It's "baaaack". Stovetop
Thumper II.
So, built myself a rig that I can play with. Here's the new model taking into account most of the comments/advice given here. First, I started with a 8gal pot, with ferrule. That's a 2" pipe about 8" up and over to 1" pipe, then down to 1/2" at the connection. No more loop-d-loop over the top thang (as per several persons mentioning issues with the design). Then, I raised the thump keg up and shortened the distance as much as possible to the stove to drive more heat (as per goose). I shortened the thump head a few inches as well. I ran higher abv low-wines instead of water (as per Dunder)
So, how did the adjustments fare?
Single run on 6 gals of All-Bran at 11%, 1 quart of 45% low-wine (corn) in
thumper.
The Good: heat up time was definitely shortened. Within 3 mins of the lynearm heating up, the first drips started coming over. That quickly built to a kind of broken stream. It was outputting at 40ml per min, but in a sort of broken/dribble/stream. Im not exactly sure how much each thing contributed to the shortened warm up time.
The Bad: it made no difference as to heads/tails compression and reflux when single running wash. Results were the same (ie., basically a potstill run that starts out a small percentage higher in abv and falls linearly as it goes.) "The magic" never happened.
I'm coming to the conclusion, based on this and other experiments, that there is a threshold amount of volume of alc that has to be present before that kind of compression/reflux can occur and be sustained (ie., for the "magic" to occur). I've got another thread going in the Theory Section to discuss some of those findings. I already know from previous experiments that increasing the abv of the
thumper charge..would not affect this. It might make the run start out a few points higher...that's about it. So, I would like to find out exactly what abv still charge in the pot...it would take to break out of the linear, falling abv/rising temp and flatten it out..ie., maintain constant abv for a good portion of the run. Secondly would be to find out if this holds regardless of which reflux system I use (ie., bubble cap, boka, CM,
thumper), or whether it varies ..and by how much. But, that's for another thread

The "theory" would suggest that no matter what you start with in the pot, that it should do this reflux "magic" the same way....perhaps the only difference being that if you start out wiht low abv, it would sustain a lower average abv over time. But, this has not been what the empirical data suggests! That's enough to know that it has an impact on the use of a
thumper. I'll leave the rest for further discussion in the other forum.
Here are the run results of the run on Stovetop
Thumper II.
1:40 from heatup till first drops. Flow-rate was average of 200ml per 5-6min range for first 1/2 run...and that expanded to about 8-9mins per 200ml towards the end of the run as it slowed down.
150ml 81% (fores)
200ml 80%
200ml 79%
200ml 78%
200ml 75%
200ml 73%
220ml 70%
200ml 67%
200ml 65%
200ml 62%
200ml 59%
200ml 55%
200ml 52.5%
200ml 50%
200ml 46.5%
200ml 45%
Flushed out rest down to 35%
A final note on the above: As you can see from the data, I'm not "loosing" alc (ie., vapor leak, etc). What's going in, is coming out. The
thumper is only working in terms of raising the abv perhaps a point or two.
Late addition: The
thumper juice volume seemed to be about 1/4 the volume of the barrel. I think that's lower than before (used to end up about 1/2 full I think). Don't know if any got sucked back up during cooling off.
But, the
thumper juice measured 5%. So, again...didn't leave much behind.