Heat transfer of a mixing tank

[AL114425]

Hi all,

I would like to ask some heat-transfer advice for my experiment using a coils to heat up a mixing tank, and here is my situation. I am trying to heat up the 10L solution in my mixing tank to 90 degree by circulating it within a coil which immerse in a thermostatic water bath (95 degree).
My goal is to heat up the solution as fast as possible yet I need to ensure the solution temperature cannot exceed 90 degree because it will affect the reaction rate.
Assume my solution initial temperature is 20 degree. I am using 10m of coils to circulating the solution with a fast flow rate to ensure the solution will not be over heated.
I can calculated the temperature profile of the solution within the coils, and I know that the profile of the tank will be similar to the coils as the initial temperature will increase rapidly and then slowly reach a limit, but I would like to ask how can I actually generate a temperature profile of the mixing tank?

As the temperature of the solution increases, I believe the energy transfer will be lower as the delta T is smaller. In this case, should I increase my flow rate in the circulation to speed up the heating?

Thanks in advancing for answering the question.

 

[IRstuff]

It will certainly help, some, but having only 5ºC headroom is not much margin. Better that you have the bath at 99ºC, and tun the fluid through it fast, all the time. This would transfer the maximum amount of heat and minimize the probability of overheating the fluid.

TTFN
faq731-376

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[zekeman]

Depends on the accuracy of the 90 C requirement.
If, say 91 were permissible and you know the thermal mass of the tank and water in the tank and can measure the thermal mass of the water in the pipe, then you could go full blown with hot water at 9 5 or 99 degree water until a thermostat says you reached , say 89 or 90, cuts off the flow and then knowing the overall thermal system, you could calculate the overshoot predictably below 91.