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Re: [Phys-l] physics of dissipation (was: T dS versus dQ)

Time is indeed a variable that doesn't get a lot of attention in the Thermo field.
These posts have been quite interesting and informative.

I'm going to try to generalize a bit - not proofs or claims of over-arching 'great truths' intended.

I took a rather unorthodox intro chem course back in the '60's. Co-taught by two world class research chemists. One a thermodynamicist and the other an analytical instrumentation guy.
One 'topic' that sticks in my mind was the discussion of extracting useful energy from chemical combustion - specifically - slow burn vs explosion. (external steam boiler vs internal combustion comes to mind.) There were two different 'names' for the 'useful' energy available under these two conditions. (I'm sure that someone will provide the names and symbols for these.)
The slow-burn always came out on top.

and now - really stretching here - is there any generalization that relates to the recent (short lived) discussion of 'Residence Time').

Are there counterexamples available where quick make less entropy than slow?

Thanks for some great discussions folks ! ! !

At 8:51 AM -0700 1/14/10, John Denker wrote:
The repeated assertion that the compression of the gas
is the same no "matter whether done slowly or quickly"
is completely untenable.

To summarize: -- slow and gradual ==> isentropic, non dissipative
-- sudden ==> dissipative