"the Old Chestnut" Where To Stick Your Probe. .. And Other N

[michael_aussie]

I happen to have an interest in control systems and temperature measurement, so I've gone the extra mile in measuring fermenter temperatures.

A ferment that "takes off" produces a lot of heat.
If any of your beer-master know how I can calculate exactly how much I'd like to know.

I ferment 3 batches at a time. For two of the fermenters, I have digital temperature sensors (about $2 each from ebay) pressed against their sides and insulated from the air, to display the temperature of two of the fermenters. The third fermenter has the probe of my STC1000 pressed, also against its side and insulated from the air. A fourth sensor is reading the air temperature of the fridge. If I'm lucky and all three fermenters "ramp up" at the same rate, then they stay in a close temperature band (roughly 1 degree). They can be 6 degrees hotter than the air temperature. However, if one lags or takes off more than the others, then the three fermenters all in the same air space can vary by 4 or 5 degrees.

I've found the best way to avoid these wide differentials is to have the starting temperatures of the 3 fermenters as even as possible =a hot one will take off, and the others take days to catch up ... where a "cold" one will take days to catch up. Also, staggered starts result in the "new" fermenter running hot, as the air temperature that a "nearly finished" fermenter needs is higher than the air temp a "hot starter" needs.

About a year ago someone started a thread where they were going to set up and continuously log many temp sensors in a fermenting fridge, including core temperatures.

I've search, but can't find this thread. The OP said he was going to report back in detail.

1. Does anyone know the thread I am referring to ... and point me to it?
2. Does any one know the energy calculations of fermenting beer?
3. Does anyone have detailed records of the temperature gradient from the outside to the core of a fermenter?

Any other nerdy temperate/heat information would be appreciated.

regards, Michael.

 

[browndog]

I happen to have an interest in control systems and temperature measurement, so I've gone the extra mile in measuring fermenter temperatures.

A ferment that "takes off" produces a lot of heat.
If any of your beer-master know how I can calculate exactly how much I'd like to know.

I ferment 3 batches at a time. For two of the fermenters, I have digital temperature sensors (about $2 each from ebay) pressed against their sides and insulated from the air, to display the temperature of two of the fermenters. The third fermenter has the probe of my STC1000 pressed, also against its side and insulated from the air. A fourth sensor is reading the air temperature of the fridge. If I'm lucky and all three fermenters "ramp up" at the same rate, then they stay in a close temperature band (roughly 1 degree). They can be 6 degrees hotter than the air temperature. However, if one lags or takes off more than the others, then the three fermenters all in the same air space can vary by 4 or 5 degrees.

I've found the best way to avoid these wide differentials is to have the starting temperatures of the 3 fermenters as even as possible =a hot one will take off, and the others take days to catch up ... where a "cold" one will take days to catch up. Also, staggered starts result in the "new" fermenter running hot, as the air temperature that a "nearly finished" fermenter needs is higher than the air temp a "hot starter" needs.

About a year ago someone started a thread where they were going to set up and continuously log many temp sensors in a fermenting fridge, including core temperatures.

I've search, but can't find this thread. The OP said he was going to report back in detail.

1. Does anyone know the thread I am referring to ... and point me to it?
2. Does any one know the energy calculations of fermenting beer?
3. Does anyone have detailed records of the temperature gradient from the outside to the core of a fermenter?

Any other nerdy temperate/heat information would be appreciated.

regards, Michael.

Michael, I was going to try an experiement like you mentioned but it was many years ago as I had a data logger with about 6 channels. Unfortunately I could not get it to work and the last I knew of it Bonj was cannabalising it for it's touch screens. Your comment about the fermenters being up to six degrees hotter than the air temp in the fridge is a bit of a worry as the temp at the center of the wort could be quite a bit higher than that measurement too. That is why I am a user and believer in thermowells.

cheers

Browndog

 

[benno1973]

I remember the thread that you're talking about, but I can't seem to find it.

I use a thermowell for temp measurement, and generally have 2 fermenters with identical yeasts and pitching rates.

 

[mika]

Is this the one you're thinking of ? Linky Doesn't look like it went anywhere.

If you're so interested in the results, do the experiment and post up your findings.

 

[benno1973]

Is this the one you're thinking of ? Linky Doesn't look like it went anywhere.

That's the one...

 

[felten]

I have heard of some experiments on where to place the probe, and the consensus from that was that the difference between a thermowell and an insulated external probe is minimal. No links though sorry.

Your comment about the fermenters being up to six degrees hotter than the air temp in the fridge is a bit of a worry as the temp at the center of the wort could be quite a bit higher than that measurement too. That is why I am a user and believer in thermowells.

cheers

hmm I think if the wort is fermenting that vigorously, then the temperature is going to be pretty consistent throughout.

 

[MHB]

Snip
A ferment that "takes off" produces a lot of heat.

The heat of fermentation is 0.16 kWh/Kg of extract converted to Alcohol/CO₂.

Unfortunately this doesn't tell you how much when, you need to look at the rate of change of gravity. Also Real verses Apparent attenuation (see German brewing techniques), using real attenuation and working in Plato (^oP) should make getting some meaningful data easier.

Personally I would expect half of the energy to be released in the 24 Hours following the lag phase, would make sure I had at least twice the cooling power required during that time.

MHB

 

[michael_aussie]

Is this the one you're thinking of ? Linky Doesn't look like it went anywhere.

If you're so interested in the results, do the experiment and post up your findings.

That's the thread!!

Superoo .. where are you???

The heat of fermentation is 0.16 kWh/Kg of extract converted to Alcohol/CO₂.

Unfortunately this doesn't tell you how much when, you need to look at the rate of change of gravity. Also Real verses Apparent attenuation (see German brewing techniques), using real attenuation and working in Plato (^oP) should make getting some meaningful data easier.

Personally I would expect half of the energy to be released in the 24 Hours following the lag phase, would make sure I had at least twice the cooling power required during that time.

MHB

thank you MHB, that's what I was after. You have fed my inner nerd.