Condensor - cooling the water on closed loop

[porter]

Planning on a closed loop heat exchange system for the condensor water. This means pumping water through tubes in the ground, much like a ground source heat pump. We aren't going to go drilling holes (too expensive) but are planning on using a loop system below the frost line.

BUT---how much pipe do we use? Size of the still doesn't really matter. We can't find anyplace with facts on how many feet of piping we need to use to bring 200deg water down to around 100 or less, at a given flow rate. I know we'll have to play with flow rates at the pump.

And since the ground will be heating up as we go, how much distance we need to be in contact with.

Any ideas?????

Other option is to bury a plastic 'septic tank' and use the cool water in it do the heat transfer. We can drop coils of the loop down into the 500gal. underground water tank and let the tank dissipate the heat to the earth around it. Not sure which way would be less expensive to install.

I do know we aren't going to pump water for 8 hours through a condensor to just run it down the drain.

Input folks???

[nuffield]

Best option is to buy a small second hand cooling tower.

[Michael J. Consuelos]

Porter,

You are describing a physics problem...and you'll need to know a few things about thermal conductivity of the coils and the tank (it will conduct to the earth around it as described).

I would suggest searching:

Thermal Conductivity Equations Formulas Calculator

Thermodynamics and Fourier's Law

I found you a calculator to plug in the numbers:

http://www.ajdesigner.com/phpthermal/thermal_conductivity_equation_heat_transfer_rate.php

It also shows the formulas for solving each of the variables if you know the others.

On nice thing about the calculator is that once you know a couple of the variables...you can play with the length of the tubing.

If physics is a scary thought...might suggest contacting the local university's physics department. In the age of "green" this would make for a great problem for grad student to publish for the craft distilling industry.

Let me know if you find this out.

Cheers,

MJC

[Gwydion Stone]

You may also consider an air-cooled heat exchanger.

[Beauport Bob]

Porter, could you be making ths a bit more complicated than you need to? I think it may take a lot of pipe to extract the heat. I would think still size does matter. You are saying "cooling for 8 hours" so this I assume it is a commercial sized still. Length of distillation will require more cooling, so as your underground pipe is insulated by its own ambiant heat there would be need for more pipe. With an underground tank, will your water temp rise over several distilling days so your cooling flow rate will rise..repeat, repeat. That may be what Mr. M.J.C. is getting to.

Will fixed & buried limit what you can do? Think Growth. What you install is finite. An outside solution is expandable. You will have more control. But, glad you have enough land (and Zoning)to do it.

How is your water? We pipe our condenser water, taken from the town at a relativly constant temp, so our flow rate is constant for cooling, to a tank (HLT?)for our next fermentations. We use the heat rather than throw it out.

Any others doing that?

[Jester]

Porter,

I have looked into this and asked some of my engineering buddies. Their answer was that I'd need about an acre of land and a mile( not literally but maybe) of pipe. Bob is right, 500 gallons of 200 degree water in an underground tank will stay warm for several days. I like your thinking but think some outside the box answers may better serve you. What is your climate like, northern communities run heat 6-8 months out of the year. I set up Bobs recycle water to his hot liquor tank(HLT). its quite simple, it fills his CIP tanks then is diverted to his hot liquor tank. it saves a lot of water and energy. I also like the air cooled suggestion. this will directly heat your distillery, or other area. your still size and efficiency will adversely affect the amount of cooling needed. general rule of thumb is twice the capacity of your still. I like the running cyclic with a tank or two. incorperate the air cooling with this and you will save a good deal of money.this will work well to a certain extent. depending on how often and how efficient you run. Water is cheap in most areas, but that's not green, responsible thinking. IMHO, it is worth the time and money up front. Kudos!

[porter]

OUTSTANDING RESPONSES, EVERYONE !!!

This is exactly the feedback I was looking for. There's a Missouri distillery who's actually doing the inground cooling method with a 140gal. unit. Haven't been nosey enough to get the details on it. I think he put the grid in under the floor of the distillery, and the floor is only 30 x40.Due to the cost I was hoping for a different way also.

-Your are correct, size of still does matter as longer run time means more heat to transfer.

-Underground storage, wondered about heat dissipation on the tank also, answered that question.

-Tubing loop length, totally unknown, and if you run 2 days in a row will the ground won't have time to recover.

So, question now is what are you using for condensor water cooling? As I said, running water to waste is not an option.

I know it sounds bad to mention radiators and distilling, but using that principle with forced air through a cooling tube grid might work.

Working ideas folks????

[delaware_phoenix]

Don't know if this would work, but maybe an adsorption chiller. Not sure if there's enough process heat in the system, but maybe. Worth a look at least.

[Paul G]

I second the cooling tower suggestion. Contact a local HVAC contractor and ask about them...they'll be the experts in that field. To get an idea of what they are, here's a handy picture of various styles: http://www.geo4va.vt.edu/A2/cooling-tower-induced-flow.gif

In essence, you're using evaporation to do the cooling for you. However, it's only a small fraction of the cooling water so it's not as if you're pouring it down the drain. As for the actual temperature of your condensing water, I *hope* it's not getting as hot as 200F or it's not going to get the job done. However, if you tell the contractor that you're speaking with that you want to maintain your water at (for the sake of example) 80F, and you know the BTU capacity of your still, he'll be able to quote a size of cooling tower based on worst case (mid-summer) conditions that will maintain that temperature.

Also, don't get hung up with the term "radiator." Where you hear about it in the negative is in old stories about moonshiners condensing their alcohol vapors in automobile radiators. They're simply a purpose built heat exchanger...one built with the wrong materials for our industry, but not for cooling engine coolant. You are on the right track, though, with the forced air through a heat exchanger idea.

The advantage of the cooling tower vs. the radiator is that the cooling tower employs evaporation where the radiator does not. The evaporative cooling gives you greater cooling capacity for a given size than a closed loop heat exchanger.

Depending on how elaborate you want to get (which can be much if you're a geek like me) there can be tons of options to tweak the capacity and/or efficiency of the setup. Combining cooling towers with storage volume, running at night vs. during the day (especially if your electric rate varies throughout the day) and other factors are all valid considerations.

If you want me to bore you with more in-depth technical-ese, feel free to ask.

Paul

[porter]

Yea, I know all about the old radiator condensor days. They had the idea right, just put the wrong fluid through the radiator

The cooling tower idea is a good idea, except I don't know what to do with it in the winter. I'm not going to put an evaporative system inside for moisture/humidity reasons. And Missouri gets a bit cold to put it outside. I think down south they call these things swamp coolers, primarily from the humidity they cause?

I agree with the 200f statement, but I want to have enough capacity it will prevent the system from steaming out should it get neglected for a short time.

[porter]

Here's an idea tossed around on this end which sounds like it will work.

We have access to scrap HVAC units rather cheap. Here we go......

Stack 3 cooling A-coils together in series, for a total of 12ton cooling capacity, first in line positioned on top. Build the box to hold them as you would the base of an air handler. Set the air handler fan system of the furnace on top of the box to draw air directly over all 3 coils.

In the winter the cold air return up through them would be pulling in from the outside and exhausting the heat to the inside. In the summer, flip the damper and pump the exhaust air to the outside. In effect, this is a closed system heat exchanger.

I know the '12ton' is just a statement, but I figure on using 3 4ton air coils or larger.

This takes out the size factor of the cooker as once it's up to temp the cooling rate is constant no matter how long you run it.

Only factor would be to watch flow rate so it balances contact time and cooling rate. But once that's achieved, it never needs to be changed. In fact, it could be controlled digitally. I plan on putting a digital control on the burner gas feed with overtemp sensors for emergency shutdown, so might as well do the same to the condensor unit.

Any thoughts or bullets to shoot through this idea????

[JohninWV]

Porter...maybe I missed it but are you on a well?

Seems like trying to figure out a way to save either money or natural resources by putting in a closed loop is negated by running a 12 ton unit.

We are saving out condenser water for mash runs and cleaning. But as I continue to run, it does fill up and go to the drain.

Interesting reading....

[porter]

Porter...maybe I missed it but are you on a well?

Seems like trying to figure out a way to save either money or natural resources by putting in a closed loop is negated by running a 12 ton unit.

Yes, we live on a well. And the shop will go on our property.

I think you misunderstand, though. We want to use ONLY THE COILS from 3-4ton units. The coils will carry the water flow from the condensor through them, and a blower will move air over the coils. Only power being used is a thermal controlled blower motor and the pump for recirculation. No refrigerant or compressor will be used. What gave us the idea was talking with someone on the radiator theory. If one radiator will cool a large diesel engine, 3 good coils from central air systems should keep a much lower btu output still cooled down. And the A-coils can be stacked within a custom box to keep them shrouded, sort of a wind tunnel effect.

[Max Action]

Porter, you might want to contact your Department of Natural Resources (or equivalent office) and find out how much groundwater you're allowed to use in your area. Use it for cooling, then pump it back in the ground or just surface runoff if that's allowed.

Of course if you have enough land, you could always build a pond. Use pond water directly, or sink your heat exchange tubing at the bottom. I know plenty of residential heating/cooling systems use this method. Much more efficient than ground source thermal.

[Jester]

WOW,

This thread has taken off in a lot of different directions. I love the conversation...one thing I would like to mention. The output water of your condenser closer to the input temperature is a great thing. This means that your heat exchange is nearing higher percentages. Its the product outlet temperature that should be very close to your water input temperature. If your output product is warmer than your input cooling media, than your heat exchanger is overworked/undersized. But thats a small part of this thread.

The easiest, greenest and cheapest way to chill your cooling media would likely be an air cooled (low voltage fan) closed loop system with a holding tank or two. Elaborate systems are great if you have the capital to do it upon setup. It would be great to do a hot water baseboard system that runs off your waste heat. Or at least is exchanged to the heating system. I think using as much water for CIP, cleaning and future mashing is the absolute best idea, since you may not need heat for certain months, if at all.

I love to talk about stuff just like this...but I will just put in a little where I think it may help. I am all about efficiency. "Exchangers" its the new "plastics" from the Graduate movie...I think

One thing to always remember-each time you do a heat exchange-you lose efficiency.

[JimmyCrackCorn]

Hey Porter,

I added 900 feet of pex tubing into my new concrete foundation. I have 25 gallons of water in a 55 gallon drum plus the water in my "shotgun" style condenser and however many gallons are in the 900 feet of 1/2 tubing. I use a sump pump to recirculate the water through the system. I can distill every day of the week with my 140 gallon pot still and never have any issues with heat building up. The ground does a wonderful job of absorbing the heat.

All of the great ideas on this thread can be added to the simple system I use to move those btu's around your production area. The hot water from your condenser can be sent to a heat exchanger to heat water for your next mash before it enters the ground for instance.

I highly recommend the pex tubing in your foundation to anyone constructing a new building. Send me a message if I can help.

Great thread!!!

Cheers,

Jim

[porter]

As for the Missouri DNR, we don't have any limitations on that, and the county has no zoning. But I'm not interested in pumping from the ground on a single use flow through basis. Going to use some type of heat exchanger. Small pond would be good, several around here do that with their homes. But when the water temp hits 85f in the shallow pond we don't have the capacity to pull down the heat quick enough. And an algae bloom is usually the result, seen that problem with HVAC heating up the pond water in the summer.

As for cost, we're looking at about $200 to put the exchanger together from scrap condensor units and an air handler. In the winter the heat would be ducted back to the building, so savings is good there. In the summer just blow it outside. Fan(s) would be thermal controlled so saving there when they aren't needed. I like the idea of baseboard water heating, but I don't think I'd get the heat transfer enough without forced air across something.

As for condensor temps, I agree fully. But to have the P-output same as the C-input we need to get the temp down on the C-input end. Getting the condensor size isn't really a problem. Oversize the sleeve and regulate the reverse-flow coolant with the flow valve.

The return side would drop into a couple of poly barrels where the pump would pick it up and keep the loop going.

FYI- Found a single condensor unit at a scrap yard, 10in thick x 4ft. square, over 100 cooling tubes passing through the aluminum, weight- 400lb. Thought that might be a little overkill

[Jester]

Many working as one...I love it. remember that air cooling will be heavily dictated by ambient temperatures. you will not reach ambient temp without massive heat exchanger( so that one from the boneyard might be a good one). co-flow vs. counterflow for what we are trying to do is a no brainer--counter flow hands down. with perfect counter flow there would be a complete exchange. input cooling would equal output product and output cooling would equal input product. this is very difficult-near impossible. doing our best is all we can do. there are programs that will help calculate this. Hysis and Aspen are two I know of. I cant use them as they are Engineer toys and exceed my abilities, however Ive had some friends run calcs for me. it works great. other wise its either trial and error or copy someone else. the radiant floor is exceptional if you are building or have a place that you can run it in the floor stringers. this is fairly expensive unless you can do these things yourself. I believe there are many who can or have friends(indentured servants) who could and would. air cooling means you need coils/yubing that have "fins" on them. water is effective enough tube in shell or tube in tube run counterflow. consider the paricidic draw or what you are useing to move your cooling media. pumps, fans and the like will needs replacing and cost pennies to run...they add up.

I know this will open a new debate...but thats why we are here. also consider that alcohol "boils/condenses" around 157 degrees..any thing south of that is liquid...very warm liquid yes.