What is a Diesel Engine ?

[Roger B]

A bit more information on hot bulb engines. The adjustable spray nozzle was fitted to the Lanz Bulldog and as rolphill says it was used to adjust the combustion conditions between light loads when a narrow spray was injected into the hot bulb and heavy loads when a wider spray was spread around the combustion chamber.

I have a couple of descriptions of the operating cycle, one from the Lanz with some useful numbers in which I have roughly translated and one from Hiscox’s book. There are PDFs of various editions of this book on the internet.

The Lanz document:
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A complete working cycle of the Lanz Hotbulb Engine requires one revolution of the crankshaft.

First Stroke:

The piston is forwards (it is a horizontal tractor engine) and the fuel air mixture ignites. Due to the expansion of the burning gasses the piston is driven back. The exhaust ports are then uncovered followed shortly by the inlet ports. The burnt gasses pass via the exhaust ports into the exhaust pipe. Due to the backwards travel of the piston the fresh air in the crankcase is compressed into the transfer pipe and then into the combustion chamber where it drives the remaining gasses out.

Second Stroke:

The forward motion of the piston closes first the inlet ports and then the exhaust ports. At this point the fuel is injected into the hot bulb where due to the lack of air it starts to vapourise. The piston now compresses the air into the combustion chamber where the mixture is once again ignited. Due to the forwards motion of the piston fresh air is drawn into the crankcase.

The crankcase is sealed. The air can only enter via the air filter and inlet valve (reed valve). The valves stops the air being blown back out when the piston starts to return and the volume is reduced. This results in an overpressure of between 0.2 and 0.4 bar which pushes the air into the combustion chamber when the inlet ports open.

The compression ratio is between 5-1 and 6.5 -1 depending on the swept volume (I think that it means combustion chamber). The fuel injection takes place around 120° to 135° before top dead centre.
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The picture in the Lanz document is a fuel preheater for highly viscous fuels like tar oils, It is attached to the water cooling system.

 

[rolphill]

I never reached the point of actually making algae biodiesel. I would've started with a little hand crank algae press and a few kiddie pools. I did like the idea of a biodiesel powered boat that putters around collecting algae. The local lake is very algae heavy.

The dimensions of the hot bulb were simply based on the limits of easy machining and what "seemed right".

You guys are gonna make me make a bulb for my big engine and try again, aren't you?

 

[The Ignoble Troll]

Sounds like a long tank, low and slow feed of clean water one end to flow out the top surface - maybe with a roller to collect the algae - at the other end? I assume the water is oxygenated by the algae? - So would CO2 bubbling at the input help provide the "carbon" for making hydrocarbons using sunlight? A form of Biological sequestration?
What a weird subject I didn't know existed! And you are making a model of an "industrial process"...
Thanks for posting that!
K2

With the cladophora species, they are filament forming, so I just wound them up from a tank and let air dry on a spool.

The cellulose is so high grade that they can make batteries out of it, it's basically the silk of natural cellulose sources.

 

[The Ignoble Troll]

I never reached the point of actually making algae biodiesel. I would've started with a little hand crank algae press and a few kiddie pools. I did like the idea of a biodiesel powered boat that putters around collecting algae. The local lake is very algae heavy.

The dimensions of the hot bulb were simply based on the limits of easy machining and what "seemed right".

You guys are gonna make me make a bulb for my big engine and try again, aren't you?

Heck yes!

And if you use methanol and heptane for the soxhlet, you could probably use the extract straight as fuel without vacuum distilling out the solvents.

 

[Nerd1000]

Another 'relative' of the diesel to look at is the Hesselman engine. Has a low compression ratio (7:1 or so) and spark ignition, runs on oil. Fuel is injected a bit before the end of the compression stroke, and ignited by the spark timed to fire as the fuel cloud from the injector passes by.

 

[GreenTwin]

Another 'relative' of the diesel to look at is the Hesselman engine. Has a low compression ratio (7:1 or so) and spark ignition, runs on oil. Fuel is injected a bit before the end of the compression stroke, and ignited by the spark timed to fire as the fuel cloud from the injector passes by.

Interesting concept.

https://www.wehs.net/hesselman.html

.

 

[Roger B]

The 5 cylinder swash plate Hulsebos Hesselman engine is on my build last for when I have finished the Junkers CLM and the Saurer Doppelphaeton engines. I will probably never get round to it
I have attached a PDF of a Hesselman brochure.

 

[The Ignoble Troll]

Love swash and wobble plate engines.

 

[Klrskies]

Another 'relative' of the diesel to look at is the Hesselman engine. Has a low compression ratio (7:1 or so) and spark ignition, runs on oil. Fuel is injected a bit before the end of the compression stroke, and ignited by the spark timed to fire as the fuel cloud from the injector passes by.

I wonder what the fuel efficiencies are on these semi-diesels' vs a true diesel? I'm guessing that's why they faded from use.

 

[The Ignoble Troll]

I wonder what the fuel efficiencies are on these semi-diesels' vs a true diesel? I'm guessing that's why they faded from use.

Efficiency is proportional to compression ratios, so not great. That's why flat heads gave way to overhead valves. Less wasted combustion space.

 

[GreenTwin]

I have mentioned before, but I had a John Deere model "H" tractor, and it had two gas tanks; a large one and a small one.
The small one was about 1 gallon, and that was for gasoline.
The larger tank was for either kerosene or perhaps diesel fuel (kerosene was probably what was readily available back in the day on the farm).

My dad explained about the gas/diesel, and so I started the deere on gasoline, got it hot, and then switched the valve to diesel.
The tractor ran fine at full throttle on diesel, with no noticeable smoke or power loss, but would not idle on diesel.

So for a low compression gasoline-designed engine, it would seem that many (most ?) could run on kerosene or perhaps diesel ? without any modifications at all.

I guess one could try it with a lawnmower, weed eater, motorcycle, etc. if you could figure out how to switch the fuel from one tank to another while the engine was running fast.

Not sure about carbon buildup when running on kero/diesel.
I have read that the small one-cylinder Lister diesels have to be "de-carboned" every so often.

.

 

[The Ignoble Troll]

I have mentioned before, but I had a John Deere model "H" tractor, and it had two gas tanks; a large one and a small one.
The small one was about 1 gallon, and that was for gasoline.
The larger tank was for either kerosene or perhaps diesel fuel (kerosene was probably what was readily available back in the day on the farm).

My dad explained about the gas/diesel, and so I started the deere on gasoline, got it hot, and then switched the valve to diesel.
The tractor ran fine at full throttle on diesel, with no noticeable smoke or power loss, but would not idle on diesel.

So for a low compression gasoline-designed engine, it would seem that many (most ?) could run on kerosene or perhaps diesel ? without any modifications at all.

I guess one could try it with a lawnmower, weed eater, motorcycle, etc. if you could figure out how to switch the fuel from one tank to another while the engine was running fast.

Not sure about carbon buildup when running on kero/diesel.
I have read that the small one-cylinder Lister diesels have to be "de-carboned" every so often.

.

I used to switch my old flat head tecumseh to 75% kerosene once it was hot. Ran better then on straight gas, no carbon. Much more power, wouldn't bog down in heavy grass.

 

[Hopper]

My grandfather ran his 1923 Harley-Davidson on kerosene when petrol was rationed in Australia during World War 2. The bike had two sections in the gas tank with two petcocks, a main filled with kerosene and a smaller reserve section that was filled with petrol. He used to start it and run on petrol until the engine was hot, then switch to kerosene. Apparently it ran just fine. The old bike had an inlet-over-exhaust valve engine (aka pocket valve) with only about 4 to 1 compression standard.

On longer trips to the family fishing shack at the coast, they would switch back to petrol when passing through small towns so the local cop could not smell that they were burning kerosene, which was illegal under rationing rules.

The kerosene was a special "power kerosene" made specially for use in tractors of the time and was supposed to be used only for agricultural work under the rationing rules. So it was a bit different from regular heating or lighting kerosene burned in stoves and lamps.

 

[Steamchick]

Add a few % of Xylene to make ignition easier/reliable. Likely to be additive to make "power kerosene". You also need some lubricating oil (>5%?.). Otherwise the kerosene will wash away any lubricant and rapidly wear the fine clearances in pumps and injectors ...and corrosion inhibitors help as there is microscopic water in suspension in the base oil that causes rusting.... etc. Microscopic particles of rust that develop while the engine is stopped and cold rapidly wear the pump and injectors.
All I remember from 1990...
K2

 

[GreenTwin]

I recall being involved in adding 3 generators to a 20MW bank, and the this particular cogen installation happened to be located adjacent to an airport.
The operators got the idea that since they purchased bulk JetA at a low price, they could use it to power their diesel generators.
They quickly ruined 20MW worth of generators (10 total) because the jet fuel was too "dry".

They rebuilt the engines at a huge cost, and changed back to diesel.

Diesel is quite oily, and it tends to be a bit messy to handle, but not nearly as bad as waste oil, which is oily and contains some toxic materials.

.

 

[The Ignoble Troll]

I recall being involved in adding 3 generators to a 20MW bank, and the this particular cogen installation happened to be located adjacent to an airport.
The operators got the idea that since they purchased bulk JetA at a low price, they could use it to power their diesel generators.
They quickly ruined 20MW worth of generators (10 total) because the jet fuel was too "dry".

They rebuilt the engines at a huge cost, and changed back to diesel.

Diesel is quite oily, and it tends to be a bit messy to handle, but not nearly as bad as waste oil, which is oily and contains some toxic materials.

.

To add, Diesel is classified as a hydraulic fluid with lubercation properties and a much lower particulate load then most other fuels.

Poor generators.

 

[NapierDeltic]

min. 8.+ ....
There is translation available, selectable in various languages

https://en.wikipedia.org/wiki/Tatra_813

Diesels using spark ignition, Diesels using gasoline, gas engines using diesel fuel ... lots of fun!