SORption studies in Adiabatic Falling Films of viscous Ammonia-based working fLuids – SORAFFAL

The SORAFFAL project aims to advance the scientific and technical understanding of adiabatic falling film absorbers using NH3-salt mixtures, with the long-term objective of developing more compact, efficient, durable, and cost-effective absorption chillers. As cooling demand increases rapidly and vapor compression systems face environmental and electrical limitations, absorption technology emerges as a promising alternative, particularly when powered by renewable thermal sources. However, market uptake remains limited due to high initial costs and technical bottlenecks, especially in sorption exchangers, which are considered the main performance-limiting component.

The project is structured around three main objectives: (1) to design and operate an innovative test bench integrating a real-time, non-intrusive infrared spectroscopy method for online monitoring of solution composition; (2) to experimentally characterize and model the absorption phenomenon in adiabatic falling film configurations, using two 3D-printed absorber geometries (with and without local mixing features); (3) to incorporate technical, economic, environmental, and safety criteria to assess the industrial feasibility of the studied mixtures, and to design an absorber for a 10?kW pre-industrial prototype.

The methodology relies on a comprehensive approach combining modeling, experimentation, and advanced instrumentation. The coupled heat and mass transfer model developed in SORAFFAL will account for local mixing effects to improve absorption predictions in viscous fluids over enhanced surfaces. The infrared composition measurement method will be calibrated, validated under impurity conditions (iron oxides), and benchmarked against conventional techniques—addressing a major gap in current diagnostic tools. At the end of the project, a virtual prototype integrating the designed absorber will be simulated to quantify improvements in system COP and compactness. Some of the innovations developed during the project will be the subject of a patent application.

SORAFFAL will generate significant advances in adiabatic absorber modeling, fluid monitoring instrumentation, and the valorization of low-carbon thermal energy. Led by an experienced consortium (CNAM, USMB, URV), the project will allow a young researcher to develop interdisciplinary expertise in a strategic domain. It directly contributes to the United Nations Sustainable Development Goals, particularly SDG 7 (affordable and clean energy), SDG 9 (industry, innovation, and infrastructure), and SDG 11 (sustainable cities and communities).