How is the temperature of thermal mass is determined?

Hello, I am working on an example in Simscape Fluids to calculate the thermal effects in a semiconductor. The structure I'm building involves a 1.5 kW thermal load passing through a thermal mass, which is cooled by a fluid flowing through a pipe, connected via thermal resistance.

The problem I am encountering is that when I run the simulation, the temperature of the thermal mass stabilizes at a certain point and does not increase further. I can observe that increasing the flow rate of the fluid in the pipe lowers the stabilized temperature of the thermal mass, indicating that the thermal mass is being cooled by the fluid. However, I can't find any port or parameter where I can define the heat transfer coefficient between the thermal mass and the pipe.

Thus, my questions are:

1. How is the heat transfer coefficient between the thermal mass and the pipe defined in this type of connection?
2. If possible, how can I calculate the temperature at the steady-state point where the thermal mass temperature stops increasing?

Thank you!

[Yifeng Tang]

The pipe block contains empirical equations for the heat transfer between the pipe wall and the fluid inside. The default is Gnielinski correlation. How would you like to set a heat transfer coefficient? Like a fixed value? Usually this coefficient varies as function of flow rate, and that's the purpse of the empirical heat transfer equations. It's possible to assign a value for the heat transfer coefficient, by using constant volume chamber instead of a pipe and adding a convective heat transfer block to the H port. You will lose the pressure drop characteristics of a pipe when you do that.