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Industry aerospacespace

In the ever-evolving field of aerospace engineering, precision, efficiency, and innovation are paramount. Conflux, together with Rocket Factory Augsburg (RFA), embarked on a rewarding project to create an additive manufactured Monel K-500 heat exchanger for the high-performance “Helix” rocket engine. The project was supported by the Moon to Mars grant from the Australian Space Agency.

This heat exchanger was designed for integration into the RFA ONE, a medium-lift launch vehicle developed to deliver satellites into orbit with high precision, flexibility, and cost-efficiency. These satellites provide critical data that support advancements in autonomous driving, smart agriculture, global communications, climate monitoring, and Industry 4.0—demonstrating RFA’s commitment to enabling transformative technologies that benefit society at large.

This case study details how Conflux harnessed the technical challenges, including material characterization of Monel K-500, high-speed flow simulations, and heat treatment optimization, to deliver a cutting-edge thermal management solution for aerospace applications.

Developing a High-Efficiency Rocket Engine Heat Exchanger

Conflux’s goal was to improve the efficiency of the rocket engine’s gas duct assembly by designing a heat exchanger capable of heating liquid helium to the high temperatures generated by a rocket engine. The heated helium would then be used as a pressurizing gas to ensure the smooth delivery of fuel and oxidizer to the engines, while maintaining stable pressure within the propellant tanks.

The key challenges included meeting aerospace compliance standards, optimizing heat transfer efficiency, and minimizing pressure drop.

 

Helix rocket engine Source: RFA

 

Conflux leveraged its configurable heat exchanger design process to adapt and refine the system, ensuring the new design met both thermal and structural requirements.

 

Heat Exchanger Integration Design for Optimized Performance

The initial gas duct design incorporated spiral channels and a flow distributor plate, providing a strong starting point. Conflux identified an opportunity to deliver greater efficiency than the current standard, with lower pressure drop for the same heat exchange.

Conflux’s enhanced design is a custom, integrated heat exchanger device that replaced the previous spiral channel system, resulting in significantly lower helium pressure drop while allowing for a thinner duct wall, reducing the overall weight of the assembly.

 

Helix engines on Stage One Source: RFA

 

Developing Novel Methodology for High-Speed Flow Simulation

Accurately simulating high-speed oxygen flow through the heat exchanger was essential and one of the significant achievements of this project. It required advanced computational modelling to ensure uniform mixing head performance and accurate thermal management.

To do so, Conflux developed a novel methodology for high-speed Computational Fluid Dynamics (CFD) simulations. This enabled precise modelling of oxygen flow and optimized heat exchanger placement. Consequently, thermal efficiency and flow distribution were maximized while maintaining structural integrity.

Cross-section of simulated oxygen flow through contours of gas duct. Source: Conflux

Material Characterization and Additive Manufacturing of Monel K-500

What is Monel K-500?

Monel K-500 is a nickel-copper alloy that combines the excellent corrosion resistance of Monel 400 with greater strength and hardness. This is achieved through the addition of aluminum and titanium.

The alloy is highly valued in various industrial sectors, including space exploration, due to its ability to maintain structural integrity under extreme conditions.

 

Tensile testing of Monel K-500. Source: Conflux

Its exceptional resistance to corrosion, high strength, and durability make it an ideal material for aerospace components exposed to harsh environments.

The versatility and reliability of Monel K-500 ensure it meets stringent aerospace application requirements, contributing to the success and safety of space missions.

Challenges of Using Monel K-500 in Additive Manufacturing

Introducing Monel K-500—a high-strength, corrosion-resistant nickel-copper alloy—as the desired material for the heat exchanger created some significant hurdles for Conflux. Early challenges centered on insufficient material characterization data and addressing print defects such as micro-cracking and porosity.

 

Test print of Monel K-500 material. Source: Conflux

To overcome these, Conflux undertook extensive microscopic and CT scanning analyses to refine printing parameters and eliminate micro-cracks. Through multiple iterative loops of printing, testing and parameter adjustments our team developed new techniques to address these issues.

Heat Treatment of Monel K-500 and Machining of Thin-Walled Geometries

Heat treating Monel K-500 posed significant difficulties, particularly for thin-walled geometries critical to the heat exchanger’s design. To address this, Conflux developed and validated specialized heat treatment processes. These processes ensured optimal mechanical properties without distortion.

Additionally, innovative machining techniques were implemented to meet the strict tolerances required for aerospace components.

 

Close-up of thin walled fins printed in Monel K-500. Source: Conflux

Rigorous Pressure Testing and Quality Assurance of Monel K-500

The final heat exchanger underwent rigorous pressure testing to confirm its suitability for RFA acceptance. This included a proof pressure test and a leak-down test, both of which the component passed successfully.

Further quality assurance measures included flushing, geometrical inspection, and cleanliness checks. These steps confirmed that the final product was ready for bench-testing and capable of delivering the required performance.

A number of RFA components are 3D printed. Source: RFA

Breakthrough Results: Enhanced Aerospace Heat Exchange Efficiency and Structural Integrity

Our successful implementation of Monel K-500 in a heat exchanger delivered superior thermal and structural performance. The project demonstrated five key advantages:

 

  1. Enhanced Thermal Performance with Monel K-500

    The final heat exchanger design met and exceeded RFA’s target helium outlet temperatures, surpassing initial thermal performance expectations.

  1. Reduced Pressure Drop for Improved Efficiency

    The Monel K-500 design significantly lowered pressure losses relative to the original spiral-wound configuration. This enhanced overall energy efficiency and reduced mechanical stress on downstream rocket engine components.

  2. Additive Manufacturing Innovation in Aerospace

    This project sets a new standard for aerospace heat exchangers by applying Monel K-500 in an additive manufacturing context, achieving both performance and manufacturability.

  1. Validated AM Process Expertise with Monel K-500

    The program confirmed Conflux’s capabilities in material parameter development, thermal post-processing, and precision machining – critical elements in delivering repeatable, high-performance AM components.

  1. Scalable Design Methodology for Larger Aerospace Systems

    The validated manufacturing and design processes are now transferable to larger-scale rocket engines and other advanced aerospace systems, enabling broader adoption of Monel K-500 in AM applications.

RFA Hot Fire Test in 2021 Source: RFA

Expanding the Role of Monel K-500 in Aerospace and Beyond

At Conflux, we solve complex thermal challenges by developing solutions through additive manufacturing. Through strategic collaboration, advanced simulation, and material science expertise, we delivered a heat exchanger that exceeded RFA’s performance targets.

Our successful use of Monel K-500 in a high-temperature, high-stress environment establishes its potential for future aerospace applications, including space exploration and hypersonics. The material’s corrosion resistance also makes it a strong candidate for marine and chemically aggressive environments.

Render of a simulated launch of RFA ONE in space Source: RFA

 

Enabling the Future of Additive Manufacturing in Heat Exchange

In partnership with innovators like Rocket Factory Augsburg and their RFA ONE launch vehicle, our technology is helping shape the future of spaceflight— delivering thermal performance that supports mission-critical reliability and long-term sustainability. This project highlights our commitment to pushing the limits of AM technology, in aerospace applications and beyond.

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