So I am sure that this topic has been beaten to death, and I apologize if I am just digging up an old topic for the millionth time, but I got to thinking about building my immersion chiller.
Thinking leads to drinking and drinking leads to the inevitable… Math
I have seen a good deal of debate regarding 1/2 inch vs 3/8 inch copper but really no discussion of 1/4 inch. From the rudimentary calculations I put together, 100 ft of 1/4 inch copper pipe gives you the same surface area as 50 feet of ½ inch with less displacement than 50 feet of 3/8.
50 ft of 3/8 copper has a total surface area of 4.91 Sq. Feet with a displacement of roughly .29 gallons
50 ft of ½ copper has a total surface area of 6.55 Sq. Feet with a displacement of roughly .51 gallons
100 ft of ¼ copper has the same surface area as 50 ft of ½” but with a displacement of only .255 gallons
(figures courtesy of http://www.aqua-calc.com/calculate/volume-cylinder-hollow)
Now logic would dictate that 1/4 inch pipe is going to have a higher head pressure (resistance) and therefore a lower flow rate than a wider pipe meaning more contact time of the water flowing through the pipe with the actual copper. Unless the water coming out of your chiller is raised to the temperature of the wort any additional contact time would lead to faster cooling. (how much faster is the real question)
I also did some rough calculations to see if you could fashion a coil of 100 feet of ¼ inch pipe to fit in an average brew pot. I use an 20 qt. pot with an inner diameter of roughly 12 inches. I believe that if you did 2 concentric coils you could fit the copper with no issues.
I brew roughly 3 gallon extracts currently which is 6.5 inches of liquid in my pot. 20 wraps of coil with an 11 inch diameter use roughly 60 feet of tubing (5 inches tall if stacked tightly or leaving 1/16 inch between the coils and not exceeding 6.5 inches). 20 10 inche coils inside the outer coils would use up an additional 52 feet meaning you would have room to tweak these dimensions significantly and still have everything fit. These measurements would leave a half inch of space all the way around the outer coil and pot and a half inch between the inner and outer coil with all of the copper submerged below the level of the 3 gallons of wort (before you even think about displacement).
Obviously you are going to spend more for 100 feet of 1/4 inch copper tubing, and will have more work creating your coil(s), but as I stated before I am a new member and new to home brewing, but I love theoretical discussion and experimentation, so I just figured I would throw this out for some of the vets to shoot down.
Thinking leads to drinking and drinking leads to the inevitable… Math
I have seen a good deal of debate regarding 1/2 inch vs 3/8 inch copper but really no discussion of 1/4 inch. From the rudimentary calculations I put together, 100 ft of 1/4 inch copper pipe gives you the same surface area as 50 feet of ½ inch with less displacement than 50 feet of 3/8.
50 ft of 3/8 copper has a total surface area of 4.91 Sq. Feet with a displacement of roughly .29 gallons
50 ft of ½ copper has a total surface area of 6.55 Sq. Feet with a displacement of roughly .51 gallons
100 ft of ¼ copper has the same surface area as 50 ft of ½” but with a displacement of only .255 gallons
(figures courtesy of http://www.aqua-calc.com/calculate/volume-cylinder-hollow)
Now logic would dictate that 1/4 inch pipe is going to have a higher head pressure (resistance) and therefore a lower flow rate than a wider pipe meaning more contact time of the water flowing through the pipe with the actual copper. Unless the water coming out of your chiller is raised to the temperature of the wort any additional contact time would lead to faster cooling. (how much faster is the real question)
I also did some rough calculations to see if you could fashion a coil of 100 feet of ¼ inch pipe to fit in an average brew pot. I use an 20 qt. pot with an inner diameter of roughly 12 inches. I believe that if you did 2 concentric coils you could fit the copper with no issues.
I brew roughly 3 gallon extracts currently which is 6.5 inches of liquid in my pot. 20 wraps of coil with an 11 inch diameter use roughly 60 feet of tubing (5 inches tall if stacked tightly or leaving 1/16 inch between the coils and not exceeding 6.5 inches). 20 10 inche coils inside the outer coils would use up an additional 52 feet meaning you would have room to tweak these dimensions significantly and still have everything fit. These measurements would leave a half inch of space all the way around the outer coil and pot and a half inch between the inner and outer coil with all of the copper submerged below the level of the 3 gallons of wort (before you even think about displacement).
Obviously you are going to spend more for 100 feet of 1/4 inch copper tubing, and will have more work creating your coil(s), but as I stated before I am a new member and new to home brewing, but I love theoretical discussion and experimentation, so I just figured I would throw this out for some of the vets to shoot down.