Gas Mass Flow Sensor Shell for Swirl-Resistant Measurement
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Solution Overview
Problem
Existing mass gas flow sensors face accuracy issues due to variations in gas flow configurations caused by flow control valves, such as butterfly valves, which introduce swirl patterns and turbulence, leading to non-uniform heat transfer and reduced measurement precision.
Innovation Solution
A gas mass flow sensor design featuring a thermally conductive shell with a temperature-sensitive resistive element and an electrical heater, partially surrounded by a housing with flow guidance elements and thermal insulators, focusing heat transfer through a leading surface orthogonal to the gas flow, thereby maintaining consistent heat transfer independent of flow configuration variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a flow control valve is used to control gas flow, then flow control capability is improved, but flow configuration variations (swirl patterns and turbulence) increase, leading to reduced measurement precision
Solution Approach 1:
The patent extracts and removes the harmful swirl patterns and turbulence from the gas flow before it reaches the sensor. Flow straightening elements are used to take out the rotational motion and chaotic flow patterns, providing a uniform laminar flow to the sensor, thus resolving the contradiction between flow control capability and measurement precision.
Solution Approach 2:
The patent introduces flow straightening elements as intermediary components between the flow control valve and the mass flow sensor. These intermediaries condition the flow by eliminating swirl and turbulence, creating a uniform flow profile that allows accurate measurement despite the presence of flow control valves in the system.
2Measurement precision
If flow guidance elements are added to focus heat transfer, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the sensor housing into distinct functional zones: a flow guidance section with streamlined leading edges, a thermal isolation section, and a sensing section. This segmentation allows each part to perform its specific function efficiently while maintaining overall system simplicity. The flow guidance elements are integrated into the housing structure rather than being separate components.
Solution Approach 2:
The patent merges the flow guidance function with the housing structure itself. The housing is designed with integrated flow straightening features and thermal isolation elements, combining multiple functions into a single unified structure. This reduces the number of separate components and simplifies manufacturing while achieving the desired heat transfer focus.
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 ensures accurate mass flow measurement by stabilizing heat transfer and reducing current variations, even at varying valve angles, thus enhancing the precision of gas flow control and measurement.
Implementation Method 1
a heated sensing device which may transfer heat into gas passing the sensing device
Implementation Method 2
heat transfer from the thermally conductive shell is focused through the leading surface of the thermally conductive shell
Implementation Method 3
The heated sensing device may be maintained at a desired temperature with an adjacent electrical heater
Implementation Method 4
a thermal insulator positioned on a non-leading surface of the shell so that heat transfer from the thermally conductive shell is focused through the leading surface
Data Source
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AI summary
A gas distribution system may include a gas mass flow sensor (206, 506) with a resistive element (230) configured to be heated, a thermally conductive shell (228, 528) surrounding the resistive element and heat-transfer control elements. The shell may include a leading surface (236, 536) oriented substantially orthogonal to a direction of gas flow. At least one thermal insulator (244, 550) is positioned on a non-leading surface (240, 242, 540, 542, 552) of the shell to focus heat transfer from the resistive element through the leading surface of the shell, so that a rate of heat transfer is independent from the variations in flow configuration. Flow guidance elements (534) may additionally be positioned to provide a flow path focused on the leading surface of the shell.