A novel laser-absorption gas sensing apparaOn-vehicle Testing at VERtus capable of measuring NO directly within vehicle exhaust was developed and tested. The sensor design was enabled by key advances in the construction of optical probes that are sufficiently compact for deployment in real-world exhaust systems and can survive the harsh, high-temperature, and strongly vibrating environment typical of exhaust streams. Prototype test campaigns were conducted at high-temperature flow facilities intended to simulate exhaust gas conditions and within the exhaust of vehicles mounted on a chassis dynamometer. Results from these tests demonstrated that the sensor prototype is fundamentally free of cross-interference with competing species in the exhaust stream, can achieve a 1 ppmv NO detection limit, and can be operated across the full range of thermodynamic conditions expected for typical vehicle exhausts. These features address the key technological drawbacks associated with electrochemical NOx sensors widely used in current aftertreatment systems while enabling an on-board diagnostic capable of determining NOx output at the tailpipe at a level of accuracy comparable to laboratory-grade instrumentation. Broadly, this novel sensor provides high-quality emissions data needed to help vehicle manufacturers develop powertrains and aftertreatment systems that meet future, more stringent emissions regulations.
