Author Topic: Heat exchange engineering question  (Read 3963 times)

Offline pacerra

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Heat exchange engineering question
« on: April 25, 2015, 11:05:06 AM »
Hello, This is my first post, I'm hoping I am in the correct forum.

I'm researching HERMS and started thinking about time efficient heat exchange-- I'm trying to figure out how many feet of 1/2 inch copper/stainless steel tubing I would need to raise the temperature of 10 gallons of wort flowing through the tube while the tube is coiled and fully immersed in  a tank of near boiling water.  The wort in the tube starts at 150 degrees f and the water in the tank is  200 f. I would like to raise thetemperature in the wort to 160 in about 5 minutes. I assume I can get the wort to flow at least 2 gpm. any other thoughts would be helpful.

Thanks
Paul

Offline twhitaker

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Re: Heat exchange engineering question
« Reply #1 on: May 19, 2015, 08:50:30 AM »
Try a 50 foot coil. My 25 footer was too slow to do that, so I don't do it that way anymore. Also very hard to clean the coil afterward.
It did work, but too labour intensive and took too long for me.
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Offline haerbob3

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Re: Heat exchange engineering question
« Reply #2 on: June 05, 2015, 03:29:54 PM »
Go with the 50 foot coil.  I use a coil that allows me to recirculate the heat exchange water, this gives me an even temp throughout the tank. The same coil is used to whirlpool hops & to chill the wort.  For cleaning I just recirculate near boiling water through it. You can use a little PBW to clean too.  I have a 2 pump system, I alternate which pump is for wort and which is for water, helps with the cleaning.

Offline durrettd

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Re: Heat exchange engineering question
« Reply #3 on: June 06, 2015, 11:50:57 AM »
This is my day to agree with h3. A 50-foot coil works well. I also circulate wort through the coil during the mash, then circulate water while chilling.

You asked about circulating 150F wort through a heat-exchanger coil in order to raise the temp to 160F. This sounds similar to a Hockhurz mash, something I've begun doing for all my lagers and some ales. When I'm raising the wort temp I try to keep the water bath cool enough that the wort will not get hot enough while passing through the coil to denature the enzymes I want active. Considering the limited time the wort spends at the elevated temperature of the water bath, this may be an unfounded concern. I monitor the temperature of the wort returning from the heat-exchanger coil to stoke my concern; the returning wort is consistently within 1 degree of the water bath. During a Hockhurz mash I'm targeting 145F then 158F. Raising the temp from mash-in at 78F to 145, I hold my water bath at about 150F. Going from 145F to 158F I hold the water bath at about 160 - 162F. The temperature initially rises very quickly then slows as the wort approaches the water bath temperature - no surprise there - so the rise time can be quite long.

So, here's the question: is h3 pacerra risking denaturing enzymes by using a 200F heat-exchanger bath, or am I wasting my time trying to keep those enzymes cool? WAGs and experimental data welcomed!
« Last Edit: June 07, 2015, 09:09:04 PM by durrettd »

Offline haerbob3

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Re: Heat exchange engineering question
« Reply #4 on: June 07, 2015, 05:56:29 PM »
Sorry for the confusion.  I should clarify.  I do not keep the heat exchange tank near 200.  I try and keep the heatEX 2 to 5 degrees above the mash temp. This maintains my hast temp in the tun.  What is a Hockhurz mash?

I generally have my mash water recirculating as I bring the water up to the mash in point.  Add my grains and monitor my mash & exchange temps.  I usually mash at 148.  My rig is manual. 

Offline durrettd

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Re: Heat exchange engineering question
« Reply #5 on: June 07, 2015, 09:08:08 PM »
Doh! Sorry, I said H3 when I meant pacerra. "Is pacerra risking denaturing the enzymes or am I wasting my time?" I'll edit my previous comment to correct the mistake.

H3, it sounds like your system is very similar to mine: minimal automation (to reachand hold the water bath temp) and recirculating through a heat-exchanger/immersion chiller.

A Hockhurz mash is a step mash with rests near the middle of first the Beta amylase range, then near the top of the Alpha amylase range. I've been pleased with the results. I get reasonably good attenuation and body by using Hockhurz. I lengthen the Beta rest and shorten the Alpha rest to lighten the body a bit, or shorten the Beta and lengthen the Alpha to increase the body. I'm not sure it makes a lot of difference, but it's interesting exploring the question. I THINK I'm getting more body to make session beers seem more robust by mashing at ~145F for 30 minutes and ~158F for 60 minutes. Eventually I may convince myself it's working. At the moment, I'm still just playing around and taking lots of notes.

Offline haerbob3

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Re: Heat exchange engineering question
« Reply #6 on: June 09, 2015, 06:30:48 AM »
THANKS, sound like we are doing the same thing.  I brew mainly Belgiums and Pilsners.  In general preferring drier beers  That is the fun part always tweaking I doubt if I ever will have a permanent rig.

 

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