Any benefit to submerging a plate HEX?

[thecebruery]

So I'm brewing in an area with frustratingly warm groundwater (~80F) that comes out at only around 4psi. That's a flowrate of about 2.4 gpm (0.15 kg/s). I have one 50-plate heat exchanger (total area of about 0.75m^2) through which I need to put ~50 gallons of post-whirlpool, 180F beer.

Even a 60 minute knockout with that flow rate/temperature combo only gets my beer down to ~86F, which is still 10 degrees higher than the highest temperature I'd want to pitch at. Putting a booster pump on the muniwater line is out of the question, and honestly wouldn't help too much. Something, somewhere, has gotta be colder.

Longterm, I'll be installing a 200L cold liquor tank under my glycol unit that I'll hold at 36F or so. But that's a few months off ...

Right now, I'm somewhat limited, money-wise and availability-of-equipment-wise (brewing in the 3rd world), to a few less than desirable options. No extra pumps, no extra heat exchangers to do two-stage, etc. But, in the opinion of all those engineers/thermodynamics experts, what's the best way to get that extra little oomph of cold? Will submerging my plate chiller in a bucket of ice water (so the connections are above the water but the plates themselves are submerged in the 32F environment) help enough to be worthwhile? What about running 20 meters of hose (I know, copper would be better) from the muniwater hookup to the heat exchanger, but coiling that 20m and submerging it in a bucket of ice water? Seems like the former would have more conduction possibility, but the latter more surface area. Are there any other options I'm not considering that are cheap/easy to do?

My fermenters are also glycol chilled, so during that 60 minute knockdown in to the fermenter, my glycol will get a headstart chilling the partial fermenter load down ... so maybe the final average beer temp will be lower than 85F. But still probably not low enough. Help!

 

[TungstenBeer]

I know your post wasn't about lagers, but bear with me...

A lot of people have trouble chilling down to lager pitching temps for many obvious reasons. So what they do instead is to chill down as far as they can go (let's say to 80F) and then let it chill down to pitching temps overnight and pitch yeast the next morning when it's at 55F or whatever you need. As long as you are confident in your sanitation process, I don't see why you couldn't do something similar.

Aside of that... when you say putting a booster line on the water system wouldn't help, I assume you mean speeding up the gph? Flow rate would definitely have a huge impact...

Have you considered recirculating back into your BK? You could always chill until the wort is at 100F or so and then switch to pumping ice water through your chiller until you get down at least to 70F (and chill the rest of the way in your fermentor).

 

[thecebruery]

Thanks, Tungsten - I hadn't thought about recirculating through the BK. I guess everything in there's just been pasteurized, so there shouldn't be any sanitation issues. With my stats (27.5C water at 0.15kg/s w/ a specific heat of 4197 flowing counterflow to 0.05kg/s of wort w/ a specific heat of 3900 through a 40-plate 0.75 m^2 heat exchanger), if I knockoff about 20 degrees in the boil kettle before switching over to my fermenter (maybe use it as an opportunity to do a low temperature hop whirlpool?), the end result will be 2-3 degrees cooler. That's probably enough to where my fermenter contents will drop to pitching temperature by the end of cleanup, so I can pitch before bed.

Thanks!!