custom phase changing material does not release heat.

Problem:
When I adjust the latent heat, there’s no change in the temperature curve of the XPS material. I anticipate a stable temperature, ranging between 305K and 320K. So the problem is that the material does not release the absorbed heat.
equations
assert(Cps > 0 && Cpl > 0)
assert(T > 0, ‘Temperature must be greater than absolute zero’)
T == M.T;
if T >= Tmelt_start && T <= Tmelt_end
phaseChangeRate == {0.001, ‘1/s’};
else
phaseChangeRate == {0, ‘1/s’};
end
if phase < 1 && phase > 0
Q == m * Cps * T.der + m * L * phaseChangeRate;
phase.der == phaseChangeRate;
else
Q == m * Cpl * T.der;
phase.der == {0, ‘1/s’};
end
end

explanation of the full code:

This code describes a thermal component that models internal energy storage in a thermal network. Here’s a breakdown of the main parts of this code:

1. **Nodes**: These are points where other components can connect. Two thermal nodes are defined: `M` (top) and `N` (bottom).

2. **Inputs**: These values can be supplied from outside. `Mdot` represents the mass flow rate (in kg/s) and `T_in` is the input temperature (in Kelvin).

3. **Parameters**: These values determine the behavior of the component. They include:
– `mass_type`: Type of mass (constant or variable).
– `mass`: The mass of the thermal component.
– `Cps` and `Cpl`: Specific heat capacity for solid and liquid, respectively.
– `Tmelt_start` and `Tmelt_end`: The temperature range where the material starts melting and stops melting.
– `L`: Specific latent heat.
– `mass_min`: Minimum mass.
– `num_ports`: The number of graphical ports.

4. **Annotations**: These are metadata that provide additional information about the component or dictate how it is displayed in a GUI. Here, it is primarily used to indicate which parameters can be modified externally and to define the component’s icon.

5. **Variables**: These represent the internal states of the component. They include:
– `m`: The mass.
– `T`: The temperature.
– `phase`: The phase (0 for solid, 1 for liquid, and values in between for a mixed phase).
– `phaseChangeRate`: The rate of phase change.
– `Q`: Heat flow rate.

6. **Branches**: These are connections between different parts of the network. Here, the heat flow `Q` from node `M` to another part of the network is defined.

7. **Equations**: These describe the mathematical relationships between the different variables and parameters. They include:
– Relationships between `T`, `Q`, `m`, and other variables, especially around phase change.
– Constraints on certain values (like that `Cps`, `Cpl`, and `T` must be positive).

8. **Connections**: These are the actual connections between the different nodes within the component. Here, node `M` is connected to node `N`.

The essence of this component is that it models a thermal mass that can store and release energy. It also accounts for phase changes, meaning it can melt or solidify within a certain temperature range.
component derdecomponent
% Thermal Mass
% This block models internal energy storage in a thermal network.

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

inputs(ExternalAccess = none)
Mdot = {0, ‘kg/s’}; % Mdot:bottom
T_in = {300, ‘K’}; % Tin:bottom
end

nodes(ExternalAccess = none)
N = foundation.thermal.thermal; % :bottom
end

parameters
mass_type = foundation.enum.constant_variable.constant; % Mass type
end

parameters (ExternalAccess = none)
mass = {1, ‘kg’}; % Mass
end

parameters
Cps = {200, ‘J/(kg*K)’}; % Specific heat solid
Cpl = {1000, ‘J/(kg*K)’}; % Specific heat liquid
Tmelt_start = {320, ‘K’}; % Start Melting Temperature
Tmelt_end = {305, ‘K’}; % End Melting Temperature
L = {100, ‘J/(kg)’}; % Specific Latent Heat
end

parameters (ExternalAccess = none)
mass_min = {1e-6,’kg’}; % Minimum mass
end

parameters
num_ports = foundation.enum.numPorts2.one; % Number of graphical ports
end

if num_ports == 2
annotations
N : ExternalAccess=modify
end
if mass_type == foundation.enum.constant_variable.constant
annotations
% Icon = ‘mass2.svg’
end
else
annotations
% Icon = ‘mass4.svg’
end
end
else
if mass_type == foundation.enum.constant_variable.variable
annotations
% Icon = ‘mass3.svg’
end
end
end

if mass_type == foundation.enum.constant_variable.constant
annotations
mass : ExternalAccess=modify
end
equations
m == {1,’kg’};
end
else
annotations
[Mdot, T_in, m, mass_min] : ExternalAccess=modify
end
equations
assert(mass_min > 0)
end
end

variables (ExternalAccess=none)
m = {value = {1,’kg’}, priority=priority.high}; % Mass
end

variables
T = {value = {300, ‘K’}, priority = priority.high}; % Temperature
phase = {value = {0, ‘1’}, priority = priority.high}; % Phase
phaseChangeRate = {0, ‘1/s’}; % Rate of phase change
end

variables (Access=private)
Q = {0, ‘W’}; % Heat flow rate
end

branches
Q : M.Q -> *;
end

equations
assert(Cps > 0 && Cpl > 0)
assert(T > 0, ‘Temperature must be greater than absolute zero’)

T == M.T;

if T >= Tmelt_start && T <= Tmelt_end
phaseChangeRate == {0.001, ‘1/s’};
else
phaseChangeRate == {0, ‘1/s’};
end

if phase < 1 && phase > 0
Q == m * Cps * T.der + m * L * phaseChangeRate;
phase.der == phaseChangeRate;
else
Q == m * Cpl * T.der;
phase.der == {0, ‘1/s’};
end
end

connections
connect(M,N)
end

endProblem:
When I adjust the latent heat, there’s no change in the temperature curve of the XPS material. I anticipate a stable temperature, ranging between 305K and 320K. So the problem is that the material does not release the absorbed heat.
equations
assert(Cps > 0 && Cpl > 0)
assert(T > 0, ‘Temperature must be greater than absolute zero’)
T == M.T;
if T >= Tmelt_start && T <= Tmelt_end
phaseChangeRate == {0.001, ‘1/s’};
else
phaseChangeRate == {0, ‘1/s’};
end
if phase < 1 && phase > 0
Q == m * Cps * T.der + m * L * phaseChangeRate;
phase.der == phaseChangeRate;
else
Q == m * Cpl * T.der;
phase.der == {0, ‘1/s’};
end
end