The pinnacle of hot air engine performance?-1903 Essex type 1

[VincentG]

I had a long winded and detailed post typed out but it was lost, so I'll cut to the chase.

The 1903 Essex type 1 offers better performance than the seemingly impressive Ford/Philips 4-215.

The Essex is driven off the hot end, a system that is so effective, it's displacer actually lags the power piston by 90 degrees. A patent describes the flywheel turning opposite of actual, so I have to wonder if it was a surprise to even the creators. It may have been brushed off at the time as insignificant.

The single cylinder Essex(63cc) is rated at 1/40th HP, and so .3 watts per cc per atmosphere.

Due to much better displacer timing, the twin cylinder model(126cc) was rated at 1/10th HP and so .6 watts per cc per atmosphere.

The 4-215 was rated at 170HP at either 150 or 200 bar. I can't find a definitive answer, so I'll use 150 to give it and edge. Papers on the engine show a linear power increase from 50 bar to 200 bar, so I'll assume linearity down to 1 bar.

This leaves the 4-215 with 1 watt per cc per atmosphere....on hydrogen!

This paper shows huge power gains of up to 35x going from air to helium on a similar type single cylinder Beta.
https://www.academia.edu/105785131/Expl ... =110392690

The old Essex, impressive as it is, is still a thermodynamic nightmare with huge room for improvement, and if ran on a monoatomic gas it seems is already the answer for home power generation.

So how has ECE technology went downhill since 1903?

essex engine.jpg (237.19 KiB) Viewed 153 times

[jpigg55]

Lyle Peterson (MrPete222/Tubalcain of YouTube) has a 6 part series of his 1903 Essex engine here: https://www.youtube.com/playlist?list=P ... DVz6RqaHms

[Tom Booth]

I had a long winded and detailed post typed out but it was lost, so I'll cut to the chase.

The 1903 Essex type 1 offers better performance than the seemingly impressive Ford/Philips 4-215.

The Essex is driven off the hot end, a system that is so effective, it's displacer actually lags the power piston by 90 degrees.

From what I've been able to tell from watching videos of Essex engines in operation the displacer begins to move back, exposing the working fluid to the heat in the center portion of the cylinder, this occurs when the power piston is 90° from TDC, that is, half way on its way towards the center (equivalent of TDC for the power piston).

However, as the piston continues towards TDC it FOLLOWS the displacer, as it retreats towards the cold end continuing to push the working fluid towards the hot central area of the cylinder and towards the approaching piston.

This results in higher compression/pressure as the working fluid is simultaneously compressed AND heated, resulting in what you've referred to as "negative dead space" in the beta.

viewtopic.php?p=21128#p21128

By following the displacer the power piston is able to partly overlap into the displacers "dead air space" as ithe displacer retreats to the cold end.

The timing is unusual and difficult to analyze due to the unusual arrangement and linkage but I've watched several videos in slow motion and have drawn several sequential diagrams of the sequence of motions so I'm pretty certain about this, though I've never had my hands on an Essex to be 100% certain.

[matt brown]

I had a long winded and detailed post typed out but it was lost, so I'll cut to the chase.

I always use copy prior long post to avoid timeout loss (don't rely on back page).

The old Essex, impressive as it is, is still a thermodynamic nightmare with huge room for improvement, and if ran on a monoatomic gas it seems is already the answer for home power generation.

So how has ECE technology went downhill since 1903?

If nothing else, the old Essex proves that hot PP trumps cold PP, but I still favor cold PP when gamma (there's something sweet about any cold running engine LOL). When using hot PP, I favor alpha, but there's many ways to scheme an "alpha" and I lean towards basic Otto (even Tom has migrated here, but appears he can't handle Otto ECE buzz). There are many reasons why the Otto cycle dominates the ICE world, yet starry-eyed ECE fanboys have written it off as a looser cycle...

[Tom Booth]

... I lean towards basic Otto (even Tom has migrated here, but appears he can't handle Otto ECE buzz). ...

Most, pretty much all references I've seen define Otto cycle as "an internal combustion" engine cycle, so an external combustion. Otto cycle seems like a contradiction in terms.

Otto, to me means simply your standard lawnmower engine for example, which I'm quite familiar with. I just really don't have a clue what your talking about when saying ECE Otto, and I have not found any references that might clarify that, as it seems to be one of your own designations or categorizations.

For example, a Google AI blurb writes:

An Otto engine is a type of internal combustion engine that uses a spark to ignite a mixture of air and gasoline. The main difference between an external combustion engine and an internal combustion engine is the location of combustion.

Sooo... ??? No clue.

[matt brown]

So much for bogus AI...

An Otto cycle is a thermo cycle

(1) adiabatic compression
(2) constant volume heat addition
(3) adiabatic expansion
(4) constant volume heat rejection

when ICE

(1) open cycle where the working fluid is substantially ambient air
(2) INTERNAL heat addition between compression and expansion processes
via volatile fuel and spark/auto-ignition/pilot flame/hot bulb
(3) heat rejection is direct to ambient
(4) engine is commonly 2 or 4 stroke, single or multi-cylinder

when ECE

(1) open cycle where the working fluid is substantially ambient air
(2) closed cycle where the working fluid is optional
(3) semi closed cycle with LP reservoir where the working fluid is optional
(4) EXTERNAL heat addition between compression and expansion processes via whatever
(5) heat rejection is direct to ambient (similar ICE) or indirect via internal cooling
(6) rare engine scheme that usually mimes 2 stroke ICE

Your Hot Potato comes to mind...

[Tom Booth]

Do you have an Essex engine, VincentG? I thought I could see one in the background of one of your recent videos.

[VincentG]

I do. Got a great deal on one that wasn't running. Just needed a cleaning and the displacer straightened.

There's no magic to the displacer movement. It does seem to take advantage of a displacer stroke longer than the power piston stroke. So when the displacer starts moving, there's not much effect at first.

In volume ratio testing, moving the displacer by hand causes the power piston to move almost entirely its full stroke. Unfortunately the engine quickly heat soaks with no active cooling. I'd like to rig up a water cooled cold end. I don't want to do any permanent modifications to this engine. It really is beautifully made and a throw back to how things used to be.

An advantage of being driven off the hot end is that the engine starts almost instantly when heat is applied.

For certain, it would make far more power with proper water cooling and a better displacer drive mechanism.

[Tom Booth]

... Unfortunately the engine quickly heat soaks with no active cooling. I'd like to rig up a water cooled cold end. I don't want to do any permanent modifications to this engine. It really is beautifully made and a throw back to how things used to be.
...

I think the single shared cylinder contributes to the "heat soaking" a lot, through direct conduction through the engine body as the "hot" and "cold" cylinders are really one and the same.

Is the cylinder stainless, ordinary steel, cast iron or what?

I'm thinking that if the cold end of the engine could be isolated better, say, with a ceramic gap between the hot and cold, it might get better performance than with water cooling.

But, like you say, you like don't want to tamper with a historic artifact.

Maybe a temporary replacement split cylinder?

.

[VincentG]

I should have given the Essex more credit than saying it's a "thermal nightmare". While it leaves a lot to be desired, it's much better than other engines of it's time.

The power cylinder and cold end are cast iron. They are connected by a long length of .015" seamless brass tube that fits incredibly well into either end. The long displacer is also constructed of this thin seamless brass. It's a material than is nearly impossible to source today.

I had a whole parts list to construct a replacement aluminum cold end and new epoxy displacer. Instead, I'm just going to display the engine in my house and appreciate it for what it is. It has given me a lot to think about and many new ideas. Money well spent.