For those of you interested in designing and building a counter-flow chiller here is a collection of related submissions to the Homebrew Digest as of February 11, 1994. Stephen Hansen Homebrewer, Archivist ------------------------------------------------------------------------------- Stephen E. Hansen - hansen@sierra.Stanford.EDU | "The church is near, Electrical Engineering Computer Facility | but the road is icy. Applied Electronics Laboratory, Room 218 | The bar is far away, Stanford University, Stanford, CA 94305-4055 | but I will walk carefully." Phone: +1-415-723-1058 Fax: +1-415-723-1294 | -- Russian Proverb ------------------------------------------------------------------------------- ------------------------ HOMEBREW Digest #598 Mon 18 March 1991 Date: Fri, 15 Mar 91 13:19 EST From: "Eric Roe" Subject: Copper counterflow chillers Regarding the use of copper tubing for wort chillers, I believe it's the way to go. As mentioned in other posts, copper has a much better heat exchange rate that stainless steel. Copper is also easy to work with. If you're making your own chiller, sweating connections is a fairly simple procedure (not to mention kinda fun). Stainless is hard to work with and expensive. Also, I don't believe you can solder stainless -- you either have to weld it, use a compression fitting, or have the ends threaded. Since copper has had quite a long history with brewing I see no problems in using it. I just wish I was lucky enough to have an eight gallon copper kettle. Also in HBD #597 Mike Zentner writes about using 1/4" OD tubing in his chiller. I made the same mistake (Greg Noonan must be nuts to recommend such small diameter tubing). Once I got the chiller assembled I decided to test it by putting water through it. The flow rate was incredibly slow. I was using 22' of tubing and I calculated it would take over an hour for 5 gallons of water to flow through. I didn't even think about the fact wort would have a heavier gravity -- luckily I didn't try using it for my beer. After the disappointing results I took it apart and replaced the 1/4" OD tubing with 3/8" OD tubing. The chiller worked much better with the larger diameter tubing. Now I can cool 5 gallons in about 20 minutes. The flow rate would be even faster if I just made a minor modification to my system. I too would recommend using 3/8" OD tubing for making counterflow chillers. As for sterilizing, I fill the chiller with water and start a siphon. Then I put the wort-in end into a pot of boiling water and let this flow through the chiller. After the boiling water has flowed through I simply place the wort-in end into the hot wort. I turn on the counterflow cold water, the siphon continues, and voila, cold wort starts coming out. No muss, no fuss; just make sure you don't interrupt the siphon at any of the above stages. Eric ------------------------------ HOMEBREW Digest #612 Wed 10 April 1991 Date: Wed, 10 Apr 91 02:31 EST From: "ASK ME IF I CARE..." Subject: Goofy wort chiller / advice? In trying to get the most efficient chill possible, I rigged up this for a wort chiller, but I have some minor questions to people using this. Sorry if this one has been hashed recently, but I picked up HBD with #574, haven't got around to the archives, and feel I should contribute SOMETHING, dammit! An immersion chiller should be more efficient with a constant flow of water for heat exchange, plus, I had heard about people doing this. What I did was straighten out about a 20' length of copper tubing, and shove it inside about 23' of garden hose, starting at the end I cut off of the garden hose. Then I cut a hole in the garden hose about four feet down from the connector end of the hose, pushed the end of the copper tube through, and made sure there was about 6" sticking out of the end of the hose and also through the hole I cut. Then I sealed the hole with RTV silicone, and coiled the whole mess back up again. Here is a simplistic diagram: <---3'----><--------------------20'--------------><-6"-> __ \\ <-- copper tubing |||\______\\_____________________________________ ||| \\ |------ <-- copper tubing ||| _____________________________________________|------ |||/ ^-- garden hose The concept is, to run the syphon right from a lauter-tun (or strainer in a bucket), through the copper tubing, while running cold water through the garden hose to achieve a REAL fast chill. Also, you can easily regulate the output temperature simply by running more or less tap water through the hose. I just got done inaugurating this device, and here are my observations: 1) This thing does NOT need 20' of copper tubing. Maybe an immersion cooler might need that length, but I was barely running the tap water, and getting wort out at ~60F. I would think 8-10' would suffice. I may split mine into two wort chillers. 2) My question: Everybody I know who uses a device like this uses a counterflow, that is, cold tap water running in an opposite direction to the wort flow. However, it just made intuitive sense to me to send both in the same direction: The hottest wort will exchange the heat with the coldest water and some sort of equilibrium will be reached by the time you reach the end of the chiller. Why would the chiller be more effective with counterflow? Which method makes it easier to regulate temperature? Enquiring minds just GOTTA know! thanks, -dr.d ------------------------------ HOMEBREW Digest #613 Thu 11 April 1991 Date: Wed, 10 Apr 91 09:07:10 -0500 From: zentner@ecn.purdue.edu (Michael Zentner) Subject: Re: Goofy wort chiller "ASK ME IF I CARE..." aka dr. d aka V057P673@ubvmsc.cc.buffalo.edu writes: > straighten out about a 20' length of copper tubing, and shove it inside about > 23' of garden hose, starting at the end I cut off of the garden hose. Then I > cut a hole in the garden hose about four feet down from the connector end of > the hose, pushed the end of the copper tube through, and made sure there was > about 6" sticking out of the end of the hose and also through the hole I cut. > Then I sealed the hole with RTV silicone, and coiled the whole mess back up > again. Here is a simplistic diagram: > > <---3'----><--------------------20'--------------><-6"-> > __ \\ <-- copper tubing > |||\______\\_____________________________________ > ||| \\ |------ <-- copper tubing > ||| _____________________________________________|------ > |||/ > ^-- garden hose This has to be about the best character schematic I've seen :-). For anyone considering this design, another option in lieu of slicing into the hose is to go out and buy one of those Y type hose adapters for each end of the garden hose, so that the copper tubing can come out of one of the ports on the Y. Regardless of the length of copper tubing you use, you'll probably have to adjust the length of the garden hose (there are adapters for this again at any hardware store). Make the cut close to one of the ends, so you can already have the Y screwed into the small piece of hose before joining the hose together. That way, you don't have to keep bending the copper in a circle to screw on the Y. Now, the other advantage of using a Y is that you no longer need to use silicone sealer. Get a hose nipple which has an ID larger than the OD of the copper and which has hose thread, so it will screw onto the end of the Y. Then, a small 3" section of vinyl tubing that fits over the hose nipple. Get successively smaller pieces of vinly tubing that fit in the big one concentrically until the ID of one matches the OD of your copper. Secure the whole thing with hose clamps and wa-la, you have a seal that would even hold up to pressure (sometimes there is pressure in my chiller, since I have installed a cooling water control valve at the outlet end). > 1) This thing does NOT need 20' of copper tubing. Maybe an immersion cooler > might need that length, but I was barely running the tap water, and getting > wort out at ~60F. I would think 8-10' would suffice. I may split mine into > two wort chillers. While certainly true in some cases, this is NOT a good general rule. The length of tubing needed is greatly dependant on the diameter of the copper being used. I agree that for 1/4" OD copper, 10' is probably a good guess, but I think you'll really have to rush the water through if you go with 3/8" OD. Another variable is the ID of the garden hose. The water flow rate will be either faster or slower depending on this as well. I don't doubt the measured results of the author, but, as they say, mileage may vary, and I've had experience now with two of these chillers. Anyone wanting more detailed descriptions of how I built mine, I can email them to you if you're really interested. There is no "right" way to build one. My comment about diameters and flow rates is based on the fact that your flow will most likely be laminar, with well developed stream-lines. When this is the case, the wort near the edge of the copper tubing will lose heat quickly, but it must carry heat from the center streamlines outward, which is not an instantaneous process in laminar flow. Same goes for the cooling water. And as far as 1/4" tubing, anyone thinking about it...think hard, because you may run into very long cool times. > 2) My question: Everybody I know who uses a device like this uses a > counterflow, that is, cold tap water running in an opposite direction to the > wort flow. However, it just made intuitive sense to me to send both in the > same direction: The hottest wort will exchange the heat with the coldest water> and some sort of equilibrium will be reached by the time you reach the end > of the chiller. Why would the chiller be more effective with counterflow? > Which method makes it easier to regulate temperature? Enquiring minds just > GOTTA know! If your outlet wort was at 60F, and you were using a mere trickle of cooling water flow, your water must have been quite cold. If you used parallel flow, both in the same direction, then the cooling water cannot have exited at a temperature above that of the wort, that is, as soon as the wort and water come to the same temperature, the wort can be cooled no further. Unless you have a very fast flow rate, with such a system, the wort can never reach the temperature of the water coming out of the tap. However, with counter-flow, the outlet wort is in "contact" with water at tap temperature, allowing the wort to reach that temperature (again, depending on lengths, rates, etc). Again, I am not trying to flame the original author as I'm sure what he/she measured is fact, but building one of these things is nothing to be totally blase' about. You can end up wasting a bit of money with a failed attempt... I know :-). There are a lot of variables to think about. Mike Zentner zentner@ecn.purdue.edu ------------------------------ HOMEBREW Digest #620 Mon 22 April 1991 Date: Fri, 19 Apr 1991 15:17 EST From: BAUGHMANKR@CONRAD.APPSTATE.EDU Subject: Sterilizing, cleaning copper in chillers Darren Evans-Young hypothesized that the sterilization method he was using for his counter-current wort chiller was the source of the recent infection of his beer. This is a subject dear to my heart because I've been using (and selling) counter-current chillers for about 8 years. I had always stored my chillers with a mild solution of clorox and water (1 teaspoon clorox per 1 gallon of water) in the chiller between brewing sessions. Since this worked for me-never an infection in 8 years-I recommended the same to my BrewChiller customers. Then a friend in the plumbing business pointed out that they use copper to sterilize swimming pools when they become real funky. It seems that copper has anti-bacterial properties. Added to that were the comments that the clorox caused little blue flakes to form inside the copper tubing. I've never worried about the blue flakes because even though blue, they were sterile, and didn't seem to affect the taste of my beer in any way. Still blue flakes were a recurring comment and I began to consider doing what Darren did, use boiling water to sterilize my chiller instead of storing it with the clorox solution in the tubing. And so far so good, but I still do a quick 30 minute clorox soak prior to brewing. I'm a paranoid at heart. :-) To insure that boiling water sterilizes the copper tubing, one must siphon it through the tubing when the chiller is dry, that is, no water in the "cooling chamber". This must be done both after a brewing session and before the next one. So my question to Darren is: Is that they way you handled your sterilization procedure? If so, given what my plumber friend said, I'd be surprised that the chiller is the source of the infection. Still I'm not a chemist and I'd be interested in what the net has to say about all of this. While we're on the subject: A few digests back, someone pointed out that new copper has oils which must be removed before first use of a chiller. That's absolutely correct. I think they use silicone oils when extruding the copper tubing. I've always recommended doing a couple of clorox soaks (1 Tablespoon clorox to 1 gallon of water, for 30 minutes) before using copper chillers for the first time. Following up or interspersing it with a couple boiling hot water rinses is a good idea as well. Cheers, Kinney | Beer is my business and baughmankr@conrad.appstate.edu | I'm late for work. ------------------------------ HOMEBREW Digest #656 Tue 11 June 1991 Date: Mon, 10 Jun 91 09:50:08 PDT From: keng@ic.MENTORG.COM (Ken Giles) Subject: Cleaning counter-flow chillers, try TSP In HBD microsoft!larryba@cs.washington.edu says: > The bummer with counterflow chillers is cleaning them out. I have never > figured out a satisfactory solution for the kitchen brewer. Commercial > microbrewers use nasty corrosive chemicals and lots of very hot water. I've had good success with TriSodium Phosphate (TSP). TSP is not so corrosive tobe dangerous (gloves are recommended but I often get it on my arms with no ill effects), but acts like a corrosive cleaner. I tried an experiment. After I rinsed and ran the usual bleach solution through my counter-flow chiller until it ran clear, I ran a solution of TSP through, and it came out yellow and eventually ran clear. The TSP was able to clean beyond the power of the bleach solution alone. No real surprise. TSP is also great for dissolving the gunk out of your blow-off hose. TSP is available in the paint section of most hardware-type stores. It's used for preparing surfaces for painting. I've heard that some homebrew suppliers sell a dry bleach/TSP combination called tri-chlor. I don't use this because I'm typically only cleaning afterword (with TSP) or sanitizing beforehand (with bleach). Stay clean, kg. ------------------------------ HOMEBREW Digest #656 Tue 11 June 1991 Date: Mon, 10 Jun 1991 15:57 EST From: BAUGHMANKR@CONRAD.APPSTATE.EDU Subject: Sterilizing chillers; straining hops Larry from Microsoft writes: >The bummer with counterflow chillers is cleaning them out. I have never >figured out a satisfactory solution for the kitchen brewer. Commercial >microbrewers use nasty corrosive chemicals and lots of very hot water. I >just rinse well after each use. Before the next use I drain all the bleach >solution used to sanitize my carboy through the chiller before draining the >hot wort through it into the carboy. I also toss the first pint of wort to >make sure no bleach gets into my wort. Probably draining a couple of gallons >of boiling water through the chiller w/o chilling water would work as well >as avoiding bleach. Maybe commercial brewers use nasty corrosive chemicals but many brewpubs use boiling water or wort just like we do. My technique is this: Follow a chilling session with a gallon or so of boiling water through the coils after draining the chiller body of its water, to cut the malt sugars from the copper. Usually I follow that up with some of the sterilant (I use 1 T. clorox per 1 gallon of water) that I've been using for that session, until the sterilant runs cool from the coil (since high temperatures destroy the disinfectant effects of clorox). Drain. Store dry. Prior to the next session of brewing, I will usually fill the chiller coils back up with the sterilant solution and let it sit for about 20 minutes. Drain. When I begin the chill routine, I run the boiling hot wort through the chiller prior to filling the chiller body with water. The boiling hot wort will sterilize the coils for sure. Toss the first few ounces of wort that comes through since some clorox will be in it. Let a quart or so of wort run through then return it to the boiler. Fill the chiller body with water and let 'er rip. The boiling wort through the coils is what really does the trick with this routine just like it does with immersion chillers. So why do I still use the clorox solution? It's simple. It only takes a minute and I'm paranoid as hell! The most effective means for straining wort into the fermenter discussion has popped back up so here again is my pot-scrubber-in-a- mesh-bag technique for filtering hops: I've never been a fan of pouring wort through a filter because filters clog and you're bound to pour at least some trub into the fermenter. Buy a copper wound pot scrubber and a fine mesh hop bag. Also get a rather thick rubber band. It also helps to have a copper pick-up tube if you're going to siphon hot wort into your fermenter. If you're cooling it first, one of those plastic pick-up tubes will do the trick. Tie the pot scrubber around the bottom of the pick-up tube (the end that's going into the wort). Then tie the fine mesh hop bag around that, in effect putting the pot scrubber in a bag. (Oh, yes, "No see- um netting" from a camping store works well, also.) Tie a small 1/4" overhand loop in one end of the rubber band. Loop the other big end around and through the handle on your boiling pot. Now slip the pick-up tube through the small end of the rubber band. If you've tied the small loop small enough, the rubber band will grab the pick-up tube at whatever position you want. Suspend the pick-up tube a couple of inches below the top level of the wort. Start your siphon. The mesh bag/pot scrubber combo will effectively filter out all the hop leaves and particles. By siphoning from the top level of the wort, you'll always be siphoning off the clearest portion of the wort. As the level of the wort recedes, slowly inch the pick-up tube down accordingly, always keeping it an inch or two below the surface. This technique will give you the cleanest possible run-off into the fermenter without clogging the siphon. Others have commented on the effect of whirlpooling the wort before starting the siphon, so I won't comment on that. Cheers, Kinney Baughman baughmankr@conrad.appstate.edu baughmankr@appstate.bitnet ------------------------------ HOMEBREW Digest #784 Wed 18 December 1991 Date: Tue, 17 Dec 91 08:23:04 EST From: Tom Dimock Subject: Counterflow chiller size Brian Capouch asks about sizes for the tubing in counterflow chillers... Everyone I know who has used 1/4" tubing has regretted it. They are just too slow. 3/8" is better. Now if you're into brewing fast, my counterflow chiller is made using 25' of 1/2" tubing, and it will take 5 gallons of boiling wort down to 80 F in under five minutes. My boiler drains from the bottom - it might be difficult to start 1/2" as a siphon. For general guidelines, I'd say about 16-18' of 3/8". Other opinions? ------------------------------ HOMEBREW Digest #784 Wed 18 December 1991 Date: Tue, 17 Dec 1991 11:48 EDT From: BAUGHMANKR@CONRAD.APPSTATE.EDU Subject: Chillers & Wet Mills Brian asks: >So I need to make a "quick-and-dirty' counterflow chiller. My question >is this: would 1/4" or 3/8" tubing make the better mousetrap? Intuition >tells me that the 1/4" would allow a much greater wort-to-coolant >surface area, since there'd be more wort (relatively) on the outsides of >the tubing than in the center. That would be at the expense of >throughput, but I'd rather have cool wort exiting slowly than hot wort >exiting fast. All the above intuitions are correct. In fact I shared them when I designed the first version of the counter-flow chiller that I sell. I chose 5/16" OD tubing for that model. 95% of the time it works fine. It's a little slower on the siphon (@ 30 minutes) but very efficient. However, it's too efficient for big, high gravity brews and the cold- break is so pronounced that some people complained that it clogged the siphon. Two years ago I switched to using 3/8" tubing. With a strong water flow it works fine. From my kitchen sink, I found that on the average the water exiting the chiller was about 10 degrees warmer than the smaller pipe. If the wort coming out is too warm there are two things you can do. (1) Use a pinch clamp on the end of the exit hose to slow down the flow of wort. (2) Try to connect to an outside faucet. The outside faucet at my house generates about three times the flow of water than does my kitchen sink. No one has yet to complain of a clogged chiller with the larger tubing, BTW. The other thing to remember is to keep the water housing of the chiller as small as possible. Heat exchangers are more efficient the more the coolant turns over. ... Kinney Baughman | Beer is my business and baughmankr@conrad.appstate.edu | I'm late for work. ------------------------------ HOMEBREW Digest #784 Wed 18 December 1991 Date: Tue, 17 Dec 91 10:49:49 CST From: dyer@marble.rtsg.mot.com (Bill Dyer) Subject: RE: Best size for counterflow chiller In HBD #783 Brian says: >So I need to make a "quick-and-dirty' counterflow chiller. My question >is this: would 1/4" or 3/8" tubing make the better mousetrap? Intuition >tells me that the 1/4" would allow a much greater wort-to-coolant >surface area, since there'd be more wort (relatively) on the outsides of >the tubing than in the center. That would be at the expense of >throughput, but I'd rather have cool wort exiting slowly than hot wort >exiting fast. >Is that logic good? Well, I thought it was good logic too but I was wrong. I made a wort chiller from 1/4" tubing immersed in ice water. It worked great as far as cooling the wort goes, but it had several other problems, namely the throughput was way too slow and on top of that it clogged. It took about an hour to cool the first 3 or so gallons of a 5 gallon batch. At that point the thing clogged and I had to run some boiling water through to clean the clog and finish the cooling. A slow throughput is one thing but over an hour is too long for me. I tried increasing the flow by raising the bucket (I sat it on top of the fridge) but that didn't help much. I am going to do one of two things to solve this problem, either shorten the length of my current copper coil or go out and buy some bigger stuff, I havn't decided yet which is better. From feeling the wort coller as it is now, the wort seemed to be cool about half way through the tubing so I can probably cut down the length by about 1/3 (it is about 30' now I think). This should increase the flow by 50% if I remember correctly. Of course to solve the clogging problem, I may keep the length and go to the 3/8 tube. Or as a third alternative I could cut the tube I have now in half a connect a Y to it. This should double the flow. Actually if I could remember all the fluid dynamics and thermodynamics I learned in college I could figure out exactly how long and how big my tube needs to be, but that is too much work so I will just guess. Later, Bill_____________________________________________________________________________ | you'll think I'm dead, but I sail away |Bill Dyer (708) 632-7081 | | on a wave of mutilation | dyer@motcid.rtsg.mot.com | | -Pixies | or uunet!motcid!dyer | ------------------------------ HOMEBREW Digest #908 Tue 23 June 1992 Date: Mon, 22 Jun 1992 10:45 EDT From: Kinney Baughman Subject: Sterilizing counter-flow chillers >:Wort Chillers. OK, I am ready to take the step. The immersion >variety seems more practical from a sanitation standpoint. I like the idea >of keeping it clean, but sterilizing it just before use by inserting it into >the boil for a few minutes before turning the water on. Oh, well. Thought I'd do my part to dispel the ever-present notion that counter-flow chillers are impractical or difficult to keep sterile. When I finish using my counter flow chiller, I drain the chiller body of water and siphon boiling hot water through the coils to cut the malt sugars. I then follow with some of my clorox sterilant solution and let it sit for about 30 minutes. Drain and store. Before using the chiller for the next brewing session, I fill it with sterilant again and let it sit for 30 minutes. As if this isn't enough, before I actually start chilling the wort, I siphon the boiling hot wort through the copper coils until the wort runs boiling hot out the bottom. (If boiling hot wort is good enough to sterilize immersion chillers, it's good enough to sterilize the counter-flow chillers or else I'm missing something.) I then fill the chiller body with water, return the collected wort back to the boiler and proceed with the chilling procedure. I've used counter flow chillers for eight years and have never had problems with contamination. Add to this the fact that copper is used to sterilize swimming pools because it has anti-bacterial properties (or so I'm told) and I've never worried an iota about contamination with my chiller. The following points are somewhat technical but I might add that counter-flow chillers have several things in favor of them over immersion chillers. (1) Shocking the wort cool produces better cold break. (2) Since you can start siphoning immediately after finishing the boil, it's a time saver. And finally (3) I'd argue that there is less chance of bacterial infection with the counter-flow chiller because any one drop of wort is going to go from boiling to pitching temperature in about 6 seconds. The down-side, of course, is that counter-flow chillers are both more difficult to make and, if you buy one, are more expensive. >From a purely technical point of view, I think counter-flow chillers win out. But from an economic perspective, immersion chillers are the winner. But whatever the case, use one or the other. Wort-chillers are essential to any homebrewery. The AHA conference was indeed a blast. As mentioned by others, it was great putting faces to email addresses. There must have been ten times the number of online brewers at this conference compared to last year so there's no way I can make disparaging comments about those I met like I did last year. So count your blessings. :-) Still I'd be remiss if I didn't say thanks to Martin Lodahl and Mike Sharpe for their outstanding lambic beer tasting and the information they provided to us regarding this most unusual of all beer styles. I thought Mike's framboise was remarkably close to style. Thank you, thank you, thank you for sharing that with us. It was nectar of the gods as far as I was concerned and feel privileged to have gotten a chance to taste some of it. Cheers, ya'll. Kinney Baughman | Beer is my business and baughmankr@conrad.appstate.edu | I'm late for work. ------------------------------ HOMEBREW Digest #944 Mon 10 August 1992 Date: Thu, 6 Aug 1992 09:57:27 -0700 (PDT) From: Paul dArmond Subject: Re: Counter Flow Chillers In HBD #941, on 3 Aug 92, Joe Rolfe asked about cutting down on water usage and getting a lower output temperature from his counterflow chiller. Here is the Rocket Science part. My source is 'Cryogenic Engineering' by Russel B. Scott, D. Van Nostrand Co. Inc. 1959. Heat exchangers are important to cyogenics because they form a very important part of the refrigerators used to liquify gases. It really is "rocket science", since you need lots of LOX and other gasses to "make der rockets go up." Other engineering books on steam power, oil refining and thermo-hydrodynamics will provide similar information. I'm not going to go into the mathematics, but try to explain everything as empirically as possible. Heat transfer equations are very heavy on differential equations. This stuff is not only hard to type without a mathematical typesetting system, but it isn't very accessible to most people. Joe's questions get right to the nub of the tradeoffs involved in heat exchangers. In the best of all worlds, you would use as little water as possible, get the biggest temperature drop, and do it as quickly as possible. Unfortunately, all three of these factors work against at least one of the others. All of these factors are expressed in the heat-transfer coefficient. This coefficient is expressed as: watts / [(cm**2)(deg K) in CGS Watts per square centimeter-degree Kelvin That's how much heat flows into the wall of the heat exchanger tube from the liquid in contact with the tube wall. The formulas assume that the tube is straight, cylinderical, and smooth, and that the flow of the liquid inside of it is turbulent (i.e. the tube is small enough that the flow doesn't channel in the center.) The factors that determine the heat transfer coefficient are: The specific heat of the fluid - This is a measure of heat (as opposed to temperature) and empirically is measured by how much ice is melted by a given mass at a given temperature. Beer wort has a higher specific heat than water. The concept of specific heat supposedly came from Count Rumford burning his mouth on some apple sauce. The apple sauce was at the same temperature as his tea which didn't burn. He had just got his first thermometer and was measuring everything in sight. The mass velocity of the liquid: g / sec cm**2 How much mass is passing through a given cross section each second. For a given tubing size, this is strictly determined by the available pressure and flow. For your water supply this is effectively limited by the maximum pressure available. The thermal conductivity of the liquid. Suprisingly, this is quite low for most liquids. Water is nearly an insulator, if all convection is supressed. I assume that wort has a low conductivity as well. Things like mercury and sodium metal have high conductivity. The diameter of the tube. For tubes that don't have a circular cross section, this is replaced by the "hydraulic radius" which is defined as the cross-sectional area divided by the wetted perimeter. In designing a heat exchanger, there are only a few of these things that we can influence. We can alter the mass velocity by turning up or down the flow on the faucet or altering the siphoning height. We can pick the diameter of the tube that we use. Remember that we are looking at maximizing the heat-transfer coefficient at one point of the tube in one direction (wort to tube or tube to water). We are only dealing with a slice, so that if the tranfer coefficient is maximized, then we will get the most heat transfer out of a given length of tubing. The transfer coefficient will also set an upper limit on the in/out temperature differential for a particular length. If the tube was infinitely long then the water out temp and the wort in temp would be equal, and the wort out temp would be the same as the water in. The drawback with an infinitely long tube is that you would collapse both your lungs before you could get the siphon started. Also for an immersion type cooler, it would not be possible to fit an infinite amount of tubing in your brew pot, no matter how tightly you coiled it. At any rate, you want the coefficient as high as you can get it. It is maximized when the tube is small (or the hydralic radius is small) and the mass velocity is big. This has several implications: 1) better heat transfer means using more water (faster flow). 2) Smaller tubes are better than bigger ones. This makes sense, since there is more surface area for the same amount of copper. It is limited by the ratio of cross sectional area to wall thickness. The very small tubes have a problem with this, in that their inside area is small compared to the relative thickness of the wall. Heat transfer is inversely proportional to wall thickness, so there is a limit to how small is small enough. Well, we don't want to use more water, so that's out. Joe is already using 1/2" tubing in his cooler, so it would be rude to tell him to get smaller tubing. Wasteful too. What we can do is decrease the hydralic radius of his tube. A circular cross-section has the lowest possible ratio of area to perimeter. This is why bubbles are round. So how about making the copper tubing not round. There are some very high efficiency florescent light tubes that have a rippled surface to increase the surface to volume ratio. The tubes look pinched, the pinches alternating 90 degrees from each other. Maybe this could be done with a pair of vice-grip plyers so the tube doesn't get pinched too much. This high ratio of surface are to volume is why the breweries use flat plate coolers, the transfer coefficient is quite high if you get away from using tubes. Multiple small tubes in parallel are also used for high efficiency heat exchangers. If you are building a cooler, here are some things to consider: * for the same price, more feet of small tube are better than fewer feet of big tube. * The coefficients in a counterflow exchanger need to match. The water side will have to have a larger flow to match the lower specific heat of water compared to wort. * If you have a choice, thinner copper tube is better since heat flow is equal to conductivity / thickness. * When using an immersion chiller, stir the wort. This will raise the mass velocity on the wort side and improve the heat transfer. Remember: water and wort are poor conductors, heat transfer takes place by convection. To get into the true "rocket science" of counterflow wort chiller design, the specific heat, conductivity and viscosity of hot beer wort need to be known. Can anybody help? ------------------------------ HOMEBREW Digest #947 Thu 13 August 1992 Date: Wed, 12 Aug 1992 22:20:14 -0700 (PDT) From: Paul dArmond Subject: RE: chillers Michael Hall has written a very good paper on the calculations required for a counter-flow type chiller. I believe that Mike mentioned that he was preparing to submit it to Zymurgy. I searched the last two months of archives for it, but came up dry. John Palkovic kindly sent me a copy. There is a rights reservation at the top, so I'm retroactively asking Mike's permission. My system's mailer keeps bouncing Mike's address. I believe I can reply if he contacts me. That being said... Mike's calculations suggest that a siphoning counter-flow cooler would need to use a length over 30' if it was made of 1/2" copper tubing, but that 25 - 30' of 1/4" tubing would give a good heat exchange efficiency. The interesting part of Mike's results is that there is a minimum length for any tubing diameter. Using a longer length does no harm, but you are buying more tube than you need. An immersion cooler will have a higher velocity, since the water is being driven by the mains pressure, rather than a siphon. Since heat transfer is proportional to velocity, the tubing lengths would presumably be shorter. In a parallel tube immersion cooler, smaller would be better. The length of the cooler tubes would be determined by the number of tubes in parallel, the I.D. of the chiller tubes, the water supply pressure and the diameter of the supply line at the tap. Most outdoor hose bibs are 1/2" pipe, while sinks are usually 3/8". FWIW, my 25' x 3/8" immersion cooler has an outlet temp near the wort temp, but only if I stir pretty fast. Also pipe is measured by I.D, but bendable tube is O.D. This means that tubing sizes are bigger than the fluid cross-section. The difference is considerable for the smaller sizes. Paul de Armond paulf@henson.cc.wwu.edu ------------------------------ HOMEBREW Digest #1188 Fri 23 July 1993 Date: Thu, 22 Jul 1993 08:40:03 -0400 (EDT) From: Kinney Baughman Subject: Siphoning through counterflow wort chillers >From: Kevin V Martin >Subject: Siphoning >I recently made two changes to my brewing procedures. I bought a wort chiller >and used hop pellets for the first time. After cooling my last batch of hot >wort, I tried to syphon the cool wort. I ended up clogging the syphon with >trub and pellet rements. Does anybody have a good way to syphon off the good >stuff and leave the trub behind? Thanks, Time for my periodic posting on filter-siphoning: - -------------------------------------------------------------------- Here is my pot-scrubber-in-a-mesh-bag technique for filtering hops: Buy a copper wound pot scrubber and a fine mesh hop bag. (Get a Chore Boy. They are made from 100% copper. Also get a rather thick rubber band. It also helps to have a copper pick-up tube if you're going to siphon hot wort into your fermenter. If you're cooling it first, one of those plastic pick-up tubes will do the trick. Tie the pot scrubber around the bottom of the pick-up tube (the end that's going into the wort). Then tie the fine mesh hop bag around that, in effect putting the pot scrubber in a bag. (Oh, yes, "No see- um netting" from a camping store works well, also.) Tie a small 1/4" overhand loop in one end of the rubber band. Loop the other big end around and through the handle on your boiling pot. Now slip the pick-up tube through the small end of the rubber band. If you've tied the small loop small enough, the rubber band will grab the pick-up tube at whatever position you want. Suspend the pick-up tube a couple of inches below the top level of the wort. Start your siphon. Note: By siphoning from the top level of the wort, you'll always be siphoning off the clearest portion of the wort. As the level of the wort recedes, slowly inch the pick-up tube down accordingly, always keeping it an inch or two below the surface. This technique will give you the cleanest possible run-off into the fermenter without clogging the siphon. (There are a couple of gizmos on the market now [one is made by Fermentech] that clip to the pickup tube, attache to the rim of the brewpot and suspend the pickup tube off the bottom of the pot.) The mesh bag/pot scrubber combo will effectively filter out all the hop leaves and particles. But the mesh can still clog and I consider it a flourish to the technique and not essential. Should it clog, the easiest thing to do is to just take it off and resume your siphon with the pot scrubber alone. An alternative is to raise the brewpot which increases the flow rate of the siphon. It's also a good idea to stir the wort, just after the end of the boil, to create a whirlpool action in the kettle. This will cause the precipitate matter to settle out into a cone in the bottom of the vessel. At the end of the siphon you'll find a "moat" of wort around the cone and be able to siphon off almost all of the cleared wort. Cheers! - ------------------------------------------------------------------------- Kinney Baughman | Beer is my business and baughmankr@conrad.appstate.edu | I'm late for work. - ------------------------------------------------------------------------- ------------------------------ HOMEBREW Digest #1206 Wed 18 August 1993 Date: Mon, 16 Aug 93 11:51:41 -0700 From: Drew Lynch Subject: YACFWCD (Yet another counter flow wort chiller design) After modifying my immersion chiller to be a "coil in a bucket -o- cold water" chiller, I finally seem to have gotten it right. Drew's Counterflow Wort Chiller Design Parts list: 50' 5/8" id garden hose 50' 3/8" od soft copper refridgeration tubing 6 ea 1.5" long pieces of 1/2" copper pipe 2 ea copper "T"s to fit above pipe 2 ea copper end caps for above pipe 4 hose clamps plastic zip ties Tools Needed: sharp knife or clippers propane torch, solder and flux standard screwdriver power drill, 1/8" bit & 3/8" bit 1) Cut off each end of the garden hose, leaving about 8" attached to each "hose end" 2) Insert the 6 pieces of copper pipe into the 6 ends of the 2 copper tees, and solder in place. 3) Drill a 1/8" hole in the end of each copper end cap. 4) Enlarge these holes to 3/8" 5) attach one end cap to each enlarged "T" so that you can look through the "T" and see light through the 3/8" hole in the end cap. 6) straighten the 50' of copper tubing, and feed through the garden hose. 7) slip a hose clamp over each end of the garden hose. 8) slip the copper "T" assembly over the end of the copper tubing, and into the garden hose. Attach with clamp. 9) Solder the copper tubing to the "T" assembly where it passes through the hole in the end cap. 10) Using the 2 remaining hose clamps, attach the hose end remnants to the "other" end of the "T" assembly. copper T ______________________________________ copper T end+-----------+ clamp Garden Hose clamp +-----------+end ===============<<<<==copper=tubing=<<<=wort=flow=direction=<<<============ cap+--+ +--+______________________________________+--+ +--+cap | | | | + + + + | clamp | | clamp | | | | | Hose end in Hose end out 11) Coil this using your favorite round object as a form. I used my old 5 gallon brewpot. Zip tie the coils together. I attached 3/8" id plastic tubing to each end of the chiller. For the "in" end, I attached a 3/8" od copper racking cane. I hose clamped a copper Chore Boy scrubber to the end of the racking cane, to filter out hop particles. To sanitize, I siphon iodophor solution through the chiller into the carboy. To start the siphon, put a female garden hose to 3/8" hose barb fitting on the "out" end and attach it to a water source, Place the "racking cane" into a bucket filled with sanitizer. Then run the water until all the air is removed from the system, disconnect the water source, and place the "out end" lower than the "in end" immersed in sanitizer. I use this same method to start the siphon from the hot wort (remember not to blow bubbles into the hot wort though). This design works very well. I was able to drop boiling wort to within 5 degrees F of the tap water temperature. I found three drawbacks: 1) The flow is very slow. It took about 20 minutes to siphon 5 gallons through the system. 2) a fair amount of wort is left in the tubing then the siphon quits. 3) a fair amount of wort is left amongst the hops in the bottom of the brew kettle. I have a small food grade pump which I may attach to the outflow of the chiller next time I use it, which should solve #1 & #2 and help #3. I may also add another, bare copper coil between the outflow of the CF chiller and the carboy. This coil will be immersed in a small ice bucket. This will minimize the amount of ice needed, and get that final, desireable drop in temperature. Drew Lynch Chronologic Simulation, Los Altos, Ca. (415)965-3312 x18 drew@chronologic.com ------------------------------ HOMEBREW Digest #1255 Tue 26 October 1993 Date: Fri, 22 Oct 93 01:09:00 +0300 From: ari.jarmala@mpoli.fi (Ari Jarmala) Subject: Slow CF chiller drose@husc.harvard.edu writes about slow CF wort chillers: HO>I bought 50ft of garden hose (a lot HO>cheaper than tygon tubing), 50 ft of 1/4" copper tubing, and built HO>a 40 ft chiller (10 feet of the hose going to the connecting lines). 1/4" tube is very thin. Try larger diameter tube. The gain: * the cross section area of the tube is the _square_ of the diameter * the flow is the cross section area times the speed of wort in the tube * the resistance to flow is reduced by increasing diameters => faster flow Increase the diameter by a factor of 2 and you get about 6 to 8 times faster volume flow. Maintain the length of the chiller. The other possibility is to increase the driving force: increase the height difference. - Ari J{rm{l{ ------------------------------ HOMEBREW Digest #1258 Fri 29 October 1993 Date: Tue, 26 Oct 1993 10:54:14 -0400 (EDT) From: "Robert H. Reed" Subject: CF Chiller Effects on Hop Character Norm Pyle writes: > With the counter-flow chiller the wort and hops remain near 100C the entire > time the wort is being chilled. From experience I know the kettle is still > extremely hot 20 minutes after turning off the flame. I would bet that > finishing hops act more like flavoring hops and that flavoring hops act more > like bittering hops with a counter-flow. Can anyone verify these assumptions? > I may alter my procedure a little bit to compensate for this. I haven't yet > decided how. Suggestions? I noticed a similar change in late hop character when I changed to using a CF chiller: I found that to obtain the same hop flavor and aroma, I had to add *more* hops *later* in the process as compared to my previous process that used an immersion chiller. One technique that I have found useful is to add hops *during* the runoff. After my boil is complete, I stir the wort vigorouslyand wait 15 min for the trub and hops to settle. During the runoff - about 25 min for 5.5 gal - I typically add whole hops in one or two additions. This has improved the intensity of my late hop character. I use a slotted pick-up tube in the boiler to avoid clogging the chiller. I feel the CF chiller has pros and cons: I get a much better cold break with my CF unit using well water. My wort exit temp is ~55-60F. Another benefit is that, given that my chiller and settling tank are disinfected, there is very little risk of infection because the wort in my boiler is still above 160F at the end of runoff. On the downside, one must deal with the cold break in the fermentor and the late hop character is decreased in the 30-40 min. the wort remains in the boiler. Rob Reed ------------------------------ HOMEBREW Digest #1260 Mon 01 November 1993 Date: Wed, 27 Oct 93 11:37:01 -0700 From: "Stephen E. Hansen" Subject: YACFC, Yet Another Counter Flow Chiller. Last week I decided to build a counterflow chiller (I had been using an immersion unit previously). I debated whether to use a garden hose or a piece of large diameter PVC pipe to enclose the copper tubing and went with the hose for simplicity's sake. I have seen one or two commercial versions of counterflow chillers that use something that looks like coiled copper in a section of PVC pipe but I couldn't find end caps that looked like they would work without more work than I wanted to put in. What I did was buy a 50' 5/8" ID garden hose and 50' of 3/8" OD copper tubing. In addition I bought two hose end replacement connectors, one male and one female, and two of those Y hose connectors with the the built in ball shutoff on each leg of the Y. I took the hose and cut it in two with 30' left on the piece with the male connector. I slid the copper tubing through the hose from the cut-off end until about 12" stuck through past the other end. Then I cut the copper tubing leaving about 12" on both ends. The male hose repair connector went on the cut end. Getting the last ten feet or so of tubing through the hose took some elbow grease but persistence paid off. Next I took the Y adapters and slid the copper tubing up the trunk of the Y and out through one of the legs until I could screw the Y onto the hose end. This was a bit tricky but if you counter-twist the hose before mating the ends it works pretty well. The hard part was getting the copper tubing past the ball valves in the Y. One fit perfectly but the other had to be drilled out with a 3/8" bit. The fit of the copper tubing in the Y is essentially watertight on one of the connectors but the other leaks a bit. I'll probably put some silicone sealer in that one. Once the Y connectors were on tight I just recoiled hose to about a 12" diameter and loosely tied the coils together. As for the female replacement connector. That goes on the cut off end of the 20' piece. giving me a short hose with two female connectors on each end. You need this to connect to the inlet of the chiller. The remaining copper got turned into a siphon cane and an aerator. The aerator was build from the description by Spencer Thomas in HBD 1081 and it works great. The next day I made an IPAR (an IPA with Rye) and the chiller worked like a champ. Compared to my immersion chiller this is MUCH easier and faster. The wort outflow wasn't much warmer, if any, than the tap water inflow. The tap water flow rate is your temperature adjustment in this setup and I was able to use a fairly slow flow of water. Obviously, with my current water temperature I could have gotten away with a shorter chiller but the water temp will warm up a bit in the summer. I siphoned the hot wort off the hops and hot break material in the kettle and into a plastic bucket with a tap valve at the bottom. The copper scruber in a mesh bag tied to the end of the copper siphon wand did a good job of keeping things clear. I took the bucket full of hot wort and set it on top of the washing machine. The chiller sat just below it on a stool, a 5 gallon carboy sat on the floor. Plastic tubing went from the outlet of the tap valve to the inlet of the chiller. More plastic tubing went from the outflow to the aerator wand stuck in the carboy. Stephen Hansen Homebrewer, Archivist =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Stephen E. Hansen - hansen@sierra.Stanford.EDU | "The church is near, Electrical Engineering Computer Facility | but the road is icy. Applied Electronics Laboratory, Room 218 | The bar is far away, Stanford University, Stanford, CA 94305-4055 | but I will walk carefully." Phone: +1-415-723-1058 Fax: +1-415-723-1294 | -- Russian Proverb =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- ------------------------------ HOMEBREW Digest #1263 Thu 04 November 1993 Date: Tue, 2 Nov 1993 8:36:29 -0800 (PST) From: Jim Cave Subject: Counterflow chillers There has been considerable debate recently on the relative merits of immersion vs. counterflow chillers. While I do not intend to try and convince others to switch to the counterflow design, it is the one that I use for the following reasons: 1) About 50% of the beers (all-grain) that I brew are lagers. I prefer very cold ferments to these beers (45 F). For much of the year, I can get my beer close to this temperature with this design. During the summer months I use an additional coil (after the counter current) which runs through an ice bath. This drops the beer an additional 10 F. This rapid drop in temperature makes for remarkable cold breaks. 2) Much of the trub falls out in the kettle. I have a hop-back and a second screen in at the outlet-valve to prevent the occassional errant hop from entering the chiller. I give the wort a quick stir to generate a whirl-pool. The counter-current flows into glass carboys. I then rack off the trub and into glass carboys (Yes I rack off the trub; the breweries I have talked to estimate that they remore 95% or more of their trub prior to ferment). 3) The unchilled beer remains well above 160F and is therefore sterile. Gravity checks can be rapidly made at the exit of the chiller and gently re- introduced to the boiler without fear of contamination. 4) When 2/3's of the wort remains in the kettle, I throw in hops for aroma (hot soak). This gives excellent aroma. A hop-back in-line with the chiller would be a better way to go but I have't come up with a rugged design yet. 5) With my boils, I always seem to end up with a gravity 4 or 5 points higher than target (and correspondingly less volume). I have recently come up with a gentle way of adjusting gravity. I fire up the sparge tank and boil water. This is introduced with a tube into the boiler with the beer (when the beer has nearly all gone through the chiller). This gently washes the hops and trub of fermentable extract. One disadvantage that I see with the counter current chiller is that the Irish moss addition is less effective, as it doesn't really enter the collecting carboys. Consequently, the beer in the collecting carboys takes longer to drop bright than it otherwise would in the boiler. However, as I mentioned, trub is also settled and filtered out in the boiler. I guess you pays your money and takes your chances!! Jim Cave 684-684-8081 "I brew.....I am" ------------------------------