ABV Calculation and Chiller/Trub losses

[infinus]

Is it just me or is there an error in the ABV calculation when taking into account chiller/trub losses?

Example A (closer to my normal setup).
Set batch size to 5.5 gallons
Total Mash water is 9.76 gallons.
Set chiller/trub losses to .3
Fermenter losses set to .5 gallons (Was playing with this number and didn't mean to leave it high but doesn't matter for this example).
Bottling volume comes out to 5.0 gallons. ABV estimate from beer smith for the given recipe has an OG of 1.077.

Example B:
Set batch size to 5.8 gallons
Total Mash water is 9.76 gallons.
Set chiller/trub losses to 0.
Fermenter losses set to .5 gallons (Just the numbers I was playing with).
Bottling volume comes out to 5.3 gallons. ABV estimate from beer smith for the given recipe has an OG of 1.073.

End of the day, both examples use the SAME grain amount and SAME water amount. In Example A I declare that I lose volume POST boil in the kettle/chiller, in example B says it all makes it out as end product. How in the world does this change the ABV? Shouldn't the ABV be calculated on total wort produced? How does "losing" some of your wort to your equipment RAISE the ABV (or OG)? Both example are producing the exact same amount of wort post boil.

[Oginme]

BeerSmith does the calculation of gravity based upon your brewhouse efficiency which is the amount of potential sugars from the grain which make it to the fermenter.  Given this, when you change the volume of wort going to the fermenter without changing the brew house efficiency, it means that you are in effect telling the model that you have the same amount of sugar but a greater amount of water.  This will result in the program calculating out a lower OG target. 

The model relies on the user inputting the proper variables into the equipment profile.  When you change just one of those variables without calculating how that changes the other variables, you change how the model calculates everything out.  Basically, you create a garbage in-garbage out scenario with your equipment profile.

[infinus]

Well that's an interesting view point on the design of the software. I can't strictly disagree, it's certainly one way to approach it. But in the scale of creating an equipment profile I can measure all of the steps and input losses for each step to a very precise value. Shouldn't the BH efficiency then be calculated off of those measurements? Why is it then left to the user to enter in an arbitrary scaling percentage to then match the output? I'd rather have it so I can measure gravity post mash and enter in my mash efficiency (since that can be measured) instead of having that be the item beer smith "estimates", then have the software calculate (or estimate) for me my brew house efficiency. If I notice an incorrect measurement in my equipment profile and tweak it, by what you are saying I then have to re-baseline my BH efficiency for any of those numbers to actually make real world sense. That seems like the entire point of the software doesn't it? If I increase the measured loss in a piece of equipment shouldn't BS lower my brew house efficiency?

I'm not trying to be argumentative, the way you stated it is certainly one way to do it. I just don't necessarily agree with the method there. But alas that's just me.

Cheers,
Mike

[Oginme]

Shouldn't the BH efficiency then be calculated off of those measurements?

Why is it then left to the user to enter in an arbitrary scaling percentage to then match the output?

I'd rather have it so I can measure gravity post mash and enter in my mash efficiency (since that can be measured) instead of having that be the item beer smith "estimates", then have the software calculate (or estimate) for me my brew house efficiency.

If I notice an incorrect measurement in my equipment profile and tweak it, by what you are saying I then have to re-baseline my BH efficiency for any of those numbers to actually make real world sense. That seems like the entire point of the software doesn't it?

If I increase the measured loss in a piece of equipment shouldn't BS lower my brew house efficiency?

Mike,

Responding to your questions from your response above:

Modeling the brewing process gives us two open material loops which must be solved.  The first material balance is volume, which requires at least one variable to be defined by the user.  In this case it is the volume to the fermenter.  The second material volume is the sugars.  To do this the user must either define the amount extracted when measuring at the beginning of the process (mash efficiency) or at the end of the process (brew house efficiency).  In this instance, the designer chose the brew house efficiency.

The choice of brew house efficiency is hardly arbitrary.  It may be a calculated guess when you first enter in your process into the software, but when the user spends the time and little effort to calculate the values to ensure the validity (or even just use the calculated value BeerSmith gives you on the 'session' tab) then it can be dialed in for that specific balance of volumes as defined by the equipment profile.

I, too, would like to use mash efficiency as my defined sugar extraction variable.  But I do not write the software nor produce the model.  In the end, either model is valid for solving the open-ended equations.

As for noticing a poor reading or estimation used for your equipment profile, this is one of the reasons I have stated many times on this forum that the user should keep track of the losses and efficiencies over several brews before locking down their equipment profile.  The software is just a set of equations and not an AI.  It does not draw any conclusions from your entered values in comparison to the targets.  It was on my wish list in the suggestions forum to have the 'vols' tab list both the target and measured values for each of the critical parameters in the equipment profile so that the user can discern if the equipment profile does need adjustment or if one of the readings is in error.  Hopefully, Brad will look to add this soon, since it is only an output of current values which are already input by the user for both the modeled and the actual readings.

Having the software automatically readjust your BHE in response to you changing a parameter outside of the equipment profile could be done, but the software does not think or recognize the intent of the user an since the BHE is one of the user defined values, there is no basis to make any adjustment within the software.  The software trying to adjust a user defined variable is a quick way for the software to get into an infinite loop which would cause the software to crash.

[infinus]

Thanks for that response, that's a great reply. I agree and concur, this is the logic path I went down last night. It really would be great for solving equipment issues as well as other brewing "mistakes" to have predicted values for everything. There are a lot of numbers that can be well modeled based on the information we know. I started creating a companion spread sheet to go with my beer smith recipes that will give me expected values for most of the steps and allow me to compare and contrast what I actually get and fill into the session tab and against my equipment profile to try and correct errors. Theoretically I can even predict mash efficiency fairly well since I do a full volume mash with no sparging. It's simply a factor of conversion efficiency which is usually consistent and how much water in/water out (absorption + evaporation) happens during the mash. Assuming the recirculation gets all of the water to a homogenous sugar state the numbers work out fairly well. It'd be great to see the introduction of a dynamically modeled mash efficiency target number for people that do this as well. On my spreadsheet I calculate the maximum theoretical plato I can get out of a bed of grain and then based on conversion efficiency a best guess as to what I will get. Honestly it comes out pretty close every time.

Thanks for the insights and discussion.

[Oginme]

I have a spreadsheet broken down with every process and batch size I have brewed.  So far, it is almost 300 brews which have been recorded, so I can track changes in process and the parameters (and variability - process or measurement induced) required for the equipment profile to function properly.  This allows me to see when something has gone astray.

Once a process engineer, always a process engineer.