geothermal fermentation cooling - will it work?

[ColeR]

Hello all, I have a interesting question for you.

I want to do some geothermal fermentation cooling my 3, 2bbl fermentors.

I want to put a 1/3hp sump pump in my brewery to push water out of a RubberMade bucket thru a 1/2in garden hose, down a 25ft drop to some marsh area about 50ft away, here it hooks up to a 1/2in copper coil buried 2ft below grade, then come back out of the marsh area thru a 1/2in garden hose where it goes back up the 25ft, in to some SS coils in my fermentors then dump back in to the RubberMade bucket. And then repeat…….

Total run will be about 125ft, does dropping 25ft then coming back the same 25 equal 0ft of head height. But there is friction loss that needs to be accounted for..

All this would be hooked up to a temp control. And only turn on when the fermentation get to warm….

So my question is - how much friction loss will I have? And will it work?

The pump I am looking at is
40gal a min at 0 head height,
and
2gal a min at 20ft head height.

Thanks
ColeR-

 

[Dynachrome]

You're going to use electricity to power the pump. How much.

You could use electricity to power an air conditioner instead.

Could you explain why you want to do this please?

 

[ColeR]

well i have a few reasons, living in western WA my ground water is about 45-55deg, first is saving water and not wasting it and i think its cheaper than some other options i could have pursued.

1. if i want to keep each fermentor at a different temp, a separate temp controller can use the same loop of cold water
2. i can use the same loop for cooling the wort in a counter flow chiller. and not waste water. it just goes in a nice circle.
3. my house is on a well, why waste all my well water, I should reuse it.
4. my brewery is in my backyard with no access to sewer and i cant put it down my septic and i don't want flood my backyard.

so my reasons are more for saving the water and not wasting it, the plus side, is i get to cool all my beer products in one way or another.

money is not what i'm doing this for.

So why wouldn't I want to do this?

and yes i do have a AC/heater unit in my brewery to keep it at 65deg year round.

the pump is only $65 hoses $50, the 50ft copper coil i got for $10.

ColeR-

 

[dlovin]

I'm not a hydraulic engineer but even though your pump is pumping the water 25' downhill there is still 25 feet of head on the uphill side, plus your coil in the ground that's another 2-3 feet plus the friction of the whole run, I really don't think that pump will be strong enough .


Sent from my iPhone using Home Brew

 

[reynolds5520]

The loop you're talking about has very little head height - just the distance from the pump on the floor to the top of the coils in the fermentors. But it does have very significant resistance from the more than 100 feet of 1/2 inch loop tubing. You would need to figure out whether there will be adequate flow rate through that long skinny tube.

I don't think this is going to work the way you think it will. Can it be made to work? Sure it can. Can it be cost effective and more efficient than a re-purposed AC unit? Probably not.

In no particular order, here's some things you need to work out:

1. What's the year round range of ground temps at your proposed coil depth? Two feet deep may not be enough to get away from seasonal variations. Your well water at 45 to 55 degrees is probably coming from deeper than 2 feet.

2. How much thermal transfer is going to happen in your 100 feet of garden hose? Even if the buried coil temp is appropriate, will it still be anywhere near that temp once it gets back to the ferementor? Insulation of those lines will be important.

3. Will the loop be circulated continuously? The first 50 feet worth of water from the loop will be at the outdoor air temp, if you cycle the pump on and off.

4. How much buried coil length will you have? Is it enough to fully exchange the heat? This will vary with soil type, temperature differential, coil material, soil moisture and probably more that I'm not thinking of. When geothermal systems are built with undersized loops, it's not unusual to see the system work for the first few years but eventually the system exceeds the thermal transfer ability of the surrounding soil - in other words, eventually the surrounding soil temperature starts to match the loop temperature.


For some reading about a DIY geothermal system, check out this link:
http://ecorenovator.org/forum/geothermal-heat-pumps/484-homemade-heat-pump-manifesto.html

The writer is from Portland, so some of his assumptions for the engineering are close to your climate.

 

[wilserbrewer]

It would be much simpler to install a well point and pump down in the marsh and pump the ground water through a coil to cool your conical. Return the ground water to the marsh with zero water usage and no heat exchanger required.

 

[ColeR]

This info is great,

I like the fact that if someone puts out a rough idea that has potential, others can supply/help with missing parts of the plan, and not just dismiss it as a dumb idea. we all have situations that are different, where my plan will not work for you, and yours will not work for me. My plan here will not work for someone in South. my house is at the base of the Cascades Mountains, ya i mean they are across the street, i look out my window and i have to look up, i got cold water under ground here and lots of, case and point that big landslide happened 15 miles from my house.

After reading these forums and others, and your replies. I'm going to try 3/4 in run of a hardline down and back, PVC or some thing like it, in the wetlands the 3/4 in will split in to 2, 1/2in copper coils buried as deep as I can, and as big as I can for better heat dissipation. Having the 2 coils will allow better flow. Then come back together in to the 3/4in for the trip up the hill.

and the up and down runs will be insulated, by that foam pipe wrap or something like it.

I'm trying to keep the loop clean (i plan on adding a small amount of StarSan), in case i have a small leak happen, that's why I would prefer not to use the marsh water itself, but if it turns out I need to, to make it work, so be it then.

Thanks reynolds5520 for the great input, and questions.
1. even if the ground temp doesn't stay the same, I'll still be better off with 60deg water than nothing. that area never see the sun, too many trees, and has continual mountain run-off from the snow melt.
2. ya plan i insulating them. to help with that
3. for the first few mins the line temp will be above what i would want, but he pump pushes 40gal a min, although restricted by the line size.
4. i picked up a 50ft coil of 1/2 copper for $10 the other day, so i plan on two separate 25ft coil runs.

ColeR-

 

[reynolds5520]

It sounds like you're on the right track to something that can work. Be sure to post updates, even if it doesn't, so we can all learn from your experience.

 

[Darkness]

I do mechanical systems here are some numbers for you
A well 210ft deep with 3/4in pipe is the equivalent of 1 ton or 12,000 BUT of heat transfer. A 1hp pump can move 7.2gpm from ground level 16ft vertical and through the well. Note this is a total of 420ft of pipe in the well, pipe down and back up.

As for the depth of your coils. Thermal change over ( stable ground temp) starts at around 4ft, in your area it might be 5ft in the winter depending on frost line. Call a local plumber and ask what the minimum depth for water lines are.

 

[Darkness]

4. How much buried coil length will you have? Is it enough to fully exchange the heat? This will vary with soil type, temperature differential, coil material, soil moisture and probably more that I'm not thinking of. When geothermal systems are built with undersized loops, it's not unusual to see the system work for the first few years but eventually the system exceeds the thermal transfer ability of the surrounding soil - in other words, eventually the surrounding soil temperature starts to match the loop temperature.


Yes, the well field is either
A- short on number of wells
B- the wells are to close the each other and soil can't handle load
C- the soil through out the well depth is not good transfer material (clay, air gaps,ie. caves)

The best case is solid rock, or the best is water. How ever your coils must remain in contact with water and not get silted in, or covered up but material in the water. Once this happens efficiency is lost and system will not keep up. Lake or pond loops must be cleaned yearly. Also the Marsh are water temp might change greatly in the summer and be warmer than you what your fermenter. Water sources roll over with the change of seasons. You would want to check temp low and at surface during the hottest and coldest part of the year to see if the temp will in fact exchange enough temp.

 

[ColeR]

I do mechanical systems here are some numbers for you
A well 210ft deep with 3/4in pipe is the equivalent of 1 ton or 12,000 BUT of heat transfer. A 1hp pump can move 7.2gpm from ground level 16ft vertical and through the well. Note this is a total of 420ft of pipe in the well, pipe down and back up.

As for the depth of your coils. Thermal change over ( stable ground temp) starts at around 4ft, in your area it might be 5ft in the winter depending on frost line. Call a local plumber and ask what the minimum depth for water lines are.

18in is the depth here for water lines

 

[wilserbrewer]

Just guessing here, but I'm starting to doubt if 50' of copper coil has enough surface area buried in stagnant water / earth to exchange heat for 3, 2B fermenters?

Will all 3 fermenters be at peak fermentation at once? What are your average summer temps like?

Not to be a kill joy, but there could come a point where running the pumps consumes more energy than other more conventional means.

I do like the project.
Cheers

 

[Darkness]

When looking at ground temp you don't get a average of 55-60 until 4 feet. The ground two feet down in the peak of summer will be warmer than that. And for heat transfer the waters source must be around 55 for optimum exchange. Think about it like this, 55deg water running around a fermenter is like setting your BK in a ice bath. The sides cool down but the middle stays warm. It would be a slow process of cooling. And there would be no Lager's being made. IMOP you would need a pond 30' deep and 80' in diameter to run 300' of pipe through. The amount of heat transfer you need verses work and cost it dosn't work out. I do geothermal in large homes and with out gov kick backs people would not do it cause the cost is to high.

This is a geo manifold and flow center for a 26 ton system.

 

[ColeR]

Excellent info here,

when i do brew it would be only once or twice given week, my brewery building has a temp controlled AC unit to keep the building at 65 all the time.

this cooling system would be just to cool the wort, once it is at fermenting temps and transferred , i would place a SS coil down in the beer and set the temp. to cycle cooler water to maintain the temp i wanted, i know i will never get to Lagering temp, i just dont want the ferm temps to get too high.

I'm going to try my plan, but based on your work, i expect it to not work, but i have to try. i do have a back up plan to use a 275gal IBC tote filled with rain/well water as a primary heat sink for the Wort cooling to get the temp down to what at least air temp is, then cycle if needed down through the water/marsh area. that way i'm only going from say 70 (average) down to the lower 45-55deg or even 60deg in the middle summer of the marsh.

even if it doesn't work i'm not really out anything, the pump and coils, i will still need.

ColeR-

 

[Kevin-K]

I would look into using a pump similar to that used in residential boiler heating.

 

[Dynachrome]

when i do brew it would be only once or twice given week, my brewery building has a temp controlled AC unit to keep the building at 65 all the time. ...

You have a unique way of using the word "only".

Look up evaporative cooling - you have a lot of shade - you may be able to get some use from it.

 

[ColeR]

Ok, I listened. I went straight to the 275gal IBC tote ($100), and picked up 200ft of some 3/4in water main line tubing, the pump will push outside temp water from the IBC thru the 3/4 line to my 2, 1/2 copper coils buried in the wetlands behind my brewery, come back up in the 3/4 line be used for cooling then dumped back in to the 275gal IBC. and repeat.

My IBC tote
3/4-in x 100-ft 100 PSI Plastic Coil Pipe
Superior Pump, Model 91330

so from my original plan
I upped the line size to 3/4 from 1/2 (up and down)
I made 2 separate 1/2 copper coils spaced apart from a single 1/2 copper coil.
I picked up the IBC tote as the main heat sink rather than rely on the wetlands. that will fill from rain run-off.

the 1/2 copper coils will still be the choke point, as the pair as a water movement area of .3925 and the 3/4in has the area of .4415, but that difference is fairly small.

So for just over $200, i hope i have a viable cooling system. that will never run out of water and only use a small amount of power to run the pump every now and then.

Thanks
ColeR-