Originally Posted by DavidinTexas
The key to heat transfer is temperature difference - the greater the delta T the more heat is transferred per unit of time. If you want to go fast run the cooling water as fast a possible. The concept of giving the cooling media time to absorb the heat is completely in error. I am certain - I am a Chemical Engineer.
Is this chemistry or physics, probably both for all I know, I'm a finance guy.
As Mal Fet says, you can certainly increase cooling rate by increasing flow, but you're not using your water very efficiently that way. I know. I carry all my run off water in buckets to various places in my yard to water plants/lawn/etc.
I thought a lot about this last night as I brewed and cooled with my pre-chiller/IC combination, and yes...it makes sense to slow the flow through the prechiller to cool the water inside the coil before it enters the IC in the brew pot.
I run it at a bit more then a trickle. Takes about 10 minutes or so fill a 6G bucket. Then I haul that bucket off to the sink for cleaning (first bucket is usually quite hot and great for cleaning!) and then watering the yard thereafter. Last night I cooled my full boil batch in hot weather in 35 minutes down to pitch temp.
I will say this, this thread got me thinking about my chilling technique and shortened my typical brewday by almost an hour. Other efficiencies during the mash/sparge steps and remembering to heat the sparge water BEFORE starting my vorlauf took another hour (almost) off. Altogether I did a full boil 5 G batch with batch sparging and the prechiller/IC setup in 4.5 hours, including cleanup. My fastest AG brew yet!