From Design to Validation: Advancing ZIMBA’s Innovative AHT Heat Pump

28.09.2026

The ZIMBA project is developing an innovative ammonia-water Absorption Heat Transformer (AHT) enhanced with an ejector to recover and upgrade industrial waste heat to useful temperature levels. Within this effort, Work Package 2 (WP2) plays a crucial role by manufacturing, assembling and preparing the project’s core technologies for experimental validation.

Led by Politecnico di Milano and supported by project partners, WP2 bridges the gap between the concepts and designs developed during the project’s initial phase and the experimental activities that will demonstrate their performance. The work encompasses the baseline Absorption Heat Transformer (AHT), the ejector system and the testing infrastructure required to assess these technologies under representative operating conditions.

Progress on the Absorption Heat Transformer

One of the key objectives of WP2 is the construction and preparation of the baseline AHT system. Significant progress has been achieved in recent months, particularly regarding the development of the falling-film absorber.

The falling-film absorber successfully underwent a series of structural, leakage and microporosity tests, confirming its integrity and readiness for the next development stages. These activities represent an important milestone, providing confidence that the component can proceed towards integration within the broader AHT system.

At the same time, major progress has been made in the assembly of the baseline AHT. All principal components have been received (e.g. plate heat exchangers, valves, membrane pumps etc), and system assembly is currently underway. This work is paving the way for the upcoming commissioning phase, during which the system will undergo its first tests.

Preparing the testing infrastructure

Experimental validation is a crucial step in demonstrating the effectiveness of ZIMBA’s technologies. To support these activities, considerable effort has also been dedicated to upgrading and preparing the testing facilities that will host the forthcoming validation campaigns.

Current activities include work on the steam compensation loop and the preparation of laboratory infrastructure required for future testing. These upgrades will enable researchers to evaluate system performance under the operating conditions relevant to industrial waste heat recovery applications.

The preparation of these facilities is essential for ensuring reliable and comprehensive testing of the AHT system and its components during the next phases of the project.

Progress on ejector development

Alongside the development of the baseline AHT, WP2 is also advancing the project’s ejector technology.

Recent achievements include the successful validation of the ejector test bench design, providing the foundation for the upcoming experimental characterisation of the ejectors. Assembly activities have already started, while the ejectors themselves have been manufactured and are ready for implementation.

The dedicated test bench will play a key role in evaluating ejector performance under varying operating conditions and will support the selection of the most suitable design for integration into the upgraded AHT system.

Looking Ahead

As WP2 progresses, the focus will increasingly shift towards commissioning, testing and validation activities.

Upcoming work will include the completion of the baseline AHT assembly, commissioning of the system, finalisation of testing facility upgrades, assessment of absorber performance and experimental characterisation of the ejectors. Together, these activities will provide the data and practical experience needed to support the next stages of technology development within the project.

By advancing from component manufacturing and assembly to testing and validation, ZIMBA continues to build the foundation for innovative solutions capable of improving the utilisation of industrial waste heat and contributing to a more efficient and sustainable industrial processes.