(Changed tag to EE... :)

Mario Mendes wrote:

> Well, I have done some more digging around on the internet and found a
> bit of information, but nothing that leads me to find the holy grail for
> my setup.  It seems that I have 2 options:
> 
> 1) heat a to the temperature I want b to be heated up to and then keep a
> constant there until b reaches the same temperature
> 2) heat b to a higher temperature than I want b to be at and then let it
> cool down while b heats up with the heat given off by a until eventually
> both reach the same temperature
> 
> For whatever reason (maybe the wrong one) I think that the second
> approach will be faster than the first, but also a lot harder to do
> without some magic formula to get some ball park values to play with.

It will be faster, because the heat transfer between A and B depends on the
temperature difference between them: higher temp diff, faster transfer.

I think a big help would be to have a temp sensor in B, or if not in B,
then between A and B. Using the temps of A and B (using several sensors if
they usually have a temp profile) would allow you to calculate the optimal
temperature of A (outside), and also to control it.

Besides the insulation between A and B, it also depends on the relative
specific heat capacities of the fluids in A and B. Not sure whether milk is
different from water; probably not much. But the capacity, together with
the power of your heat source, determines the resulting profile and that
determines the surface temp on the outside you need to reach for the speed
optimum point. You can simplify that quite a bit if you stir A or otherwise
can make sure that all of A is at the same temperature.

Also, the speed optimum point will overheat the outside of B a bit (to
reach the target temp in the center as quick as possible). That may have to
be limited, too.

Gerhard

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