I’m developing some property and buddy has some pretty neat ideas about some wood gasification to power our greenhouses. We’ve got gasable pulp by the truckload and running it as a generator we cut our price per KW down by about 50%.
Now, I wanted to take it a step further.
Since we’ve got a pretty good source of co2, and a pretty ready source of heat. I was curious if it’s possible to use heat to run a system to pressurize the co2 into a liquid state, then the usual expansion to chilling. Or using vacuum or something of the like?
I mean it’s easy enough to just use a pump and pressurize the gas for later use.
But I was just curious if there’s a way to tie in my extra/waste heat and use that as part of my pressurizing system (then using some air cooling to remove the heat later)
how would you make one of those work in reverse. i just read about the piston workings for the beta type if that’s what he were to use like how would one even make that operational running in reverse?
Stirling engines can be used to both make heat and cold with mechanical energy supplied, or can convert heat or cold to rotary motion.
To make cold with a Stirling, the motor is turned backwards with a electric motor.If you wanted to make heat the engine would be reversed in direction.
Stirling engines can also run off a temperature differential as a power source.
Absorption chilling is for sure the way to go for using heat to make cold but absorption units are actually pretty rare in North America because the COPs standalone are terrible. For doubling up with any heat source (like, say, waste heat from distillation) though they’re fantastic.
I was trying to think of a method to power a chiller essentially using an isostatic press concept but I don’t think it would be feasible without some sort of piston/diaphragm/valve assembly that would make it more complicated than just a regular vapor compression chiller (which would defeat the point entirely). Short answer is probably just use electricity from boiling water powered by the bonfire.
Also, of course it would be r744, it’s my favorite refrigerant!
What you would probably want to do is use waste heat from your steam turbine to run the adsorption cycle. Then depending on scale (probably not worth it unless you’re generating 250+ KW) you would reboil the waste water from the adsorption cycle which exits at a higher temp. This essentially reheats your reject water to be back up to a usable temp.
We have to put in 5MW of power generation here in the next few years and I really want to do this with the waste heat from natural gas turbines. Only thing is I’m cheep AF and it’s hard to get your hands on used adsorption units in the 200+ ton range
Wait, Wait!!! LOL Are you saying you could harness that energy from one of those to make an immersion coil to substitute dry ice for recovery or distillation???
That would probably be a tall order but it could be done in theory. Stirling engines are awesome but despite having been around forever, they’re very challenging to make practical. I built one one in school once, the tolerances needed to make it work well were hell
Preface: this neither simple nor efficient but it would probably work and meets the ridiculous requirements thrown down by @cyclopath to make a bonfire powered CO2 chiller. Also, it would take a ridiculous amount of coordination and stages to get to cryo temps, but possible nontheless.
Take a hydraulic/pneumatic cylinder with sufficient pressure rating. Remove the shaft from the piston (I guess not necessary but none is the rest of this lol). Supply CO2 to both sides of the piston, and seal the cylinder.
Heat one end of the piston while keeping the other at ambient temp with radiator or swamp cooling. This will compress one side of the system like an isostatic press. The heat removed from compression is the refrigeration capacity of one cycle. If you can hit 8-900psi, you would even be able to condense the CO2.
After that, open the “cooled” end through an orifice/expansion valve and boom, you have refrigeration. Add enough pistons and you might even have continuous refrigeration.
Is this in any way better than using a steam engine to run a piston compressor? Fuck no. But hey, solving silly problems takes silly solutions
Yep, that would work! In principle that’d be essentially the same as using a gas booster pump as a refrigeration compressor with the drive gas being supplied by heating a big vessel full of CO2. Now that you mention it, I do have a bunch of Haskel AGDs in inventory lol
I’m very curious, if done properly and safely; Could Sterling Engines be used to make indefinite cryogenic energy and/or continue to move cryogenic energy indefinitely.
You will need to compress the co2 vapors to a pressure where you can condense the vapors at close to ambient temperatures.
These pressures will exceed 900psi on the high side of the compressor. To condense at lower pressures you will need a liquid coolant but this will only get your pressures down to 600psi. To condense with pressures lower than 300psi you will need some sort of refrigeration.
Commercial units are producing liquid Co2 out of waste streams of exhaust for around $.80 a pound.
