Dr. rer. nat. Steven Wagner

Research Group Leader HTPD


work +49 6151 16-28925
fax +49 6151 16-28900

Work L6|01 109
Otto-Berndt-Str. 3
64287 Darmstadt

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High Temperature Process Diagnostics

In close cooperation with industrial partners our research group investigates the development and application of innovative laser-based in situ diagnostic measurement techniques in the exhaust gas of internal combustion engines (ICE) as well as all other dynamic combustion processes.

Recently our research aims at the absolute measurement of gas species concentration in the exhaust system using various after-treatment scenarios. Future efforts will also concentrate on the measurement of fluid temperature and film thickness. In very close cooperation with other research groups we use present and future results from fundamental research transferring their results into new and innovative applied technologies for industrial use.

The research group High Temperature Process Diagnostics is embedded in the institute Reactive Flows and Diagnostics.

Current Position

Future regulations for exhaust emissions will require further reduction of pollutants emitted by modern internal combustions engines. New, innovative engines as well as exhaust after-treatment techniques have to be developed and optimized to meet these requirements. Promising methods include Selective Catalytic Reduction (SCR) via injection of an ammonia-H2O solution and Exhaust Gas Recirculation (EGR).

Basic understanding of the general injection and vaporization processes, the process chemistry, and the near-wall reactive flows of these exhaust conditionings (SCR, EGR) are needed to optimize pollutant minimization. Advanced and new diagnostics for determination of absolute species concentrations, reaction rates, film thickness parameters as well as spatial and temporal fluid development within the exhaust tract are required.

Research Focus and Future Developments

The measurement of absorbing species such as ammonia (NH3) and water (H2O) greatly benefits from the use of direct, non-intrusive, probe-less, real-time absorption measurement techniques; the use of extractive techniques cannot provide the time-critical resolution required for proper analysis to understand the combustion and reaction dynamics of the exhaust after-treatment. Our research addresses development and application of innovative laser-based in-situ absorption measurement methods.

We will pursue narrow-linewidth diode lasers (DFB, VCSEL) to extend laser absorption spectroscopy to the technologically interesting mid-infrared region. We will also investigate the use of broadband laser sources (Super Continuum Light Source – SCLS) for absorption-based exhaust diagnostics. In cooperation with industrial partners, we will investigate the practicality of new laser technologies for the measurement of gas species concentrations, process temperatures, film thickness (as well as urea deposition on the walls), during different after-treatment procedures.

Recent improvements in laser technology will be used to significantly enhance the contactless diagnostic methods for current as well as future exhaust after-treatment systems.

The activities of HTPD group have a high potential for developing critically-needed multi-species measurement sensors to follow the spatial and temporal development of next-generation exhaust treatment systems.