Gas-temperature imaging in a low-pressure flame reactor for nano-particle synthesis with multi-line NO-LIF thermometry

Multi-line NO-LIF temperature imaging was applied to measure two-dimensional gas-temperature fields in a low-pressure, premixed flat-flame nano-particle generator during nano-particles synthesis. It was the first time that this calibration-free technique was applied in a low-pressure combustion system. The laser fluence was limited to 4 kW/cm² in order to avoid saturation of the LIF signal, which influences the temperature results. While minimizing the elastically scattered light, the efficiency of the LIF detection system improved. This enables measurements with low tracer concentrations that do not influence the nano-particle generation process or the flame chemistry. An optimized scan range for excitation spectra was applied to measure flame temperatures between 600 and 1500 K in a 175×50 mm² field with an accuracy of ±2%. It was found that the TiO₂ nano-particle generation process does not influence the flame temperature under typical operating conditions. Pressure effects on the temperature distribution were investigated. The data is required for the simulation of nano-particle formation based on kinetic modeling. PACS 07.20.Dt; 42.62.Fi; 61.46.Df