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	FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
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Contents:
  Re: efficiency ("steve.alexander")
  And another thing ! ("steve.alexander")
  Efficiency ("Chad Stevens")
  Grain Bill and Colour (Alexandre Enkerli)
  re: Hydrometers, Batch Sparging efficiency ("Mike Dixon")


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Date: Sat, 01 Oct 2005 03:44:29 -0400
From: "steve.alexander" <-s at adelphia.net>
Subject: Re: efficiency

Ricardo Cabeza arrived at essentially the correct
solution on the efficiency issue under the 
assumption that equilibrium is reached.  *If* you
sparge forever, then a continuous sparge collects
5-7% more of the extract into the boiler.

I have microscopic differences w/ Chad in the details of
his analysis;  The extract has unaccounted volume, there
is no need to calculate mass, since we are only interested
in %effic, the 65% assumed efficiency already includes
the sparge inefficiency, and some guys named Cauchy &
Riemann have a much cleaner means of assessing the
continuous case than any Microzaftig Excel sheet could
ever produce [fergawdsakes Chad, at least exercise your
HB frugality and use the free OpenOffice suite].

The problem is this - reaching equilibrium doesn't
happen in a real-world sparge where sparge time is
limited.  I haven't run the numbers, but the direction
of this correction is clear; batch isn't even as bad
as Chad calculates.

Diffusion of the extract from the grist to the wort
takes time, and the rate of diffusion is dependent
on the difference in the concentrations, well
actually the concentration gradients overall, and
so we expect the rate of extraction to fall as the
wort-to-grist gradient drops.  When time is limited
the extraction is stopped, but that terminal rate
of extraction (the amount of extract lost by limiting
time) isn't the same for batch vs sparge. 

If we perform a batch vs a continuous sparge over the
same fixed amount of time, then the batch will approach
equilibrium more closely for each batch, (but at a
higher SG, so a bit less efficiently as Chad's calc
shows).  For the fixed time period continuous sparge,
there is less time to approach equilibrium, so there
is a relatively greater efficiency drop for continuous
as time is reduced.

In all, if we limit the amount of *time* available 
for the sparge, then that 5-7% advantage for
continuous will decrease and MAY even become
negative(advantage to batch) in the extreme case.
To do a proper analysis would require a numerical
quantization of the diffusion.  I have hopes that
John Palmer will weigh in on this topic.

I will point out that Chad's numbers are very good HB
values for the water/sparge/grist ratios, however
traditional commercial UK ale brewing uses more sparge
water, up to 9 US gallons total water for the 10lbs !
And this will be used over 3, and possibly ever 4
cycles (first runnnings + 2 or 3 sparges!).

Batch vs Continuous is a pointless argument - you
can get very good efficiency with either, efficiency
so high that your beer flavor will suffer !   I
know - I used to seek that extraction efficiency
grail; nowadays I seek better flavor, so I try to limit
my efficiency.

 -S








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Date: Sat, 01 Oct 2005 04:26:51 -0400
From: "steve.alexander" <-s at adelphia.net>
Subject: And another thing !

Special thanks to Fredrick for noting the recent JIB archives
are open again.  They had been for a couple years, then they
were closed - so three cheers.

If anyone thinks the brewing science articles are irrelevant
should take a look at the most recent issue of JIB where there
is an article on mash viscosity which has relevance to the
discussion of extraction efficiency.

For many years I have preached the your HB books are wrong
and that the increased temperature of mashout has a negligible
impact on mash viscosity.   There are graphs to prove it in
the several articles on mash rheology.

http://www.scientificsocieties.org/jib/contents/current.htm

 -S





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Date: Sat, 1 Oct 2005 09:05:22 -0700
From: "Chad Stevens" <zuvaruvi at cox.net>
Subject: Efficiency

Ms. Burley (You're always calling us females - brewsters - despite 90% of
HBD BREWERS being male   ;o) you just had to throw down the gauntlet....

You can talk all the theory you want to, but for ME, in MY system, with the
various methods and widgets for fly sparging I've tried over the years (and
I realize at 18 years and a few hundred batches, my experience doesn't count
for squat on this page) my efficiency is consistently lower with fly
sparging than with batch sparging; fly = mid 60's to low 70's, batch = low
80's.  And the efficiency I get with batch sparging is more consistent.
Just dump the water in, mix, let it sit for ten minutes, run it off.
Simple, no muss, no fuss.

You can talk all the theory you want to, but I know from experience what
works best in my system.

For what it's worth (I still love ya man!),

Chad Stevens
QUAFF
San Diego



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Date: Sat, 1 Oct 2005 12:41:08 -0400
From: Alexandre Enkerli <enkerli at gmail.com>
Subject: Grain Bill and Colour

Already sent a private message to Darrell about this but maybe it could 
be discussed here.

Darrell was asking about using
> the pils so as to get the lightest (if you want it), and use dark 
> malts to add color and flavor

It might not be what he had in mind but it reminded me of the practice 
of some brewers (including pros) who add rather large amounts of very 
dark malts to a grain bill which would produce a rather pale beer 
instead of using the whole palette of malt types with just a touch of 
darker grains. Randy Mosher's /Radical Brewing/ contains 
recommendations on developing complex grain bills and it's hard to 
disagree with him that such a grain bill provides depth and complexity.
Tried a few porters recently and they all tasted like a bunch of very 
dark malts were added to the base malt with nothing in between. These 
beers often have a rather harsh roasty character instead of a round 
overall maltiness with roasty highlights. Can't say these beers are 
incredibly interesting. Those brewers may have gotten the colour right, 
but they might as well put food colouring in a pale ale.
Of course, it's cheaper to dump roasted barley in the wort than to mash 
many different grains, which might be a reason why some breweries use 
so much dark malt.
It's harder to control a complex grain bill. But different malts can 
contribute a lot to the finished product, including mouthfeel, depth, 
and complexity. Some malt flavours may hide other flavours but, more 
interestingly, some combinations produce a completely new flavour which 
couldn't be achieved any other way. In fact, even hop-heavy beers can 
benefit from a complex grain bill. The malt flavours complement the hop 
flavours instead of competing with them.

Thoughts?

Alexandre
http://dispar.blogspot.com/
http://www.livejournal.com/users/enkerli/
http://blog.criticalworld.net/



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Date: Sun, 2 Oct 2005 14:09:18 -0400
From: "Mike Dixon" <mpdixon at ipass.net>
Subject: re: Hydrometers, Batch Sparging efficiency

In a previous digest Ricardo Cabeza demonstrated a mathematical calculation
for batch sparging and an excel sheet output he uses for fly sparging.

The biggest problem with the calculation was Chad calculated batch sparging
on a no-sparge process.  All water added to the tun in one large quantity.
A batch sparge process would add sparge water in batches, or more than one
addition, most times people do TWO batches.  The calculation was not
performed for that, and other than through experience I am not sure how it
could be.

Now as far as batch sparging creating a greater efficiency than fly
sparging, that would only be possible if the fly sparging process was
channeling at some point during the sparge or if the fly sparging process
was performed too fast for the sugars to be rinsed from the grains.  Both of
which could certainly be the case.

I have not batch sparged enough to see a definitive increase or a decrease
in efficiency as compared to my fly sparging efficiency.  However the beauty
of batch sparging for the homebrewer as I see it, is the ability to obtain
the wort as fast as the valve and plumbing on your tun will allow during and
after the vorlauf.  It also does not allow channeling so a single outlet
filter point is all that is required due to the homogenous nature of the
tun.

One final note would be from Chad's later posting in point #2 about most
homebrewers using Phil's sparge arm. No offense to Dan, but it is certainly
not required to perform a fly sparge and I know very few people that use
one. Just perf up some foil, place it on top of the grainbed and sparge
away. If the homebrewer than changes the batch sparging the foil idea can go
along for the ride...

Cheers,
Mike Dixon
Wake Forest, NC
www.ipass.net/mpdixon



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