Gas Concentration Measurement Using Capillary Laminar Flow
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Solution Overview
Problem
Existing gas concentration measurement devices face challenges such as measurement errors due to environmental factors, flow imbalances, and maintenance issues, particularly in applications like extinguishing systems where accurate and real-time gas concentration monitoring is critical.
Innovation Solution
A device comprising a preheating module, a capillary laminar flow differential pressure conversion module, and a processing module that uses a capillary laminar flow unit to generate differential pressure changes, allowing for accurate measurement of gas concentration with a flow limiting element to maintain constant volume flow and temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If integral heating method is used for constant temperature and constant current micro differential pressure generator, then temperature control is achieved, but the system becomes vulnerable to environmental factors and measurement accuracy deteriorates
Solution Approach 1:
The patent divides the heating system into separate heating units for different channels rather than using integral heating. Each channel has its own heating element, allowing independent temperature control and reducing vulnerability to environmental factors affecting the entire system.
Solution Approach 2:
The patent implements local temperature control by providing heating units specifically for each measurement channel. This allows targeted temperature maintenance at critical locations (differential pressure generator channels) rather than uniform heating, improving measurement accuracy while reducing environmental sensitivity.
2Ease of operation
If flow controller is used to control flows of four channels together, then flow control is achieved, but flow imbalance occurs due to blockage and processing technology factors, leading to measurement error
Solution Approach 1:
The patent replaces the single flow controller managing all four channels with individual flow control mechanisms for each channel. This segmentation allows each channel to be controlled independently, eliminating flow imbalance caused by blockages or processing variations in other channels.
Solution Approach 2:
The patent implements localized flow control by providing separate flow control capabilities for each measurement channel. This ensures that flow conditions can be optimized and maintained independently in each channel, preventing measurement errors caused by inter-channel flow imbalances.
3Ease of manufacture
If through-hole solution is adopted, then equipment processing is simplified, but equipment processing convenience is reduced and gas mixing occurs in pressure stabilizing cavity, deteriorating response time
Solution Approach 1:
The patent removes the pressure stabilizing cavity and through-hole structures from the design. By extracting these components, the patent eliminates gas mixing issues and response time delays while maintaining manufacturing feasibility through alternative structural approaches.
Solution Approach 2:
Instead of using through-holes and pressure stabilizing cavities to manage gas flow, the patent inverts the approach by using sealed channels with controlled flow paths. This reversal eliminates the gas mixing problem inherent in through-hole designs while maintaining manufacturing simplicity through different structural means.
4Temperature
If temperature sensor detects temperatures of heating block and pressure measuring block, then temperature monitoring is achieved, but gas concentration measurement accuracy deteriorates due to environmental changes affecting heating block temperature
Solution Approach 1:
The patent removes the heating block from the measurement system and replaces it with direct channel heating elements. Temperature sensors now only monitor the measurement channels themselves, eliminating the confounding factor of heating block temperature variations that do not directly reflect gas concentration changes.
Solution Approach 2:
The patent implements localized temperature monitoring by placing temperature sensors directly in the measurement channels where gas flow occurs. This ensures that temperature measurements directly reflect the conditions of the gas being measured, rather than the temperature of surrounding structural components like heating blocks.
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 provides high measurement accuracy, fast response, long-term stability, and convenient maintenance, enabling both rapid and long-term gas concentration monitoring.
Implementation Method 1
a preheating module electric heating unit configured to heat the gas flow channel to conduct and heat the to-be-measured gas
Implementation Method 2
flow channels of the plurality of capillaries become a main channel of a gas flow, so as to form a laminar flow structure
Implementation Method 3
a capillary laminar flow unit having a plurality of capillaries
Implementation Method 4
a differential pressure sensor having two ends respectively connected to the upstream differential pressure measuring hole and the downstream differential pressure measuring hole, wherein the differential pressure sensor is configured to measure a differential pressure between the differential pressure measuring holes
Implementation Method 5
a flow limiting element located at a downstream outlet of the differential pressure conversion module housing, wherein the flow limiting element is configured to maintain a constant volume flow flowing through the device for measuring a gas concentration
Implementation Method 6
a preheating module thermocouple arranged perpendicular to a gas flow direction
Data Source
AI summary
Provided is a device for measuring a gas concentration, including: a preheating module configured to preheat and rectify an input to-be-measured gas to output a first stage gas; a differential pressure conversion module connected to the preheating module, wherein the differential pressure conversion module is configured to allow the first stage gas flowing through to generate a differential pressure change value; and a processing module configured to acquire a volume concentration of the to-be-measured gas according to the differential pressure change value; wherein the differential pressure conversion module comprises a capillary laminar flow unit having a plurality of capillaries, and flow channels of the plurality of capillaries become a main channel of a gas flow, so as to form a laminar flow structure. A method for measuring a gas concentration is further provided, including measuring a concentration of a to-be-measured gas using the above-mentioned device for measuring a gas concentration.