btu generated during fermentation?

[pilotdane]

Does anyone know how many btu is generated when fermenting an average gravity ale? I know there are many variables but I'm looking for a general number. How much heat needs to be removed from the fermentor during active fermentation to hold a stable temperature?

 

[gallagherman]

I'd be impressed if anyone posts the thermodynamic math for this. I am sure that many different things come into play. Fermentation activity is never constant; it picks up rate very quickly at the beginning and then peaks and slowly slows down. Throughout the time the heat energy released is different. you'd also have to think about strain specific characteristics. Also the OG and FG of the wort, because different densities of fluid have differnt heat capacities. Too many things. Making head hurt. Maybe thats my homebrew. Just get a fridge and a temp controller!

 

[ClaudiusB]

If I remember correctly, each kg of fermentable extract produces 580kJ (580kWs) of heat energy.

Cheers,
ClaudiusB

 

[ClaudiusB]

Lets assume we have 5 gallon (18.93 liters) im fermenter with a SG of 10% Plato.
10% P = 1.89 kg extract and 1.42 kg is fermentable (assuming 75% of 1.89kg)

823.6 kJ (823.6 kWs) heat has to be removed over the fermentation time.

Cheers,
ClaudiusB