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Posted:
9 years ago
3 nov. 2015, 05:14 UTC−5
You can define the temperature with a piecewise function, if that is what you need. How is the cable warmed up? If it is done with electric current, then heat production is
rs*I^2 (W/m^3)
where rs is the resistivity of the cable (Ohm*m) and I the current density (A/m^2). Then you will have a problem where heat production and loss are competing, resulting in a temperature profile which depends on the heat capacity of the materials and the heat transfer coefficients as well as the exterior temparature.
BR
Lasse
You can define the temperature with a piecewise function, if that is what you need. How is the cable warmed up? If it is done with electric current, then heat production is
rs*I^2 (W/m^3)
where rs is the resistivity of the cable (Ohm*m) and I the current density (A/m^2). Then you will have a problem where heat production and loss are competing, resulting in a temperature profile which depends on the heat capacity of the materials and the heat transfer coefficients as well as the exterior temparature.
BR
Lasse
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Posted:
9 years ago
3 nov. 2015, 05:23 UTC−5
Thanks for the quick response
The cable is warmed up with a heating mat laying around the cable.
The conductor is preheated with induction. But for the conductor I though there has to be a very simple method to get a minimum temperature of 80 degC in the conductor.
Thanks for the quick response
The cable is warmed up with a heating mat laying around the cable.
The conductor is preheated with induction. But for the conductor I though there has to be a very simple method to get a minimum temperature of 80 degC in the conductor.
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Posted:
9 years ago
3 nov. 2015, 06:35 UTC−5
Is the mat insulated from its environment so that no heat flux is taking place outwards?
Is the mat insulated from its environment so that no heat flux is taking place outwards?
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Posted:
9 years ago
3 nov. 2015, 06:46 UTC−5
Yes. I simulated the mat with a piecewise and it works great. I simulated the heating mat with a Bézier polygon and selected this boundary with a temperature what is given by the piecewise.
Now I only have to create a temperature of 80 degC at the conductor. It is possible that it will get hotter due to the heating mat, but it may not get below 80 degC. The conductor is a domain and not a boundary so I can’t select the conductor with a temperature.
Yes. I simulated the mat with a piecewise and it works great. I simulated the heating mat with a Bézier polygon and selected this boundary with a temperature what is given by the piecewise.
Now I only have to create a temperature of 80 degC at the conductor. It is possible that it will get hotter due to the heating mat, but it may not get below 80 degC. The conductor is a domain and not a boundary so I can’t select the conductor with a temperature.
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Posted:
9 years ago
3 nov. 2015, 06:50 UTC−5
But if the conductor is, say, copper its temperature is practically throughout the same as its surface concentration next to the mat.
But if the conductor is, say, copper its temperature is practically throughout the same as its surface concentration next to the mat.
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Posted:
9 years ago
3 nov. 2015, 07:16 UTC−5
Let's say I have a cable of 10 meter. I put heating mats on 1 m of the cable( in the middle). the heat is going through(if insulated to the outside) the insulation to the conductor (copper indeed). The problem here is that a lot of heat is transported along de cpper, because the meters that are not heated up are at a temperature of, say, 20 degC. If I manage to have the conductor in the whole cable at a minimum temperature of 80 degC, then there will flow less heat away from the heating mat.
This is my idea of course. I am not sure that this is physically right.
Let's say I have a cable of 10 meter. I put heating mats on 1 m of the cable( in the middle). the heat is going through(if insulated to the outside) the insulation to the conductor (copper indeed). The problem here is that a lot of heat is transported along de cpper, because the meters that are not heated up are at a temperature of, say, 20 degC. If I manage to have the conductor in the whole cable at a minimum temperature of 80 degC, then there will flow less heat away from the heating mat.
This is my idea of course. I am not sure that this is physically right.
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Posted:
9 years ago
3 nov. 2015, 07:31 UTC−5
Maybe important to say: I want the heat as much as possible in the insulation of the cable
Maybe important to say: I want the heat as much as possible in the insulation of the cable
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Posted:
9 years ago
3 nov. 2015, 08:06 UTC−5
Attached a very simple model.
BR
Lasse
Attached a very simple model.
BR
Lasse
