Tomographic Gas Measurement Device with Rotatable Optical Layers
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Solution Overview
Problem
Current methods for measuring ammonia concentration in diesel engine exhaust aftertreatment systems suffer from poor temporal resolution and measurement uncertainties due to deposition and chemical reactions, limiting the effectiveness of NOX emission reduction in SCR technology.
Innovation Solution
A device utilizing rotatable measurement layers with multiple optical paths in the deep ultraviolet spectral range, combined with non-dispersive absorption spectroscopy and Tikhonov regularization, to provide high-resolution 2D images of ammonia concentration distribution before and after the SCR catalyst converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If discrete position extraction methods are used to measure ammonia concentration, then measurement simplicity is maintained, but temporal resolution deteriorates and measurement uncertainty increases
Solution Approach 1:
The patent transitions from discrete point measurements to continuous 2D cross-sectional imaging by introducing a second spatial dimension. Multiple optical paths arranged in different positions and angles through the cross section enable tomographic reconstruction, transforming the measurement from one-dimensional point data to two-dimensional distributed concentration fields, thereby achieving high temporal resolution without sacrificing operational simplicity
Solution Approach 2:
The patent replaces mechanical sampling systems with optical measurement systems. Instead of physically extracting gas samples through discrete positions, the system uses light absorption measurements along multiple optical paths to non-intrusively determine ammonia concentration distribution, eliminating mechanical complexity while improving temporal resolution through direct optical detection
2Device complexity
If discrete position extraction methods are used to measure ammonia concentration, then device complexity is reduced, but measurement uncertainty increases due to depositions and chemical reactions
Solution Approach 1:
The patent replaces mechanical sampling systems with optical measurement systems. Instead of physically extracting gas samples through discrete positions, the system uses light absorption measurements along multiple optical paths to non-intrusively determine ammonia concentration distribution, eliminating mechanical complexity while improving temporal resolution through direct optical detection
Solution Approach 2:
The patent introduces light as an intermediary substance to transfer information about ammonia concentration from the measurement cross section to detectors. The optical paths serve as intermediaries that carry absorption signal information without direct contact with the exhaust gas, eliminating the need for physical sample extraction and associated measurement uncertainties
3Measurement precision
If multiple optical paths are used to increase information gain, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent divides the measurement system into segmented optical paths, each providing independent concentration information from different positions and angles. The 20 light paths are segmented into multiple measurement layers that can be independently configured and adjusted, allowing systematic coverage of the cross section while maintaining manageable system complexity through modular organization
Solution Approach 2:
The patent organizes multiple optical paths into layered structures at different heights and angles within the cross section. This three-dimensional arrangement of measurement layers allows comprehensive coverage of the exhaust flow profile while systematically managing the complexity of multiple optical paths through structured spatial distribution
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
Enhances the accuracy and temporal resolution of ammonia concentration measurement, improving the NOX emission reduction efficiency by optimizing the gas distribution analysis in diesel engine exhaust systems.
Implementation Method 1
Within absorption spectroscopy the light absorption by the gas of intertest is wavelength specific. By detecting the light absorption at the sensitive wavelengths with possibly no other gas species absorbing in this spectral range the line concentration can be determined. The concentration estimation follows the Beer-Lambert absorption law
Implementation Method 2
The concentration estimation follows the Beer-Lambert absorption law (Eq. 1). The absorbance A is defined by the ratio of the incident light and the detected light and is used to calculate the line concentration c using the calibrated absorption coefficient α and the path length I
Implementation Method 3
the developed measurement system applies non-dispersive techniques using an optical bandpass filter in the desired spectral range in combination with a photodiode
Implementation Method 4
By applying as many optical paths as possible in different positions and angles through the cross section the information gain can be increased only limited by the optical access to the cross section. In this application 20 light paths are instrumented through the cross section. The resulting inverse problem is reconstructed by appliance of Least Squares regression and Tikhonov regularization leading to 2D images of the ammonia concentration distribution
Data Source
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AI summary
A tomographic absorption-based measurement system to detect gas concentration distribution within a pipe is presented. Multiple line concentrations are measured in-situ by applying nondispersive absorption spectroscopy e.g. in the deep ultraviolet (DUV) region. The detectors consist of photodiodes in combination with optimized transimpedance amplifiers (TIV) allowing high sampling rates up to several kHz while providing a high signal-to-noise ratio (SNR). In order to improve the tomographic reconstruction, the invention comprises two measurement layers that can be rotated relative to each other to select the most suitable angle between the two layers for measurements.