Cooling in Power Electronics Open-Pored Aluminum Casting Promises More Space with Less Weight

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Taiwan Machine Tool & Accessory Builders' Association (TMBA)

Conventional cooling concepts in power electronics are increasingly reaching their physical limits. The design possibilities for traditional external heat sinks are often exhausted. A novel architecture now promises significantly reduced space requirements while simultaneously increasing performance.

In conventional thermal management, the problem lies deep: up to 90 percent of the thermal resistance arises from convection. Designers have been trying for decades to compensate for this through higher fin density (fins, pins, or lattices). However, this creates a physical conflict of objectives: denser fins mean a thinner heat-conducting cross-section. The fin efficiency decreases significantly because the heat has to laboriously travel through the material to the surface.

The bottleneck thus shifts from convection to conduction. Developers often resort to expensive stopgap solutions: copper instead of aluminum or extremely costly high-end thermal interface materials (TIMs). "That's often the wrong lever for the wrong ten percent of the problem. The issue is postponed but not solved," explains Eugen Pfeifer, Managing Director of Automoteam, ahead of his presentation on September 30 in Würzburg (Germany).

Open-Pored Structure thanks to Metamaterials

Its approach reverses the principle: the fluid moves to the heat source rather than the other way around. While conventional heat sinks follow the "outsider principle" and only act on the outer surface, the so-called PORECOOL technology activates the entire 3D volume of the heat sink. The core volume of the metal is no longer thermally inactive.

The secret lies in a new cavity microstructure, known as vascular metamaterials. Instead of solid blocks, an open-porous structure, such as aluminum casting, is used. The heat-conducting cross-sections correspond to those of conventional high-performance heat sinks, but the convective surface area is far greater. Integrated effects like a "golf ball effect" enable entirely new heat transfer phenomena and push the physical boundaries of thermal systems.

This new approach promises advantages for thermal management:

• Volume and weight: Reduction by up to 70 percent.
• Effective surface: Up to 9 times larger specific surface area.
• Performance: Increase in cooling capacity by up to 200 percent.

Problems with Contamination?

Developers are often skeptical of open-pored structures, fearing that the pores inside the material could become clogged. Pfeifer addresses these concerns: "Since the medium is divided into thousands of micro-pulsating flows, it flows without barriers and without the classic backpressure zones of conventional cooling fins."

In daily use, practice even shows up to ten times longer service intervals compared to standard filters. And if dust does accumulate: The system can be highly efficiently cleaned by simple backflushing, such as reversing the polarity of the fan.

Shorter Development Times

Conventional heat sink developments often take several months. Metahybrid takes a faster approach with a two-stage, AI-supported process. In the traditional process, each design must be manually modeled in CAD, meshed, and iteratively tested in time-consuming CFD simulations (Computational Fluid Dynamics).

In Phase 1, an AI-supported algorithm calculates a multidimensional solution space, testing thousands of configurations. The result is a database that provides reliable answers to technical and strategic questions, almost completely eliminating time-consuming CAD/CFD iterations. In the next step, the most promising variants are manufactured as real prototypes for laboratory measurements. These can often be directly implemented in the customer's system. The simulation model is then finally optimized using the real measurement data.

In the second phase, the focus is on series development and production. Once the so-called MVP is validated, the system is finalized for manufacturing. An MVP (Minimum Viable Product) is the first version of a product with just enough features to be functional and provide real value to the customer. Since the design is already digitally and empirically refined, late changes to the series design are almost completely eliminated. (heh)

In his lecture "Disruptive Cooling Architecture: Open-pored Aluminum Casting for Power Electronics, AI Infrastructures, and Data Centers." on September 30, Eugen Pfeifer addresses the advantages of PORECOOL. This is intended to tackle space problems that were previously considered unsolvable.

Further Topics in the Thermal Management Track

Thermal Management

Beyond the Standards: When Copper and Aluminum Are No Longer Enough

Basic Day Thermal Management

Live Experiments and Generative Design: How Professionals Cool Modern Electronics

Link: https://porecool.com/