensate for this slow burning then needing late, late exhaust valve opening best past actual BDC making cylinder purging difficult.
Actual hydrogen gas is effectivly weak too occuping too much in cylinder volumn crowding out needed oxegen in comparision to denser HC chained gasoline, propane or even methane.
Hydrogen is wickedly fast burning under compression, but with no guts staying power/energy like a carbon based fuel. And hydrogen burns right up along surfaces giving a lot of into the intake backfires requiring shorter opening duration and quicker intake valve closing making cylinder filling even more an issue. Hydrogen also is the easiest hotspot in cylinder pre-ignighted of all of the fuels. Have to go with colder spark plugs; remove all combustion chamber shear edge; incerase cylinder head coolant flows to keep valve edge temps down; and keep the lubricating oil carbon deposits minimized and cleaned out. Sucks as a motor fuel. Opps. No actually Blows(up). Poofgas. Watch the Hindenberg burning video. Fast. Hot. Poof. Then done. A gasoline vaporized mix lite off of that same volumn would have killed more people from it's wicked overpressure event.
Now mixed carbon monoxide and hydrogen together with some nice combustion speed modifing nitrogen is what makes actual woodgas with its also 1-4% created CH4 methane a much better useable IC four cycle engine blended fuel than a purist producer or blau flare gas.
Ha! Ha! Woodgas carried in soot is just more carbon fuel to an IC piston engine.

Regards
Steve Unruh

"Use it up. Wear it out. Make do. Or do without."
"Trees are the Answer" to habitat, water, climate moderation, food, shelter, power, heat and light. Plant, grow, and harvest more trees. Then repeat. Trees the ultimate "no till crop". Trees THE BEST solar batteries. Now that is True sustainability.


Jens

Quote from: Dualfuel on October 02, 2013, 08:33:55 AM
The piston fires its charge, shooting the stick straight up. The stick is actually a rack (from rack and pinion fame). A rack is a gear that isn't circular, but linear or straight. The rack falls down when the pressure under the piston is relieved. When the rack falls, its weight is what drives the pinions (circular gears) on the fly wheels.

I kind of figured it was a rack of some sorts but it never occurred to me that the down stroke was what transferred the power. Thanks!