Residence Time Chamber Isoaxial Sampling Emissions
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Solution Overview
Problem
Current sampling systems for emissions from combustion engines lack accuracy due to temperature gradients causing particle loss and fail to simulate realistic atmospheric conditions, leading to incomplete chemical composition analysis and increased sampling errors.
Innovation Solution
A residence time chamber with a vertical flow axis providing at least 30 seconds of plug-flow conditions, combined with isoaxial sampling probes and controlled sampling rates, minimizes boundary effects and allows for simultaneous sampling of multiple species, ensuring accurate and precise emission product sampling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If emission gases are diluted with filtered air in a mixing chamber, then the emission products are prepared for sampling, but temperature gradients cause significant particle loss during dilution
Solution Approach 1:
The patent extracts the dilution function from the mixing chamber by introducing a separate residence time chamber. The dilution process occurs in the residence time chamber where gases can mix without the temperature gradient problems that cause particle loss in conventional mixing chambers. This separation allows dilution to occur under controlled conditions that prevent thermophoresis-induced particle deposition.
Solution Approach 2:
The residence time chamber acts as an intermediary between the emission source and the sampling system. It provides a controlled environment where dilution can occur without the harmful temperature gradients, serving as a buffer zone that protects particles from loss while still achieving the necessary mixing and dilution of emission gases with air.
2Measurement precision
If conventional sampling systems are used, then sampling can be performed, but they fail to simulate realistic atmospheric conditions leading to inaccurate chemical composition analysis
Solution Approach 1:
The residence time chamber is designed to maintain specific parameters (temperature, pressure, residence time of at least 30 seconds) that simulate realistic atmospheric conditions. By controlling these parameters, the system accurately reproduces the environment in which emission products naturally evolve, enabling precise measurement of chemical compositions under conditions that match real-world atmospheric behavior.
Solution Approach 2:
The system performs preliminary conditioning of emission gases in the residence time chamber before sampling occurs. During this residence time, chemical equilibria are established and reaction products form through nucleation, condensation, and coagulation processes that mirror atmospheric conditions. This preliminary action ensures that samples reflect true atmospheric behavior rather than artifacts of the sampling process.
3Adaptability or versatility
If multiple sample runs are performed to detect different chemical compounds, then comprehensive chemical assessment is achieved, but sampling errors increase and results become less accurate
Solution Approach 1:
The residence time chamber serves as a universal conditioning environment that can accommodate multiple different chemical analyses simultaneously. By establishing chemical equilibria and allowing reaction products to form in a single controlled environment, the system enables comprehensive detection of various chemical compounds (trace elements, ions, carbon species, PAHs, SVOCs) without requiring separate sample runs, thereby maintaining sampling accuracy while achieving versatile chemical assessment.
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 enables reliable chemical equilibria under ambient conditions, reducing particle losses and sampling errors, and allows for the simultaneous analysis of various emission components, enhancing the accuracy of emission measurements and engine design strategies.
Implementation Method 1
the conditions under which ambient exhaust reaction products may form through both homogeneous and heterogeneous nucleation
Implementation Method 2
condensation, and coagulation
Implementation Method 3
condensation, and coagulation
Implementation Method 4
The vertical orientation of the residence time chamber greatly reduces particulate matter losses due to the effects of gravity on the particles
Implementation Method 5
provide at least 30 seconds of residence time under plug-flow conditions
Data Source
AI summary
A residence time chamber and sampling apparatus for use in a system for sampling emission products from an emissions source, for example combustion engines including gasoline, diesel and natural gas engines, for subsequent measurement and analysis of the emission products. The results of the analysis can be used to formulate decisions on changes in engine design strategy, and can be used to determine the effectiveness of aftertreatment systems on the emissions source. The residence time chamber includes a plurality of isoaxial sampling probes, with a plurality of sampling trains connected to the sampling probes to take simultaneous representative emission samples for subsequent analysis. The residence time chamber minimizes many noise factors which can affect the accuracy of the test system, by applying isokinetic sampling and by reducing the interaction of the sampling gas and the particulate matter with the sampling probe inlets and with the various surfaces of the residence time chamber.