Heat transfer from a conductor 6

[Jgrovdal]

Hi
I am currently trying to calculate the temperature a conductor will reach when applying 50 amps to it. The conductor is an 16mm^2 copper stranded wire. The length is 2m. I am trying to make a model in Matlab to calculate it, is it possible to make it that way? Or is there a better way?

The model I am trying to use is the one from this paper:

https://jffhmt.avestia.com/2020/006...8h2ixV_BSjyU-UAkNXsbN6VYkFfs4mOLGBqWJ7T0AL2TY

But it has not been successful yet.

My problem seems to be that there still is some variables that is missing and therefore my calculations don't give me a result. For now I miss the Prandtl number and can't continue.

The variables I have found:
L = 2; %Length
I = 50; %Current
R_ref = 5.54830155*1^-4; %Reference resistance
alfa_T = 0.00393; %Resistance at temperature rise
T_ref = 21; %Reference temperature for Resistance
r_c = 1/2*12.1*10^-3; %Radius core
r_i = 1/2*15.45*10^-3 ; %Radius whole
g = 9.81; %Gravitation
l_alfa = 2*r_i; %Characteristics of the length of structure
sigma = 5.6704*10^-8; %Stefan Boltzmann constant
epsilon = 0.95; %Assumed after an paper
rho = 3.19*10^-8; %Ohm per meter
pi = 3.14; %Pie
lambda_c = 386; %Thermal conductivity conductor
c_c = 3.4*10^6; %Specific heat capacities conductor
c_i = 2.245*10^6; %Specific heat capacities isolation
lambda_i = 0.21; %Thermal conductivity conductor
M = 5; %Parameter - Gaver-Stehfest-algorithm (Dimensionless)
T_E = 25; %Temperature ambient
T_EK = T_E+273.1;
T_S = 25; %Temperature surface
T_SK = T_S+273.1;
T_0 = 21; %Reference temperature
beta = 1/T_EK; %Coefficient of thermal expansion
lambda_air = 25.90; %Thermal conductivity Air maybe 0.0246

Thanks in advance

 

[prc]

IR stuff; I am referring to LV bushing turrets in large generator transformers. Three LV bushings are mounted on a flat plate on the top of the transformer. The bushings will be carrying a current of the order of 10 kA. Oil temperature under the bushings will be the same as that of the transformer tank oil since oil is moving inside the transformer tank. Outside of the metal mounting plate will get heated up due to eddy currents (from the flux from high current flow) and other circulating currents. This outside metal temperature is only from the current flow on the surface and will not be brought down much by inside oil flow. It will be cooled by ambient air only.

Hence logically when ambient air comes down from 30deg C to 0deg C, the metal temperature should come down from 100 C to 70 C and oil temp 75C to 45 C. The oil temperature is coming down ( it is cooled by tank-mounted radiators) but the metal temperature is not coming down to that extent. Hence my query.

 

[IRstuff]

I'll just say that Fourier's Law dictates heat flow from hotter objects to cooler, so there's no way your terminals can stay at 100C without the corresponding cooler environments not changing as well.

TTFN (ta ta for now)
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[prc]

Will the change be linear? I mean temperature of metal drops the exact figure as the drop in ambient temperature?

 

[IRstuff]

Fourier's law states that heat flow is proportional to temperature delta, so in the first order, if your heat flow hasn't changed, then the temperature difference must be the same.

Now, in reality, the apparent radiative transfer proportionality constant isn't constant, since that heat flow is proportional to absolute temperature to the 4th power. Additionally, the convection coefficient changes as a function of temperature as well, since both density and viscosity changes with temperature.

TTFN (ta ta for now)
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