The geeks only section of the latest Zymurgy says a 25’ immersion chiller with 65f groundwater will chill 5 gallons of boiling wort to 68f in ~10 minutes. Is this possible? I don’t think my double chiller (2x25’x3/8"), could do this!
Edit- I missed this: length of immersed coil is 46’x3/8". I still have a hard time believing it’s possible.
what diameter?
The article doesn’t specify the diameter used for the study but cites 3/8" diameter as "typical ".
I can chill 10 gallons in 14 min in winter, 50 ft 1/2 inch.
Have not read that yet. Might be theoretical best case with circulating wort.
I can chill 6 gallons to 68f in 8 minutes in winter, circulating wort, with 55f water. No issue with the numbers on the colder chilling water. I just don’t believe a 46’x3/8" IC can chill to 68f in 10 minutes with 65f water.
Brewed today and it took my chiller (basically 2 x 25’ chillers running in parallel) 14 minutes to reach 68f with 65f water. What am I doing wrong?
Too many theoretical variables. You okay at that
I’m okay with the time it takes to chill. But the study in Zymurgy says they’re getting it done in 10 minutes vs. my 14 minutes.
The variables:
They chilled 5 gallons, I did 5.5.
They used a 46’x3/8" coil. I use 2 separately-fed 25’x3/8" coils. Theoretically, this should give mine an advantage, at least enough to make up for the slight difference in volume.
We both used 65f water to chill.
I circulate the wort continuously, in the opposite direction of chiller flow.
My chiller flow rate is 3 gpm. So is theirs.
So how do they chill so much faster? Or do they? Perhaps the article is based strictly on calculations, with no scientific data, and is really just theoretical bs?
It does look like calculations were used for the graph. The data point for the immersion being below the counterflow is counterintuitive. You could e-mail Zymurgy and ask the question there, and I suspect the author would respond. Worked for me a while back when I had a question.
I use a 50 ft. 3/8" immersion chiller. My ground water averages about 55F…a bit warmer at the height of summer and a bit lower in mid winter. Before I started doing the recirculated chilling thing, it took bout 30 min. to go from boiling to 0F. With recirculation it takes about 10-13 min.
The only unknown variable I can think of that might make a sizeable difference is spacing between coils. My coils kind of lay on top of each other which could reduce surface area and impede the flow of the circulating wort. My chiller’s based loosely off JaDeD brewing’s Hydra. http://jadedbrewing.com/collections/frontpage/products/the-hydra
Time to get out the soldering torch!
Spacing the coils will expose ll the area.
The linked chiller - talk about surface area!
i have not read the full article, but i don’t find it counterintuitive. if they recirculated the wort with a paddle briskly around the immersion coils the heat transfer gradient could be significantly higher, including th e tranfer at the air interface and the wort kettle interface. in fact, an argument could be made that this is significantly better than that from pumping a laminar layer through a counter flow or even a cross flow heat exchanger.
It was calculations in fig 4. Assumed 3 gallons per min. For both sides of the counterflow, which will be turbulent flow for the sizes used. Maybe a e-mail is in order.
I was a chemical engineer, now a patent attorney. I have a copy of Perry’s where the data they use comes from. The article is purely a paper study. Their calculations are reasonably accurate for doing comparisons among common cooling options. I would not assume that they are accurate for other purposes. I do not consider what they are doing “BS,” but I’m not surprised that one person’s real world data does not coincide with an estimate from a paper study.
Theoretically, counterflow cooling should always be faster than batch immersion cooling for same coolant flow rate and same heat transfer area assuming proper design because in counter flow the coolant exiting the cooler is cooling wort at the initial temperature. In immersion cooling, very little of the coolant is cooling wort at the initial temp.
yes, but you are assuming stagnant flow around the immersion cooler. if you move the wort around it is similar to a typical bi flow heat exchanger. i would argue that the volumetric flow rate from a paddle moving the wort around the immersion coil is probably on the order of gallons per second as compared to a pump pumping it through a heat exchanger. similar to how air moves over an engine be it air cooled or liquid cooled. as long as something is moving air over the fins it will cool faster.
Old MechE here. In Table 2, he has the counter flow with slightly higher Area for the study, the U is roughly a wash. My quandary is how does the immersion suddenly perform better than the counterflow with just a 5F change in cooling water? I think it has to do with the definition of the Delta T avg for an immersion. I might have to pull my dusty Heat Transfer book off of the shelf.
I’m not assuming stagnant flow. I’m assuming that the water in the pot cools over time due to the immersion cooler.
so are you assuming that the water in the pot (being cooled) is moving only under natural circulation?
The reason I say that countercurrent should theoretically always be better is because the flow of coolant through a countercurrent chiller is always exposed to wort at the initial temperature (~212 F), while an immersion chiller is only exposed to ~212 F for a very short moment because the immersion chiller cools the entire mass of wort.