Post by Uncle Buddy on Jan 15, 2021 0:30:52 GMT -8
Mean effective pressure or m.e.p. is the real--i.e. average--pressure created through the whole stroke as I understand it.
So you're hypothesizing that Neal's compressor put 50 psig into the delivery pipe so that the m.e.p. through the compression stroke was 15 psig average resistance.
And then to get the 50 psi into a 140-225 psi tank he needed a secret valve, the equalizer or something so secret he left it out of the patent. Or else so well known he couldn't patent it so why not leave it out of the patent instead of giving away the real secret that he knew about putting low pressure air into a high pressure tank.
Do you think the two sides of the piston worked differently?
Yes, I think so. Otherwise, why would Neal have used different valves?
To my mind, that big old valve on top must have a special function.
(I)f the check valve had a strong spring on it, the air would wait and enter only when a partial vacuum was inside the cylinder. It would thus be refrigerated.
The two likely options for "special" springs would be weak and strong. A weak spring would merely open the valve faster or more completely, but as you've pointed out, air doesn't need much help to push its way into a cylinder with a receding piston.
On the other hand, a strong spring would indeed work as you say, and I believe you've got it right about refrigeration.
I believe that if you lower the pressure by 10 psi you're going to lower the temperature dramatically.
According to the formula from Compressed Air Power Secrets, room temperature ambient air (70of, 15 psia) pulled down to 5 psia will drop to -73of. If you could get to 2 psia, it would be -160of.
(I)f you refrigerate the inside of the cylinder, you'll be refrigerating the cylinder walls also.
Discussion about Neal compressor inlet valve delay. Here are some thoughts which I think are accurate, but needs more discussion. Neal's machine needs to conserve energy, I believe the correct way to analyze is to account for all energy. Looking at Simons page 32. As piston begins to move, the backside is being expanded because inlet valve is still closed. With adiabatic formulas, both compression and expansion are the same so far as work requirements. Work=Energy. On Simons graph, let's say the inlet valve finally opens where the narrow vertical PV line is, halfway up the compression curve. Then there will be a shaded area beginning at A and curving downward until it meets that vertical line where the inlet valve finally opens. This is increased energy required of the compressor piston, early in the compression stroke. After valve opens, the inrushing air enters a cold cylinder at backside of piston, which will help to remove heat of compression, which saves some energy. But, there was an energy cost to hold that inlet valve closed to draw the vacuum. So, it makes me wonder if, in the end, there will be any energy savings by this method? Discussion?
ALTERNATE EXPLANATION from NEAL patent. * * * At #1, the pressure from news articles was sometimes 135 and sometimes 150 psi.
I definitely agree that there is some confusion about the details of Neal's machines. Actually, that is one of the reasons for starting this thread. The 1940 news article gives a specific information about the Model 39 which helps distinguish it from the earlier 16 cylinder model that was the subject of the patent.
When it comes to the patented model, though, I think the historical record is consistent that Neal represented the storage tank pressure associated with his 16 cylinder model to be at least 200 psi. First, we have the patent itself in which Neal clearly discloses the tank pressure:
"The storage tank 7 with the equalizer is so constructed that it is possible to pump air into the said tank with a tank pressure of two hundred pounds, while the compressors are only pumping against fifteen pounds or atmospheric pressure."
Secondly, newspaper reports published contemporaneously with Neal's filing of his application with the patent office on January 9, 1934 also relay a tank pressure of at least 200 pounds:
1. The Arkansas Gazette (2/14/1934): "with a tank pressure of 200 pounds." 2. The Hope Star (2/14/1934): "a tank pressure of 225 may be maintained."
Finally, after Neal was issued his patent on February 11, 1936, we have The Arkansas Gazette again reporting, on 2/21/1936, "a tank pressure of 200 pounds."
It's true that the 1988 interview with Neal's son mentions a tank pressure of 140 to 150 pounds, but that comes immediately after the discussing the Model 39. The Camden News article from 5/30/1940 posted in this thread seems to confirm that the tank pressure for the Model 39 was, indeed, 150 pounds.
The part we have not discussed is the missing step of going from 50 psig to 135 psig, that is where the "secret valve" comes into the picture.
Thank You Renny, great content in posts with the attachments! The rewording is exactly the type of feedback that is needed for a forum like this to make forward progress. I must be honest that was having doubts about the forum since discussions and feedback are not happening. Have some bombshell discussions about Neal regarding the connections at the cylinders. Was not sure about posting if only for lurkers to steal and run. But if there is positive collaboration happening, then I receive helpful feedback in which case the benefit is worth the cost of releasing valuable discoveries about Neal. This will take a few posts to explain completely but all the math is what you have already gone through in your attachments. Thanks for the explanation to clear up the 200 lbs versus 135. This helps a lot with what I will shortly be posting. Please keep connected and provide as much feedback as possible. Hoping other readers will join as well. Even if to say it is not understood or sounds like BS, need to hear that if that is the case. When the only communications is by post, do not know what is the level of understanding of readers, unless as you have done, it is reworded in their own words. This extra effort really pays off in clearing things in one's own mind. I have said many times before, the only times I make progress on this, is when engaged in active dialogs. Left alone my progress always slows down to a crawl. You will definitely value what I will be posting in a couple of posts, and there is no high-power math in it. Can see The Unc drooling right now.
Thank You Renny, great content in posts with the attachments!
No problem, Tommy. Your alternate explanation for what Neal may have meant by pumping against atmospheric pressure is intriguing. Still mulling over the implications of the compression cylinders discharging less volume, but at a higher pressure, into the system.
Thanks for the explanation to clear up the 200 lbs versus 135. This helps a lot with what I will shortly be posting.
It seems the best that can be done based on available information. There is always the danger that something may have been misreported somewhere along the way. But since the information made its way into his patent, it *should* be pretty reliable unless Neal himself was mistaken for some inexplicable reason. IMO, though, even a machine compressing free air to "only" 135 psi would still be pretty darn impressive.
Please keep connected and provide as much feedback as possible.
I don't mind pitching in if I can help. Just have to find a way to keep that pesky "real life" from intruding!
Neal's patent shows two rows of cylinders, separated by 60 degrees. The crankshaft pins evenly distribute the firing order of the cylinders, whether motor or compression. Since the cylinders are double acting, they repeat every 180 degrees. With the 60 degree spacing, this creates the capacity for total of three rows of cylinders. It is not easily possible to build the block with three rows of cylinders, but the crankshaft timing was originally designed for even distribution of three banks of cylinders.
Studying the patent figures, I would say these drawings are professionally made, for 1934 era. Most patents only include a schematic overview. Leads to thinking the patent submission drawings are a small part of a larger set of complete drawings for the compressor. Neal was a shoe repairman, would not have the expertise to produce drawings like these, and would not have the funds to hire it out. So where did the prints originate?
Looking closely at the machine construction, I believe this machine was professionally designed. It is not a commercial design, but instead is a professionally designed demonstration machine. A designer would need to first build a demonstration machine, and then gather investors or find a buyer to make the next big move up to commercial production. Neal owned a shoe repair shop, so what was the source for the professional design work? Who would fabricate the crankshaft?
Why has nobody fabricated a copy of Neal's compressor? Because it is too expensive in time and money, unless having full prior knowledge of the working principle. Just imagine how expensive it would be 90 years earlier from today?
The Unc has long speculated that Kiser may have bequeathed his work to Neal. This is certainly possible. The kidnapping of Neal's daughter may have resulted in Neal losing possession to the compressor machine. The early 30's was a lawless time, gangsters like Dillinger, Bonnie & Clyde, the Lindburgh baby kidnapping. The Germans also travelled the world collecting technology at this same time. There are several possible suspects for the kidnapping.
After losing the original machine, did Neal attempt to use his set of prints to build the Model 39 using a recycled engine block? The Model 39 was a single bank of cylinders.
Many years later, Neal generated a new patent, for a women's moccasin shoe. Why? Because he had experience getting a patent, he learned how to do that several years earlier with the air compressor.
We have not found any historical evidence of Neal producing manifestations of different air running devices for whatever purpose, in the many years following the patent. Surely there are many possibilities for spin-off devices from the original concept. Why? The answer is because Neal did not possess the depth of knowledge on the subject, necessary for the spin-off concepts. This leads to the scenario that Neal received the original air compressor after it had been previously designed. Historical records do show that Kiser had connections with the university level engineering world.
On Neal's figure 1, notice where the tank supply air pipe enters the motor cylinder. There is shown a small rectangular block just next to the heater. This block is the end of the slide valve. When the machine is running, the slide valve will protude outward and inward during the cycle, by about 1/2 inches either way. Seems like this would produce a lot of rattling noise. Also seems like there would be air leakage around the slide valve. I wonder how much air leakage?
Also notice this is a small inline heater, the temperature rise will be small, not large here. It depends on the machine rpms. For this and several other reasons, I think the rpms will be low, around 100.
Post by Uncle Buddy on Feb 25, 2021 23:15:31 GMT -8
Tommy, according to your recent text documents, this is what I think you're saying. The two engine cylinders run at full pressure and exhaust not to atmosphere but to supply the lower end of the compressor cylinders which are really motor cylinders. These are expansive and their job is to compress the air that's taken into the top end of the compressor cylinder. Then crankshaft work pushes the expanded air out of the bottom end of the compressor cylinder into the tank supply pipe. Everything's attached to the same crankshaft but in this way the crankshaft doesn't have to run the compressor because the first stage engine exhaust runs the compressor. The 15 psi resistance mentioned in the patent is the mean effective pressure in the tank supply pipe. The gauge pressure of the tank supply pipe is not 15 psi but maybe 100 psi. Neal's secret valve has to be inserted to raise the pressure from 100 to 200 psi so the air will go into the tank.
If what I said above is correct, then the question is, what runs the secret valve, which I assume is going to be a pulsed injector? Or have you lost the injector?