Low Cost Fluid Flow Sensor Using Dual RTD Temperature Differential
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Solution Overview
Problem
Existing air filtration systems lack accurate and cost-effective methods for monitoring and controlling airflow and ionization levels, which can lead to inefficient operation and potential damage to downstream equipment.
Innovation Solution
A low-cost fluid flow sensor system comprising a first resistance temperature detector, a second resistance temperature detector, and a controller that receives signals from these detectors to determine airflow and temperature, allowing for controlled operation within a specific temperature range, and an optional ionization detector to monitor ion levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a flow sensor is added to control filter operation, then power consumption is reduced and system life is extended, but device cost and complexity increase
Solution Approach 1:
The patent combines the flow sensing function with the existing temperature detection system by using the same resistance temperature detector (RTD) for both temperature measurement and flow detection. The RTD normally measures temperature, but when air flow is absent, the lack of cooling effect allows the RTD to detect flow conditions through temperature differential comparison between two RTDs. This merging eliminates the need for a separate flow sensor, reducing device complexity and cost while maintaining the ability to control power consumption based on flow conditions.
Solution Approach 2:
The resistance temperature detector serves multiple functions: it measures air temperature for filtration control and simultaneously detects air flow presence through thermal convection effects. By making the temperature detection system multi-functional, the patent avoids adding dedicated flow sensing equipment, thereby reducing overall system complexity while achieving both temperature-based and flow-based control capabilities.
2Measurement precision
If expensive precision flow sensors are used, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The system uses the existing temperature detection infrastructure to provide flow measurement services. The RTDs continuously monitor temperature, and the control system automatically analyzes temperature differentials to determine flow conditions. This self-service approach allows the system to perform both temperature and flow measurements using the same components, eliminating the need for expensive dedicated flow sensors while maintaining adequate measurement precision for control purposes.
Solution Approach 2:
The patent changes the interpretation parameter of the RTD output from solely temperature measurement to include both temperature and flow information. By monitoring the temperature differential between two RTDs and analyzing the cooling effect caused by air convection, the system extracts flow information from temperature data. This parameter change allows existing low-cost temperature sensors to function as flow sensors, significantly reducing manufacturing costs while providing sufficient measurement precision.
3Device complexity
If the system operates without flow monitoring, then device complexity is reduced, but harmful effects occur from running the filter in no flow conditions
Solution Approach 1:
The system implements feedback control by continuously monitoring temperature differentials between two RTDs to detect flow conditions. When the temperature differential indicates absent or insufficient air flow, the control system receives feedback and automatically shuts down the filtration system. This feedback mechanism prevents harmful operation in no-flow conditions without requiring complex additional sensors, as it utilizes the existing temperature detection capability to provide the necessary flow monitoring feedback.
Solution Approach 2:
The system performs preliminary detection of flow conditions by continuously monitoring temperature differentials before allowing the filtration system to operate. The RTDs are always active and provide advance warning of flow absence through temperature changes, enabling the control system to take preventive action by shutting down the filter before harmful no-flow operation can occur. This preliminary action approach ensures safety without requiring complex real-time flow sensors.
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 system effectively controls airflow and ionization, reducing power consumption, extending system life, and preventing damage by accurately determining airflow and ion levels within a calibrated temperature range, enhancing the operational efficiency and safety of air filtration systems.
Implementation Method 1
a first resistance temperature detector configured for generating a flow signal
Implementation Method 2
the flow signal is based on a fluid velocity
Data Source
AI summary
A system and method for a low cost fluid flow sensor is described. One embodiment includes a fluid flow sensor comprising a first resistance temperature detector configured for generating a flow signal, wherein the flow signal is based on a fluid velocity, and wherein the first resistance temperature detector is configured for a fluid temperature range; a second resistance temperature detector configured for generating a temperature signal, wherein the temperature signal is based on a fluid temperature; and a controller coupled to the first resistance temperature detector and the second resistance temperature detector, the controller configured for receiving the flow signal and the temperature signal, wherein the controller takes a first controller action when the temperature signal is within a temperature signal range substantially representative of the fluid temperature range, and the flow signal is within a flow signal range, wherein the flow signal range is determined based on the temperature signal.