High Resolution Fast Response NOx Sensor for High Fuel Efficiency Vehicles

The Office of Energy Efficiency and Renewable Energy (EERE) Vehicles Technologies Program (VTP) is focused on developing technologies to enable average new vehicle fuel economy of more than 60 miles per gallon for cars and more than 43 miles per gallon for trucks by 2025. Many advanced combustion technologies to improve fuel efficiency rely on lean burn, which results in increased oxygen content in the engine exhaust. These conditions lead to overall reduction of emissions, but at the expense of increased concentrations of NOx. Several technologies are used to mitigate the additional NOx, including Selective Catalytic Reduction (SCR), and regenerative NOx traps. On-board NOx monitoring is a key component technology to enable cost effective implementation of NOx mitigation technologies. Phase I will develop miniaturized, solid-state, multi-element NOx sensors with filters that will serve as protection and removal of interfering species, with requirements based on transportation applications. In addition to the sensor element fabrication, packaging and signal conditioning approaches will be developed, producing an integrated NOx sensor prototype. We envision a sensor comparable in packaging and ease of implementation to an automotive oxygen sensor, now ubiquitous in vehicles advanced control systems. For acceptance in the transportation market, the technology must meet challenging performance requirements while being suitable to achieve low costs when produced in large volumes. Commercial Applications and Other Benefits The initial application for the proposed NOx sensor will be incorporation in aftermarket NOx cleanup systems installed in heavy-duty diesel vehicles. For instance the 6.7 L Ford super duty trucks come equipped with a Selective Catalyst Reduction (SCR) system that uses urea for NOx reduction. We envision similar exhaust systems will become available to retrofit older trucks. Aftermarket applications offer an excellent pathway for market entry, and will pave the way to future incorporation in new high fuel efficiency vehicles based on lean-burn technology. Tailpipe NOx sensors are not limited to SCR systems. The sensors will ensure NOx concentrations are compliant with current regulations, and since it will collect data during all driving conditions, it will enable developing emissions profiles that are more representative than simulated smog checks.