Johns Hopkins APL Researchers Developing New Heatsink Using Additive Manufacturing

Engineers at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, are developing a new thermal-management capability to help manage heat in systems where space and weight are limited.

SPEAR, derived from Smart Phase-change Enhanced Re-entry, combines phase-change materials (PCMs) with additive manufacturing to create compact, high-capacity heatsinks. PCMs absorb and store heat as they change from one physical state to another, allowing them to hold more heat without rising in temperature as quickly as traditional materials. The approach is designed for systems where electronics generate heat but have limited ways to release it, while still needing to meet strict size, weight, and power (SWaP) constraints.

“PCM heatsinks can be useful anywhere you have electronics that generate a lot of heat over a short period of time,” said Yoni Ferneau, a mechanical engineer at APL. “That could include hypersonics, space systems, radio-frequency electronics, transmitters, interceptors, and other transient or low-duty-cycle systems.”

A phase-change heatsink uses the melting of a material to store heat, similar to how ice melting in a drink keeps it cool, said Greg Merboth, a senior mechanical engineer at APL.

As the material changes from solid to liquid, it can absorb and store heat more efficiently than a traditional metallic heatsink, enabling a more than 50% reduction in size and weight while maintaining thermal capacity.

Built and Tested In-House

Traditionally, phase-change heatsinks are built through complex assemblies of machined parts, but recent breakthroughs in additive manufacturing offered the team a different approach.

“Because of advances in additive manufacturing, we thought it would be feasible to fabricate our own single-piece phase-change heatsinks,” Merboth said.

The SPEAR team has built initial heatsinks and a test unit to evaluate the concept. The team started with a baseline aluminum heatsink and manufactured two SPEAR heatsinks for side-by-side testing. One SPEAR heatsink was the same volume as the aluminum version, showing how much more thermal storage capacity the phase-change design could provide in the same amount of space. The other was designed to match the traditional aluminum heatsink’s thermal capacity, showing how much size and weight could be reduced while storing the same amount of heat.

The PCM heatsinks were filled, sealed, and successfully tested with no leaks. The team then tested the SPEAR heatsinks against the traditional metallic design, demonstrating the expected performance and SWaP benefits.

To demonstrate the comparison more easily, the team built an integrated test unit, which applies heat to multiple heatsinks at once and records and displays the resulting real-time temperature changes to show how each design responds under similar conditions. The testing also highlights the value of APL’s design, fabrication, and evaluation team: The SPEAR heatsinks were designed and 3D-printed, and the demonstration unit’s hardware, software, and packaging were also developed in-house, allowing the team to quickly test, compare, and refine the concept.

“SPEAR shows how our engineers can take a shared technical challenge and develop a capability that can be adapted for different mission needs,” said Danielle Hilliard, who oversees design, engineering, and fabrication at APL.