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Zigan L.,A-D Technologies | Schmitz I.,A-D Technologies | Flugel A.,A-D Technologies | Knorsch T.,ESYTEC Energie und Systemtechnik GmbH | And 4 more authors.
Energy and Fuels | Year: 2010

Mixture formation in spray-guided direct injection spark ignition engines (SG-DISI) with late injection timing is mainly controlled by spray atomization and evaporation and strongly depends on fuel properties. The influence of fuel composition on the liquid spray structure was determined for a 12-hole solenoid injector with integral and light sheet Mie scattering as well as phase Doppler anemometry (PDA). Late injection timing in a high pressure atmosphere was simulated in an injection chamber (1.5 MPa, 293 and 673 K) to characterize the spray propagation and evaporation of alkanes with high and low volatility (n-hexane, n-heptane, n-decane) and a 3-component mixture of these alkanes with similar fuel properties like gasoline fuel. Under high chamber pressure and low ambient temperature, the spray propagation and the resulting droplet sizes are similar for all fuels. However, for n-decane, the droplet size distribution is shifted to smaller droplets and the spray appeared to be less dense because of fuel-dependent internal nozzle flow which results in a reduced injected fuel mass. In contrast, under high ambient temperature conditions for more volatile fuel components, the liquid spray length is reduced and droplet size as well as droplet momenta are decreased. Small amounts of high boiling fractions delay the evaporation and support the overall spray stability also for multicomponent mixtures which is indicated by increased spray length as well as larger droplet sizes and momenta. Moreover, the droplet size distributions and the small liquid Peclet numbers (PeL ≈ 1) of the 3-component fuel indicate a demixing of light and heavy boiling components in the 3-component fuel under conditions which are typical for DISI strategies with late injection. © 2010 American Chemical Society. Source

Schluter S.,ESYTEC Energie und Systemtechnik GmbH | Schluter S.,Friedrich - Alexander - University, Erlangen - Nuremberg | Seeger T.,University of Siegen | Popovska-Leipertz N.,ESYTEC Energie und Systemtechnik GmbH | And 2 more authors.
Technisches Messen | Year: 2014

The composition of raw biogas is subject to fluctuations that can affect downstream processes. In this study a species independent probe based on linear Raman scattering is presented. The sensor system is capable of identifying and quantifying all relevant bio gas components in a low pressure regime with high accuracy and precision within a short measurement time. © 2014 Walter de Gruyter Berlin/Boston. Source

Birkigt A.,Volkswagen AG | Michels K.,Volkswagen AG | Theobald J.,Volkswagen AG | Seeger T.,Friedrich - Alexander - University, Erlangen - Nuremberg | And 6 more authors.
International Journal of Engine Research | Year: 2011

One of the critical parameters for the occurrence of spark-knock and pre-ignition of highly charged spark-ignition (SI) engines is the compression temperature. The investigation of the compression temperature and a better understanding of the combustion behaviour inside the combustion chamber are of great importance for avoiding these phenomena and also for further downsizing of engines. Pure rotational coherent anti-Stokes Raman spectroscopy (RCARS) is an innovative tool providing information on the compression temperature by using only two small line-of-sight optical accesses on the cylinder wall. In this work, RCARS measurements were performed in motored and fired operation, and the results obtained from RCARS spectra have been used in combination with isentropic calculations to improve the accuracy of the compression temperature determination. Studies on the compression temperature by the variation of the intake temperature, the engine load, and the fuel were conducted and the influence of evaporation enthalpy on the compression temperature is discussed. © Authors 2011. Source

Schluter S.,Friedrich - Alexander - University, Erlangen - Nuremberg | Krischke F.,Friedrich - Alexander - University, Erlangen - Nuremberg | Popovska-Leipertz N.,ESYTEC Energie und Systemtechnik GmbH | Seeger T.,Friedrich - Alexander - University, Erlangen - Nuremberg | And 6 more authors.
Journal of Raman Spectroscopy | Year: 2015

The spontaneous Raman scattering technique is an excellent tool for a quantitative analysis of multi-species gas mixtures. It is a noninvasive optical method for species identification and gas phase concentration measurement of Raman active molecules, since the intensity of the molecule specific Raman signal is linearly dependent on the concentration. Applying a continuous wave (cw) laser it typically takes a few seconds to capture a gas phase Raman spectrum at room temperature. Nevertheless in contrast to these advantages the weak Raman signal intensity is a major drawback. Thus, it is still challenging to detect gas phase Raman spectra in a low-pressure regime with a temporal resolution of only a few 100 ms. In the presented study a fully functional gas phase Raman system for measurements in the low-pressure regime (p ≥ 980 hPa (absolute)) is presented; it overcomes the drawback of the weak Raman effect by using a multipass cavity to enhance the Raman signal. The signal amplification of a retro-reflecting cavity is experimentally compared to a near-confocal cavity. A description of this sensor setup as well as of the calibration procedure, which also allows the quantification of condensable gases, is presented. Moreover the functionality of the sensor system is demonstrated in a measurement campaign at an anesthesia simulator under clinical relevant conditions and in comparison to a conventional gas monitor. Copyright © 2015 John Wiley & Sons, Ltd. Source

Schluter S.,University of Siegen | Schluter S.,Friedrich - Alexander - University, Erlangen - Nuremberg | Seeger T.,University of Siegen | Seeger T.,Friedrich - Alexander - University, Erlangen - Nuremberg | And 3 more authors.
Technisches Messen | Year: 2016

The spontaneous Raman scattering is an excellent noninvasive optical tool for identifying and quantifying majority species within a multi species gas mixture. However, the effect is very weak. At ambient pressure typically several seconds or minutes are required to capture a gas phase Raman spectrum. In this study a new Raman sensor will be presented, which is capable to monitor and to evaluate such spectra in a few 100 ms fully automated. © 2016 Walter de Gruyter Berlin/Boston. Source

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