brewtarget-devs team mailing list archive

[Philip Lee <rocketman768@xxxxxxxxx>]

Welcome Tim!

You are right about the can of worms. Storing multiple efficiency numbers
definitely sounds like a good idea to me, and adjusting loss/efficiency
numbers for recipe ingredients could be interesting.

On Fri, Mar 8, 2013 at 3:21 PM, Tim Payne <swstim@xxxxxxxxx> wrote:

> Efficiency is indeed a can of worms.  BeerSmith picks the nit by reporting
> two efficiencies - mash efficiency (conversion + lauter or to-the-kettle)
> and total brewhouse efficiency (to-the-fermentor).  But as you mention
> BeerXML uses "total brewhouse efficiency" in the recipe/equipment
> definitions.  I think the typical way of calculating here is all
> fundamentally flawed - efficiency is a function of both the equipment and
> the recipe; trub loss can be significantly higher with a high hop load if
> you filter before the fermentor (needed with plate chillers) or use leaf
> hops.  Also lauter efficiency varies with OG and sparge method.  This is a
> hot button issue for me and it's one of the top items on my personal todo
> list to try to rectify, or at least decouple the issues somehow.
>
> Just off the top of my head I propose adding equipment parameters for
> "mash efficiency", "vol loss per pellet hop oz/g", "vol loss per leaf
> oz/g", and maybe "mash efficiency loss per OG point".  Existing trub loss
> would be a constant across recipes and would be chiller/deadspace/break
> loss.  Zeroing the loss fields would keep things the same for the folks who
> don't filter anything or just don't care.  I will add a blueprint for this
> soon.
>
> Adding more confusion is that definition of "brewhouse efficiency" varies
> depending on who you talk to.  There's a bit of discussion here:
> http://braukaiser.com/wiki/index.php?title=Understanding_Efficiency and
> there's lots more if you search homebrewtalk.  So, I like to use "total
> brewhouse efficiency" to clarify when possible.
>
> Tim
>
> PS Hey all, another new guy here.
>
> On Fri, Mar 8, 2013 at 8:43 AM, Philip Lee <rocketman768@xxxxxxxxx> wrote:
>
>>
>>
>> On Thu, Mar 7, 2013 at 9:12 PM, mik firestone <mikfire@xxxxxxxxx> wrote:
>>
>>> In a small word, the brewnote efficiency calculations are rather messed
>>> up. I'm using the postboil gravity when I should be dealing with the
>>> preboil. I'm trying to unwind this right now but I keep running into weird
>>> things.
>>>
>>> I am specifically looking at Recipe::recalcBoilGrav() and trying to
>>> figure out why the boil gravity (aka, SG) is worried about trub/chiller
>>> losses. Trub/chiller loss shouldn't have anything to do with the preboil
>>> gravity, should it?
>>>
>>
>> You'd think it wouldn't have anything to do with it. However, there is a
>> nit to be picked...
>>
>> BeerXML says the recipe efficiency is brewhouse efficiency, which is
>> "to-the-fermentor" efficiency. Meaning, if I have 5.00 kg grain with 76%
>> yield (3.80 kg sugar), and my brewhouse efficiency is 70%, I get 5.00 kg *
>> 0.76 * 0.70 = 2.66 kg into the fermentor. Now, how would you go about
>> finding how much sugar is in the kettle? Since the recipe's efficiency is
>> "to-the-fermentor", we can't use that number directly; we need
>> "to-the-kettle" efficiency. Since you are always losing some amount of
>> sugar at each step of the brewing process, it must be the case the your
>> "to-the-kettle" efficiency is somewhat higher than your "to-the-fermentor"
>> efficiency. How much more?
>>
>> eff_tokettle = eff_tofermentor / (1 - trubChillerLoss/finalVolume)
>>
>> To extend the previous example, suppose my final volume is 20 L and I
>> lose 1 L in the transfer from kettle to fermentor.
>> eff_tofermentor = 0.70
>> trubChillerLoss = 1 L
>> finalVolume = 20 L
>>
>> sugar_kettle = 2.66 kg / (1 - 1L/20L) = 2.80 kg (73.7% efficiency to
>> kettle)
>> sugar_lost = 1L/20L * 2.80 kg = 0.14 kg
>> sugar_fermentor = 2.80 kg - 0.14 kg = 2.66 kg (70.0% efficiency to
>> fermentor)
>>
>> I highly doubt any other software is picking this nit, but it definitely
>> exists. You can see for this typical example that all your OG-related
>> numbers would be off by about 4% if you don't calculate the kettle
>> efficiency to be different from the brewhouse efficiency.
>>
>> --
>> Philip G. Lee
>> rocketman768@xxxxxxxxx
>>
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-- 
Philip G. Lee
rocketman768@xxxxxxxxx