With a 25’ by (x) IC, is it better to runn water through it at slow speed (more contact time) or at a faster pace to get warming water out of system faster? I have tried it both ways, and in the warm summer with warmer ground water, it took quite a while at fast speeds. My second to last batch I used a dramatically slower speed to reduce water usage and temp dropped quickly with cold ground water. My next batch done yesterday, about same temp ground water, took almost 40 minutes compared to 20 the last time I tried this slower speed. i do not as of yet recirculate, but do stir the pot. It seem so me that both slow and fast have worked under different circumstances, just wondering in general which is the better method? Any input would be greatly appreciated.
IIRC faster is good until you have 100F or so, at which time you should slow it down for a chance for more heat exchange.
I run mine at the minimum speed my hose bibs vacuum breaker can handle without leaking. Maybe 2 gallons per minute? So I guess I run it slow.
With 80° ground water, and 16 lbs of ice in my prechiller, I can get 6 gallons from boil to 90 in 40 gallons. I give up at 40 gallons no matter what and let the freezer take it further. Four weeks ago I was able to get it down to 65°
I would think slow running chill water is only important if you are running the water through a prechiller.
Aside from that you want the coldest water possible inside the copper. I personally believe that the chilling rate is kind of like half-life. At least it seems like it. 212° to half way to ground water temp in X time, then the next half in X time, then then next half… the final 5° seems to take the longest.
Gotta agree. No arguments that using less water is a good thing for everybody, but I can’t see a scenario where running slower would chill faster than running fast, unless you’re maybe running through an ice water loop ala Jamil Z. After all, the object is to remove the warmer water from the coils and replace it with cooler water to exchange more heat, no ? However I’m no fluid dynamics expert, so if wrong I’ll stand corrected.
It depends what your goal is. For fast chilling, high flow is better because you want max temp difference across the entire chiller surface. If you want to consent water use, slower is better to maximize the heat removed by each gallon of chilling water. With either strategy you will get diminishing returns at some point.
Makes sense. Definitely diminishing returns at close to ground water temps regardless.
Palmer talked about it on an episode of brewstrong way back. I think he said too fast is wasteful because you are not giving the water time to absorb the heat. What I took away from it is if you measure the outflow and it is not much warmer then the in, you are going to fast.
I can say that with my setup, the first 5 gallons is about 130°, second is more around 110°, third is maybe 90°, and after that it’s below 80°. Going into the chiller is maybe 50° with the prechiller.
Edit to finish thought - had to pull dinner out of the oven
Cool, I’ll see if I can dig it up. I just know I cooled a beer a couple weeks ago to 64F in ~ 10 or 11 minutes running wide open, with the cold-ass ground water temps. But I’m always open to trying something new if it’s legit. Thanks Steve !
Good luck looking. I’ll see if I can find it. Pretty sure it was before 2011. Maybe a q&a episode.
Steve brings up a most excellent point – namely that if you measure the temperature of the outgoing water, you will get a good feeling for how efficiently the chilling process is working. A few degrees less than the wort temp is good efficiency.
I found this article quite helpful:
I am on a well, so the only conservation for me is electric to run the pump.
The area and Delta-T are big parts of the equation. You are talking about the rate in summer with warmer water and higher flow compared to winter with cooler water and lower flow. You can’t make any judgment with all of the variables not being the same.
You want the fastest coolant flow if you want to minimize time, as you will have the highest Delta T across the chiller, so the most heat transfer. Slow it down if you want to minimize water usage. If you slow too much you get into laminar flow, which is not good for heat transfer, stay over a liter a minute. Keeping the wort circulating is good for heat transfer.
I will ask all of you that say slow, how does the water pump in you car flow vs. engine load operation?
I put a sprinkler on the end and water my lawn or veggies. That takes care of some wastage and slows the water as well. Also, having done the whole ice-water recirc, prechill, fiddle with the flow rates thang etc… My conclusion is to drop some frozen water bottles in at about 100F and stop the water flowing. The ground water here in summer is around 88-90F.
+1.
The water pump flow volume increases with engine RPM’s of course. The thermostat may close a bit to throttle the flow if it gets too cold. If the radiator gets clogged then it shows up first by the engine running hotter at highway speeds. I imagine this is because there is less cooling area available as the radiator gets clogged rather than the flow being impeded. Does that sound right?
I’m confused. Where do you put the hops?
I don’t know but I knew a kid with a hopped up engine.
Correct Jeff. The pump output is low at idle, rises in a parabolic curve with RPM, as the max heat is generated at max power, which is at high RPM.
When working in Germany I learned that the Autobahn was not the worst case design case, it was easy due to the high flow of air through the radiator. Worst case was pulling a trailer on a hot day up a pass in the Alps. High heat generation, low flow of warm thin air. Made perfect sense. That coolant - air - has to carry the heat away.
Thanks for all the responses everyone. I guess I will go faster to cool faster, and find a purpose for the water. I also really like what I have seen elsewhere on here about cooling to a specific point, say 80, and letting stand overnight for a pitch the next day after finishing cooling in a cold basement, etc. I guess I knew the answer was faster cools faster, just got caught up in the trap of not realizing that it was the colder ground water (larger delta) that was making the difference, I thought it was changing the speed of flow. Thanks again and good brewing to all!