Thermal Flow Sensor Housing With Dual Heat Paths for Liquids
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Solution Overview
Problem
Existing fluid flow measurement devices, such as hot wire sensors, face challenges when measuring liquids due to rapid deterioration and increased thermal conductivity, which reduces the range of temperature variation and sensitivity.
Innovation Solution
A device with a heating element and a housing that defines two thermal paths with different conductivities, allowing controlled heat transfer to the fluid, reducing the power required for the heating element while maintaining sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hot wire sensors are used to measure fluid flow, then flow rate measurement is achieved, but the sensor deteriorates rapidly when exposed to liquids
Solution Approach 1:
The patent introduces a housing as an intermediary component that separates the heating element from direct contact with the liquid. The housing acts as a protective barrier while still allowing thermal energy to transfer to the fluid, thus protecting the heating element from rapid deterioration caused by liquid exposure while maintaining flow measurement capability
Solution Approach 2:
The housing is designed as a thin-walled structure that provides protection against liquid damage while maintaining sufficient thermal conductivity to allow heat transfer to the fluid. This thin film approach protects the heating element without significantly impeding the thermal path needed for flow measurement
2Measurement precision
If hot wire sensors are used in liquids, then flow measurement is possible, but the range of temperature variation is reduced due to increased thermal conductivity
Solution Approach 1:
The patent applies local quality by creating different thermal conductivity regions in the housing. The housing has regions with different thermal conductivities that are strategically positioned to control heat flow paths. This allows the sensor to compensate for the high thermal conductivity of liquids by concentrating heat transfer through specific paths, thereby maintaining adequate temperature variation range for measurement
Solution Approach 2:
The patent changes the thermal conductivity parameters of the housing structure by using materials with different thermal properties in different regions. This parameter modification allows optimization of heat transfer characteristics to maintain sufficient temperature variation despite the high thermal conductivity of the liquid being measured
3Reliability
If the housing encloses the heating element, then protection is provided, but heat transfer to the fluid is reduced
Solution Approach 1:
The housing is designed as a thin-walled structure that provides mechanical protection while minimizing thermal resistance. The thin film design ensures that the housing does not significantly impede heat transfer to the fluid while still providing adequate protection against liquid damage and mechanical stress
Solution Approach 2:
The patent employs composite material construction for the housing, combining materials with different thermal and mechanical properties. This allows the housing to provide adequate mechanical strength and protection while maintaining sufficient thermal conductivity for effective heat transfer to the fluid
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 effectively measures fluid flow rates in liquids by concentrating heat transfer and reducing power consumption, enhancing accuracy and durability.
Implementation Method 1
Heat generated at the heating element is conducted to the fluid along a plurality of thermal paths between the heating element and the exterior of the housing, and into the fluid
Implementation Method 2
Temperature change is determined either using a temperature sensor or indirectly based upon change in resistance of the wire. Change in temperature can be used to determine mass flow rate or flow rate
Data Source
AI summary
A device for measuring the rate of flow of a fluid comprising. The device includes a heating element, a housing, and a detector. The heating element is located in an interior of the housing, the housing defining a first thermal path from the heating element to a first region of an exterior of the housing and a second thermal path from the heating element to a second region of the exterior of the housing. The detector is configured to detect a property associated with transfer of heat from the heating element to the exterior of the housing. The first thermal path has a first thermal conductivity and the second thermal path has a second thermal conductivity. The first thermal conductivity is greater than the second thermal conductivity. The first region of the exterior of the housing is smaller than the second region of the exterior of the housing.