Multistatic TDR Probe Water Detection in Fuel Tanks
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Solution Overview
Problem
Existing TDR level sensing devices cannot accurately determine the presence of water in a storage tank, especially in fluids like reformulated gasoline and alcohol/gasoline mixtures, due to signal attenuation and inability to differentiate between adjacent fluids.
Innovation Solution
A TDR level sensing device with a water sensing circuit that uses multistatic probes and a float-coupler system, along with a water detection device capable of monitoring conduction and dielectric constants, to detect the presence of water by measuring time delays and changes in capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If TDR level sensing devices use basic unistatic probes, then the device complexity is low, but the measurement precision deteriorates due to signal interference and inability to detect water in certain fluids
Solution Approach 1:
The patent divides the sensing system into separate transmitting and receiving probes (multistatic configuration), allowing independent optimization of each component. This segmentation enables the transmission probe to focus on signal generation while the receiving probe focuses on detecting reflected signals and water contamination, thereby improving measurement precision without requiring a completely complex new design
Solution Approach 2:
The patent introduces a dielectric barrier or coating on the probes that acts as an intermediary between the probe and the fluid. This intermediary layer prevents direct contact between the probe and certain fluids (like reformulated gasoline) that would cause signal attenuation, while still allowing detection of water through dielectric constant differences, thus improving water detection accuracy
2Measurement precision
If TDR devices use improved multistatic probes with float-coupler, then the measurement precision improves for fluid level detection, but the ability to detect water presence deteriorates due to signal attenuation in reformulated gasoline and alcohol mixtures
Solution Approach 1:
The patent changes the operating parameters of the TDR system by using multiple frequencies and measuring both time-domain reflectometry signals and dielectric constant values. By analyzing changes in these parameters (propagation time, dielectric constant) across different fluid conditions, the system can distinguish between reformulated gasoline (which attenuates signals) and water contamination, thereby restoring water detection reliability while maintaining fluid level measurement precision
Solution Approach 2:
The patent makes the sensing system multi-functional by enabling it to perform both fluid level measurement and water detection using the same multistatic probe structure. The system achieves this universality by processing multiple signal characteristics (time delay, dielectric constant, signal attenuation) from the same hardware configuration, allowing a single device to address multiple measurement needs
3Reliability
If capacitance-based sensors are used to detect water, then the water detection capability is available, but the reliability deteriorates when used with reformulated gasoline and alcohol/gasoline mixtures due to dielectric absorption
Solution Approach 1:
The patent replaces pure capacitance-based detection with a hybrid approach combining TDR (time-domain reflectometry) and dielectric constant measurement. Instead of relying solely on capacitance changes that are affected by dielectric absorption in reformulated fuels, the system uses electromagnetic wave propagation time and multiple frequency measurements to detect water, thereby achieving reliable water detection in challenging fuel compositions
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
Enables accurate measurement of fluid levels and detection of water presence in storage tanks, even in challenging fluids like reformulated gasoline and alcohol/gasoline mixtures, by effectively distinguishing water from other fluids based on conduction and dielectric properties.
Implementation Method 1
A time domain reflectometry (TDR) level sensing device uses a technique that involves connecting a time domain reflectometer to a conductive element (e.g., a probe, a transmission line, etc.) and immersing the conductive element in a liquid. The time domain reflectometer generates a pulse (i.e., electromagnetic signal)... The pulse generally propagates along and/or proximate the conductive element. A processor in or associated with the TDR level sensing device measures the time taken by the pulse to make a round trip between the reflectometer and the surface of the liquid.
Implementation Method 2
The water detection device monitors at least one of conduction and a dielectric constant between exposed ends of the first and second multistatic probes such that a presence of the water in the storage tank is detected.
Implementation Method 3
The water detection device monitors at least one of conduction and a dielectric constant between exposed ends of the first and second multistatic probes such that a presence of the water in the storage tank is detected.
Data Source
AI summary
An apparatus for measuring a level of a fluid and detecting water in a storage container is provided. The apparatus comprises a signal-based fluid level measurement apparatus and a water detection device. The signal-based fluid level measurement apparatus has a first multistatic probe conveying a first signal and a second multistatic probe conveying a second signal. The first and second multistatic probes are electrically coupled by a float-coupler. The signal-based fluid level measurement apparatus determines the level of the fluid in the storage container based at least in part on a time delay between the first and second signals. The water detection device is operably coupled to the fluid level measurement apparatus. The water detection device monitors at least one of conduction and a dielectric constant between exposed ends of the first and second multistatic probes. As such, a presence of the water in the storage tank is detected.