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Joule heating of an alternate current
Posted Mar 7, 2017, 8:30 a.m. EST Heat Transfer & Phase Change Version 5.2 2 Replies
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Hello,
I am trying to simulate what happens to the temperature of a transmission line that has an alternate current flowing through it. I have the Joule heating physics and I have been able to successfuly simulate the temperature on the line with a direct current. I have applied a voltage on the cable with a ground and a terminal node, and for the AC I tried defining a fasor in the Parameters for the tension appied in the terminal like 1.377*exp(i*(2/3)*pi)[V]. But I son't know if that is the correct way to define an alternate voltage?
Also I was told to use frequency domain study instead of time-dependant. Bu in my case, I want the temperature due to a current of specifically 60Hz, so the frequency domain didn't make much sense to me. Besides, the frequency-domain study doesn' t seem to solve the heating part of the problem, only the eletric currents. Should I use time- dependant?
Thank you in advance for any help,
Luciana
I am trying to simulate what happens to the temperature of a transmission line that has an alternate current flowing through it. I have the Joule heating physics and I have been able to successfuly simulate the temperature on the line with a direct current. I have applied a voltage on the cable with a ground and a terminal node, and for the AC I tried defining a fasor in the Parameters for the tension appied in the terminal like 1.377*exp(i*(2/3)*pi)[V]. But I son't know if that is the correct way to define an alternate voltage?
Also I was told to use frequency domain study instead of time-dependant. Bu in my case, I want the temperature due to a current of specifically 60Hz, so the frequency domain didn't make much sense to me. Besides, the frequency-domain study doesn' t seem to solve the heating part of the problem, only the eletric currents. Should I use time- dependant?
Thank you in advance for any help,
Luciana
2 Replies Last Post Mar 7, 2017, 9:19 a.m. EST
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Posted:
8 years ago
Hello Luciana,
Based upon your problem description, you may find this article helpful:
www.comsol.com/blogs/how-to-model-the-electromagnetic-heating-of-underground-cables/
Please note that you will need to have the AC/DC Module for this type of modeling.
Best Regards,
Based upon your problem description, you may find this article helpful:
www.comsol.com/blogs/how-to-model-the-electromagnetic-heating-of-underground-cables/
Please note that you will need to have the AC/DC Module for this type of modeling.
Best Regards,
Please login with a confirmed email address before reporting spam
Posted:
8 years ago
Hello,
thank you for your swift reply.
I had seen that model and that is exactly how I am defining my voltage, so I guess that must be right.
But instead of eletromagnetic heating I am using Joule heating physics, is it now possible to do it this way? I had no trouble simulating the temperature this way with a DC voltage so I think it must be a very simple mistake but I can't seem to find it.
The Frequency-Stationary Study like in the example is able to solve the Eletric currents part, but if I add the heating and also the laminar flow I have in the model it gives the following errors:
Failed to find a solution.
Segregated Step 2
Error in user-defined function.
Function: comp1.mat2.def.rho
Failed to evaluate variable.
Variable: comp1.ht.rho, Defined as: (comp1.mat2.def.rho(comp1.ht.fluid1.minput pressure/unit Pa cf,comp1.ht.fluid1.minput temperature/unit K cf)*unit kg cf)/(unit m cf^3)
Failed to evaluate expression.
Expression: (comp1.ht.d*((comp1.ht.Cp*(-comp1.ht.rho))*(((comp1.Ty*comp1.ht.uy)+(comp1.ht.ux*comp1.Tx))+(comp1.Tz*comp1.ht.uz))))*dvol
Failed to evaluate Jacobian of expression.
Expression: (-comp1.ht.rho*comp1.ht.Cp*(comp1.ht.ux*comp1.Tx+comp1.ht.uy*comp1.Ty+comp1.ht.uz*comp1.Tz)*test(comp1.T)*comp1.ht.d)*(dvol)
Returned solution is not converged.
- Feature: Stationary Solver 1 (sol2/s1)
thank you for your swift reply.
I had seen that model and that is exactly how I am defining my voltage, so I guess that must be right.
But instead of eletromagnetic heating I am using Joule heating physics, is it now possible to do it this way? I had no trouble simulating the temperature this way with a DC voltage so I think it must be a very simple mistake but I can't seem to find it.
The Frequency-Stationary Study like in the example is able to solve the Eletric currents part, but if I add the heating and also the laminar flow I have in the model it gives the following errors:
Failed to find a solution.
Segregated Step 2
Error in user-defined function.
Function: comp1.mat2.def.rho
Failed to evaluate variable.
Variable: comp1.ht.rho, Defined as: (comp1.mat2.def.rho(comp1.ht.fluid1.minput pressure/unit Pa cf,comp1.ht.fluid1.minput temperature/unit K cf)*unit kg cf)/(unit m cf^3)
Failed to evaluate expression.
Expression: (comp1.ht.d*((comp1.ht.Cp*(-comp1.ht.rho))*(((comp1.Ty*comp1.ht.uy)+(comp1.ht.ux*comp1.Tx))+(comp1.Tz*comp1.ht.uz))))*dvol
Failed to evaluate Jacobian of expression.
Expression: (-comp1.ht.rho*comp1.ht.Cp*(comp1.ht.ux*comp1.Tx+comp1.ht.uy*comp1.Ty+comp1.ht.uz*comp1.Tz)*test(comp1.T)*comp1.ht.d)*(dvol)
Returned solution is not converged.
- Feature: Stationary Solver 1 (sol2/s1)