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.