Radial Sensor Probe for Exhaust Gas Sampling
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Solution Overview
Problem
Conventional SCR systems for reducing NOx emissions in diesel engines lack effective feedback control due to inadequate sensing of exhaust gas characteristics, leading to inefficient reductant distribution and potential measurement errors caused by point-measurement sensors that poorly represent the spatial distribution of components in the exhaust stream.
Innovation Solution
A fluid sensor module with radially extending arms and extractors that create a pressure differential to sample fluid from multiple points within the exhaust stream, providing more accurate sensing of component concentrations and enabling closed-loop feedback control by positioning sensors between SCR catalyst beds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If point-measurement sensors are used to sense exhaust gas characteristics, then the device complexity is reduced, but the measurement precision deteriorates due to poor spatial distribution representation
Solution Approach 1:
The sensor probe is segmented into multiple arms (typically three arms at 120-degree intervals) with multiple sensing points distributed across the exhaust stream cross-section. This segmentation allows the sensor to capture spatial distribution of components rather than relying on a single point measurement, thereby improving measurement precision while maintaining reasonable device complexity.
Solution Approach 2:
The invention transitions from one-dimensional point measurement to two-dimensional area measurement by distributing sensing points across the exhaust stream cross-section. The multiple arms extend radially outward from the center, creating a planar array of sensing points that sample different regions of the exhaust flow, thus capturing spatial variations in component concentrations.
2Measurement precision
If multiple sensing points are distributed across the exhaust stream cross-section, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
Each arm of the sensor probe is designed with specific sensing points positioned at predetermined radial distances from the center. The sensing points are strategically located to sample representative regions of the exhaust stream, with each local sensing zone contributing to the overall area-weighted average calculation. This local quality approach allows precise measurement without requiring uniform distribution of complex structures throughout the probe.
Solution Approach 2:
Multiple sensing points across different arms and radial positions are merged into a single area-weighted average component concentration value. The controller integrates signals from all sensing points, weighting each by its respective area contribution, to produce a unified measurement that represents the entire exhaust stream cross-section. This merging reduces data processing complexity while maintaining measurement precision.
3Extent of automation
If sensors are positioned upstream of the SCR catalyst, then feedback control capability is provided, but measurement accuracy deteriorates due to inadequate reductant mixing
Solution Approach 1:
The sensor probe is positioned to sample exhaust gas after reductant injection but before the SCR catalyst, allowing feedback control to be implemented. However, the multiple sensing points are strategically distributed to account for incomplete mixing, and the area-weighted averaging algorithm compensates for spatial non-uniformities, providing accurate measurements even under preliminary mixing conditions.
Solution Approach 2:
The controller acts as an intermediary that processes signals from multiple sensing points and calculates the area-weighted average component concentration. This intermediary computation step bridges the gap between incomplete physical mixing and the need for accurate feedback control measurements, enabling precise control decisions based on representative exhaust gas composition data.
4Measurement precision
If area-weighted average component concentration is calculated from distributed sensing points, then measurement precision improves, but the device complexity increases due to additional processing requirements
Solution Approach 1:
The area-weighted average component concentration measurement enables feedback control of the reductant dosing system. The controller continuously monitors exhaust gas composition at multiple points, calculates the area-weighted average, and adjusts reductant injection rates to optimize SCR performance. This feedback loop improves measurement utility while the calculation algorithm is designed to be computationally efficient, minimizing processing complexity.
Solution Approach 2:
The invention changes the measurement parameter from simple point concentration to area-weighted average concentration. This parameter transformation is achieved through a straightforward calculation that weights each sensing point's reading by its respective area contribution. The mathematical operation is simple and computationally efficient, avoiding complex signal processing while delivering superior measurement precision.
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 solution enhances the accuracy of reductant dosing and NOx reduction efficiency, improves fuel efficiency, and reduces ammonia slip by capturing a representative sample of the exhaust gas characteristics, overcoming the limitations of traditional point-measurement sensors.
Implementation Method 1
The at least one extractor includes a fluid flow channel that is communicable in fluid receiving communication with fluid flowing through the fluid flow channel of at least one of the at least two arms
Data Source
AI summary
According to one embodiment, a sensor module includes a sensor probe that has at least two arms coupled together at a central location with each of the at least two arms extending radially outwardly away from the central location. Each of the at least two arms includes one of a plurality of openings and an elongate opening extending radially along the arm. The at least two arms define fluid flow channels therein. The sensor module also includes at least one extractor coupled to the probe. The at least one extractor includes a fluid flow channel that is communicable in fluid receiving communication with fluid flowing through the fluid flow channel of at least one of the at least two arms. Further, the sensor module includes at least one sensor that is communicable in fluid sensing communication with fluid flowing through the at least one extractor.