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The problem at hand is a steady state thermal problem, thus the steady-state thermal analysis system will be used. Click on Steady-State Thermal(ANSYS) as shown in the image below.
Continue to hold down the left mouse button and drag Steady-State Thermal (ANSYS) into the Project Schematic area. You will then see a green rectangle appear as shown below.
Drag Steady-State Thermal (ANSYS) to the green box which will then turn red and contain text saying "Create standalone system".
Now, release the left mouse button to create the standalone system.