[RASMB] Temperature control

[Arthur Rowe]

Hi all -

The issue of temperature control raised by Jack Kornblatt is an important
one. The absolute temperature of the rotor is probably not defined (or
claimed) to better than a few tenths of a degree, but at least once the
thing has settled down the constancy seems acceptable (better than 0.1 deg
usually). For most velocity work this is fine. Although if you happen to
want to study the effect of varying temperature one would like to know the
true temperatures, not just to have the reassurance that whatever they are,
they are steady !

As Peter Schuck says, there is no escape from pre-equilibration if you want
to be really sure you have no effects caused by minor changes in
temperature. However, I doubt that in most cases the stability of the
boundary is in question if we are merely talking of the odd degree or
fractions of a degree. Convective stirring is pretty unlikely. After all -
temperature control systems were absent from the earliest AUCs, and people
got stable boundaries and s values similar to modern ones, even with a
temperature drift amounting to whole degrees !

One can of course evaluate s values use the integral  of f(T)*(omega)^2.dt
in place of (omega)^2, where f(T) is the temperature correction factor at
the temperature T appertaining at time t.  Assuming that no component in the
system shows significant temperature-dependent effects, that's valid. I
recall that years ago I did this - no doubt for some good (but
un-remembered) reason . . .

Best wishes for your project, Jack - and kind regards to all on RASMB

Arthur

--
*******************************************************
Arthur J Rowe
Professor of Biomolecular Technology
NCMH Business Centre
University of Nottingham
School of Biosciences
Sutton Bonington
Leicestershire LE12 5RD   UK

Tel:        +44 (0)115 951 6156
            +44 (0)116 271 4502
Fax:        +44 (0)115 951 6157
email:      arthur.rowe at nottingham.ac.uk
            arthur.rowe at connectfree.co.uk (home)
Web:        www.nottingham.ac.uk/ncmh/business
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