Exhaust Gas Dilution Device Using Ejector for Particle Loss Reduction
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Solution Overview
Problem
Conventional exhaust gas dilution devices suffer from measurement accuracy issues due to particle loss on the inner surfaces and require high-pressure air for operation, leading to inefficient particle counting and increased compressor costs.
Innovation Solution
The device incorporates a head part with a through-hole, an ejector unit with a nozzle part, and a dilution part that uses primary and secondary dilution air to generate dilution gases, reducing particle loss and eliminating the need for compressed air by employing high-speed primary dilution air for effective decompression and room temperature secondary dilution to prevent moisture condensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional mixing chamber is used to dilute exhaust gas, then dilution function is achieved, but particle loss occurs due to adhesion to inner surfaces reducing measurement precision
Solution Approach 1:
The invention extracts the harmful adhesion effect by eliminating the large inner surface area of the mixing chamber. By using a conical shape with continuously varying cross-section, the surface area is minimized while maintaining dilution function, thereby reducing particle loss through adhesion to chamber walls.
Solution Approach 2:
The invention changes the geometric parameters of the mixing chamber by implementing a conical shape where the cross-sectional area varies continuously along the flow direction. This parameter change optimizes the balance between providing sufficient mixing volume and minimizing wall adhesion losses.
2Measurement precision
If a large amount of dilution gas is required for the ejector, then dilution ratio is improved, but high-pressure air supply is needed increasing device complexity
Solution Approach 1:
The ejector is designed to self-generate the required high-pressure air flow by utilizing the kinetic energy of the primary dilution air. The conical mixing chamber converts pressure energy to kinetic energy, creating a low-pressure zone that draws in secondary dilution air, eliminating the need for an external compressor.
Solution Approach 2:
The invention uses pneumatic principles where the primary dilution air flows through the conical chamber, creating pressure differential that drives the secondary dilution air through the ejector. This pneumatic coupling achieves the required high-pressure air supply without mechanical compressors.
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 design enhances measurement precision by minimizing particle loss and eliminating the need for compressed air, improving the dilution ratio and maintaining accurate particle counting while preventing moisture condensation, thus enhancing the overall measurement accuracy.
Implementation Method 1
an ejector with which dilution air is secondarily mixed with the first dilution gas
Implementation Method 2
effective decompression may be achieved in the diffusion part by the primary dilution air moving at high speed through the first discharge flow path
Implementation Method 3
the exhaust gas and the primary dilution air are mixed in the first discharge hole, generating a primary dilution gas
Data Source
AI summary
An exhaust gas dilution device according to an exemplary embodiment of the present invention includes a head part, ejector unit, a nozzle part, and a dilution part. The head part has a space part into which an exhaust gas flows and a through-hole formed through the center axis direction to be connected to the space part. The ejector unit is coupled to the head part and has a first discharge hole formed passing through the center axis direction to be connected to the through-hole and connected to a first inlet to which primary dilution air is supplied. The nozzle part is inserted into a first discharge hole through the through-hole and has a second discharge hole that penetrates in the center axis direction so that the exhaust gas flowed into the space part is sucked and ejected into the first discharge hole as the primary dilution air moves through the first discharge hole. The dilution part has a first flow path part into which a primary dilution gas, which is generated and discharged after the exhaust gas and the primary dilution air are mixed in the first discharge hole, flows, and a second flow path part connected to the first flow path part and guiding secondary dilution air to be mixed with the primary dilution gas, and generates a secondary dilution gas as the primary dilution gas and the secondary dilution air are mixed.