Submitted by tomb on Fri, 12/02/2011 - 12:20
Posted in
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.
Chiller
Glad things seem to be working out!
plate chiller
Hey. I posted on FB but thought I'd follow up here. Pardon if I answer with some stuff you already know! I in no way mean to be condescending - just trying to cover all bases. What material is the chilled made of? I assume you are using counter flow right? Also, to maximize heat xfr w/ a "once thru" system you want your hot (gravity fed) fluid to be as slow as possible and your heat sink to have a high flow rate. As an ME you may be like "duh" but sometimes we forget the simplest of details.
MOC is 304 SS, (from Keg
MOC is 304 SS, (from Keg Cowboy)and yes counter flow.
I'm going to turn the chiller 180 degrees so the hot gravity feed inlet is on the bottom and the outlet is up top. This way maybe I will ensure the chiller is fully flooded. Will try with hot water today.
Cooling Issue Solved
Got the wort to cool as it should by turning the plate chiller 180 degrees so that now it is completely flooded, however now it seems to air lock a bit with only about 1 foot of head pressure pushing the wort through. That can be solved more easily. Thanks for your input.