What size cooler for gylcol reservoir

[ajdelange]

The usual statement of the zeroth law is that if A is in thermal equilibrium with B and C is in thermal equilibrium with B then C is in thermal equilibrium with A i.e. they are all at the same temperature and no heat exchange will occur between them. Yes, this allows us to design thermometers but the obvious implication here is that if material on one side of a heat exchanger is at the same temperature as the material on the other there will be no passage of heat between them.

With respect to the Second Law what we are interested in is the Carnot's statement of it: There is no engine operating between two reservoirs as efficient as a Carnot engine. As the efficiency of a Carnot engine is easy to calculate (1 - Tc/Th) we can bound the performance of a cyclic machine. As a refrigeration machine uses a Carnot cycle run backwards we easily get the maximum COP of a refrigeration machine as Tc/(Th-Tc) = 1/(Th/Tc - 1). Thus the closer Th to Tc the more heat you can transfer per unit of work. This is relevant to discussions of where to set evaporator temperature relative to your "hot reservoir" (air) temperature. Obviously the closer you can get it the higher the machine's COP, SEER etc and the happier the tree huggers are. Obviously (Zeroth Law) you can't have it higher than the lowest temperature you want to cool to.

 

[jddevinn]

Ok from original conversation.

I've been thinking about the cooling reserve to rapidly cool the wort after the boil is complete. I think I've come up with something I'm going to try next time I brew.

In my 3 vessel system, when the HLT is empty during the sparge I'm going to:

1. Fill HLT with "cold" tap water
2. Connect one of the lines from my glycol reserve to the HERMS coil of the HLT
3. Cool the HLT down to ~40°F, assuming I have 60% of the rated cooling of the A/C this will take about an hour. So it should be done when the boil is nearing complete.
4. Cool the wort down to about 100°F using cool tap water, this is normally quick.
5. A single pass of the 40°F chilled water should knock my 12 gallon batch to around 65°F

Hopefully I can cut the chilling down to 5 or 10 minutes!! If successful I'll likely start a seperate thread and look at getting a rain barrel or similar to use as a dedicated secondary "coolant" reserve.

 

[Drumminguy81]

Ill be doing something similar, but instead of cooling a vessel of water im doing it on the fly. I have 2 plate chillers, one is hooked up with the glycol as the cooling source, with my tap water hooked to the wort in side which should chill my water down quite a bit, it then goes to the second plate chiller as the chilling water with the hope I can cool 20 gallons from 200 down to 68 in a single pass. This is all speculation though.. ill report back after I try it.

 

[homebrewdude76]

I bought a used AC unit and started to open it up.
I dont really need a large cooler for this thing.

I am thinking of cutting the bottom steel in order to bring the cooling portion directly into the cooler.

Need to think how to wire this thing. I would prefer to bypass all controlls and use a control unit.

View attachment 1477239826352.jpg

View attachment 1477239835142.jpg

 

[Drumminguy81]

You're on the right track. Cut the bottom, carefully bend the coil to fit in the cooler with a small notch so the lid will close. Bypass the thermostat and controls and use a temperature controller like an inkbird to switch it on and off and get the glycol to your desired temperature.

 

[homebrewdude76]

Cut more metal to make more room for cooler

 

[homebrewdude76]

Photo

 

[homebrewdude76]

The andoid app always has issues...

View attachment 1479137714527.jpg

 

[homebrewdude76]

This is what I came up with. Just need to figure out what pump to push through the conical cooling coil

View attachment 1483574067446.jpg

 

[jddevinn]

This is what I came up with. Just need to figure out what pump to push through the conical cooling coil

FYI, I use this pump https://www.amazon.com/gp/product/B0009X8O2E/?tag=skimlinks_replacement-20.

Anything similar will work. The higher flow rate that you get the faster you can transfer heat (to a point).

 

[ajdelange]

I bought a used AC unit and started to open it up.
I dont really need a large cooler for this thing.

I am thinking of cutting the bottom steel in order to bring the cooling portion directly into the cooler.

Need to think how to wire this thing. I would prefer to bypass all controlls and use a control unit.

With respect to the image in that post: when the evaporator is completely frosted over like that it means that it is full of refrigerant. That's because not enough heat to boil it all has been supplied (as would normally be when the thing is shrouded up and the fan is blowing warm air over it). The problem here is that your compressor won't last long if you are slugging it with liquid refrigerant. If you are going to run it in the open like this get some load on it such as a fan close by blowing room air over it.

 

[jddevinn]

Also pay attention so that it does not frost in the glycol bath. It needs to be completely submerged. I ended up having to make a "manifold" that split my recirculated water return to more evenly flow through the evaporator and keep the entire thing near a constant temperature.

 

[homebrewdude76]

Any suggestions on what size pond pump to get. I am thinking bigger is better to keep the water moving in the cooler.

Also suggestions on a quick release fittings for the cooling hoses.