Flowing Fluid Temperature Sensing With Frictional-Heating Correction
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Solution Overview
Problem
Existing methods for determining medium temperature in flowing fluids, particularly at higher flow velocities or Reynolds numbers, result in significant deviations from the true core temperature, exceeding 4 K, due to frictional heating and heat transfer processes.
Innovation Solution
A method that accounts for frictional heating by incorporating medium parameters such as density, viscosity, thermal conductivity, heat capacity, and pressure difference to calculate medium temperature from wall temperature, using a measuring system with electronics to determine these parameters and apply correction factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If temperature sensors are arranged outside the line to avoid contact with the medium, then the device complexity is reduced and ease of operation is improved, but measurement precision deteriorates due to frictional heating effects at higher flow velocities
Solution Approach 1:
The patent applies parameter changes by introducing correction factors that depend on flow velocity, density, viscosity, and thermal conductivity parameters. The measuring system calculates a correction factor based on these physical parameters to compensate for frictional heating effects, thereby maintaining measurement precision while keeping the temperature sensor externally arranged
Solution Approach 2:
The patent implements feedback by using measured flow velocity, density, and other medium parameters to dynamically calculate correction factors that are applied to the wall temperature measurement. This feedback loop compensates for frictional heating effects in real-time, improving measurement precision without changing the external sensor arrangement
2Reliability
If temperature sensors are arranged outside the line, then reliability is improved by avoiding contact with the medium, but measurement precision deteriorates due to heat transfer processes and frictional heating
Solution Approach 1:
The patent changes the measurement approach by introducing correction factors based on medium parameters (density, viscosity, thermal conductivity, flow velocity). These parameter-based corrections compensate for the heat transfer and frictional heating effects that occur when sensors are externally arranged, maintaining both reliability and precision
Solution Approach 2:
The patent uses correction factors as an intermediary element between the wall temperature measurement and the true medium temperature. These correction factors, calculated from medium parameters, mediate the relationship between the external sensor reading and the actual medium temperature, compensating for thermal effects
3Measurement precision
If correction factors based on medium parameters are introduced to compensate for frictional heating, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by using a single correction factor calculation approach that works across different medium types and flow conditions. The measuring system uses general parameters (density, viscosity, thermal conductivity, flow velocity) that can be obtained through standard sensors, making the solution universally applicable without requiring complex medium-specific calibration
Solution Approach 2:
The patent merges the temperature measurement function with flow and medium parameter measurement functions. By combining wall temperature sensing with flow velocity and medium parameter detection, the system creates an integrated measurement approach where correction factors are calculated from multiple parameter sources, improving precision while distributing complexity across standard sensor components
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
Achieves a medium temperature determination with an accuracy of less than 3 K deviation from the true temperature, even at flow velocities greater than 0.1 m/s and Reynolds numbers above 100, by compensating for frictional heating effects.
Implementation Method 1
a coupling body, for example made of a thermally conductive adhesive, that thermally connects the same temperature sensor to the wall
Implementation Method 2
result in significant deviations from the true core temperature, exceeding 4 K, due to frictional heating and heat transfer processes
Data Source
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AI summary
In the method according to the invention, the substance (FL) to be measured is allowed to flow through a line in a specified flow direction, and a wall temperature value XTw is ascertained which represents a wall temperature Tw, namely the temperature of a wall enclosing a lumen of the tube. Furthermore, a density value Xp which represents the density p of the substance to be measured flowing in the line, a viscosity value Χμ which represents the viscosity μ of the substance to be measured flowing in the line, a temperature conductivity value Χλ which represents the temperature conductivity λ of the substance to be measured, a thermal capacity value Xcp which represents the specific thermal capacity cp of the substance to be measured, and a pressure differential value ΧΔρ which represents a pressure differential Δρ produced within the substance to be measured flowing in the line in the flow direction are ascertained and then used to ascertain a characteristic number value Xv for a characteristic number V of the substance to be measured, said characteristic number characterizing a heating of the substance to be measured flowing in the line as a result of dissipation, wherein the characteristic number V of the substance to be measured corresponds to a calculation formula: V = ƒ(Δp,p,μ,λ,c p ) = Pr a ∙ Ec b · ζ c , which is determined by an Eckert number Ec of the substance to be measured flowing in the line, a Prandtl number Pr of the substance to be measured flowing in the line, and a pressure loss coefficient ζ of the line as well as by a line-specific first exponent a, a line-specific second exponent b, and a line-specific third exponent c. Finally, a temperature value XTM which represents the temperature TM of the substance to be measured is ascertained using the characteristic number value Xv and the wall temperature value XTw. For this purpose, a measuring system according to the invention additionally comprises a temperature sensor, which is thermally coupled to a lateral surface of the wall, for generating a temperature measurement signal, which responds to a change in the temperature Tw of the wall with a change in at least one signal parameter, and a measuring and operating electronic system which is electrically connected to the temperature sensor.