What if the next advance in aerospace cooling came from making a material less solid?

Aircraft engineers face a difficult design contradiction. Modern aircraft must accommodate increasingly demanding electrical, electronic and mechanical systems, yet the space available to manage their heat remains limited. Every cooling component has consequences for weight, volume, power consumption and system integration.

The challenge becomes particularly interesting as aviation explores greater electrification. Batteries, power electronics, motors and other electrical systems introduce heat loads that must be managed within tightly constrained aircraft architectures. The European Union-funded TheMa4HERA project, for example, is investigating thermal-management technologies for future hybrid-electric regional aircraft, including the additional heat generated by electrical power storage and generation.

What if part of the answer lay in the internal architecture of the material itself?

This is the engineering question behind Duocel®, the open-cell foam technology developed by ERG Aerospace. Its interconnected structure allows fluids to pass through a network of solid metal ligaments and open pores, creating a large internal surface area for heat-transfer applications.

The principle is compelling. Instead of relying exclusively on conventional tubes, plates or fins, engineers can explore a porous material as an active part of the thermal-management system.

But how does this structure work, where could it make a difference, and what would it take for its potential to translate into wider industrial adoption?

Thermal management is rarely an isolated engineering problem. It affects how an aircraft is designed, how its systems interact and how much room remains for other equipment. The issue is becoming increasingly relevant as aircraft architectures evolve. More-electric and hybrid-electric concepts introduce additional electrical equipment, while power generation, conversion and storage all require careful temperature control.

The European research landscape reflects this concern. Projects such as TheMa4HERA are investigating how future aircraft might manage additional thermal loads while accommodating the demands of hybrid-electric propulsion.

The implications extend beyond finding a more powerful cooling component. A thermal-management solution must work within the wider aircraft architecture. Its mass, physical dimensions, pressure losses, energy requirements and integration all influence the final design.

This is where material selection becomes particularly interesting.

Where Could Advanced Materials Make a Difference?

Open-cell metal foam could offer potential contributions across several areas of aerospace thermal management:

Technology	Potential contribution
Hybrid-electric propulsion	Could support heat exchangers designed to manage additional thermal loads from electrical propulsion systems
Power electronics	Could provide high surface-area structures to support heat dissipation from power conversion equipment.
Battery thermal management	Could offer a porous heat-transfer medium for systems requiring controlled temperature regulation.
Aircraft heat exchangers	Could increase the available heat-transfer surface within a compact structure, subject to pressure-drop and system-efficiency requirements.
Two-phase cooling systems	Could provide a porous structure through which liquid and vapour move during heat-transfer processes.

These are potential application areas, not confirmation that Duocel® is currently deployed in every system listed. Suitability depends on material selection, operating conditions and full-system testing.

Why this matters: A component that transfers heat effectively but introduces excessive pressure loss or requires substantial supporting structure may offer little overall advantage. Engineers need to understand the performance of the complete system, rather than one attractive material property in isolation.

ERG Aerospace Corporation was established in 1967 and has manufactured its Duocel® open-cell foam technology for aerospace and other specialist industries.

The structure is different from what the word foam might suggest. Duocel® is not a conventional polymer foam or a material made from sealed bubbles. It consists of a network of solid ligaments forming interconnected cells with open pores. Fluids can move through the structure rather than remaining trapped within it.

According to ERG’s technical explanation of Duocel® structure and material characteristics, three principal design variables influence the material’s properties:

• Base material: Duocel® can be produced using metals, carbon and ceramics. The selected material influences its physical, thermal, electrical and chemical characteristics.
• Pore size: ERG uses pores per inch (PPI) to describe the structure’s pore density. This influences the available surface area and the way fluids move through the material.
• Relative density: This describes the proportion of the structure’s overall volume occupied by solid material. It is closely related to ligament cross-section and influences properties including strength.

These variables matter because the same general architecture can be adapted to different engineering requirements. A structure designed to facilitate heat transfer will not necessarily have the same configuration as one intended for impact absorption or electrical applications.

The material’s internal geometry therefore becomes part of the design process.

The objective is not simply to make a material as porous as possible. Engineers must select a suitable balance between available surface area, structural requirements, fluid movement and thermal performance.

For applications where compactness matters, that flexibility creates an interesting design opportunity.

A promising material is only part of the engineering equation. Aerospace adoption requires confidence in how a component behaves throughout its intended operating life.

For Duocel® thermal-management applications, several questions remain central.

Can performance be predicted reliably?

Thermal conductivity, heat-transfer behaviour and pressure drop need to be understood under representative operating conditions. ERG describes in-house engineering capabilities that include thermal modelling, testing and design optimisation.

Can the component be manufactured consistently?

Pore structure, ligament geometry, relative density and material selection influence performance. Repeatability matters when components must meet defined specifications across production runs.

Can it withstand the operating environment?

Aerospace components may experience vibration, thermal cycling, pressure changes and demanding environmental conditions. ERG lists testing capabilities that include thermal cycling, shock and random vibration, proof and burst pressure, and micro-CT scanning.

Does it improve the complete system?

The relevant comparison is not simply between two materials. It is between two engineered solutions. A useful evaluation must account for thermal performance, pressure losses, weight, volume, manufacturing cost, integration and maintenance requirements.

ERG states that it has produced Duocel® components for applications including Mars landers, satellites and commercial and military aircraft, and describes these as Technology Readiness Level 9 components. This is a company-reported statement; individual programmes and component qualifications should be assessed in their own context.

The company also identifies an AS9100-certified quality management system. Certification is relevant to aerospace supply-chain assurance, but it should not be interpreted as automatic qualification of every material or component for every aircraft application.

For aerospace manufacturers and system integrators across the UK and Europe, the next question is therefore practical: where does the material offer a measurable advantage over established alternatives, and can that advantage be demonstrated at component and system level? That is where technical promise becomes an industrial business case.