Sign in to follow this  
biopon

Double dipping with ethanol

Recommended Posts

biopon    226

Heating ethanol to gaseous state loses about 14% of the heat energy contained in it, as the gas SHC is lower. Cooling the gas takes less effort to phase it back to liquid, than heating it up.

It's a nice scenario, but the SHC difference isn't very large, and the time and effort required to take advantage of it may not be worth it in the end. Or so I said to @avc15, seemingly crapping on the notion that he brought up. (Sorry, if it came across that way, I didn't mean to.)

Anyway, I was playing with compact and efficient arrangements of liquid and gaseous ethanol, and stumbled upon a very interesting configuration that seems to cause multiple phase changes for the price of 2;  massively boosting the ethanol bonus.

Behold:

ethanol1.gif.578b8f2f7cd7c74d17f31c9fb5a529c3.gif

It's just vacuum, some radiant pipes (with the top right segment above the opening being insulated - this is important), and 50kg/tile ethanol on the bottom row. I was running -0.1 degree water in the upper pipe from right to left, and 99.8 degree water in the lower pipe from the left to right. 

One very important detail is that the configuration needs some time to warm up; specifically, the airflow tiles themselves need to be comfortably above the ethanol phase change point. I've found 82 degrees and above to be golden. This may take a while as the ethanol mechanic is very actively fighting it, but once you break the barrier:

My cold water output tank averaged to 8.9 degrees (up from 0.1), a gain of 376kDTU per 10kg packet. My hot water tank was at 86.7 degrees, a loss of 547kDTU per packet. A 45.5% boost to cooling efficiency.

I think the following is happening: 50 degree-ish cool liquid ethanol is sitting atop the airflow tiles, condensing the steam coming from below, but eventually evaporating, and condensing back onto the airflow tiles. For some reason, it's not exchanging heat with the 100kg hot tile below, only with the gas within. 

It is very weird though: I never see ethanol steam near the top radiant pipes, ever. It's just vacuum there. 

ethanol2.gif.6adbb80bfd1bdb27ba900dd5317c67f9.gif

ethanol3.gif.5c0076dda96fb2f5a582d12bc967e870.gif

The uses are obviously limited due to the temperature ranges, but partway cooling a pre-space sour gas boiler, or super efficiently harvesting cool steam - there are lots of possibilities.

I'd love to know what you guys think of the actual mechanics involved. I'm only guessing about the liquid layer proccing multiple phase changes, but how else do you explain a 45% increase in efficiency, when you can't even get half of that normally?

 

 

 

 

  • Like 1

Share this post


Link to post
Share on other sites
biopon    226
2 hours ago, mathmanican said:

This may add to your fun.

Hm is that why this is getting so little interest? The thing is though, that crab cooler thing is not practical at all. It's a high-effort fun build but he's operating that aqautuner at full power with less than 10% efficiency. The concept above is 145% efficient; it gets water halfway to supercoolant in the right temperature band.

Share this post


Link to post
Share on other sites
Juggzor    1
9 hours ago, biopon said:

For some reason, it's not exchanging heat with the 100kg hot tile below, only with the gas within.

This is because airflow and mesh tiles act as debris. They do not exchange heat with tiles above them.

Check out the following post: 

 

  • Like 1

Share this post


Link to post
Share on other sites
biopon    226

@Juggzor, thanks. That explains some of the general weirdness surrounding them.

On a general note, I guess to better explain why I think this discovery is interesting, here's a real life example: a bog-standard cool steam condenser.

doubledip-standard.thumb.gif.1adb5a5da6240c7618aa35870e0bee5d.gif

The turbine was not connected to the power network, the coolant has been preconditioned to 20C and allowed to return to this temperature after the eruption. At this point the hydrogen consumed from the reservoir was measured. During one eruption cycle, the AT used 19.3kg of H2.

doubledip-doubledip.thumb.gif.81e57e1ea32a90bc34b763a77864ecc4.gif

Same conditions as for the standard setup, except the AT is cooling the ethanol gas, the geyser is heating the ethanol liquid with a separate loop, like so:

image.thumb.png.d69c247b09465d62aaddc49ded8fbdf3.png

One eruption cycle: 8.4kg H2 used. 

I tried measuring the crab cooler as well, but it wasn't able to return to 20C before the next cycle started, and that was the end of it.

doubledip-crab.thumb.gif.ca79e085a157b901023fc6d56caad931.gif

I suppose I should clarify that this isn't meant to be a precise measurement of the benefit you get from using that weird double-dip ethanol buffer. Controlled tests show an extra 45% cooling created from nothing when simply circulating two liquids against each other. 19.4kg vs 8.4kg H2 simply indicates that the ethanol buffer is very beneficial, but difference between the builds can account for some of that. 

Share this post


Link to post
Share on other sites
avc15    416
14 hours ago, mathmanican said:

This may add to your fun.

Making sure to differentiate between this and that. Biopon's build is exploiting some glitch that forces multiple state changes along the same heating& cooling cycle, multiplying its effectiveness many times.

Right up your alley, @mathmanican :D

12 hours ago, biopon said:

Hm is that why this is getting so little interest?

Yes, the ethanol cycle is kind of an oddity. Interesting but not very useful except when you use an... (remove expletives)... er... make use of a glitch in the physics to get a few times more work out of it :b

Edited by avc15
  • Like 1

Share this post


Link to post
Share on other sites
biopon    226
16 minutes ago, avc15 said:

make use of a glitch in the physics to get a few times more work out of it

So I just realized why this isn't all that useful after all.

It is kind of useful, but not that useful.

The thing is, whatever you're trying to cool will end up at most 78-ish degrees (wherever ethanol actually pleases to condense.) And this is OK, but you have infinite, power positive cooling at 125 degrees from turbines (or even down to 95 degrees if you use their output, but this gets clunky if you need volume). So your sweet spot is 125->78, or even 95-78, what's that good for? Other than condensing cool steam? I guess you could use it to go heavy on aquatuners made out of gold amalgam before you get steel & plastics, that's actually not bad, but you'd need to use about half of the AT's output to cool itself. 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this