pgentile
Still learning
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they would more likely go neutral at the same time. .
Not really but closer.
they would more likely go neutral at the same time. .
Nothing too new here, but I had the following image to share. Let's say I have two identical planks of wood, that I happened to have hewn from an oak tree in the the Zemplen forest. I tie rocks to them (to make them sink); I throw one into the local high school swimming pool, and I throw the other into a baby wading pool. Do you think they would become "neutral" at the same time, or at different times? What is your reasoning?
It has to do more with what @Ajmassa5983 said in an earlier post. It's the number of batches that's getting you to neutral not time.
With the small volume barrel you reach your theoretical 35 units faster due to dilution to volume.
If you had a small barrel and a large barrel side by side and change out the wine when you hit your target dilution/units, but only refill the barrels with wine at the same time, they would more likely go neutral at the same time. But because the smaller barrel gets to the unit level quicker you are going to have new wine refills in shorter increments than the larger barrel, resulting it going neutral sooner.
Yes you understand correctly, but the last batch in the small barrel would still finish quicker than the last batch in the larger barrel, so the smaller barrel would go neutral faster.If I'm understanding correctly the small barrel would sit empty until the larger reached the target extraction. In that case I agree the time to neutral would be the same.
It's early so I might not be thinking clearly through this, but if both are fully submerged then both would be exposed to the same surface area to liquid. I say neutral at the same time.
Now keep in mind, the HS swimming pool is likely to be more chlorinated and have a deep end with more pressure and the wading pool likely to have more urine in it, but they should have minimum affects on the planks going neutral.
Yes you understand correctly, but the last batch in the small barrel would still finish quicker than the last batch in the larger barrel, so the smaller barrel would go neutral faster.
OK let's start here using round numbers and assumptions:
200 liter barrel has 6500 sq. in.
20 liter barrel has 1400 sq. in.
Assume the number of units of potential oak extration is equal to the number of sq. in.
The potential number of units of extraction per barrel for a 200 liter barrel is 6500/200 or 32.50 unit/gallon
The potential number of units of extraction per barrel for a 20 liter barrel is 1400/20 or 70.00 units/gallon
So for the sake of simplicity let's call 35 and 70 half or double depending on how you look at it.
Now when removing the wine from the smaller barrel once it reaches the 35 unit extraction level you only have 35 units left.
If the rate of extraction is a constant the timeframe for the extraction takes half the time for a smaller barrel. Thus becoming neutral sooner.
Boy I can't wait to see the responses. LOL
PS, @sour_grapes I'm still thinking about you pool scenario. Don't have anything yet.
I really like the way you set this up.
Let me use your assumptions, namely, "if the rate of extraction is a constant." (It is probably more complicated, but let's use that for now.) The rate of extraction per area will be constant. Therefore, as @pgentile said, you will get your desired concentration faster. In your example, it would take exactly 1/2 the time as for the large barrel (and, as you say, you will have used up 1/2 of the small barrel's oak essence, or 35 units). Then you swap out the wine for a new batch in the small barrel, but leave the big barrel sitting. Now, you will extract the remaining 35 units of the small barrel. This again takes 1/2 of the time as the whole process takes for the large barrel. Therefore, they both become neutral at the same time.
Of course, we know the rate of extraction is not really constant. I am going to make another post discussing that, but I haven't reached a conclusion.
Wating anxiously. Unfortunately I have to go to my boat to change the bilge pumps so it doesn't sink. LOL but not really.
I'm going to leave this one go for now. What is experimentally known is smaller barrels do give off oak faster and they go neutral around 18 months. There has to be something not being taken into consideration.
Well, I have looked at this a number of times/ways, and just don't see any explanation for a shorter time for smaller barrels to become neutral.
I tried two more things today (again, on the theoretical front). Because the oak essence will come out fast at first, and then more slowly after some of it is used up, I tried a simple model where the rate of extraction varies with time t. (I chose it to be proportional to exp(-t/T) because that is easy to handle mathematically.) I found, as expected, that for the smaller barrel, the time to oak-up the first batch was smaller than the time to oak-up the second. But the sum of those times is exactly the same as the time to oak-up the larger batch that has half the Area/Volume ratio.
Next, I recognized that the math of diffusion is rather well-known. It is well-described by Fick's Law; by "well-described," I mean there is a mechanistic, molecular-level theory of diffusion that leads to a fairly simple mathematical result. When we compare the predictions of Fick's Law to actual experiments, across a wide, wide range of phenomena, you get very good agreement. The "mathematical result" I cited above is a differential equation, but you have to solve it for the situation at hand; for example, it can describe both, say, dumping a load of dye into a lake, or, say, drying wood in a kiln, but you need different solutions to that differential equation to reflect those different initial conditions.
These expressions are kinda complicated. Just for example, I was playing around with expressions like these (for the concentration c of oak essence left in the wood as a function of depth x and time t):
View attachment 49776
where erf() is a complicated but well-known mathematical function.
But the thing is there is very little in these exercises to distinguish large barrels from small ones.** Like the planks in the two swimming pools, the extraction of oaky goodness from the wood just goes how it goes, not "knowing" if it is diffusing into a large volume or a small one. It became clear to me as I was playing with this that there was not even a way to encapsulate the information about the size of the barrel (except as described in ** below). I am forced to conclude that barrels of all sizes become neutral at the same rate.
** There is one, minor effect that differs between the case of large and small barrels, namely, the concentration of oak in the wine increases faster for the small barrel, and thus could possibly slow down the continued outdiffusion of oak essence from the wood. However, this is problematic for two reasons. First, it should be a very small effect, because the concentration of the oak flavors in the wine is many orders of magnitude smaller than in the wood. Moreover, this effect works the wrong way: if taken seriously, it would indicate that small barrels should take longer to attain neutrality.
@Johnd, thanks for your comments. I must admit that I misunderstood your post the other day. I thought you were saying that small barrels did become neutral faster, and I took your claim (which I misunderstood) very seriously. I should have spent more time on reading comprehension than on Fick's Law!
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