Wort Chilling System Concept

[Mindsculptor]

So, I've been thinking about wort chillers and how, frankly, pathetic their performance is. My biggest area of interest before homebrewing was high end computer gaming and the water cooling systems needed to keep those computers from frying themselves. The required performance to accomplish this is absolutely extreme; your heat exchange surface (the processor) is smaller than a wallet photo, the processor itself can reach uncooled temps just short of 300 degrees, and the cooling system has to be able to keep the processor under 200 degrees under continuous max load. The reality is that even entry-level AIO water coolers can often keep the processor in the 150-160 degree range.

So, why is it that computer water coolers can accomplish a real time 50% reduction in temps with the processor always working against it and yet it takes 20 minutes to cool wort from boiling to room temp when no heat is being added to the wort? The answer is thermodynamics. A computer cooling system maximizes the volume of the cooling medium (water and air through a radiator) acting against the surface of the processor, which means the processor's heat always has somewhere to go and the cooling medium can't be saturated. Yet it seems to me that wort chillers do the opposite in that they maximize the volume to be cooled against the working fluid the wort's heat is being dumped into. The result is that the working fluid (the water) is being saturated by heat energy.

Now how do we fix this? The first, and easiest, answer is that the relationship between the working fluid (water) and the wort by pumping the latter through the chiller that has been immersed in a container filled with cold water. Once you have done that, you can reach into your bag of tricks; dry ice is often available at the same places CO2 gas is or you can use pre-diluted antifreeze. The second answer is that you maximize your heat transfer surface (the coil) by using as much volume within the coolant vessel (cheap pot or igloo cooler) as possible. Someone here posted a "ribcage" design that seemed to work well and I've also seen concentric designs, although I have a couple ideas bouncing around in my head that are radical.

Thoughts and questions are welcome.

 

[chefjaypeek]

5 or 10 gallons of wort has a LOT more thermal mass than a processor chip. So even with a processor continually adding heat, it is really not the same comparison.

Granted, using a prechiller or pumping ice water through a plate or counterflow chiller is more efficient than 60-80 degree tap water through an immersion chiller, it still takes time to remove 140-160 degrees of water from 5 or 10 gallons of sugar water.

 

[phreaky]

Most processors will put off 300-500 btu/h. To cool 10 gallons of wort you need to shed roughly 14,000 btus in 10-15 minutes. Obviously a huge difference. I too would like to come up with something more efficient, but in the end, whether water, ice, or something you've cooled in your fridge ahead of time, it's going to cost you something.

 

[BanditBrewCo]

I have been toying with the idea of an automobile radiator inline with a water pump and IC. Being that it is winter with temps around me are in the 30-40s during the day and dropping, I want to try and recirculate water through my IC into a radiator with a high volume fan pushing cold ambient air through it. Any thought's?

 

[Mindsculptor]

It's not just total energy, it's also energy density. Those higher end processors are putting out 150 watts (at a minimum) over a two square inch area, or 75 watts per inch. That wort containing about 4 kilowatts of energy has an energy density of 5 watts per square inch assuming a 50'x3/8" immersion chiller. My contention is this:

1) If you brought the wort to the cooler fluid, instead of the other way around, your chill times will drop well below ten minutes with no other changes. Yes, this is going to require a pump and a spare Igloo.

2) If you bump the tube thickness up to 7/8", you have a heat sink area of about 2.5w/sq inch. That is absolutely 5 minute chill time if you use the same volume of ice water.

3) If you use twisted, finned, or other specialty heat exchange pipes, I think you're talking single cycle chills.

 

[Mindsculptor]

I have been toying with the idea of an automobile radiator inline with a water pump and IC. Being that it is winter with temps around me are in the 30-40s during the day and dropping, I want to try and recirculate water through my IC into a radiator with a high volume fan pushing cold ambient air through it. Any thought's?

You're going to get rapid chilling. Very rapid. I'd almost be tempted to run the wort through the radiator, but presumably its used and they're not food safe even new.

 

[insanim8er]

Maybe you should try other methods. What cooling methods have you tried?

I use a plate chiller and it chills my wort as fast as I can run it through.

 

[BanditBrewCo]

Running wort through the radiator would be a very bad idea, lol. I am more looking at water conservation over time savings. Current IC and tap water cool 5.75 gal in around 9-11 minutes (220 to 75 degrees) but uses just over 17 gallons of tap water to do it. I collect this water and reuse a good portion for cleaning when brew is complete or doing a double batch day but there is still a lot of waste water. I am thinking more along the lines of 2-4 gallons being recirculated between the IC and radiator/fan combo while hopefully not adding too much more time to drop temps.

A plate chiller is a little out of my price range at this time with the holidays and everything else coming up.

 

[rgauthier20420]

Why not buy a big water storage drum like this? It would be very easy to attach a small pump to the valve leaving the drum to pump it through a pre chiller, through a chiller, and back right into the drum. No water lost at all and you can re-use as much as you want.