Isothermal Resonator for Density Viscosity Measurement
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Solution Overview
Problem
Existing fluid density measurement devices face challenges in accurately measuring fluid density and viscosity due to thermal non-equilibrium, mechanical stresses, and limitations in downhole and process environments, particularly with magnetic and piezoelectric transducers, which compromise accuracy and durability.
Innovation Solution
A fluid density measurement device with a resonator that maintains an isothermal state through temperature regulation, using a housing with a chamber and aperture, a drive rod, and transducer assembly, allowing for perpendicular vibration and temperature measurement to accurately determine fluid density and viscosity, suitable for process and downhole use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resonator is completely immersed in the fluid to be measured, then the temperature becomes uniform enabling accurate correction of thermal influences, but the device complexity and susceptibility to corrosion increase
Solution Approach 1:
The resonator is divided into two distinct portions: an enclosed portion housed within a protective chamber that is isolated from the fluid, and an exposed portion that extends into the fluid for measurement. This segmentation allows the resonator to maintain temperature uniformity through thermal coupling while protecting the transducer assembly from corrosive fluid exposure.
Solution Approach 2:
A thermal coupling mechanism (such as a thermally conductive housing or heat transfer path) serves as an intermediary between the enclosed and exposed portions of the resonator. This intermediary enables thermal equilibrium to be maintained across the resonator length without requiring complete fluid immersion, thus protecting sensitive components while ensuring accurate temperature-compensated measurements.
2Device complexity
If the resonator is only partially immersed in the fluid, then the device complexity is reduced, but non-uniform temperature distributions make frequency calculation difficult and limit measurement accuracy
Solution Approach 1:
The resonator is segmented into enclosed and exposed portions, allowing partial immersion while maintaining isothermal conditions through thermal coupling of the enclosed portion to the exposed portion. This eliminates the need for complete immersion while ensuring uniform temperature distribution across the entire resonator.
Solution Approach 2:
The patent replaces the traditional approach of using mechanical insulation or complex thermal management systems with a simplified thermal coupling design where the housing or mounting structure provides the necessary thermal path, reducing device complexity while maintaining measurement accuracy.
3Measurement precision
If magnetic or piezoelectric transducers are used in the resonator, then the resonant frequency can be measured, but the transducers are prone to corrosion and mechanical failure in downhole and process environments
Solution Approach 1:
The transducer assembly is segregated into the enclosed portion of the resonator, isolated from direct contact with the fluid. This protects magnetic or piezoelectric transducers from corrosion and mechanical failure while maintaining their functionality for driving and sensing the resonator's vibrational response.
Solution Approach 2:
The housing or mounting structure serves as an intermediary that transmits vibrational forces from the exposed portion to the transducer in the enclosed portion, enabling the transducer to function without direct fluid exposure. This intermediary path preserves measurement capability while ensuring transducer reliability in harsh environments.
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 and robust measurement of fluid density and viscosity by maintaining the resonator in an isothermal state, reducing thermal non-equilibrium effects and enhancing durability, making it suitable for both laboratory and industrial applications.
Implementation Method 1
A resonator... that vibrates perpendicularly to a portion of its own surface... By measuring both the frequency decrease and the damping of such a flattened torsionally oscillating body, it is possible to measure both the density and the product of density and viscosity
Implementation Method 2
Due to inertial and viscous forces, the displaced fluid loads the resonator with additional mass (i.e. mass loading), increasing its inertia and decreasing its resonant frequency
Implementation Method 3
A fluid density measurement device with a resonator that maintains an isothermal state through thermal insulation and temperature regulation
Implementation Method 4
Said torsionally oscillating sensor also experiences an increase in its damping due to viscous dissipation in the fluid in which it is immersed. Said viscous dissipation is, at least for a Newtonian fluid, dependent on the product of density and viscosity of said fluid
Implementation Method 5
The sensor exposes a cylindrical surface to the fluid, which surface oscillates in torsion, and is therefore affected by shear stresses caused by shearing the fluid in contact with said surface
Data Source
AI summary
A fluid density measurement device (8) that includes a housing (54), defining a chamber (18) and an aperture; a resonator (10′) having length that is at least 5 times greater than its smallest diameter and having a longitudinal axis and a nodal plane, transverse to the longitudinal axis. The resonator further includes tube (44) having a first end and a second end; a second-end closure (52), closing the second end; and a drive rod (48) centrally attached to the second-end closure and extending to the tube first end. Further, the device includes a resonator transducer assembly (22) and the resonator is sealingly joined to the aperture at the nodal plane, so that an enclosed portion (10A′) extends into the chamber and an exposed portion (10B′) extends outside of the chamber, and wherein the chamber tends to assume the temperature of the exposed resonator portion, causing the resonator to be isothermal.