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Activating Equations
Posted 12.08.2020, 07:08 GMT-4 Heat Transfer & Phase Change, Heat Transfer, Battery Design Version 5.4 4 Replies
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How to activate equations (used in heat source) for particular temperature? And how to intepret them into the heat source (Q)
- 400[K] 500[K] Q_sei*exp(a_sei/T[K])
- 500[K] 530[K] Q_n*exp(a_n/T[K])
- 530[K] 600[K] Q_sei*exp(a_sei/T[K])
- 600[K] 620[K] Q_n*exp(a_n/T[K])
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Hi Naresh,
You can use Boolean expressions using inequalities, such as
Q_sei*exp(a_sei/T[K]*(T>=400[K]&&T<500[K])+Q_n*exp(a_n/T[K])(a_sei/T[K]*(T>=500[K]&&T<530[K])+...
All those terms will be zero where and when the temperature is outside their limits and equal to the desired expression inside the desired temperature ranges. Here I assume that Q_sei, a_sei, etc. are defined as constants or variables. You should probably also add terms for temperatures outside of the range (above and below) 400 K to 620 K; otherwise, the heat source will be zero for those temperatures.
Best regards,
Magnus Ringh, COMSOL
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Dear Magnus,
Thank you so much,, this has solved the issue stated.
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Hi Naresh,
You can use Boolean expressions using inequalities, such as
`Q_seiexp(a_sei/T[K](T>=400[K]&&T=500[K]&&T
Dear Magnus Ringh,
Could you please sort this out for me.
Theme: Heat transfer between bodies in a room filled with air
The initial temperature of one cell is 1000[K] and the others' are at room temperature. The temperature of other cells will increase due to heat conduction through air over time. As soon as the other cells reach 363[K], the temperature has to take a sudden jump to 1400[K]. No reactions, no heat sources. Just a simple jump of temperature is needed to check the heat wave propagation. How can I achieve this?
Many thanks.
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Hi Naresh,
For this type of modeling questions, I suggest that you contact COMSOL's technical support. However, I think that a maximum nonlocal coupling operator, defined in domains away from the heater, would be useful for setting up a conditional expression to achieve what you want to simulate.
Best regards, Magnus Ringh, COMSOL