A laser-absorption sensor for in situ detection of biofuel blend vapor in engine intakes

A novel, mid-infrared laser-absorption sensor was developed for measurements of biofuel blend (E85) vapor in the intake runner a single-cylinder internal combustion engine. The used two interband cascade lasers to target region strong E85 absorbance near 3.35 µm. were co-aligned and fiber-coupled into engine, two-color, online-offline differential absorption strategy provide sensitive mole fraction reject interference due beam-steering fuel droplet spray. An intensity-modulation spectroscopy (IMS) sensing scheme employed low-frequency additive noise allow frequency-domain multiplexing lasers. High-resolution cross-section conducted static cell at range intake-relevant conditions. Validation experiments performed laboratory setting demonstrate accuracy rejection capability. deployed on development engine during dynamometer testing time-resolved measurement rate 40 kS/s, which corresponds one per crank angle degree 6700 rpm. Time-resolved average key performance insights systems high-performance engines.