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Lineair temperature increase in Heat transfer

Posted May 8, 2012, 11:51 a.m. EDT Version 4.2a 3 Replies

Frank Thomson
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Hi there,

I am modeling an autoclave and i am trying to increase the temperature at specific time intervals. I entered the formula for the temperature increase in the variables but i doenst work.

This is the formula. ( every 2 minutes the temperature will go up 2 degrees C.)
T=T0+2t

What is the best way to do this?

thanks in advance.
3 Replies Last Post May 9, 2012, 3:01 a.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago May 8, 2012, 12:14 p.m. EDT
Hi

I believe something like

T=T0+2[K]/(60[s])*t

should work better (assuming T0 has units of Kelvin) if you have left the time in the default "seconds" units. 2*t has units of seconds and you want it in K/min

pls take care with temperature and absolute values, COMSOL uses Kelvin by default, even if the slop of degC and K are the same, it might be translted differently, depending on how you use your variables. The easiest is to work in SI and Kelvins

--
Good luck
Ivar
Hi I believe something like T=T0+2[K]/(60[s])*t should work better (assuming T0 has units of Kelvin) if you have left the time in the default "seconds" units. 2*t has units of seconds and you want it in K/min pls take care with temperature and absolute values, COMSOL uses Kelvin by default, even if the slop of degC and K are the same, it might be translted differently, depending on how you use your variables. The easiest is to work in SI and Kelvins -- Good luck Ivar
Frank Thomson
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Posted: 1 decade ago May 8, 2012, 1:05 p.m. EDT
Thanks for the quick answer!!

will try it tomorrow right away
Thanks for the quick answer!! will try it tomorrow right away
Frank Thomson
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Posted: 1 decade ago May 9, 2012, 3:01 a.m. EDT
It is working. Did it as follows:
Global definitions:
T0=293K
T1=400K
t=0[s]

Variables
Temp T0+2[K]/(60[s])*t

Heat Transfer:
Temperature : if(Temp<T1,Temp,T1)


It is working. Did it as follows: Global definitions: T0=293K T1=400K t=0[s] Variables Temp T0+2[K]/(60[s])*t Heat Transfer: Temperature : if(Temp

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