Some members of the Stirling Engine Society have been playing about with various designs of Thermal Lag Engine. I'm hoping that there will be some examples at the midlands exhibition later this month, to have a tinker with. (I do know that one of the people who has been building these devices will be there.)

There have been various theories suggested for how these odd little engines work - some slightly more feasible than others. But there still seem to be a number of unknowns. I suspect it is high time that thermal plasmonics was thrown into the mix - just to confuse matters still further

If you google around, you can find examples of some thermal lag engines online - along with some videos. The challenge (as always) is to improve the efficiency of the current devices - so that they might find more of a use than just being cute.

I also see that our friend Allan Organ is now getting in on the act - with his latest (unaffordable) textbook.

There was a Stirling Engine rally in Hereford last Sunday. Here is a short video (under 3 minutes) of some of the engines on display.

Quote from Frogfall

I've long suspected that the designers of regenerative "Caloric" engines, such as John Ericsson (1803-1889) believed that Caloric possessed some form of inertia. I don't think Ericsson (or his contemporaries) could quantify it - but it might explain some of the design features of the early engines, which seem slightly bizarre today (with our currently accepted thermal theories).

Just thought I'd post a little update.

The sudden shifting of heat along a heated bar, plunged in water, could be amenable to calculation through variations of the Drude model for thermal conductivity.

Note that the model involves laws (such as the Wiedemann-Franz law) rather than full theory, however it does give a route to introduce such concepts as phonons and "thermal inertia".

China tests a Stirling cycle power converter in orbit

They have used twin free piston units, horizontally opposed and possibly electrically synchronised - in an effort to overcome balance issues. Heat is from radioactive decay - but the article below doesn't mention the source type (The previously abandoned NASA unit, above, used Plutonium-238).

If fact, the Phys.Org article is ridiculously dumbed-down and bizarrely compares the generator to a hydroelectric dam rather than to other heat engine generators or solid state thermoelectric systems.

China tests a Stirling engine in orbit

The China National Space Agency (CNSA) has made considerable progress in recent years with the development of its Long March 5 (CZ-5) rocket and the completion…

phys.org

The reporter is a little confused over the technology, but it is an interesting development all the same.

New Chinese thermoacoustic Stirling engine breaks power record

Patented by NASA but never developed, Chinese scientists have managed to reach a major milestone in the development of a thermoacoustic Stirling engine.

interestingengineering.com

Photo of the unit mentioned in the above story (tracked down by a fellow member of the Stirling Engine Society).

Quote from Alan Smith

a 'free-piston' internal combustion engine of similar overall form

This has been mentioned before. There is a handy page on wikipedia about free piston engines (including their use as gas generators)

Free-piston engine - Wikipedia

en.wikipedia.org

The first practical type go back to Raul Pateras, in France, in the 1930s. The wartime Junkers designs were similar in concept. There were also the weird "Lutz" donut shaped free piston designs.

People in lots of countries have played around with them over the years - but they have never displaced crank-based piston engines, for a number of technical reasons. Maybe one day

Sent to me by a fellow member of the Stirling Engine Society - and written by ChatGPT.

I wonder if ChatGPT can write the music too?

Quote

Instructions:

Write a song for the Stirling Engine Society, extolling the virtues of a silent engine in a boat.


(Verse 1)
In the quiet dawn, when the mist rolls by,
Sails unfurling 'neath the morning sky.
With a hum so soft, like a whispered dream,
Stirling's gentle engine, on waters serene.

(Chorus)
Oh, Stirling Engine, silent and true,
In our boat, we trust in you.
No roar of motor, no clatter of steam,
Just tranquil waters, a sailor's dream.

(Verse 2)
Through valleys of blue, where the rivers bend,
Stirling's pulse beats, a steadfast friend.
With elegance and grace, it propels us on,
In harmony with nature, from dusk 'til dawn.

(Chorus)
Oh, Stirling Engine, silent and true,
In our boat, we trust in you.
No roar of motor, no clatter of steam,
Just tranquil waters, a sailor's dream.

(Bridge)
No fumes to choke, no deafening roar,
Just the whisper of wind, and waves on the shore.
With Stirling's heart, our voyage unfurls,
In peaceful waters, we conquer the world.

(Chorus)
Oh, Stirling Engine, silent and true,
In our boat, we trust in you.
No roar of motor, no clatter of steam,
Just tranquil waters, a sailor's dream.

(Outro)
So here's to the Stirling, our silent guide,
Through oceans of calm, we'll gently glide.
With each gentle turn, we'll forever sing,
Of the Stirling Engine, our silent king.

Display More