Probe System for CO2 and H2O Measurement in Engine Fluid Streams
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Solution Overview
Problem
Internal combustion engines face challenges in measuring spatial and temporal nonuniformities of CO2 concentrations in complex fluid streams, which affect NOX emissions and engine efficiency due to variations in EGR distribution, temperature, and water vapor concentrations.
Innovation Solution
A probe system using swept-λ lasers and diode lasers to measure CO2 and H2O concentrations, with a processor normalizing signals to determine accurate CO2 concentrations, capable of handling both cool external EGR and hot backflow exhaust species, and designed to withstand engine vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If CO2 absorption spectra are measured at higher temperatures, then the measurement can capture hot backflow exhaust species, but temperature correction is necessary which complicates the measurement process
Solution Approach 1:
The patent uses water vapor concentration as an intermediary parameter to determine temperature. Instead of directly measuring temperature and applying complex corrections, the system measures H2O concentration which correlates with temperature, and uses this relationship to automatically adjust CO2 measurements. This intermediary approach simplifies the overall measurement process while maintaining accuracy across varying temperatures.
Solution Approach 2:
The system continuously monitors water vapor concentration and uses this feedback to dynamically correct CO2 absorption spectra measurements. The processor receives H2O concentration data and automatically adjusts the CO2 measurement parameters in real-time, creating a closed-loop feedback system that maintains measurement accuracy without requiring manual temperature correction intervention.
2Measurement precision
If multiple measurements are taken to account for spatial and temporal nonuniformities, then measurement accuracy improves, but measurement time increases
Solution Approach 1:
The patent combines multiple measurement functions into a single integrated probe system that simultaneously measures CO2 concentration, water vapor concentration, and temperature. By merging these measurements into one operation rather than taking separate measurements for each parameter, the system achieves high measurement precision without the time penalty of multiple sequential measurements. The combined data are processed together to account for spatial and temporal nonuniformities.
Solution Approach 2:
The measurement system is designed with multi-functionality, using a single probe and measurement cycle to gather CO2 concentration data, H2O concentration data, and temperature information simultaneously. This universal approach allows the system to capture the full picture of intake charge conditions in one measurement event, improving precision while minimizing time loss compared to separate specialized measurements.
3Reliability
If the probe is designed to withstand engine vibrations, then reliability improves, but device complexity increases
Solution Approach 1:
The patent employs flexible optical fibers and thin-walled but vibration-resistant housing structures to protect the measurement components from engine vibrations. The optical fibers used for CO2 and H2O measurement are inherently flexible and resistant to vibrational damage, allowing the probe to withstand harsh engine environments without requiring complex rigid shielding. This approach improves reliability while keeping the structural complexity manageable.
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
Enables rapid and accurate measurement of CO2 concentrations in complex fluid streams, improving engine efficiency and reducing NOX emissions by providing precise data for EGR system refinement and engine performance optimization.
Implementation Method 1
A first laser light source is a swept-λ laser configured to produce light output over a sweep range that includes a region having a significant absorption feature of CO2
Implementation Method 2
The second laser light source is configured to produce light output that includes a region having a significant absorption feature of H2O
Implementation Method 3
A lens is disposed proximate to a second end of each of the first and the second pitch optic cables for directing the first and second lights through a sampling chamber to a mirror
Implementation Method 4
A first catch optic cable has a second end disposed proximate the lens for receiving light output from the first laser light source that is reflected from the mirror
Data Source
AI summary
A diagnostic system for measuring temperature, pressure, CO2 concentration and H2O concentration in a fluid stream is described. The system may include one or more probes that sample the fluid stream spatially, temporally and over ranges of pressure and temperature. Laser light sources are directed down pitch optical cables, through a lens and to a mirror, where the light sources are reflected back, through the lens to catch optical cables. The light travels through the catch optical cables to detectors, which provide electrical signals to a processer. The processer utilizes the signals to calculate CO2 concentration based on the temperatures derived from H2O vapor concentration. A probe for sampling CO2 and H2O vapor concentrations is also disclosed. Various mechanical features interact together to ensure the pitch and catch optical cables are properly aligned with the lens during assembly and use.