Device for measuring gas flow in a duct
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing gas flow measurement devices in ventilation systems face challenges in accurately measuring low-rate gas flows without generating noise and require straight duct portions, which are often not feasible in curved ducts, leading to energy inefficiencies and imbalanced air pressure.
Innovation Solution
A device comprising two tubes with distributed input units and chambers, arranged to face different directions, which can be suspended between a valve and a duct bend, allowing for accurate gas flow measurement by sensing pressure differences between the tubes, enabling precise flow control without the need for straight duct sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a metal sheet blocks more than 20% of the duct cross-section to measure very low air flows, then measurement precision is improved, but turbulence and noise generation increase
Solution Approach 1:
The invention divides the measurement function into multiple distributed input units (at least three) arranged along the tube instead of using a single large blocking element. Each input unit has an opening facing a different direction, allowing the system to measure low flows through distributed pressure sensing rather than bulk flow obstruction, thereby avoiding turbulence and noise while maintaining measurement precision.
Solution Approach 2:
The invention replaces the traditional mechanical flow obstruction method (metal sheet blocking duct) with a pressure differential sensing system using tubes and input units. This substitution allows measurement of very low air flows without physically blocking the duct, eliminating the turbulence and noise generated by large blocking elements while maintaining the ability to detect low flow rates.
2Adaptability or versatility
If state of the art devices are used in curved ducts without straight portions, then device adaptability is improved, but measurement precision deteriorates due to improper flow patterns
Solution Approach 1:
The invention positions the input units with openings facing different directions to sense pressure from various local flow directions. This local quality approach allows the device to accurately measure flow patterns in curved ducts where flow direction varies locally, rather than requiring uniform straight flow patterns, thereby maintaining measurement precision in adaptable duct configurations.
3Measurement precision
If distributed input units with chambers are used instead of simple pressure taps, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The invention merges the pressure sensing function with the structural tube body by forming chambers within the tube structure itself. The chambers are integrated into the tube walls rather than being separate components, and multiple input units share common chambers, reducing the number of discrete parts while maintaining the precision benefits of distributed pressure sensing with directional openings.
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 device provides accurate flow readings even at low flow rates and reduces noise generation, allowing for efficient energy management by enabling precise control of gas flows in curved ducts, thus minimizing energy loss and ensuring comfortable ventilation.
Implementation Method 1
when the gas flows past the sheet a pressure difference between the two sides is generated, which is proportional to the square of the air speed
Data Source
Figure 1~2
Figure 3~6C
Figure 7~10
AI summary
Device (100) for measuring gas flow in a duct (10), comprising a first tube (101) and a second tube (102), which tubes extend about a center axis (120); each tube having a channel (104) and being provided with a connector (105) and a plurality of distributed input units (110); each input unit including an opening (111) into the channel and a chamber (112) surrounding the opening, which chamber has an open end (113) and a rear end (114); wherein the open ends (113) of the chambers on the first tube (101) face a first direction, and the open ends of the chambers on the second tube (102) face a second direction which is different from the first direction.