Fraunhofer Institute for Production Technology IPTResearch project "HÄLT – Highly Efficient Refrigeration Cycles with Propane"
Heat transition meets material transition: rethinking sustainable cooling cycles
Global production of residential heat pumps is expected to triple to around 17 million units by 2035, with projected revenues of roughly 80 billion euros and annual growth rates exceeding eight percent. Industrial heating and cooling technology is already growing by five to seven percent, while the cooling market is expanding at double-digit rates.
The rapid shift to natural refrigerants such as propane is an important step for the environment, but it does not address Germany’s lack of resources. Replacing gas burners and conventional systems with heat pumps on a large scale significantly increases demand for import-critical materials such as copper, permanent magnets, and aluminum.
In effect, the energy transition is becoming a materials transition. A sustainable long-term transition in heating will require manufacturers to use materials much more efficiently when producing heat pumps and chillers.
This is exactly the issue addressed by the Fraunhofer joint project HÄLT – Highly Efficient Refrigeration Cycles with Propane.
Highly efficient cooling cycles with half the material
A team of scientists from four Fraunhofer institutes is developing new refrigeration cycle architectures for heat pumps and chillers that significantly cut material use. The project aims to reduce the material used in the refrigeration cycle by at least 50 percent—without sacrificing energy efficiency or service life. By using the natural refrigerant propane (R290), these solutions help reduce greenhouse gas emissions and meet upcoming regulatory requirements
The research aims to develop technological options for material-efficient heat pump and cooling systems and prepare them for industrial use.
Two complementary manufacturing approaches
The researchers are combining two complementary manufacturing approaches for propane refrigeration cycles within a modular platform: the KOMPAKT development track uses additive manufacturing to produce highly integrated refrigeration components optimized for limited installation space. In parallel, the LEICHT track focuses on material-efficient series production using lightweight sheet metal structures.
The project partners are developing, simulating and comparing both approaches on a shared digital platform. A common system architecture, consistent thermodynamic models, and standardized evaluation methods allow them to comprehensively assess material use, energy efficiency, and life cycle impacts.
Digital process chains and quality assurance
Within the KOMPAKT track, Fraunhofer IPT is developing the digital process chain for the additive manufacturing of refrigeration components. The institute is focusing on assuring the quality for additive manufacturing processes, integrating and optimizing individual process steps, and collecting and using data consistently across the entire process chain.
Fraunhofer IPT has extensive experience combining additive and subtractive manufacturing methods and has integrated digital technologies and sensor systems into additive manufacturing processes.
Digital twin and digital product passport
A key research focus at Fraunhofer IPT is developing a digital twin for additively manufactured refrigeration components, along with a digital product passport. This passport contains information on the materials used, process parameters, and energy and resource consumption. It provides a foundation for quality assurance, efficiency assessment, life cycle analysis, and recycling strategies.
In HÄLT, the team at Fraunhofer IPT is building a digital infrastructure that consolidates all production and measurement data collected throughout the manufacturing process chain. The researchers can then link this data, for example, to models describing relevant component properties.
Fraunhofer IPT's digital framework dPart® is an established tool for creating complete, data-consistent digital twins across the entire value chain—from process planning to manufacturing and quality assurance. The framework is complemented by a patent covering the generation of virtual geometries and data processing. As part of HÄLT, the researchers are expanding dPart® to include a digital twin for the additive LPBF process: In addition to the subtractive machining processes already covered, the framework will, for the first time, fully digitize and integrate additive manufacturing and the subsequent milling used to finish 3D-printed parts.
To validate the approach, the institute will manufacture demonstrators of an integrated refrigeration cycle and compare them with their digital twins, which will allow the team to systematically analyze deviations and develop robust manufacturing strategies.
Close collaboration with industry
More than 20 industrial companies have already expressed interest in the research project. They will receive regular updates on its progress and contribute in an advisory capacity. By the end of the project, the partners aim to identify concrete opportunities for bilateral research and development projects that can transfer the platform toolkit, digital tools, and evaluation methods to industrial-scale applications.
Project Partners
- Fraunhofer Institute for Solar Energy Systems ISE
- Fraunhofer Institute for Production Technology IPT
- Fraunhofer Institute for Machine Tools and Forming Technology IWU
- Fraunhofer Institute for Production Systems and Design Technology IPK
Funding
The project "HÄLT – Highly Efficient Refrigeration Cycles with Propane" is funded by Fraunhofer Gesellschaft as part of PREPARE.