FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
Digest Janitor: pbabcock at hbd.org
***************************************************************
TODAY'S HOME BREW DIGEST BROUGHT TO YOU BY:
Sponsor The Home Brew Digest!
Visit http://www.hbd.org/sponsorhbd.shtml to learn how
Support those who support you! Visit our sponsor's site!
********** Also visit http://hbd.org/hbdsponsors.html *********
DONATE to the Home Brew Digest. Home Brew Digest, Inc. is a
501(c)3 not-for-profit organization under IRS rules (see the
FAQ at http://hbd.org for details of this status). Donations
can be made by check to Home Brew Digest mailed to:
HBD Server Fund
PO Box 871309
Canton Township, MI 48187-6309
or by paypal to address serverfund@hbd.org. DONATIONS of $250
or more will be provided with receipts. SPONSORSHIPS of any
amount are considered paid advertisement, and may be deductible
under IRS rules as a business expense. Please consult with your
tax professional, then see http://hbd.org for available
sponsorship opportunities.
***************************************************************
Contents:
Re: Slaking heat (bill keiser)
simple(ish) way to account for slake heat (Matt)
* * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* The HBD Logo Store is now open! *
* http://www.hbd.org/store.html *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Beer is our obsession and we're late for therapy! *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * *
NOTE: With the economy as it is, the HBD is struggling to
meet its meager operating expenses of approximately $3400
per year. If less than half of those currently directly
subscribed to the HBD sent in a mere $5.00, the HBD would
be able to easily meet its annual expenses, with room to
spare for next year. Please consider it.
As always, donors and donations are publicly acknowledged
and accounted for on the HBD web page. THank you
Send articles for __publication_only__ to post@hbd.org
If your e-mail account is being deleted, please unsubscribe first!!
To SUBSCRIBE or UNSUBSCRIBE send an e-mail message with the word
"subscribe" or "unsubscribe" to request@hbd.org FROM THE E-MAIL
ACCOUNT YOU WISH TO HAVE SUBSCRIBED OR UNSUBSCRIBED!!!**
IF YOU HAVE SPAM-PROOFED your e-mail address, you cannot subscribe to
the digest as we cannot reach you. We will not correct your address
for the automation - that's your job.
HAVING TROUBLE posting, subscribing or unsusubscribing? See the HBD FAQ at
http://hbd.org.
LOOKING TO BUY OR SELL USED EQUIPMENT? Please do not post about it here. Go
instead to http://homebrewfleamarket.com and post a free ad there.
The HBD is a copyrighted document. The compilation is copyright
HBD.ORG. Individual postings are copyright by their authors. ASK
before reproducing and you'll rarely have trouble. Digest content
cannot be reproduced by any means for sale or profit.
More information is available by sending the word "info" to
req@hbd.org or read the HBD FAQ at http://hbd.org.
JANITORs on duty: Pat Babcock (pbabcock at hbd dot org), Jason Henning,
and Spencer Thomas
----------------------------------------------------------------------
Date: Tue, 03 Mar 2009 07:26:27 -0500
From: bill keiser <bk2 at sharpstick.org>
Subject: Re: Slaking heat
i've never seen this done, but can you pour out a couple quarts every
few minutes, reheat with a double boiler or microwave to strike temp and
pour back in to keep the temp flat during mash?
this would be doable for those of us primitive brewers who are using an
old hacked up cooler instead of a fancy brew sculpture.
bill keiser
> . . . if heat is generated during the mash, then
> we should somehow be taking this into account in our calculations of
> strike water temperature.
>
> Fred L Johnson
> Apex, North Carolina, USA
>
------------------------------
Date: Tue, 3 Mar 2009 08:59:50 -0800 (PST)
From: Matt <baumssl27 at yahoo.com>
Subject: simple(ish) way to account for slake heat
I think the following may be the simplest way to include slake
heat in mash temp equations. (BTW I haven't been academically
precise with physical definitions and units. Note also that slaking
heat of course only applies to the first infusion, in which dry malt
is hydrated.)
Any decent existing mash temp equation already has a term (we'll
call it "A") that accounts for initial heat that the dry grain brings
to the table. This'll look something like
A = grain_mass * grain_heat_capacity * temp_of_grain.
(In Bill's version this is the term Tg*0.4*Wg.) However, the grain
also brings extra "slaking heat" to the table as it gets hydrated.
The total heat the grain brings is then
B = ( grain_mass * grain_heat_capacity * temp_of_grain )
+
( grain_mass * grain_heat_of_hydration )
To account for slaking heat we might just replace A with B in our
equations, but it may be more simple/practical if we re-arrange B:
B2 = grain_mass * grain_heat_capacity *
( temp_of_grain + bonus_slake_temp)
where we've invented a "bonus_slake_temp" with units of temperature.
This technically equals grain_heat_of_hydration divided by
grain_heat_capacity -- the amount by which the slaking heat
would increase the temp of the dry grain itself. An approach to
finding the value of bonus_slake_temp on a given system is below.
THE POINT IS THAT THE EFFECT OF SLAKE HEAT CAN BE ACCOUNTED FOR BY
JUST ADDING A LITTLE "BONUS" TO THE INITIAL DRY GRAIN TEMP. One
could do this even with existing computer implementations
(spreadsheets, promash) that don't explicitly address slaking heat.
Thus we have two "fudge factors": mash tun thermal load and "bonus
slake temp". These can BOTH be calculated for a given system, based
on a single mash that includes two infusions (such as a single
infusion to 150F, plus a mashout infusion) as long as we carefully
record the volume and temp of water, and initial and final mash
temp, for each infusion.
To calculate the fudge factors we'd start with the second infusion:
slaking heat is not a factor there so the "mash tun thermal load"
can be found on its own. Then, with knowledge of the mash tun
thermal load, we'd tackle the first infusion and find the value of
bonus_slake_temp that makes the calculation match reality. I won't
go into the math--if you've bothered to read this far you're surely
geeky enough to do it on your own.
Simple methods with a single fudge factor are certainly good enough
to work well in a narrow operating range (say, for single infusions
near 150F). That's what I do and I'm happy with it. But they
don't work as well for step mashes with protein rests and I'd wager
this two-fudge-factor method would work a lot better. I haven't
tried it but I will.
Matt
------------------------------
End of HOMEBREW Digest #5517, 03/03/09
*************************************
-------
