Thermal Circuits 2: Nodal Networks

Thermal nodal networks are used to predict the behavior of large complex interacting systems. By breaking down components into thermal resistances and capacitances, representing them as an electrical circuit, and using linear algebra, we can solve simultaneous equations to determine how temperatures evolve in time. This method can solve for time-varying, temperature varying, and non-linear thermal behavior between arbitrary numbers of nodes. Common applications include modeling vehicles, structures, or products with heat sources and sinks that must be kept within specifications.

[@kylemarquis738]

I would suggest differentiating heat from power. Power can come in many forms, but here, your equations are only for heat flow. As a result, I think it would be better for viewers if you use the words heat. Also, it's more common to see Q for heat instead of P.

[@PersonaRandomNumbers]

I've never really considered thermal behavior of circuits before, but this is pretty informative! The circuit analogy is surprisingly powerful -- though it would be nice to be explicit about the relations; charge as (thermal) energy, voltage as temperature. I enjoyed the little hint of linear approximations applied to complicated thermal systems near the end.

[@leandrocarg]

I've been delving into this analytic technique for the past days and it's been a fun ride so far, your previous video and this one helped a lot. I'm now able to understand and calculate how my electronics will behave thermally like never before. Next big thing is to understand distributed elements/thermal transmission lines which can't be modeled used lumped element methods.

[@precisionstuff-sv9zu]

Great to hear it. A lot of common geometries (plane, cylinder, sphere) and typical boundary conditions (constant temp, constant heat flux, constant resistance) have analytical solutions which are really powerful. For more complex geometry or boundary conditions you can take a component and slice it into many small nodes and then simulate as a nodal model and approximate the true diffusion equations.

[@ChiefBridgeFuser]

Be an EE because everybody wants to do it with V=I*R 😂. Trouble is, all of their R's are less constant. Thanks for the video!

[@SkyhawkSteve]

Hadn't seen anyone approach thermal analysis for electronics like this before. There are published values for thermal resistance of power devices, heatsinks, etc. Are there standard values for thermal resistance for circuit board, which would be the typical path for heat flow from device to device? The copper in the board can vary greatly from design to design. Never saw anyone get interested in a transient model like this, where thermal mass and heat flow was considered. Usually the thermal analysis just focuses on the max ambient temperature and the max dissipation of devices during steady state conditions. Can you provide the specifics of the cases where this sort of analysis is considered essential?