Sensor Module with Radial Arms 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, which can impact system efficiency and longevity.
Innovation Solution
A fluid treatment system with a non-bypass sensor module that includes a sensor probe with radially extending arms and extractors, creating a pressure differential to accurately sense component concentrations in the exhaust gas, allowing for closed-loop feedback control and improved NOx reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional 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 of components in the exhaust stream
Solution Approach 1:
The sensor probe is divided into multiple arms (typically three arms at 120-degree intervals) with multiple sensing ports distributed along each arm. This segmentation allows the sensor to sample exhaust gas from multiple spatial locations simultaneously, capturing the non-uniform component distribution in the exhaust stream and improving measurement accuracy without requiring a single complex multi-functional device
Solution Approach 2:
The sensor probe transitions from a single-point measurement approach to a multi-dimensional sampling approach by extending arms radially outward from the central axis into the exhaust stream. The sensing ports are distributed along the length and radius of these arms, creating a two-dimensional sampling array that captures spatial variations in component concentration across the exhaust stream cross-section
2Measurement precision
If sensors are positioned at the center or outer periphery of the exhaust stream, then the device complexity is minimized, but the measurement precision deteriorates due to inadequate representation of the entire exhaust gas composition
Solution Approach 1:
The exhaust stream is segmented into multiple sampling zones by distributing sensing ports along multiple arms positioned at different radial distances and angular locations. This segmentation ensures that each zone is sampled independently, and the combined data provides a comprehensive representation of the entire exhaust gas composition, avoiding the bias of single-point measurements at center or periphery only
Solution Approach 2:
Measurements from multiple sensing ports distributed across three arms are merged and averaged to produce a single representative component concentration value. This merging of multiple spatial samples compensates for local non-uniformities and provides a more accurate overall exhaust gas composition than any single point measurement could achieve
3Productivity
If reductant dosing is controlled using open-loop control with map-generated dosing rates, then the device complexity is reduced, but the productivity deteriorates due to inefficient NOx reduction and inability to adapt to actual exhaust conditions
Solution Approach 1:
The sensor module provides real-time feedback on actual exhaust gas component concentrations (NOx, ammonia, hydrocarbons) to the control system. This feedback enables closed-loop control where the reductant dosing rate is continuously adjusted based on measured exhaust conditions, allowing the system to adapt to varying engine operating conditions and maintain optimal NOx reduction efficiency, unlike open-loop control which relies on predetermined maps
4Measurement precision
If the sensor probe intrudes into the exhaust stream to capture samples, then the measurement precision is improved, but the productivity deteriorates due to potential disruption of exhaust gas flow and reductant distribution
Solution Approach 1:
The sensor probe is designed with a streamlined central body and radially extending arms that minimize cross-sectional area and flow disruption. The sensing ports are positioned to sample exhaust gas with minimal intrusion, and the arms are configured to allow exhaust flow to pass around them. This local optimization of probe geometry reduces flow resistance and minimizes disruption to exhaust gas flow patterns and reductant distribution while still capturing representative samples
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
The system provides accurate and efficient NOx reduction by capturing representative exhaust gas samples, enhancing fuel efficiency and reducing ammonia slip, while minimizing intrusive effects on the fluid flow.
Implementation Method 1
creating a pressure differential to accurately sense component concentrations in the exhaust gas
Data Source
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AI summary
A fluid treatment system comprises a housing defining a fluid flow channel through which fluid is flowable in a fluid flow direction from an inlet to an outlet of the housing, a first fluid treatment device positioned within the fluid flow channel between the inlet and outlet, a second fluid treatment device positioned within the fluid flow channel between the first fluid treatment device and the outlet, and at least one sensor module comprising a sensor probe positioned within the fluid flow channel between the first and second fluid treatment devices. The sensor probe comprises a plurality of hollow arms extending radially outward from a radially inward portion to a radially outward portion of the fluid flow channel. Each of the arms comprises apertures facing a direction substantially opposite the fluid flow direction, the apertures being in fluid receiving communication with a sample portion of fluid flowing through the fluid flow channel. The sensor module further comprises at least one sensor communicable in sensing communication with fluid received through the apertures.