Advanced tech without electricity/internal combustion?

alj_sf wrote:

Thucydides wrote:...
Stirling engines are still niche players (primarily used for AIP rigs on conventional submarines), but perhaps economic considerations might change to the extent that Stirling engines can move into other niches.
...

Early Stirlings had indeed bad power/mass ratios because of lack of low-friction seals allowing to pressurize them at least 5 bars. This is a solved problem.

Modern Stirlings with 10/12 bars internal pressure are quite good, but the IC tech is so developed everywhere that it is much cheaper to produce. Stirlings are also the most efficient engine possible.

The main use nowadays of stirlings is for cryo generation (used as motor) or as generators either in solar applications or cogeneration. There is a renewed interest for small stirlings (a few cc) where IC and diesel are very inefficient.

In Safehold case, IC is no go because of the electrical problem, and if Diesel can be made without, you have launch problems. Stirlings on the other hand, can replace any steam engine with a better efficiency (fuel economy) for a lower mass and insurance against boiler explosion. So there is no reason that in Safehold, they cannot become the main engine if the seals can be made. Teflon and the like are out of question of course but textile seals highly charged with graphite, while onerous to make should work.

Another advantage of stirlings is that they are extremely reliable.

Here's a question: what would power the stirling engine?

Here's a question: what would power the stirling engine?

Stirling engines can operate using any external heat source provided that:

a. there is a temperature differential between the "hot" end and the "cold" end, and,

b. The design of the engine is properly calibrated to take advantage of these temperature differentials.

Go to any website that sells Stirling engines and you will often find plans or even for sale models of engines that can be powered by the heat of a cup of tea or the thermal energy of your hand. Looking at those designs and comparing them to historical power generating Stirling engines, like the Phillips Stirling engine will show there are a great many changes needed to operate in a low temperature differential environment.

For the most part, getting a heat sink for Stirling engines on Safehold won't be much of a problem (Stationary and Naval applications will be fairly easy). Experimental car engines demonstrated one of the big issues with Stirlings in compact configurations; the size of the radiators was quite large compared to a conventional IC engine.

WRT Diesels, many early diesels were started by using compressed air, or a "cartridge" starter could be used for smaller engines (using a shotgun type shell to induce enough gas into the cylinder to start the machinery rotating. Or a team of really strong guys could crank the engine by hand....

Zakharra wrote:

alj_sf wrote:[snip]

In Safehold case, IC is no go because of the electrical problem, and if Diesel can be made without, you have launch problems. Stirlings on the other hand, can replace any steam engine with a better efficiency (fuel economy) for a lower mass and insurance against boiler explosion. So there is no reason that in Safehold, they cannot become the main engine if the seals can be made. Teflon and the like are out of question of course but textile seals highly charged with graphite, while onerous to make should work.

Another advantage of stirlings is that they are extremely reliable.

Here's a question: what would power the stirling engine?

Pretty much anything. Stirlings are pure heat engines; there are toy versions you can put over your mug of tea and industrial versions that work off concentrated solar heat, but in terms of fuel you care much more about the temperature differential the engine's designed for than the specifics of the fuel. Coal, wood, oil, metal filings in buckets of acid, it really doesn't matter to the engine so long as you hit the right temperature range.

The higher the temperature of the heat source, the more efficient, but also the higher the working pressure and the more heat the regenerator has to handle.

On the plus side, low maintenance, few parts, and no worries about boiler water. All you have to do to start it is light the fire.

Another question then: can a stirling engine produce more horse/dragon power than a steam engine? Assume a triple expansion type that is being built on Safehold. Could a stirling engine provide power (compressed air or drive shafts) for a factory? What real use would it be to Safehold that makes it worth developing?

Zakharra wrote:Another question then: can a stirling engine produce more horse/dragon power than a steam engine? Assume a triple expansion type that is being built on Safehold. Could a stirling engine provide power (compressed air or drive shafts) for a factory? What real use would it be to Safehold that makes it worth developing?

Stirling engines are simpler, safer, more fuel efficient, and closed-cycle, so you don't have to worry about feed water as you do with a steam engine. You'd be optimizing price, especially price over the operating lifetime, rather than power. For stationary applications -- powering a factory -- this is exactly what you want. (Stirling engines were used as factory and domestic power sources in actual history.)

I wouldn't be surprised if, given Safehold's materials science limits, steam, and particularly steam turbines, weren't going to scale to a larger size, leaving steam as the warship engine application. Making a Stirling locomotive, though, and avoiding the awkward problem of providing water to the steam locomotive, might be a worthwhile thing to try on Safehold. Fixed installations even moreso; steam is dangerous in unskilled hands ("there's a stick of dynamite in a bucket of water"), and a simpler, safer engine where you don't have as much of a training problem is just what you want as the factory model starts spreading.

Small (to about 10 hp, or so) single cylinder diesels are started by hand: you open the cutoff valve, spin the flywheel really fast, close the cutoff valve.

They are still being produced, in that very configuration, with starting handle.

Really big diesels are still started by compressed air.

For a diesel, electricity is a convenience, not a requirement.

Thucydides wrote:

Here's ae question: what would power the stirling engine?

Stirling engines can operate using any external heat source provided that:

a. there is a temperature differential between the "hot" end and the "cold" end, and,

b. The design of the engine is properly calibrated to take advantage of these temperature differentials.

Go to any website that sells Stirling engines and you will often find plans or even for sale models of engines that can be powered by the heat of a cup of tea or the thermal energy of your hand. Looking at those designs and comparing them to historical power generating Stirling engines, like the Phillips Stirling engine will show there are a great many changes needed to operate in a low temperature differential environment.

For the most part, getting a heat sink for Stirling engines on Safehold won't be much of a problem (Stationary and Naval applications will be fairly easy). Experimental car engines demonstrated one of the big issues with Stirlings in compact configurations; the size of the radiators was quite large compared to a conventional IC engine.

WRT Diesels, many early diesels were started by using compressed air, or a "cartridge" starter could be used for smaller engines (using a shotgun type shell to induce enough gas into the cylinder to start the machinery rotating. Or a team of really strong guys could crank the engine by hand....

Stirling engines are low power 1/3 hp is a big Stirling engine. Without modern metals ect they weigh more than a steam engine of the same HP. There is a reason they are not in common use they cannot compete with IC engines or electric motors. Less complex than steam? Those modern materials [like Aluminum for the displacer piston] are coming from where?

Steam Engines or Diesel IC engines I can see but, little 1/3 hp engines to run a sewing machine in some lady's home get real there is only so much machine time available and making many low powered engines requiring an open flame no.

Poker

pokermind wrote:Stirling engines are low power 1/3 hp is a big Stirling engine. Without modern metals ect they weigh more than a steam engine of the same HP. There is a reason they are not in common use they cannot compete with IC engines or electric motors. Less complex than steam? Those modern materials [like Aluminum for the displacer piston] are coming from where?

Steam Engines or Diesel IC engines I can see but, little 1/3 hp engines to run a sewing machine in some lady's home get real there is only so much machine time available and making many low powered engines requiring an open flame no.

Poker

Really ?

the Swedish navy stirlings are > 100 HP.

In the 70s, Philips toyed with a 1200 HP engine prototype (a reverse use of their big liquid air plants cryo generators). They still sell those for cryo.

there is in UK a cogeneration unit with 3 kW of electricity and 15 kW of thermal.

Stirling Energy Systems use 25 kW thermogenerators in its solar dishes systems

Most hobbyists and DIY are indeed small stuff, but that is not the case for industrial applications using hydrogen as working fluid.

In fact, the bigger the engine, the more it is competitive vs an IC engine.

Btw, besides seals, the main reason IC supplanted stirlings is that without a good regenerator Stirling cannot get a good ratio of power to mass for mobile application.

This problem was not solved before the 50's, when the thermodynamic involved started to be understood and simulated, and cheap ceramics and platinum mosses became available.

The regenerator for a high power unit (> 10 kW) can fit today a cartridge of 2 inches radius and 3 inches long, but it is very tricky to calculate as it must be just at the edge of thermal balance to be efficient.

The role of the regenerator is to isolate the hot and cold ends without putting pressure differential on the working fluid. When the fluid goes from the hot end to the cold one, the fluid must gives at most as possible of its heat to the regenerator and when coming back, get back as much of it as possible.

Early regenerators had 30% of worse efficiency. Modern ones are >85% (even go to 97% but pressure losses then occur).

pokermind wrote:Stirling engines are low power 1/3 hp is a big Stirling engine.

Because we treat them as toys, mostly; look at the Japanese Sōryū-class submarines, which have four 2,000 HP Stirling Engines in their AIP system. There's nothing inherently small about Stirling engines.

pokermind wrote:Without modern metals ect they weigh more than a steam engine of the same HP. There is a reason they are not in common use they cannot compete with IC engines or electric motors. Less complex than steam? Those modern materials [like Aluminum for the displacer piston] are coming from where?

I'd say the reason is that the IC engines got massive development money for aircraft in the Great War and nothing else caught up. Like turbocompound engines versus gas turbines, it's got something to do with the historical accidents of when and how development happened.

Electric is of course Right Out on Safehold for the foreseeable.

Stirling engines are inherently less complex than steam; closed cycle, so no boiler, no water or fire tubes, no condenser that has to deal with water quality issues, no valves, it's just plain simpler mechanically. They're also quiet, which, in a setting where factories probably occur next to housing (people mostly walk to work!) is a good thing.

The "modern metals" don't need to include aluminium; good steels and copper heat sinks will work fine, Safehold's industry is not yet at a size to make the inherent rarity of copper really problematic.

Also, for a stationary engine, such as is powering a factory, I don't really care how much it weighs, I care how much it costs. A Stirling engine's more efficient than a steam engine; I'm going to pay much less in fuel over the life of the engine. It's inherently mechanically simpler; it will be less expensive to make. If Safehold has a way to get the internal pressure up to 10 bar or so, which does involve sliding seals, this is a really obvious engineering choice because they're starting with 1900-or-so steel technology, rather than 18-low-number steel technology.

For a traction engine, particularly a railroad locomotive, not having to worry about feedwater is a big deal. So is fuel efficiency, because going twice as far on the same coal means I as the railroad operator need half as many coaling stations that don't need to also supply water which means this costs less.

pokermind wrote:Steam Engines or Diesel IC engines I can see but, little 1/3 hp engines to run a sewing machine in some lady's home get real there is only so much machine time available and making many low powered engines requiring an open flame no.

Except this actually happened. The concept of a "domestic engine" isn't still with us thanks to electricity, but it was around for a long time. Something that will run the washing machine is a very big deal; washing devours time and effort and we see now a pattern of development where washing machines are the first appliances purchased and make a huge difference to education. (Because Mom now has time and energy to read to kids.) And since powered textile mills on Old Charis are driving the price of clothes down, the need for washing is going up.