Lump Mass model – steady state

In this calculator you can calculate the steady state
temperatures of a network of bodies. Follow the steps, and if you are
ready press the button calculate and evaluate the results in the graph.

In a lumped capacity model, a thermal system is divided in to

  • Heat Capacities
  • Thermal Couplings

The heat capacities are called Nodes, and it is assumed that the temperature in one node is uniform. Heat capacities can be:

  • Large parts
  • Thermally conductive parts
  • Multiple parts with good thermal conducion between them
  • Parts with "important" temperatures

In the image above, a three node system is shown. Part 1 is in contact with body 2 by a few connection points. Body 2 is in contact with body 3, which is a large and surrounds the other parts.
In the picture to the right, the conductive couplings and radiation couplings identified. Body 1 has a heat source.

Use the calculation tool to calculate the temperatures.

Step 1 Input system size

#nodes How many nodes does the system contain?(2-6)
if you change this, all data will be lost.

Step 2 Input thermal couplings

from to type value[W/K]

Step 3 Constant temperatures nodes (e.g. heatsinks)

node temperature [K]


Step 4 Input Heat loads

node Power [W]


Step 5 Calculate

Press calculate to evaluate the results



(drag blocks to rearrange locations)

This calculator was made for educational purposes only. No rights can be obtained from the results you calculate. If you have comments please contact


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