Time constant of a thermal model with multiple masses and units

[dipan]

Hi,

i have modeled a thermal system in simscape: the unit includes a polymer casing inside which there is a heater, heat spreader and a fluid sample in that order. i wish to validate this model by hand calculations such as finding the time constant. However i do not know how to find the time constant of such a system. Any ideas/suggestions ? the individual elements covering the fluid sample are also masses that store heat. If i keep the heater input at zero and start the simulation keeping the fluid temperature at 100 C with all other componenets at 25 C then i get resulting temperature profile which asymptotically reaches 25 C. How can i be sure that such a model is correct ? Is there any other calculation verification possible ? thanks for the help.. and please let me know if u need further explanation of the unit. I really need to prove that my Simscape model is correct before i can move on..

thanks ..

 

[Navin A S]

The time constant of a system can be calculated by dividing the thermal capacity (mass x specific heat) by the average thermal resistance. It is important to note that the thermal resistance will vary depending on the thermal properties of the components in the system. If you have the thermal properties of each component in the system, then you can calculate the average thermal resistance of the system by summing up the individual resistances. Once you have the average thermal resistance, then you can calculate the time constant of the system. To validate your Simscape model, you can compare the results of your hand calculations with the results of your Simscape model. If the results match, then you can be reasonably sure that your Simscape model is correct. Additionally, you can also compare the temperature profile generated by your Simscape model to actual experimental data to further validate your model. I hope this helps!