Porous Conduit Dilution Device for Exhaust Gas Sampling
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Solution Overview
Problem
Existing gas sampling systems face challenges in accurately simulating dilution processes for exhaust gases, particularly in providing adequate residence time for particle formation and growth while maintaining appropriate dilution ratios, leading to inconsistencies in test results due to particle deposition and reentrainment mechanisms.
Innovation Solution
A dilution device with a porous conduit system that includes a central porous conduit and a surrounding diffuser conduit, allowing for controlled dilution of exhaust gases with additional residence time, simulating atmospheric processes by adjusting the dilution ratio and residence time within the dilution tunnel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional dilution tunnel is used to dilute exhaust gases, then the dilution process can be performed, but particle deposition on walls occurs due to thermophoresis and mechanical processes, leading to measurement errors and variability
Solution Approach 1:
The patent employs porous conduit members with controlled pore sizes and distributions to facilitate uniform gas mixing while minimizing particle deposition. The porous structure allows dilution air to permeate through the conduit walls, creating a distributed injection pattern that reduces localized high-velocity jets and shear forces that would otherwise cause particle deposition on tunnel walls.
Solution Approach 2:
The system uses pneumatic control to regulate dilution air flow rates and mixing characteristics. By controlling the pressure and flow of dilution air through the porous conduits, the system optimizes mixing efficiency while maintaining conditions that prevent particle deposition, thereby improving measurement accuracy.
2Measurement precision
If the dilution tunnel size is reduced for portability, then the system becomes more practical, but residence time for particle formation and growth is insufficient, affecting measurement accuracy
Solution Approach 1:
The patent incorporates variable geometry elements and adjustable flow control mechanisms that allow the dilution tunnel to dynamically adapt its effective volume and flow characteristics. This enables the compact system to provide sufficient residence time for particle formation and growth by optimizing flow velocities and mixing zones according to specific measurement requirements.
Solution Approach 2:
The design nests multiple functional elements within the compact dilution tunnel structure, including porous conduits, mixing zones, and measurement sections. This nested arrangement maximizes the effective utilization of space, allowing adequate residence time for particle processes to occur within a reduced overall system size.
3Volume of stationary object
If proportional sampling is used for large effluent sources, then the dilution tunnel size is reduced, but the system complexity increases to manage flow rate control and dilution ratios
Solution Approach 1:
The patent implements self-regulating flow control mechanisms where the dilution system automatically adjusts to maintain proper dilution ratios. The porous conduit design and pressure differential arrangements enable the system to self-balance flow rates without requiring complex external control systems, thereby reducing overall device complexity while maintaining compact size.
Solution Approach 2:
The dilution tunnel is designed with multi-functional capabilities, serving as both the mixing chamber, residence time volume, and flow regulation element. This integration of multiple functions into a single compact structure reduces the need for separate control components, thereby minimizing device complexity while achieving proportional sampling for large effluent sources.
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 solution enhances the accuracy of gas sampling by providing increased residence time for particle formation and growth, reducing variability in test results and improving the simulation of atmospheric dilution processes, thereby enhancing the reliability of exhaust gas analysis.
Implementation Method 1
a first porous conduit (112) defining an internal flow passage and having a plurality of pores that communicate an outside region external of the first porous conduit with the internal flow passage of the first porous conduit
Implementation Method 2
diffusion, gravitational sedimentation and turbulence
Data Source
AI summary
A dilution device includes an inlet port and an outlet port. The dilution device also includes a first porous conduit defining an internal flow passage. The first porous conduit has a plurality of pores that communicate between an outside region external of the first porous conduit and the internal flow passage. The dilution device also includes a second porous conduit disposed around the first porous conduit. The second porous conduit defines a first chamber peripherally about the first porous conduit. The second porous conduit has a plurality of pores that communicate between an outside region external of the second pours conduit and the first chamber. The dilution device further includes a housing disposed around the second porous conduit. The housing defines a second chamber peripherally about the second porous conduit. The housing has an inlet port in communication with the second chamber. The first porous conduit includes a port at a first end of the first porous conduit in communication with the second chamber.