Combustion of liquid ammonia, assisted by plasma discharges, as a novel and clean energy conversion method

Periodic Reporting for period 1 - CAIPIRINH3A (Combustion of liquid ammonia, assisted by plasma discharges, as a novel and clean energy conversion method)

Berichtszeitraum: 2024-11-01 bis 2026-04-30

CAIPIRINH3A aims to overcome the technical barriers, hindering the uptake of ammonia as an alternative fuel, by developing and demonstrating an entirely novel technological concept: The Plasma Mist Ammonia (PlasMi-NH3) burner - a first of a kind, plasma-enabled, self-learning combustor, burning efficiently liquid ammonia with ultra-low NOx emissions. Leveraging detailed and accurate kinetic models, innovative injectors, non-equilibrium plasma systems for plasma assisted combustion and tailored combustion control strategies, CAIPIRINH3A will generate a truly vibrant and multiphase cocktail of chemical species that will activate multiple synergetic effects for enhanced combustion, in a smart framework. The targeted performance metrics are outstanding and go far beyond current paradigms: a) Thermal efficiency comparable to conventional diesel engines (~40%) b) Tier 4 NOx emissions (≤7.5 g/kWh). c) > 50% decrease in ignition delay and extension of flammability limits by >20%. d) Near zero ammonia concentration in exhaust (<10 ppm). The technological feasibility and future potential of CAIPIRINH3A’s concept will be investigated through extensive testing at TRL4 and holistic impact assessment studies. Seamlessly integrated in a future clean ammonia economy and in line with strategic EU action plans (Fit for 55, Green Deal), CAIPIRINH3A holds promise for a sustainable future for our societies with vast environmental and socioeconomic impact in power generation and all transportation sectors. This will be further fostered via targeted communication, and dissemination as well as the development of tailored business models for future exploitation. Hence, CAIPIRINH3A paves the way for a disruptive solution, which is eminent and urgent, towards the re-orientation of the energy conversion sector from fossil fuel-based to carbon free-based combustion systems and the ultimate goal of climate-neutral Europe by 2050.

During the first 18 months, CAIPIRINH3A made significant progress in the development of a novel plasma-assisted liquid ammonia combustion technology capable of achieving efficient, low-emission and carbon-free energy conversion. Focus was put on improving the scientific understanding of ammonia combustion and plasma-assisted combustion processes. Advanced chemical kinetic models were developed and experimentally validated, providing accurate predictions of ammonia ignition, flame propagation and pollutant formation. In parallel, new computational tools were created to simulate the interaction between plasma discharges and combustion chemistry, enabling the investigation of plasma-assisted ammonia combustion under a wide range of operating conditions.

Significant advances were also made in numerical simulation tools and simulations. New computational fluid dynamics (CFD) frameworks were established to investigate ammonia injection, evaporation, atomization and combustion processes. The models incorporate advanced descriptions of ammonia thermodynamics and phase-change phenomena and provide the basis for future optimization of combustor performance and emissions. On the experimental side, dedicated facilities for liquid ammonia injection and combustion studies were successfully designed, constructed and commissioned. A bespoke ammonia injector was integrated into the testing infrastructure, while initial spray experiments validated the system's operation and set the ground for future liquid ammonia testing campaigns. Moreover, a plasma-assisted ammonia combustor was commissioned and successfully operated, demonstrating substantial improvements in flame stability and reductions in pollutant emissions under plasma-assisted conditions.

Considerable progress was achieved in the development of plasma technologies tailored for ammonia combustion. Novel nanosecond pulsed plasma systems and surface dielectric barrier discharge actuators were designed, manufactured and experimentally characterized to a certain extent. For the first time within the project, plasma discharges were successfully generated and studied in ammonia environments under nanosecond pulsed excitation, providing valuable information on plasma dynamics towards deeper understanding of ammonia dissociation processes. New plasma actuator concepts based on advanced additive manufacturing techniques were also developed and validated, demonstrating their suitability for future integration into combustion systems. To support the design and optimization of future plasma-assisted combustion systems, advanced numerical models of plasma behaviour were developed, including reduced-order models capable of reproducing plasma-induced effects with significantly lower computational requirements than conventional simulation approaches.

Overall, the work performed during the reporting period established the scientific, numerical and experimental foundations required for the next project phases, including the integration, optimization and demonstration of the Plasma Mist Ammonia (PlasMi-NH3) combustor concept. The project has already generated a substantial body of new knowledge in ammonia combustion, plasma-assisted combustion, plasma physics and advanced energy conversion technologies.

CAIPIRINH3A advances beyond the state of art by combining, for the first time within a unified technological framework, liquid ammonia combustion, advanced plasma-assisted combustion techniques, tailored ammonia injection systems, detailed chemical kinetics and digital modelling tools. This integrated approach addresses some of the most important barriers currently limiting ammonia adoption as a carbon-free fuel, including poor ignition characteristics, limited flame stability, narrow flammability limits and the formation of pollutant emissions.

During the first 18 months, the project generated several results that go beyond existing knowledge and technological capabilities, including the development and experimental validation of advanced ammonia combustion kinetic models, the creation of dedicated plasma-assisted combustion simulation tools, the successful demonstration of nanosecond plasma discharges in ammonia environments, the development of novel plasma actuator concepts based on additive manufacturing techniques, and the establishment of advanced numerical frameworks capable of simulating both ammonia combustion and plasma-assisted combustion processes. Dedicated experimental infrastructures for liquid ammonia injection, spray characterization and plasma-assisted combustion were also successfully commissioned, providing capabilities that are currently available only at a limited number of research centres worldwide.

Results generated so far provide important scientific and technological foundations for future development of highly efficient, low-emission ammonia combustion systems. In particular, combining plasma-assisted combustion with direct liquid ammonia utilization can enable combustion systems with improved ignition characteristics, enhanced flame stability, reduced pollutant emissions and increased operational flexibility. These advances could support the future deployment of ammonia as a carbon-free fuel in sectors that are difficult to electrify, including maritime transport, heavy-duty transportation, power generation and selected industrial applications.

The project also generates important modelling and digital-design capabilities. Developed kinetic models, reduced-order models and CFD frameworks provide tools for accelerating the design, optimization and scale-up of future ammonia combustion systems while reducing development costs and experimental requirements. Such capabilities are expected to support both industrial innovation and future research in ammonia-based energy systems. To ensure successful uptake of project results, further work is required in several areas, including the continued validation of the developed models under representative operating conditions, the integration and demonstration of the complete plasma-assisted liquid ammonia combustor, further optimization of injector and plasma-system designs, and the evaluation of long-term performance, reliability and scalability. Additional efforts will be needed to support future industrial deployment via techno-economic assessment, environmental impact evaluation, market uptake activities, exploitation planning and IP management. Post-project, wider adoption of ammonia-based energy systems will benefit from continued research and demonstration activities, supportive regulatory frameworks, harmonized safety procedures and standards for ammonia utilization, and further investments in ammonia-related infrastructure and value chains. The results generated by CAIPIRINH3A provide important building blocks towards these objectives and contribute to Europe's ambition for climate-neutral, secure and sustainable energy systems.

Periodic Reporting for period 1 - CAIPIRINH3A (Combustion of liquid ammonia, assisted by plasma discharges, as a novel and clean energy conversion method)

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