Has there been any work done in this area past or present? A simple example would be freon gas heated by the sun and then the pressure used to lift weights that would drive generators as it came back down. No intake or exhaust valves so they would rely on natural cooling to cycle. Possibly use a water source to cool the coils for more cycles. I don’t know how they could be configured but basically have highly expandable gasses been used in solar energy experiments?
Are you thinking about something different than a Stirling Engine? A study on two-phase, two-component Stirling engine - NASA/ADS
And if so, what are the benefits you perceive over a Stirling design?
To be honest with you I don’t know anything about this at all. It just seems naturally heated gasses could be an effective way to produce energy however they could find ways to harness it.
Then the answer to your question is yes. Freon can make Stirling engines more effective, and the way to utilize expanding gases to produce energy is to use a Stirling engine.
This is what solar power towers do. They use solar power to heat water, generating steam that drives turbines to produce electrical power.
There are variations that allow for energy storage so the energy supply can be time-shifted to meet nocturnal power demand - but in the end, they’re generating steam to produce mechanical power (and then electrical power).
I was thinking more in terms of no exhaust type engines. Something where cooling had to take place for a cycle to complete itself. So the primary challenge I would imagine would be in how rapidly we could cool the gasses.
? Not following.
No exhaust gases here: heat water, generate steam, run through turbine, cool/condense steam into liquid water, send water back to solar furnace tower.
What am I missing?
(rereads OP)
OK, I see you don’t want any flow. Not seeing the value of such a restriction. If you want to dump heat from your working fluid, it makes sense to send it to a device that specializes in cooling, rather than leaving it in a place where you have to alternate between heating and cooling.
You can design a heat engine that will operate anywhere you have a hot and cold source close together. One location that has been proposed in on the arctic ice. That seems unlikely at first but you have 32 degree water underneath (the hot source) and -20 to -50 above the ice as the cold source. That’s a substantial temperature difference. You need to tailor the working fluid for each application.
The earliest practical steam engines, Newcomen engines, cooled the steam inside the cylinder. However, they were extremely inefficient because you end up cooling the entire cylinder as well, instead of just the gas. And then on the next cycle it heats up again. It’s also just plain difficult to cool, because there’s not much surface area between the gas and outside. The Newcomen engine sprayed water inside the cylinder to cool the steam because simply cooling the cylinder would have made for too slow an engine.
The solution is to keep the hot and cold cylinders separate, with the gases flowing between them. You can increase efficiency even further by putting a heat exchanger and heat store between the cylinders. That heat exchanger can do its job properly because there’s no cylinder there, and you can give it a lot of surface area like a typical heat exchanger.
And that’s just a Stirling engine, as naita mentioned. It’s really about the simplest heat engine you can imagine that’s not horribly inefficient. It’s closed, as you wanted, and can work with just about any working fluid you want. Small ones can run on the heat difference between your hand and the ambient air.
This can even be done in oceans without ice. I think I’ve read of a project in the Caribbean Sea. The plan is to find regions with a large-ish difference between surface water temperature and deeper water temperature, and build a heat transfer engine to take advantage of that.
Keep in mind that your efficiency is limited by the hot and cold temperatures (see Carnot wiki below), so for a given surface area, one needs to consider whether more power can be generated with solar panels.
But yes, solar Stirling engines are a thing.