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Simultaneous laser induced fluorescence (LIF) imaging of formaldehyde and a fuel-tracer have been performed in a direct-injection HCCI engine. A mix of N-heptane and iso-octane was used as fuel and Toluene as fluorescent tracer. The experimental setup involves two pulsed Nd:YAG lasers and two ICCD cameras. Frequency quadrupled laser radiation at 266 nm from one of the Nd:YAG lasers was used for excitation of the fuel tracer. The resulting fluorescence was detected with one of the ICCD cameras in the spectral region 270-320 nm. The second laser system provided frequency tripled radiation at 355 nm for excitation of Formaldehyde. Detection in the range 395-500 nm was achieved with the second ICCD. The aim of the presented work is to investigate the applicability of utilizing formaldehyde as a naturally occurring fuel marker. Formaldehyde is formed in the low temperature reactions (LTR) prior to the main combustion and should thus be present were fuel is located until it is consumed.

Cycle resolved wall temperature measurements have been performed in a one cylinder port injected optical Scania D12 truck engine run in HCCI mode. Point measurements at various locations were made using Laser-Induced Phosphorescence (LIP). Single point measurements with thermographic phosphors utilize the temperature dependancy of the phosphorescence decay time. The phosphorescence peak at 538 nm from the thermographic phosphor La2O2S:Eu was used to determine temperature. A frequency tripled 10 Hz pulsed Nd:YAG laser delivering ultra violet (UV) radiation at 355 nm was used for excitation of the phosphor. Detection in the spectral region 535 - 545 nm was performed every cycle with a photo multiplier tube connected to a 3 GHz oscilloscope. Measurements were made at four points on the cylinder head surface and two points on the outlet and inlet valves respectively. For each location measurements were made at different loads and at different crank angle degrees (CAD).