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]

Conductivities matrix [W/K]
node1 node2 node3 node4 node5 node6
node1 0 0 0 0 0 0
node2 0 0 0 0 0 0
node3 0 0 0 0 0 0
node4 0 0 0 0 0 0
node5 0 0 0 0 0 0
node6 0 0 0 0 0 0

Convection matrix [W/K]
node1 node2 node3 node4 node5 node6
node1 0 0 0 0 0 0
node2 0 0 0 0 0 0
node3 0 0 0 0 0 0
node4 0 0 0 0 0 0
node5 0 0 0 0 0 0
node6 0 0 0 0 0 0

Radiation matrix [W/K]
node1 node2 node3 node4 node5 node6
node1 0 0 0 0 0 0
node2 0 0 0 0 0 0
node3 0 0 0 0 0 0
node4 0 0 0 0 0 0
node5 0 0 0 0 0 0
node6 0 0 0 0 0 0



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

node temperature [K]

'Node temperatures[K]'
node1 node2 node3 node4 node5 node6
T - - - - - -

Step 4 Input Heat loads

node Power [W]

Heat load[W]
node1 node2 node3 node4 node5 node6
Q 0 0 0 0 0 0

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 info@dspe.nl.


References

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