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Unread 03-20-2005, 02:48 AM   #22
Incoherent
Cooling Savant
 
Join Date: Sep 2003
Location: Vallentuna, Sweden
Posts: 410
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t, T, τ

Lower case t = time (to 1/2 Temp rise) = half life
Upper case T = temperature
Greek letter tau τ = time constant (t/ln(2)) = mean life

The mean life equals the time constant.
These problems (heating/cooling, charging/discharging, radioactive decay) all follow the equation e^-t/τ. τ (tau) is the time constant, in our case: thermal resistance*volume*heat capacity. An electrical equivalent is τ=R*C, C, capacitance I am equating to volumetric heat capacity and resistance R to C/W. Can't find a decent link right now, later.

Last edited by Incoherent; 03-20-2005 at 02:56 AM.
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