Hi all! I'm analyzing a fermenter and the water cooling system that cools it down. In analyzing this I've found kW and kWh required to cool down the fermenter using Q = dt*cp*m However when I try to find the overall heat transfer coefficient U using the data, I find that it varies with either Q or M. I use the equation: Q = A*U*dtm At first Q is high due to an extreme cooling from 121 C to 35 C. After that during bacterial fermentation the temperature should stay the same. However this second stage gives me a lower U-value (twice) than during the extreme cooling in the beginning. Does any of you have a suggestion to why this is happening? Can you at all use this formular to calculate a heat transfer coefficient for water cooling systems, or can it only be applied for heat exchangers?