Parallel Venturi Exhaust Gas Sampling Apparatus
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Solution Overview
Problem
Existing exhaust gas sampling apparatuses face challenges in accurately obtaining a diluent gas flow rate when combining multiple venturis, leading to inconsistent collection amounts in diluted exhaust gas and diluent gas bags, which complicates background correction and increases apparatus size and cost.
Innovation Solution
The apparatus connects multiple venturis in parallel for both the sampling part and flow rate control part, allowing for accurate control of diluent gas flow rates matching the diluted exhaust gas flow rates, using venturis with different critical flow rates to ensure consistent sampling and reduce size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple needle valves are combined in parallel to control diluent gas flow rate for multiple venturis, then the flow rate control capability is improved, but the pressure condition becomes different from single valve operation causing fluid to not flow at set flow rate
Solution Approach 1:
The patent creates a copy of the venturi structure in the diluent gas flow path. By providing a second venturi (acting as a flow control element) that replicates the flow characteristics of the first venturi (in the exhaust gas path), the system achieves accurate flow rate control. The copy venturi is designed with the same geometric parameters to ensure identical flow characteristics, allowing the diluent gas flow rate to match the exhaust gas flow rate accurately even when multiple venturis are combined in parallel.
2Reliability
If multiple needle valves are provided for each venturi to maintain constant flow rate, then the flow rate control is improved, but the apparatus size and cost increase
Solution Approach 1:
The patent makes the venturi structure universal by using the same venturi design for both exhaust gas sampling and diluent gas flow control. The second venturi in the diluent gas path serves the dual function of flow control and pressure regulation, eliminating the need for separate needle valves. This multi-functional use of the venturi structure reduces the number of components while maintaining reliable flow rate control.
Solution Approach 2:
By copying the venturi structure instead of using needle valves, the patent achieves reliable flow control with fewer components. The copied venturi structure inherently provides stable flow characteristics through its geometric design, eliminating the need for complex valve mechanisms and reducing overall apparatus size.
3Reliability
If multiple needle valves are provided for each venturi to maintain constant flow rate, then the flow rate control is improved, but the cost increases
Solution Approach 1:
The venturi structure serves multiple functions: exhaust gas sampling, diluent gas flow control, and pressure regulation. This eliminates the need for expensive needle valves and reduces the total component count, thereby lowering manufacturing costs while maintaining reliable flow control.
Solution Approach 2:
The patent uses a copied venturi structure instead of expensive needle valves. The venturi geometry can be manufactured using standard machining processes, making it more cost-effective than precision needle valves while providing equally reliable flow control through its inherent aerodynamic design.
4Measurement precision
If diluted exhaust gas amount and diluent gas amount are made substantially the same, then the background correction accuracy is improved, but the apparatus complexity increases when combining multiple venturis
Solution Approach 1:
The second venturi in the diluent gas path serves as both a flow control element and a matching device. By designing this venturi with identical geometric parameters to the first venturi, the system automatically achieves matched flow rates for exhaust gas and diluent gas, ensuring accurate background correction without requiring complex control systems or multiple valves.
Solution Approach 2:
The copied venturi structure in the diluent gas path ensures that the flow characteristics match those of the exhaust gas path. This geometric copying automatically balances the flow rates, making the diluted exhaust gas amount and diluent gas amount substantially the same, thereby achieving accurate background correction with simple apparatus configuration.
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 configuration allows for precise control of diluent gas flow rates, ensuring accurate background correction and consistent gas collection in both bags, while minimizing apparatus size and cost by using parallel venturi connections.
Implementation Method 1
a sampling part for collecting diluted exhaust gas... configured to include a plurality of venturis
Implementation Method 2
although a needle valve determines a flow rate on the basis of a differential pressure between pressures on upstream and downstream sides of the valve
Data Source
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AI summary
The present invention is one that, in the case where a sampling part is configured to include a plurality of venturis, with suppressing an increase in size of an apparatus and an increase in cost, accurately obtains a diluent gas flow rate in accordance with a diluted exhaust gas flow rate obtained on the basis of a combination among the plurality of venturis, in which the sampling part 8 collecting part of diluted exhaust gas is configured to parallel connect the plurality of venturis that control the flow rate of the diluted exhaust gas, and a flow rate control part 9 provided in a diluent gas sampling flow path SL2 is configured to parallel connect a plurality of venturis that control the flow rate of diluent gas to be introduced into a diluent gas analyzing device.