I’m having trouble cooling a 5 gallon batch of wort down to pitching temperature with my new plate chiller. The following data is provided to help with any suggestions.
I use a 40 plate welded heat exchanger 7.5” wide x 4” deep x 3” thick front to back.
Inlet water temperature last use was 55 degrees F and is run through a XL type immersion chiller with ½” diameter copper tubing sitting in 3-4 gallons of ice water. The discharge pressure at the hose bib is 60 PSI and the pressure drop is 20’ of 5/8” garden hose and then the copper tube chiller and another 20’ of 5/8” garden hose. The garden hose is not straight but also not kinked. The plate chiller discharge pressure drop is through 15’ of 5/8” garden hose and maybe 2-3 feet of elevation rise.
The heat exchanger inlet sits about 8” below the boil kettle outlet and I use gravity to move the wort through it. I use a ½” ID tube about 36” long between the kettle and heat exchanger. With the valve wide open I get a pretty good flow. The chiller is cleaned well in both directions after use, so I’m confident it is not clogged.
I have used this chiller 5 times now and each time I vary both the flow of wort and the flow rate of the cooling water, but can not find the correct combination of flows. If I remember my engineering heat transfer class, counter flow surface temperature means everything, so I think if the spaces between the plates are “flooded” then I have maximum surface area contact, but have tried all combinations of flow with no luck.
During the most recent use I was only able to get the temperature down to an average of 95 degrees. I must be doing something wrong, I based on everything I read I should be able to get my pate discharge temperature down below 70 degrees F.
With a mechanical engineering back ground, I’m embarrassed to not be able to figure this out. Any help is appreciated.
Are you sure the chiller is flooded? If you are using gravity, then the kettle needs to be above the level of the recieving vessel, and the recieving vessel needs to be above the level of the chiller. Cooling water is similar, and the outlet should be at a higher level than the chiller to ensure proper flooding.
If there isn’t a substantial delta between cooling water input vs output temp (which is true for me running cooling water very fast and wort quite slowly), I doubt that it would make much difference which direction the wort and water are flowing.
That sound right, or is this idea based on some other concept I’m not seeing?
You sure your wort flow isn’t too fast? The general rule of thumb is that faster cooling water flow coupled with slower wort flow will get you as close to the theoretical min output temp (that of the cooling water) as you can get.
As far as flooding the chiller, I use a shirron chiller that has all 4 ports on the top side, and I lay it on its back so they’re all pointing up, so I believe the entire chamber has to be full in order to push anything out of output port. My kettle output is about 1 foot above and the top of the receiving vessel is about 1 foot below.
A while back I did find that having an excessively long hose from kettle output to chiller input seemed to cause flow problems. Never quite figured out why because I don’t think there was that much impedance in the series, but perhaps the fact that the long hose drooped down below the chiller input so there was a rise before you got there did it…
Anyway, I started using a hose that was no longer than needed (which for you where your chiller and kettle valve are around 8 inches apart, would probably be no longer than 12-15 inches unless your chiller is a good lateral distance from the kettle for some reason). Ever since I took the slack out of that hose, I’ve had no problems…
If there isn’t a substantial delta between cooling water input vs output temp (which is true for me running cooling water very fast and wort quite slowly), I doubt that it would make much difference which direction the wort and water are flowing.
That sound right, or is this idea based on some other concept I’m not seeing?[/quote]
They are designed for “counterflow” which will provide the best results and efficiency. The wort can only get as cool as the water, so it’s best to have the coldest water chill the wort at the wort output.
If there isn’t a substantial delta between cooling water input vs output temp (which is true for me running cooling water very fast and wort quite slowly), I doubt that it would make much difference which direction the wort and water are flowing.
That sound right, or is this idea based on some other concept I’m not seeing?[/quote]
No, if the flows are not in the opposite directions, CFC (plate) chillers don’t work. Check your flow directions!
Right, that’s what I was thinking you might be saying. That does make sense in theory, but again in my case I don’t think there is a whole lot of difference between temps at input and output of my Shirron. I haven’t paid much attention lately, so maybe my recollection about the delta is wrong.
I suppose at worst it might allow me to get the same results with less cooling water (better efficiency, as you mentioned)
I am running a march pump to my chiller and for the first few batches I was having the same issue. I started turning the flow of my wert way down and the flow of my water way up and can now get my wort from boiling to 65isg in about ten-fifteen minutes.
Bingo. May not be the same problem that the OP is having, but moving in this direction will always help.
You need only look at this therminator data (click on the “data” tab on the page) to see the relationship between cooling water flow, wort flow, and the delta between your cooling water temp and your output wort temp to see the trend…
