Counterflow chiller idea...Doable?

[GParkins]

Here in South Florida, water temps out of our well aren't what anyone would call remotely chilly, even in January. It's got me thinking.

I just brewed a batch of a Sierra Nevada clone, and I had a horrible time with my CFC, due to 2 whole-hop additions during the boil and no screen (!) on my beer keg boil kettle. The gunky hot wort constantly stopped up my wimpy ⅜" tubing on the CFC. Fortunately, the beer is forgiving, and it's happily fermenting as I type this.

Furthermore, in an effort to lower my supply water temp, I coiled the supply hose in a large igloo fishing cooler and filled it with 60lb. ice. Unfortunately, once the water started flowing, the thick rubber hose acted as an insulator, not a conductor of the ice water in the cooler. I was getting just below input water temps at the the CFC inlet.

I stated nosing around for ideas, and came across this manufactured CFC:



My thinking is to use ⅞" and ⅝" tubing as in the example, but to build the thing into a 10-gallon Rubbermaid round cooler. It has about a 13" i.d., so perhaps an 8-10" o.d. of the copper coil would work. Instead of terminating the tubing like the pic, I'm thinking of drilling 3 additional holes in the cooler. One down low next to the existing valve hole, and two up top.

The top would have hot wort in (½" barb) and spent cooling water out (¾" MH), and the bottom would be chilled wort out (½" barb) and cooling water in (¾" FH). On brew day, I'd fill the cooler with ice water, and the improved conductivity of the copper would solve my coolant water problem, and the combination of ¼" larger diameter wort tubing and a screen on my boil kettle will solve the gunking problem.

I would have to mount my boil kettle high enough that the output barb was even with the chiller's inlet barb, and the chiller cooler's outlet barb would have to be 6" or so above the mouth of a 6 ½ gal. glass carboy.

Cleanup would be accomplished by running a hot pbw solution through the wort loop, followed by a good fresh water rinse. On brew day, a fresh water rinse followed by a couple of gallons of StarSan through the wort loop should handle the sanitation side of things. The rest of it can just be hosed out.

I can see it pretty clearly in my mind's eye, but I'm so new to this that I can't see the potential traps. Any advice?

 

[billl]

Lots of folks in your situation use a much simpler idea. They buy a cheapo pond pump and use it to recirculate ice water through the water side of the chiller. Just toss the pump into any type of big bucket or cooler and fill with ice water. Since the pump only touches the water and not the wort, it doesn't need to be a high quality brewing pump or anything and it doesn't need to be sanitized.

 

[GParkins]

Someone suggested a pond pump, but for an immersion chiller, which I don't want to use. Facepalming myself right now for not making the jump to use the pond pump with the counterflow. Thank you!

...I still think a CFC built into a 10-gallon cooler would look all Gucci and TurboSwagTastic. I think the cooler would also protect the copper from the bumps and dings of non-brewing days.

 

[billl]

If you want to test out the concept, you could always just get the wort flowing as usual and then put the CFC in a tub of icewater to see how it will work. The wort should keep flowing even if you tip it sideways and/or make out tubing flow over a bump etc as long as you don't break the syphon and keep the end of the out tube lower than the lowest point of the CFC.

 

[govner1]

Lots of folks in your situation use a much simpler idea. They buy a cheapo pond pump and use it to recirculate ice water through the water side of the chiller. Just toss the pump into any type of big bucket or cooler and fill with ice water. Since the pump only touches the water and not the wort, it doesn't need to be a high quality brewing pump or anything and it doesn't need to be sanitized.

^^^++1-This

 

[GParkins]

One way to supercharge the whole concept would be to build the CFC into the cooler, fill it with an ice cream churn-style slush of ice, water, and rock salt, and do the same with a pond pump in a tub full of the same mix. If you could keep it from freezing solid, the combination of the sub-freezing coolant water and the highly conductive copper in a sub-freezing slush bath could potentially set temperature drop records. The only way to beat that would be to use glycol solutions.

Hmmmm.

 

[hartlesj]

The water flowing would actually act as an insulator from the ice. It's flowing,thought the cooler and out the inlet. Since it's warmer it would act almost as in insulator to the wort. Granted there would be some heat transfer but the efficiency would be way down. If you wanted to keep the ice and cooler look, do away with the counter flow part and just use a single coil in the cooler surrounded by ice. The inlet would be at the top, coil down to the bottom, then outlet through the cooler spigot hole. Have a valve and thermometer at the outlet and throttle the flow of the wort to get the right temp. I'm a steam engineer in the Navy so heat transfer is kinda my thing.

 

[doug293cz]

One way to supercharge the whole concept would be to build the CFC into the cooler, fill it with an ice cream churn-style slush of ice, water, and rock salt, and do the same with a pond pump in a tub full of the same mix. If you could keep it from freezing solid, the combination of the sub-freezing coolant water and the highly conductive copper in a sub-freezing slush bath could potentially set temperature drop records. The only way to beat that would be to use glycol solutions.

Although salt can make ice water colder than 32°F, it will not absorb any more total heat. It takes a certain amount of added heat to melt ice into water (known as the heat of fusion.) In order for ice to melt it must absorb this extra heat from its surroundings. A given amount of ice will absorb a constant amount of heat to melt regardless of the temperature at which it melts. It's this extra heat absorption while melting that gives ice more cooling power than water at the same temperature. Adding salt to ice doesn't change the amount of heat that will be absorbed to melt the ice.

Since salt doesn't change the cooling capacity (total amount of heat it will absorb by melting) of ice. Adding salt will not improve cooling capacity of your system. The only way to do that is to add more ice. Might as well skip the salt.

Salt should increase the rate of cooling somewhat, as increasing the temperature differential between the coolant and wort will increase the rate at which heat transfers. But a constant amount of heat must be removed from the wort to get it from one temperature to another lower temperature. So you need the same amount of ice whether you use salt or not.

Brew on