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Journal Article

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

Clees Sean
Cha Daniel H.
Biswas Pujan
Boddapati Vivek
Cassady Sean J.
Strand Christopher L.
Hanson Ronald K.
French Benjamin
Gilmour Alastair
Hawk Kevin C.
Stitt Joseph M.
Ferlet Xavier
Journal Name
Proceedings of the Combustion Institute
Publication Date