Cooling Emulsions

[ildikora]

An emulsion of a known composition has to be cooled from 80C to 50C, at a constant rate, in an interval of 100 minutes with water. The cooling water temperature can be setted at different temperatures (i.e.10DGC lower than emulsion in the vessel). How can I calculate the flow rate of the cooling water in the jacket to achieve the constant cooling rate?
Thank you.

 

[StoneCold]

ildikora
If you want a constant cooling rate the rate of water will have to increase constantly as the emulsion cools off. Temperature change is a way to break emulsions but I suppose you alread know that. A simple way to calculate out the required flow rate is to do the heat transfer calculations at four different emulsion temperatures. That will give you four cooling water rates and you can draw a line between the points to see what the curve would look like. If you have a desired cool down rate (Q) then solve Q=U*A*deltaTlm to find a cooling water outlet temperature. Then use Q=mass*cp*(T.hot-T.cold) to find the mass flow rate of cooling water. There are a few assumptions that you have to make. Like an overall heat transfer coeficient (U) but that should not be too hard. You just need an estimated flow rate any way if you are going to automate the cooling water flowrate as it will be constantly changing from a low rate to a higher one to compensate for the reduced temperature differential.
Does that make sense?

Regards
StoneCold

 

[olynyk]

Ildikora, did you mean that you could set the temperature of the water continuously, i.e., keep it 10C lower than the emulsion at all times? Or just that you could set it at a certain temperature at the beginning and then it stays the same throughout the process?

 

[ildikora]

Thank you for the answers, Stonecold and Olynyk.
The cooling will be done in stages. For some of the stages the temperature difference between emulsion and cooling water will be bigger for others smaller.
I will experiment the constast flow rate of the cooling water and the automated one.
Also, I will try to do the heat transfer calculations...
ildikora