simscape variable thermal mass - initial condition issue

Hi everyone,

I have created a custom component representing a thermal mass, which mass is varying based on an input.

when I compare the results of a constant mass via the default simscape block and my custom block, the initial conditions are different, however the same initial temperature is specified. anyone experiencing the same issue? how can this be solved?

cheers

Benoit

here is the custom block code

component mass_custom
% Thermal Mass
% This block models internal energy storage in a thermal network. The rate
% of temperature increase is proportional to the heat flow rate into the
% material and inversely proportioanl to the mass and specific heat of the
% material.

% Copyright 2005-2016 The MathWorks, Inc.

inputs
    S = {1, 'kg'}; % S:top
end

nodes
    M = foundation.thermal.thermal; % :top

end

parameters
%     mass_cu    = {1,   'kg'      }; % Mass Copper
%     mass_iron    = {1,   'kg'      }; % Mass Stator Iron
    sp_heat = {447, 'J/(kg*K)'}; % Specific heat
end

variables
    % Differential variables
    T = {value = {290, 'K'}, priority = priority.high}; % Temperature

    Q = {0, 'W'}; % Heat flow rate
end

branches
    Q : M.Q -> *;
end

equations
    assert(S > 0)
    assert(sp_heat > 0)
    T == M.T;
    Q == S * sp_heat * T.der;
    assert(T > 0, 'Temperature must be greater than absolute zero')
end

end

Answer 1

[Juan Sagarduy]

Hello Benoit,

It seems strange. Have you got the chance to share the files?

BR/Juan