Optical NOx Sensor Eliminates Diffusion Delay
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional NOx sensors face significant measurement delays due to sequential diffusion processes, limiting their efficiency in determining NOx concentrations in exhaust streams, which affects the real-time monitoring of catalytic converters in internal combustion engines.
Innovation Solution
A multi-component fluid composition and concentration sensor system with multiple sensing elements and a reference surface, utilizing thermal, optical, or morphological changes to determine fluid component concentrations through a lookup table-based calibration process, allowing for precise and rapid measurements of NOx, CO, and HC in IC engine exhausts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional electrochemical diffusion-based NOx sensors are used, then measurement of NOx concentration can be achieved, but significant measurement delays occur due to sequential diffusion processes
Solution Approach 1:
The patent replaces the mechanical/electrochemical diffusion-based sensing mechanism with an optical detection system. The system uses a light source to illuminate the exhaust stream and photodetectors to measure light absorption at specific wavelengths, eliminating the slow diffusion process inherent in electrochemical sensors while enabling rapid real-time NOx concentration measurements
Solution Approach 2:
The patent changes the measurement parameter from electrochemical potential/diffusion to optical absorption characteristics. By measuring the absorption of light at specific wavelengths (210-250 nm for NOx) compared to reference wavelengths, the system achieves rapid concentration determination without the time delays associated with electrochemical diffusion processes
2Measurement precision
If sequential diffusion processes are used in multi-chambered sensors, then NOx concentration can be determined, but measurement time increases to half a second or more
Solution Approach 1:
The patent replaces the sequential electrochemical diffusion process with simultaneous optical measurements. Multiple photodetectors measure light absorption at different wavelengths concurrently as the exhaust stream passes through the optical path, eliminating the sequential chamber-by-chamber measurement approach and achieving rapid real-time detection
Solution Approach 2:
The optical measurement system maintains continuous measurement capability as the exhaust stream flows through the detection cell. Unlike sequential electrochemical methods that require step-by-step processing through multiple chambers, the optical system continuously monitors light absorption, providing uninterrupted real-time data on NOx concentrations
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces measurement delays, enabling real-time monitoring of NOx and other catalyzable fluid components, improving the efficiency of catalytic converters and providing immediate feedback on their performance.
Implementation Method 1
a first active catalyst sensor positioned within the housing and configured to catalyze a catalyzable first fluid component in the fluid stream during the first time period when the fluid stream contacts a surface of the first active catalyst sensor
Implementation Method 2
a first temperature sensor connected to the first active catalyst sensor and configured to measure the first deviation of temperature value
Data Source
AI summary
A multi-component fluid composition and concentration sensor system and method. The system can be configured with multiple sensing elements whereby each specifically responds to different combinations and concentrations of multiple fluid component mixtures. Because these responses can be captured and committed to a lookup table during an initial calibration sequence, subsequent measurements of unknown mixtures of the same gases will match known states found in the lookup table and the fluid concentrations can be deduced. The number of sensing elements with unique responses to the fluid mixtures should equal the number of unknown fluids that are active on the sensing surfaces, similar to how solving for multiple variables requires no fewer equations than there are unknowns, i.e. “3 equations and 3 variables.” A reference surface can also be present in the fluid composition and concentration sensor so that the effects measured by the sensing surfaces can be determined against a relevant control that is not sensitive to the active fluids being measured.