SS Brewtech Chronical 2.0 Conical Chiller

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May 2, 2011
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I am awaiting delivery of a 17 Gal SS Brewtech Chronical 2.0 and want to have my cooling system in place when it arrives. I searched the many cooling threads here, but haven't found some of the information I am looking for.

Sorry for the background detail - my ultimate questions follow that.

My typical brew the most recent 5 years has been about 12 gallons, split into two 7 gal Fermonsters. For temperature control, I removed the doors of a dorm fridge/freezer and built a 5-sided box out of 3/4" insulation board. The open side of the box is the same as the fridge/freezer and I simply push the box up against the fridge (with weatherstripping making an OK seal). The top actually just sits on the 3 sides. So I essentially just increased the fridge inside volume by 3X.

I use a cheap ebay PID controller to cycle the fridge compressor, with the temp probe in mid-air close to the fermentors. I have a 12V computer fan circulating the air inside the box/fridge 24/7 so the freezer, fridge, box compartments stay at an even temp.

My setup is in a Florida garage (large, high ceilings, and pretty well insulated - so maybe 90 degrees F in summer, possibly 95 F worst case?) My fermentation temps range from 50F to 77F. I monitor the PID probe, two other probes insulated & taped to the side of the Fermonsters, a Tilt in one fermentor, and another thermocouple in the the fridge air. I have learned that the wort will run about 4 or 5 degrees warmer than the PID set point for the first 2 days, then everything equalizes. Both fermentors track each other exactly, and neither deviates with ambient garage temp swings or fridge compressor cycles. I have never cold crashed, but I like the idea of being able to do so.

Surprisingly, the fridge duty cycle is very short, despite the increased thermal load, poor insulation and sealing.

I will be using a water or glycol reservoir in the dorm fridge and pumping through the FTSs coil (lid mount) of the Chronical 2.0. I believe there are two ways I can operate the chiller:

1) Let the fridge keep the glycol at some cold temperature (obviously, lower than the wort target), and use the PID to cycle a recirculation pump in the glycol.

2) Run the glycol pump continually and let the PID control the fridge so as to maintain the target wort temp (more like what I am doing now).

I have not seen this 2nd approached discussed, but I am thinking it may be the better approach for several reasons. This would keep the temperature differential across the entire system lower than method 1, and is more energy efficient. It would also be more continuous in cooling, and I expect, result in less temp variation in the wort. The reservoir volume could be less (since the continuous flow and lower gradient results in the same overall thermal work). Air transfer to the reservoir in the fridge may be adequate rather than needing to immerse the evaporator coil in the reservoir.

I don't have data such as the surface area of the 17 Gal conical, thermal conductivity through the neoprene jacket, surface area of the cooling coil, so I really can't analyze the cooling capacity required for my environment, or estimate the temperature gradients. I guess I will try both approaches to see the performance differences, but I wanted to have an idea of the total glycol mass and flow rate required given the expected heat transfer before next brew-day.


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