Documentation Help Center. Thermal modeling provides data that helps you to estimate cooling requirements for your system by using the thermal ports. For example, the IGBT Ideal, Switching block, which models a three-terminal semiconductor device, has thermal variants that can simulate the heat generated by switching events and conduction losses.
For more information on selecting the parameter values, see Improving Numerical Performance. For explanation of the relationship between the Thermal Port and Temperature Dependence tabs in a block dialog box, see Electrical Behavior Depending on Temperature.
If you want to simulate the generated heat and device temperature, expose the thermal port by:. When the thermal port is exposed, the Block Parameters window for that block contains an additional tab, Thermal Port. Which parameters are visible depend on the value you set for the Thermal network parameter:. Cauer Thermal Model.
Foster Thermal Model. External Thermal Model. All blocks with optional thermal ports include an optional internal thermal model to keep your diagram uncluttered. This figure shows an equivalent model of the internal Cauer thermal model for semiconductor devices. Port H corresponds to thermal port H of the block. The two Thermal Mass blocks represent the thermal mass of the device case and the thermal mass of the semiconductor junction, respectively.
The two Conductive Heat Transfer blocks model the thermal resistances. Because of this resistance, the junction will be hotter than the case under normal conditions. If the device has no heat sink, then you should connect port H to a Temperature Source block with its temperature set to ambient conditions.
If your device does have an external heat sink, then you must model the heat sink externally to the device and connect the heat sink thermal mass directly to port H. If you choose to simulate the internal thermal network of the block through Cauer model, the following parameters will be visible:.
Thermal mass parameterization — Select whether you want to parameterize the thermal masses in terms of thermal time constants By thermal time constantsor specify the thermal mass values directly By thermal mass. For more information, see Thermal Mass Parameterization.
In this tutorial, we will learn how to model the joule heating and thermal expansion in a MEMS heating circuit. The device consists of a thin, nichrome layer pattern on a thicker glass layer. Electric current conduction through the nichrome layer produces joule heating. Most of the material properties are assumed to be constant, except the thermal conductivity of glass. The effect of spatial inhomogeneity in the material property is incorporated by adding a random component to the conductivity, which varies as a function of the Y-coordinate of the glass layer.
We will then perform data fitting to obtain the parameters for temperature-dependent electrical conductivity and specify the limits of thickness of glass and nichrome layers. These parameters will be updated in the model.
The model will be solved within a nested for-loop that will allow us to investigate the design space. Let us go ahead and get into the geometry building steps to save some time. The simulation will actually start with the Structural Shell interface. This will be assigned only to the nichrome layer, which is what we are modeling as a shell.
Very similarly, we will assign the nichrome layer as the shell or the boundary of interest. We will go ahead and then add a Boundary Heat Source boundary condition to the same surface and here we will basically connect the Thermal Stress interface to the surface losses produced by the Electric Currents, Shell interface.
This gets assigned to the glass layer. Once we have solved the model, we can create several plots to look at some of the quantities of interest. I mention that there is a randomness that we added to incorporate the effect of spatial inhomogeneity. We can see that randomness when we compare the conductivity distribution over space with the color map, here. We also create custom plots, which will only plot the temperature for the extreme design points.
Once we have solved the problem for all these design cases, we can also create plots of interest. Such as the average temperature on the lower surface, the standard deviation of temperature on the lower surface, and surface plots of the Maximum Interface Stress and Heat Transfer Efficiency. All of these as functions of the thickness of the glass layer as well as the nichrome layer.
Here is our first plot, bunch of subplots actually, which shows the temperature at the different extremes of our design space. Minimum and maximum value of the glass thickness, and also minimum and maximum value of the nichrome layer thickness.
We see that the effect of changing the glass thickness is not so much on the average temperature, but there is some significant effect when we change the thickness of the nichrome layer. The thicker it is, the higher the temperature.To browse Academia.
Skip to main content. Log In Sign Up. Allam Mohamed. The model couples the physics phenomena involved in one way only.
However, as explained below, you can easily modify it to simulate a two-way coupling between the electric current and the heating of the actuator. The assumption of constant material properties means that the coupling between physics phenomena is one way only: the electric current through the actuator heats up the material, but the current itself is not affected by the temperature rise.
The cold arm anchor and all other surfaces are electrically insulated. Ground Applied voltage Figure 2: Electrical boundary conditions. Because the structure is sandwiched, all other boundaries interact thermally with the surroundings by conduction through thin layers of air. The line graph in Figure 5 provides more detailed information about the temperature along a single edge facing the substrate plane. Figure 5: Temperature along the actuators longest edge facing the substrate. By default, the first material you define applies to all domains.
This boundary condition applies to all boundaries except the top-surface boundary and those in contact with the substrate. A Temperature condition on the substrate contact boundaries will override this Heat Flux condition so you do not explicitly need to exclude those boundaries. In contrast, because the Heat Flux boundary condition is additive, you must explicitly exclude the top-surface boundary from the selection.
Click the Convective heat flux button.
Solving PDE of electrothermal coupling with f coefficient in stationary
Temperature 1 1 On the Physics toolbar, click Boundaries and choose Temperature. Temperature ht The second default plot group shows the temperature distribution on the surface see Figure 4. Related Papers. Comsol Multiphysics. By Maria Eugenia Becerril Ortiz. By sawon olid. By Uc Daovan. By asad esmailzadeh. Download pdf. Remember me on this computer.
Enter the email address you signed up with and we'll email you a reset link. Need an account? Click here to sign up.Documentation Help Center. This example shows a Peltier device working in cooling mode with a hot side temperature of 50 degC. The first subplot shows the COP as a function of current for several temperature differences.
It can be observed that, for the same current value, the COP value is lower for larger temperature differences. This happens because at higher temperature differences, the natural heat conduction from the hot side to the cold side tends to be greater. The temperature source connected to the hot side of the Peltier module allows to represent an ideal heat sink. That is, a sink capable of dissipating an infinite amount of heat without increases in temperature at the hot side.
This representation gives us a good approximation for the COP and cooling flow curves. The second graph shows how the heat flow evolves with the input current. As the current increases, the heat extracted from the cold side increases until it reaches a maximum value. After this peak, due to joule heating, increases in current lead to a decrease in the cooling flow.
The last graph shows the operating current that maximizes the COP value for each temperature difference. This optimum operating point provides useful information when choosing the TEC controller output current. The plot below shows the results for the Peltier Device's coefficient of performance and heat pumping capacity against input current at various temperature differences.
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Joule Heating. Thread starter charahim94 Start date Oct 12, I want to find the increase in the temperature of a resistor due to joule heating. I mean that if we apply some electrical power to a resistor then the electrical energy is converted to heat energy due to joule heating.
The heat energy will increase the temperature of the resistor. Is it possible to calculate the increase in the temperature of the resistor? I will appreciate any help. Mapes Science Advisor. Homework Helper. Gold Member. Hi charahim94, welcome to PF. The resistor's temperature over time isn't just a function of the electrical power, but also a function of the heat transfer mechanisms to the surroundings. As soon as the resistor's temperature increases above room temperature, conductive, convective, and radiative heat transfer will transfer energy away.
Remember, though, that the true temperature increase in practice will always be lower. Does this answer your question? Mapes, Thanks for the reply. SoIf i assume that there is no heat transfered then the joule heat will increase the temperature of resistor.
To me, that sounds like getting the best of both worlds. Let me explain.
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COMSOL Multiphysics, on the other hand, allows you to customize and combine any number of physics, the way you want to. Most engineering problems revolve around finding optimal design parameters or operating conditions for a device. The device itself functions based on certain principles of physics or even multiple physics. Say, you want to design an electrical heater that has a thin metallic layer deposited on top of glass. The heater works based on the principle of Joule heatingwherein a current passed through the metallic layer produces heat in the metallic layer, which then in turn creates a spatially varying temperature profile in both the metal and the glass layers.
As a design engineer, you might want to ensure that the stress generated due to thermal expansion at the interface of glass and metal is not too high to cause mechanical failure of the device. You also know that from a practical stand-point, you can control the thickness of the glass and metallic layers within the dimension limits provided by the fabrication specification. The app shown here can solve the COMSOL model recursively for a set of design points, and create a response surface that you or a decision-maker could then use to make an educated engineering decision.
Heating Circuit response surface. To make the simulation more realistic, you could even use experimental data that describes the variation in material properties as a function of temperature.
Besides solving the type of problem described above, you can perform a host of advanced modeling operations as a result of the flexibility provided by the interfacing tool. Below, I have listed some of its key benefits:. You will also see a series of short tutorial videos showing the details of setting up and solving the design optimization problem of the heating circuit.
This consent may be withdrawn. Thank you for sharing us this useful blog. Could you please do me a favor. For most case, the output of the function is a single value. But now I want to get a elasticity matrix from the external function which has six components.Documentation Help Center. The model is for a heating system that includes a heater plant modelcontrolled by a thermostat controller modelto heat a room environment model to a set temperature. While this is simple model, the processes for creating model structure and algorithm design are the same processes you will use for more complex models.
Modeling begins with completion of tasks that are outside of the Simulink software environment. Define model requirements and derive mathematical equations. Collect data for model parameters and output signal data measurements to validate simulation results. Before designing a model, consider your goals and requirements. The goals for modeling the house heating system are:.
Once you understand your modeling requirements, you can begin to identify the components of the system. The house heating system in this tutorial defines a heating system and its relationship to a room. It includes:. The thermostat monitors the room temperature regularly and turns the heater on or off, depending on the difference between the set temperature and the room temperature.
Temperature of the room T r o o m. Heat gain: Thermal energy transferred from the heater Q g a i n to the room. Heat loss: Thermal energy transferred from the room Q l o s s to the outdoor environment.
A differential equation defines the relationship between these variables, but since heat transfer is defined in terms of changing temperature, only room temperature is a state variable. The temperature of the air in the heater is constant at T heater and the room temperature is T room.
Thermal energy gain to the room is by convection of heated air from the heater, with a heat capacity of c air. Heat gain for a mass of air in the heater, m h e a t e r a i ris proportional to the temperature difference between the heater and the room:.
A fan takes room air, and passes it through the heater and back to the room. Thermal energy loss from the room is by conduction through the walls and windows, and is proportional to the temperature difference between the room temperature and the outside temperature:.
Define the rate of temperature change in the room by subtracting the rate of heat loss from the rate of heat gain:. Most of the parameter values needed for the house heating model are published in standard property tables.
The flow rate for the heater is from a manufacturer data sheet. List the variables and coefficients from your equations and check for dimensional consistency between the units. Since the unit of time for the model is hours, convert published values for the thermal property of materials from units of seconds to hours.
Equation Variables and Constants.