Is the dead space really a problem when doing a full volume mash?

[kohalajohn]

Well,

that's interesting.

 

[doug293cz]

The following quote is from a private Conversion, published with permission:

Doug,

I"ve been following your postings on this. I'm messaging now because I'm considering whether to do up a plumbing job to "fix" the above.

It would involve adding a T with adaptors, to the recirc hose in my bzg4. the main 1/2 inch ID silicone hose would continue to vorlauf the grain bed. But it would T into a 1/4 inch line running through the lift hole and whirlpool the "dead space" wort.

But is such work really necessary?

I agree with your earlier thoughts that having stagnant low sugar wort is inefficient, as that low sugar wort should be pulling sugars out of the grain bed.

But I think I saw a posting from you recently, where you said that to your surprise, any advantage in such dead wall whirlpooling was not significant.

Your further thoughts appreciated. And of course move this to public if you wish.

Splitting the recirc flow between the grain bed and stagnant zone outside of the basket will give you a few percent increase in mash (specifically lauter) efficiency - on the order of 2 - 5%, depending on grain bill weight. The analysis of one specific case is above in this thread. Whether this increase in efficiency is enough to justify the work of modifying the recirc plumbing is a decision that only you can make.

Brew on

 

[kohalajohn]

No, I draw from the bottom drain, then split the pump output between both the top recirc and the side mound "drain" which actually becomes a whirlpool return instead. I'll see if I can find a picture. If not, I have a couple units I'm modding later this week.

Good morning and happy Canada Day.

Bobby, if I understand correctly, you are happy with a no sparge full volume, but you do go to the trouble of putting in a splitter to capture the dead wall space sugars. Do I have this right?

Also, are you making and selling dead space recirculation kits? I've been pondering design issues. I want an easy connect/disconnect to my main recirc hose, but also nothing that could slip loose and spray wort everywhere.

I'm thinking that if I did it, I'd have an entirely separate dedicated system, hanging on a separate recirc arm, for this job.

 

[Broken Crow]

https://www.brewhardware.com/product_p/spincyclesubmerge.htm
https://www.ontariobeerkegs.com/circ-22mm-hole-punch-knock-out.html
https://www.ontariobeerkegs.com/Tees_c_1622.html or: https://www.brewhardware.com/product_p/3wvalvet.htm
...just my best guess..I don't have a brewzilla.

 

[tracer bullet]

something like this could slip between the outside of the basket and inside of the main unit:

https://www.brewhardware.com/product_p/spincycleoverboard.htm

Pump needed, of course. Helps later as well when chilling, if you use a copper coil.

At some point skip the basket and do the bag. Skip the fight altogether.

 

[Broken Crow]

something like this could slip between the outside of the basket and inside of the main unit:

https://www.brewhardware.com/product_p/spincycleoverboard.htm

Pump needed, of course. Helps later as well when chilling, if you use a copper coil.

At some point skip the basket and do the bag. Skip the fight altogether.

Here in Canada, the Brewzilla has gone on sale quite a bit at a good price and I've often been tempted to get one but use a wilser bag https://www.brewhardware.com/SearchResults.asp?Search=wilser&Submit= instead of the malt pipe....wouldn't the Spin Cycle Submerge be a less intrusive option?

 

[mashdar]

Good morning and happy Canada Day.

Bobby, if I understand correctly, you are happy with a no sparge full volume, but you do go to the trouble of putting in a splitter to capture the dead wall space sugars. Do I have this right?

Also, are you making and selling dead space recirculation kits? I've been pondering design issues. I want an easy connect/disconnect to my main recirc hose, but also nothing that could slip loose and spray wort everywhere.

I'm thinking that if I did it, I'd have an entirely separate dedicated system, hanging on a separate recirc arm, for this job.

In case you didn't know, Bobby runs a real-deal LHBS in NJ that has shifted to also being a great regional+ online option. He makes his own custom electric AIO systems, and does a bunch of welding/fabricating. He also has a great selection of fittings (e.g. my IC has some sweet compression 90s on it so my hoses connect vertically and don't kink).
https://brewhardware.com

 

[hungupdown]

......The rigorous formula for the volume of the gap = height * pi * (R^2 - r^2) where R = vessel radius & r = pipe radius. But that only makes a difference between 4.2 & 4.3 L of dead water volume.

Brew on

Why would any formula only be correct for only a limited range of values?
It's like saying your cars speed must be between 20MPH and 30MPH, providing the time is between twenty past and half past.

The rigorous liquid volume is 30.095 L in the vessel at end of mash, and 4.3 L of that is water, so we have 30.095 - 4.3 = 25.8 L of wort. We collect 25 L of wort and water when we lauter, but again 4.3 L of that is "plain" water, so actual wort collected is 20.7 L, and we have:

Lauter efficiency = 100% * 20.7 L / 25.8 L = 80%​

Brew on

I've never before seen a formula, even from someone who can spell rigorous, claiming that 'lauter efficiency' was the ratio of unused mash water, to utilised mash water. And ignore the percentage of sugars extracted.

 

[doug293cz]

Why would any formula only be correct for only a limited range of values?
It's like saying your cars speed must be between 20MPH and 30MPH, providing the time is between twenty past and half past.

I never said the formula I gave for the volume between a cylinder and a surrounding cylinder was limited in any way (it's not. In fact it works even if the cylinders are not concentric.) Where did you get the idea that I said that?

What I said was that in this particular case, the difference between the approximate formula that you used (which employed the average diameter of the annular ring space between the basket and vessel) vs. the rigorous formula (using the larger and smaller radii) was small. The larger the difference between the two radii, the larger the error will be when using the approximate formula.

I've never before seen a formula, even from someone who can spell rigorous, claiming that 'lauter efficiency' was the ratio of unused mash water, to utilised mash water. And ignore the percentage of sugars extracted.

That's not at all what I said. Lauter efficiency is defined as the mass of sugar (more rigorously extract, which includes all dissolved material - sugar, soluble starch, proteins, lipids, etc.) collected in the BK divided by the mass of sugar created in the mash. Now, if the wort in the mash is homogeneous, and no sparge is done, then the ratio of wort volume in the BK to the wort volume in the mash is equal to the lauter efficiency.

The first case I analyzed assumed the wort was homogeneous at the end of mash (i.e. no effect from the stagnant volume between the basket and vessel.) I did a rigorous calculation of the wort volume at the end of mash (which is higher than the strike volume due to the added volume of the extract in solution) and then used to boil:mash ratio to calculate the lauter efficiency (since the required constraints were met.)

The second case required simplification, since there is no way to know how much diffusional mixing occurs between the stagnant water and the mash wort. So I chose to do a worst case analysis that assumed zero mixing. For this case the effective wort volume at the end of mash would be equal to the wort volume in the first case minus the stagnant volume outside the pipe (which would be just water.) The wort volume collected for boil also needs to be reduced by the volume of stagnant water to account for the stagnant water not contributing any sugar to the boil after lautering. Think of it like this: you have a mash and some water set off to the side. At the end of mash, you lauter and your efficiency is boil wort volume / mash wort volume. Now if you dump the water you had set aside into the boil, the lauter efficiency is not affected because the amount of sugar in the boil is not changed.

Brew on

 

[day_trippr]

I believe this sentence threw the respondent...
"But that only makes a difference between 4.2 & 4.3 L of dead water volume."

Cheers!

 

[doug293cz]

I believe this sentence threw the respondent...
"But that only makes a difference between 4.2 & 4.3 L of dead water volume."

Cheers!

Could be. Reading comprehension is hard.

Brew on

 

[hungupdown]

I never said the formula I gave for the volume between a cylinder and a surrounding cylinder was limited in any way (it's not. In fact it works even if the cylinders are not concentric.) Where did you get the idea that I said that?

What I said was that in this particular case, the difference between the approximate formula that you used (which employed the average diameter of the annular ring space between the basket and vessel) vs. the rigorous formula (using the larger and smaller radii) was small. The larger the difference between the two radii, the larger the error will be when using the approximate formula.



That's not at all what I said. Lauter efficiency is defined as the mass of sugar (more rigorously extract, which includes all dissolved material - sugar, soluble starch, proteins, lipids, etc.) collected in the BK divided by the mass of sugar created in the mash. Now, if the wort in the mash is homogeneous, and no sparge is done, then the ratio of wort volume in the BK to the wort volume in the mash is equal to the lauter efficiency.

The first case I analyzed assumed the wort was homogeneous at the end of mash (i.e. no effect from the stagnant volume between the basket and vessel.) I did a rigorous calculation of the wort volume at the end of mash (which is higher than the strike volume due to the added volume of the extract in solution) and then used to boil:mash ratio to calculate the lauter efficiency (since the required constraints were met.)

The second case required simplification, since there is no way to know how much diffusional mixing occurs between the stagnant water and the mash wort. So I chose to do a worst case analysis that assumed zero mixing. For this case the effective wort volume at the end of mash would be equal to the wort volume in the first case minus the stagnant volume outside the pipe (which would be just water.) The wort volume collected for boil also needs to be reduced by the volume of stagnant water to account for the stagnant water not contributing any sugar to the boil after lautering. Think of it like this: you have a mash and some water set off to the side. At the end of mash, you lauter and your efficiency is boil wort volume / mash wort volume. Now if you dump the water you had set aside into the boil, the lauter efficiency is not affected because the amount of sugar in the boil is not changed.

Brew on

You said:
"The rigorous formula for the volume of the gap = height * pi * (R^2 - r^2) where R = vessel radius & r = pipe radius. But that only makes a difference between 4.2 & 4.3 L of dead water volume".

Saying that only makes any difference over a particular range, of only 0.3L, dead space water. Is clearly stating the formulae only applies over a limited range.

 

[hungupdown]

....
What I said was that in this particular case, the difference between the approximate formula that you used (which employed the average diameter of the annular ring space between the basket and vessel) vs. the rigorous formula (using the larger and smaller radii) was small. The larger the difference between the two radii, the larger the error will be when using the approximate formula....
Brew on

That very rigorous calculation only applies if the malt pipe is rigourously centered, exactly central in the boiler body. And both are exactly circular.
I know my BZ isn't, it's oval by at least 3mm.

 

[doug293cz]

You said:
"The rigorous formula for the volume of the gap = height * pi * (R^2 - r^2) where R = vessel radius & r = pipe radius. But that only makes a difference between 4.2 & 4.3 L of dead water volume".

Saying that only makes any difference over a particular range, of only 0.3L, dead space water. Is clearly stating the formulae only applies over a limited range.

Let's try again. Your approximate equation for volume gave a result of 4.2 L. The rigorous equation for volume gave a result of 4.3 L. The difference between the volume calculations, in this particular case, is small, and won't materially affect the conclusions from a bunch of calculations that have lots of other approximations.

Brew on

 

[hungupdown]

I did a rigorous calculation of the wort volume at the end of mash (which is higher than the strike volume due to the added volume of the extract in solution) and then used to boil:mash ratio to calculate the lauter efficiency (since the required constraints were met.)
Brew on

That, like most of your reply, sounds mostly like verbal diarrhoea.
The wort volume after mashing can never be greater than the strike water, due to grain absorption.

 

[doug293cz]

That very rigorous calculation only applies if the malt pipe is rigourously centered, exactly central in the boiler body. And both are exactly circular.
I know my BZ isn't, it's oval by at least 3mm.

No, the rigorous equation applies whether the cylinders are concentric or not. Think about removing the smaller cylinder's volume from the larger cylinder's volume - position of the smaller cylinder makes no difference in the resulting volume.

Gee, you used a circular assumption in your calculation too - didn't you? For an elliptical cross section, you would just replace the area for a circle equation with the area for an ellipse equation. If the cross sections aren't nice regular shapes easily described by an equation, then things get a bit more complicated.

Brew on

 

[hungupdown]

S

No, the rigorous equation applies whether the cylinders are concentric or not. Think about removing the smaller cylinder's volume from the larger cylinder's volume - position of the smaller cylinder makes no difference in the resulting volume.

Gee, you used a circular assumption in your calculation too - didn't you? For an elliptical cross section, you would just replace the area for a circle equation with the area for an ellipse equation. If the cross sections aren't nice regular shapes easily described by an equation, then things get a bit more complicated.

Brew on

Sorry, you're quite correct on that.
If only the BZ profiles were exactly circular, the way of calculating the dead space to the exact mL, would be important.

 

[doug293cz]

That, like most of your reply, sounds mostly like verbal diarrhoea.
The wort volume after mashing can never be greater than the strike water, due to grain absorption.

When you dissolve sugar in water the volume of the resulting solution is greater than the volume of water you started with, due to the volume occupied by the sugar in the solution. Same with a mash - the volume of wort in the mash prior to lautering is greater than the volume of the strike water. It is true that the volume collected when lautering is always less than the volume of wort that existed in the mash prior to lautering, and this is due to grain absorption.

Brew on

 

[hungupdown]

When you dissolve sugar in water the volume of the resulting solution is greater than the volume of water you started with, due to the volume occupied by the sugar in the solution. Same with a mash - the volume of wort in the mash prior to lautering is greater than the volume of the strike water. It is true that the volume collected when lautering is always less than the volume of wort that existed in the mash prior to lautering, and this is due to grain absorption.

Brew on

The (possibly correct) figure is that volume increases by 61.7% of the weight of maltose, but there seems to be disagreement on whether the same figure applies to sucrose.

What exactly is grain absorbtion ratio? I've often wondered, but never found any concise answer.

As you point out any sugars extracted will increase the volume after lautering.
So does the amount absorbed (and used in calculating absorbtion ratio) equal:
1) Strike water volume - volume after lautering
2) Strike water volume - volume after lautering - volume increase due to sugars.
(volumes being corrected for temperature)

Case (1) would mean that absorbtion ratio would vary depending on mash efficiency (and sugars extracted).
Case (2), should give the same result, whether you extracted any sugars, or not, (say doing only a cold steep, or you added grain at 80C).

Brewfather grain absorbtion ratio, is just a system wide figure. Which would only give correct results for case (2).

 

[hungupdown]

No, the rigorous equation applies whether the cylinders are concentric or not. Think about removing the smaller cylinder's volume from the larger cylinder's volume - position of the smaller cylinder makes no difference in the resulting volume.

Gee, you used a circular assumption in your calculation too - didn't you? For an elliptical cross section, you would just replace the area for a circle equation with the area for an ellipse equation. If the cross sections aren't nice regular shapes easily described by an equation, then things get a bit more complicated.

Brew on

No, the rigorous equation applies whether the cylinders are concentric or not. Think about removing the smaller cylinder's volume from the larger cylinder's volume - position of the smaller cylinder makes no difference in the resulting volume.

Gee, you used a circular assumption in your calculation too - didn't you? For an elliptical cross section, you would just replace the area for a circle equation with the area for an ellipse equation. If the cross sections aren't nice regular shapes easily described by an equation, then things get a bit more complicated.

Brew on

I knew that my Brewzilla system body was slightly elliptical at the top (though never checked if that was a regular ellipse or not), but is fairly circular at the bottom (though the fist one I'd been sent, was elliptical here, with it's long axis in a different direction).
But I don't know what the average Brewzilla shape is, so it's sensible to keep things clear, by just showing calculations for a circle.
The important thing was to show that there could be around 4.2L of under utilised surrounding water, above top of the malt pipe perforations.
Claiming that your rigorous calculations made some difference, was just added confusion.

What I said was that in this particular case, the difference between the approximate formula that you used (which employed the average diameter of the annular ring space between the basket and vessel) vs. the rigorous formula (using the larger and smaller radii) was small. The larger the difference between the two radii, the larger the error will be when using the approximate formula. ............
The more rigorous math leads to the same conclusion as the previous math: the dead space water not being mixed well with the main wort has a much smaller effect on efficiency than anecdotal reports would lead us to believe.

As your 'rigorous' method of calculating dead water void area, actually gives exactly the same result, as the calculation from circumference that I'd used:

Malt pipe: external dia. 272mm
System body: internal dia. 300mm

diameters (mm)	272​	300​
using areas
radii	136.00	150.00​	​
circle areas	58106.9​	70685.83​
void area (mm2)	12578.94​
using circumference
average diameter (mm)	286​
average circumference (mm)	898.4955​
void width (mm)	14.00​
void area (mm2)	12578.94​

 

[hungupdown]

No, the rigorous equation applies whether the cylinders are concentric or not. Think about removing the smaller cylinder's volume from the larger cylinder's volume - position of the smaller cylinder makes no difference in the resulting volume.

Gee, you used a circular assumption in your calculation too - didn't you? For an elliptical cross section, you would just replace the area for a circle equation with the area for an ellipse equation. If the cross sections aren't nice regular shapes easily described by an equation, then things get a bit more complicated.

Brew on

No, the rigorous equation applies whether the cylinders are concentric or not. Think about removing the smaller cylinder's volume from the larger cylinder's volume - position of the smaller cylinder makes no difference in the resulting volume.

Gee, you used a circular assumption in your calculation too - didn't you? For an elliptical cross section, you would just replace the area for a circle equation with the area for an ellipse equation. If the cross sections aren't nice regular shapes easily described by an equation, then things get a bit more complicated.

Brew on

...........
That's not at all what I said. Lauter efficiency is defined as the mass of sugar (more rigorously extract, which includes all dissolved material - sugar, soluble starch, proteins, lipids, etc.) collected in the BK divided by the mass of sugar created in the mash. Now, if the wort in the mash is homogeneous, and no sparge is done, then the ratio of wort volume in the BK to the wort volume in the mash is equal to the lauter efficiency.

The first case I analyzed assumed the wort was homogeneous at the end of mash (i.e. no effect from the stagnant volume between the basket and vessel.) I did a rigorous calculation of the wort volume at the end of mash (which is higher than the strike volume due to the added volume of the extract in solution) and then used to boil:mash ratio to calculate the lauter efficiency (since the required constraints were met.)

The second case required simplification, since there is no way to know how much diffusional mixing occurs between the stagnant water and the mash wort. So I chose to do a worst case analysis that assumed zero mixing. For this case the effective wort volume at the end of mash would be equal to the wort volume in the first case minus the stagnant volume outside the pipe (which would be just water.) The wort volume collected for boil also needs to be reduced by the volume of stagnant water to account for the stagnant water not contributing any sugar to the boil after lautering. Think of it like this: you have a mash and some water set off to the side. At the end of mash, you lauter and your efficiency is boil wort volume / mash wort volume. Now if you dump the water you had set aside into the boil, the lauter efficiency is not affected because the amount of sugar in the boil is not changed.

Brew on

Your earlier post on the first case, and second case:

............... (first case)​

Volume of wort = 31.22 kg / (0.9982 kg/L * 1.0393) = 30.095 L
Lauter efficiency = 100% * 25 L / 30.095 L = 83%

You don't say, but I assume the above was for 25L of wort collected (as in second case).

How did you arrive at 25L?

Ran your calculations (in Excel), to help me understand them better.

2nd column uses water densities for strike at 65°C, and mashout at 77°C, when lauter effeciency drops around 1%

Rightmost column is your calculations

	20°C	65°C	77°C
DW Density of water kg/L)	0.9982​	0.9805​	0.97346​
	20°C	65°C/77°C
Deadspace (L)	0.0​	0.0​
Dry weight of 4kg grain (kg)	3.84​	3.84​		Dry weight of grain = 0.96 * 4 kg = 3.84 kg
Max extract = dry weight *0.8 (kg)	3.07​	3.07​		Max extract = 0.80 * 3.84 kg = 3.072 kg
Strike water (L)	28.20​	28.20​
Weight of strike water (kg)	28.15​	27.65​		Weight of strike water = 0.9982 kg/L * 28.2 L = 28.15 kg
Wort weight (kg)	31.22​	30.72​		Wort weight = 3.072 kg + 28.15 kg = 31.22 kg
Max °P = 100°P * MaxExtract /WortWeight (°P)	9.84​	10.00​		Max °P = 100°P * 3.072 kg / 31.22 kg = 9.84°P
SG	1.0393​	1.0393​		SG = 1.0393 (interpolated from 1918 Bureau of Standards tables)
Wort volume = WortWeight /(DW * SG) (L)	30.09​	30.36​		Volume of wort = 31.22 kg / (0.9982 kg/L * 1.0393) = 30.095 L
Wort collected (for 25L total) (L)	25.00​	25.00​
Wort retained / absorbed (L)	5.09​	5.36​
Lauter efficiency (wort collected / wort volume)	83.1%​	82.3%​		Lauter efficiency = 100% * 25 L / 30.095 L = 83%

............( 2nd case)


The total liquid volume is 30.095 L in the vessel at end of mash, and 4.3 L of that is water, so we have 30.095 - 4.3 = 25.8 L of wort. We collect 25 L of wort and water when we lauter, but again 4.3 L of that is "plain" water, so actual wort collected is 20.7 L, and we have:

Lauter efficiency = 100% * 20.7 L / 25.8 L = 80%​

Brew on

Taking account of 4.3L deadspace (unused).
Again, lauter efficiency is about 3% less, whichever temperatures you compare.

	20°C	65°C/77°C
Deadspace (L)	4.3​	4.3​
Dry weight of 4kg grain (kg)	3.84​	3.84​
Max extract = dry weight *0.8 (kg)	3.07​	3.07​
Strike water, less deadspace water (L)	23.90​	23.90​
Weight of strike water (kg)	23.86​	23.43​
Wort weight (kg)	26.93​	26.50​
Max °P = 100°P * MaxExtract /WortWeight (°P)	11.41​	11.59​
SG	1.0470​	1.0470​
Wort volume = WortWeight /(DW * SG) (L)	25.77​	26.01​
Wort retained / absorbed (using same amount as in first case) (L)	5.09​	5.36​
Wort collected (wortVolume - wortRetained) (L)	20.67​	20.64​
Lauter efficiency (wort collected / wort volume)	80.2%​	79.4%​
Dilution, from addition of deadspace water (collected / (collected + deadspace)	82.8%​	82.8%​

 

[doug293cz]

I knew that my Brewzilla system body was slightly elliptical at the top (though never checked if that was a regular ellipse or not), but is fairly circular at the bottom (though the fist one I'd been sent, was elliptical here, with it's long axis in a different direction).
But I don't know what the average Brewzilla shape is, so it's sensible to keep things clear, by just showing calculations for a circle.
The important thing was to show that there could be around 4.2L of under utilised surrounding water, above top of the malt pipe perforations.
Claiming that your rigorous calculations made some difference, was just added confusion.



As your 'rigorous' method of calculating dead water void area, actually gives exactly the same result, as the calculation from circumference that I'd used:

Malt pipe: external dia. 272mm
System body: internal dia. 300mm

diameters (mm)	272​	300​
using areas
radii	136.00	150.00​	​
circle areas	58106.9​	70685.83​
void area (mm2)	12578.94​
using circumference
average diameter (mm)	286​
average circumference (mm)	898.4955​
void width (mm)	14.00​
void area (mm2)	12578.94​

Welp, it's time for me to eat some crow. I was incorrect when I claimed that the formula used by @hungupdown to calculate the volume difference between two equal height cylinders with different radii/diameters was approximate and not rigorous. That's what I get for believing my intuition rather than going thru the math. I try to present the best information possible, and I hate it when I get things wrong.

Both of our calculation formulas are rigorous, an produce the same result. Both are valid for all ranges of radii/diameters. I will show below how they are actually equivalent. Feel free to skip the following unless you enjoy the nerdy stuff.

------------------------------------------------------------------------------------------------------------------------------------------

The formula for the volume of a cylinder is:

V = H * pi * R^2, where H is the height of the cylinder, and R is the radius​

​

So, the difference in volume between two cylinders is:

Delta V = V1 - V2 = (H1 * pi * R1^2) - (H2 * pi * R2^2)​

​

If the heights are equal then H1 = H2 = H, and

Delta V = H * pi * (R1^2 -R2^2)​

​

The above is the formula that I used in my analysis in this thread.

The expression a^2 - b^2 can be factored into the expression (a + b) * (a - b), thus the delta V equation above can be factored into:

Delta V = H * pi * (R1 + R2) * (R1 - R2)​

​

The average radius is (R1 + R2) / 2, and the average diameter is the average radius * 2, so the average diameter = R1 + R2. The gap width, if the cylinders are concentric, is R1 - R2. Hungupdown used the following formula for the difference in volume for two cylinders of equal height:

Delta V = H * pi * average Diameter * gap width, or ​

Delta V = H * pi * (R1 + R2) * (R1 - R2)​

Thus the two methods of calculation are equivalent.
------------------------------------------------------------------------------------------------------------------------------------------

I do stand by the rest of what I have written in this thread.

Brew on

 

[doug293cz]

The (possibly correct) figure is that volume increases by 61.7% of the weight of maltose, but there seems to be disagreement on whether the same figure applies to sucrose.

What exactly is grain absorbtion ratio? I've often wondered, but never found any concise answer.

As you point out any sugars extracted will increase the volume after lautering.
So does the amount absorbed (and used in calculating absorbtion ratio) equal:
1) Strike water volume - volume after lautering
2) Strike water volume - volume after lautering - volume increase due to sugars.
(volumes being corrected for temperature)

Case (1) would mean that absorbtion ratio would vary depending on mash efficiency (and sugars extracted).
Case (2), should give the same result, whether you extracted any sugars, or not, (say doing only a cold steep, or you added grain at 80C).

Brewfather grain absorbtion ratio, is just a system wide figure. Which would only give correct results for case (2).

There are actually two different grain absorptions that can be used. The most common is more correctly called "Apparent Grain Absorption" and is equal to strike plus sparge water volume minus the pre-boil volume. The "Apparent Grain Absorption Rate" is equal to total "Apparent Grain Absorption" divided by the grain bill weight. The other one is seldom actually used, and we'll call it "True Grain Absorption" which is equal to the wort volume in the mash at the end of mash plus sparge water volume minus the pre-boil volume. The "True Grain Absorption Rate" is equal to the total "True Grain Absorption" divided by the grain bill weight. Grain absorption doesn't really apply in the case of a fly sparge, if the grain bed isn't completely drained at the end of the sparge.

The true grain absorption is the actual wort volume retained by the spent grain after lautering. However, it is not very useful in brewing calculations. The apparent grain absorption is what you need to know in order to determine how much total water (strike plus sparge) that you need to use in order to hit your target pre-boil volume.

What is used in all brewing software is the apparent grain absorption rate, since that is what they need in order to do required water volume calculations.

Brew on

 

[hungupdown]

Thought it might be interesting, to re do the calculations for efficiency impact of 4.3L deadspace, when using a larger grain bill of 6kg.

Cant work out where doug293cz got 25L collected wort volume came from. So replaced that with calculated amount, by deducting grain absorbtion.

Efficiencies do drop with a higher grain bill.

Efficiencies also drop with a higher apparent grain absorbtion ratio.
If finer crushes have higher absorbtion, due to more surfaces where wort adheres. that might mean that a coarser crush could give better AIO effeciency.

Effeciency is down to under 65%, with 6kg; 1L/kg absorbtion; and deadspace.
Not shown, but at 1.2L/kg, it goes down to 60%.

Again this is for the Brewzilla gen4 35 L. Mash with maximum fill (grain + water to 31L).
Either with 4.3L deadspace, where the water outside the upper (unperforated) malt pipe is not used during mashing. Or with zero deadspace, where outer recirculation (or other form of mixing) is done.

Table shows 4kg / 6kg grain; 0L / 4.3L deadspace; grain absorbtion ratio of 0.8 / 1.0

Lauter Efficiency. Brewzilla gen4 35L with maximum 31L fill
	65°C	77°C
DW Density of water )kg/L)	0.9805​	0.97346​
Grain Weight (kg)	4​	4​	6​	6​		4​	4​	6​	6​
Dry weight grain, assuming 4% moisture (kg)	3.84​	3.84​	5.76​	5.76​		3.84​	3.84​	5.76​	5.76​
Total Strike Water for 31L max fill (L) =31L - GW *2/3 L/kg	28.33​	28.33​	27.00​	27.00​		28.33​	28.33​	27.00​	27.00​
Deadspace (L)	0.0​	4.3​	0.0​	4.3​		0.0​	4.3​	0.0​	4.3​
Volume Strike Water used	28.3​	24.0​	27.0​	22.7​		28.3​	24.0​	27.0​	22.7​
Weight of Strike Water =VSW * DW@ 65°C (kg)	27.78​	23.56​	26.47​	22.26​		27.78​	23.56​	26.47​	22.26​
Max Extract = dry weight *0.8 (kg)	3.07​	3.07​	4.61​	4.61​		3.07​	3.07​	4.61​	4.61​
Wort Weight = WSW + ME (kg)	30.85​	26.64​	31.08​	26.86​		30.85​	26.64​	31.08​	26.86​
Max °P = 100°P * MaxExtract /WortWeight (°P)	9.96​	11.53​	14.83​	17.15​		9.96​	11.53​	14.83​	17.15​
SG =1+(Plato/(258.6-((Plato/258.2)*227.1)))	1.040​	1.046​	1.060​	1.070​		1.040​	1.046​	1.060​	1.070​
Wort volume = WortWeight /(DW@77°C * SG) (L)	30.48​	26.15​	30.11​	25.78​		30.48​	26.15​	30.11​	25.78​
Wort collected (for 25L total) (L)	25.00​	20.70​	25.00​	20.70​		25.00​	20.70​	25.00​	20.70​
Grain Absorbtion Ratio (L/kg)	0.8​	0.8​	0.8​	0.8​		1.0​	1.0​	1.0​	1.0​
Wort retained / absorbed (L) = GW *GAR	3.20​	3.20​	4.80​	4.80​		4.00​	4.00​	6.00​	6.00​
Wort collected	25.13​	20.83​	22.20​	17.90​		24.33​	20.03​	21.00​	16.70​
Lauter efficiency (wort collected / wort volume)	82.5%​	79.7%​	73.7%​	69.4%​		79.8%​	76.6%​	69.7%​	64.8%​
Dilution, after mixing in deadspace water	100%​	83%​	100%​	81%​		100%​	82%​	100%​	80%​

 

[doug293cz]

Cant work out where doug293cz got 25L collected wort volume came from

I used the data that you used in this post as the inputs for my calculations

Here's the line from that post that says the amount of wort collected was 25 L:

"If all the water was utilised during mashing, then on draining and getting 25L:"​

​

Brew on

 

[hungupdown]

I used the data that you used in this post as the inputs for my calculations

Here's the line from that post that says the amount of wort collected was 25 L:

"If all the water was utilised during mashing, then on draining and getting 25L:"​

​

Brew on

It was good to see your workings explained, A nice method.

 

[hungupdown]

Updated Brewzilla void volume calculation.
The deadspace volume, from above malt pipe perforations, to 31L fill, is 4.6L

Brewzilla gen4 35L
Void area - outside malt pipe (mm2)	12579​
Water level rise (mm /L)	14​
Top of malt pipe perforations, is at fill level (L)	5​
Fill (L)	31​	30​	28​	26​	24​	22​	20​	18​	16​
Deadspace (L)	4.6​	4.4​	4.1​	3.7​	3.3​	3.0​	2.6​	2.3​	1.9​

 

[Beekeeper]

Thanks to @kohalajohn for this level of detail, but I think I'll push the big "ignore" this thread button.
Y'all have fun, but I have completely lost interest in seeing any more on this topic.

 

[hungupdown]

Efficiency calculations, with corrected 4.6L deadspace.
This brings efficiencies down, if deadspace water not utilised (non zero deadspace values in table).

Effect of deadspace outside malt pipe, on Lauter Efficiency.
Brewzilla gen4 35L with maximum 31L fill	Deadspace (above lower perforations) = 4.6L
	65°C	77°C
DW Density of water )kg/L)	0.9805​	0.97346​
Grain Weight	4​	4​	6​	6​		4​	4​	6​	6​
Dry weight grain, assuming 4% moisture (kg)	3.84​	3.84​	5.76​	5.76​		3.84​	3.84​	5.76​	5.76​
Total Strike Water for 31L max fill (L) =31L - GW *2/3 L/kg	28.33​	28.33​	27.00​	27.00​		28.33​	28.33​	27.00​	27.00​
Deadspace (L)	0.0​	4.6​	0.0​	4.6​		0.0​	4.6​	0.0​	4.6​
Mash Strike Water	28.3​	23.8​	27.0​	22.4​		28.3​	23.8​	27.0​	22.4​
Weight of Strike Water =MSW * DW@ 65°C (kg)	27.78​	23.29​	26.47​	21.98​		27.78​	23.29​	26.47​	21.98​
Max Extract = dry weight *0.8 (kg)	3.07​	3.07​	4.61​	4.61​		3.07​	3.07​	4.61​	4.61​
Wort Weight =WSW + ME (kg)	30.85​	26.36​	31.08​	26.59​		30.85​	26.36​	31.08​	26.59​
Max °P = 100°P * MaxExtract /WortWeight (°P)	9.96​	11.65​	14.83​	17.33​		9.96​	11.65​	14.83​	17.33​
SG@20°C =1+(Plato/(258.6-((Plato/258.2)*227.1)))	1.040​	1.047​	1.060​	1.071​		1.040​	1.047​	1.060​	1.071​
Wort volume = WortWeight /(DW@77°C * SG) (L)	30.48​	25.87​	30.11​	25.50​		30.48​	25.87​	30.11​	25.50​
Grain Absorbtion Ratio (L/kg)	0.8​	0.8​	0.8​	0.8​		1.0​	1.0​	1.0​	1.0​
Wort retained or absorbed (L) = GW *GAR	3.20​	3.20​	4.80​	4.80​		4.00​	4.00​	6.00​	6.00​
Wort collected	25.13​	20.55​	22.20​	17.62​		24.33​	19.75​	21.00​	16.42​
Lauter efficiency (wort collected / wort volume)	82.5%​	79.5%​	73.7%​	69.1%​		79.8%​	76.4%​	69.7%​	64.4%​
Dilution, from mixing in deadspace water	​	18%		21%			19%		22%

 

[doug293cz]

I think the important take-away after all the nerdy analysis, is that if the stagnant water volume in an AIO system is less than about 15% of the total liquid volume, the loss of efficiency, just due to the stagnant volume effect, is small, and will not cause large losses of mash efficiency (even tho there is a real effect.)

Brew on