# BTU's generated during primary fermentaion



## Fred1 (Oct 11, 2006)

We are trying to design a cooling system that will automatically keep the temperature during the primary fermentaion stage within the desired range. The concept is similar to the cooling coils that are commercially avaialble except the plan is to have an open loop system with tap water circulated through the coil.


The current obstacle to completeing the design is calculating the BTU's generated by the fermentation process. Any pointers on where to find such information would be apreciated.


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## Dean (Oct 11, 2006)

Tough question, however, I don't think that you will easily find an answer as different yeast strains, coupled with differing levels of sugar, temperature rates, etc, will all contribute to the BTUs created during fermentation. 

If I start with a large starter, I have a colony that will generate much more heat at once than a slower starting yeast. How about build a regulator that adjusts water flow based on a temperature probe inside the wine to keep the wine at a user programmable optimum temperature? I know I'd like to ferment non-kit whites at about 58F and Reds at about 74F with a cap temp up to 84F. But I'd like to set those optimum temps myself, and for that, you'd need to restrict the water flow with some sort of actuator. Just thoughts though, and I don't know what ideas you have for the unit.


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## rshosted (Oct 11, 2006)

what if you took a constant flow of water, but rather than change the flow you change the temperature of water in a recyclable sealed system. So if the probe in the wine comes up too high then a compressor could turn on and cool the water down, or heat it up.

Actually a better idea is using a peltier system. Thus you don't have a compressor and it can heat or cool as needed with the same system. Since you will need electricity anyway, you could use the peltier system to heat or cool the wine. 
Furthermore, peltier systems are very energy efficient and since most wines take 12-24 hours to settle before one adds yeast it would have enough time to get the juice to a suitable starting temperature. 

If you really wanted to get very high tech, you could have two thermostats that use a CPU to controll the temperature. one could be measuring the water at 'intake' into the wine cooling/heating system and the other at the 'exit'. It could determine the difference in temperature and make changes via heating or cooling respectively. 

This has great potential for the home winemaker, with the fact that you could ultimately use the CPU for a large number of testing references and effectively have it measure CO2 ouput. Thus you could actually graph out a 'fermentation curve' with the CPU and have wines start quicker, take longer to ferment (enjoy more contact time with certain strains of yeast) and know when they are done. It could also keep track of alcohol content and raise or lower the temp to stop the process when the winemaker hits their target ABV or sugar level.

Oh crap, my wine glass is empty. Hold on while I program my robot dog to go get me another glass....






Awesome idea, Let us know what you find out. (though, I will admit we seemed to hijack your post from what you intially wanted it to be).

Okay back to what you asked: I think it would depend. I would suspect that different juices/sugar levels have a different heat transfering rate. Therefore depending on the yeast strain, level of yeast actually used to innoculate, and the stage of fermentation that number could change a lot. I would suggest you test with some sugar water vs yeast. set up a program that logs the temperature changes and ambiant temp and it should give you a reasonable baseline. 

Ok I'll stop now, before I hurt myself with another bad idea. 

Cheers,
-Ryan


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## Funky Fish (Oct 12, 2006)

How big of a fermentation are you talking about? If it's just a 6 gallon batch, why don't you putit in a temperature-controlled environment? Like, get an old fridge cheap, an external thermostat, and control the temperature of the fermentation that way?


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## Fred1 (Oct 16, 2006)

Dean
We appreciate that there are many variables involved in the fermentaion process. We are, however, looking for an oirder of magnitude estimate for what the water flow rate will have to be for the systems we are considering.


Currently we have a pipe within a pipe system with the outer pipe about 18" in length and made of stainless steel. We also have a control switch that is connected to a stainless steel temperature probe. A valve is opened when the selectable temperature set point on the control valve is exceeded. This allows cold tap water (about 56 degrees) to flow through the system.


We are also considering a "water jacket" approach; basically immersing the 55 gallon primary fermentaion drum in another container having cold water in it.


The former tube within a tube approach takes up less space but may be less efficient at removing heat.


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## Fred1 (Oct 16, 2006)

This year we fermented (2) 55 gallon containers that had about 45 gallons of liquid and skins in them plus about 35 gallons of white grape juice. 
Fred


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