Flow-Line Temperature Measurement With Friction-Heating Correction
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Solution Overview
Problem
Existing methods for determining the temperature of a substance flowing in a line, such as a pipe, often result in significant deviations from the true core temperature, especially at higher flow velocities or Reynolds numbers, with errors exceeding 4K, due to heat transfer dynamics not accurately accounted for.
Innovation Solution
A method and system that utilize wall temperature measurements combined with parameters like density, viscosity, thermal conductivity, and pressure differential to calculate a corrected core temperature of the substance, using a characteristic number formula to minimize temperature deviation to less than 3K.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wall temperature measurement is used to determine substance temperature, then measurement simplicity is improved, but measurement precision deteriorates due to heat transfer dynamics not being accurately accounted for
Solution Approach 1:
The patent applies parameter changes by introducing multiple physical parameters (density, viscosity, thermal conductivity, specific heat capacity, flow velocity, pressure differential) into the temperature calculation. The corrected substance temperature is determined by combining the wall temperature measurement with these additional parameters through dimensionless numbers (Eckert number, Prandtl number, Reynolds number) and a correction formula, transforming a simple wall temperature measurement into a comprehensive temperature assessment that accounts for friction-induced heating and heat transfer dynamics.
2Device complexity
If temperature sensors are arranged outside the line, then device complexity is reduced, but measurement precision deteriorates at higher flow velocities with errors exceeding 4K
Solution Approach 1:
The patent uses the line wall as an intermediary element. Instead of placing sensors directly in the substance (which would increase complexity), the wall serves as a thermal mediator that transfers heat from the substance to the externally mounted temperature sensor. The sensor measures wall temperature, and through the correction methodology involving flow parameters and thermal properties, the core substance temperature is derived indirectly with high accuracy despite the external sensor position.
3Device complexity
If friction-induced heating is not accounted for, then calculation simplicity is improved, but temperature deviation increases to more than 4K at high Reynolds numbers
Solution Approach 1:
The patent converts the harmful effect of friction-induced heating into a beneficial measurement correction. Instead of ignoring the temperature rise caused by viscous dissipation at high flow velocities, the methodology explicitly calculates this heating effect using the Eckert number (which represents the ratio of kinetic energy to enthalpy) and subtracts it from the wall temperature measurement. This transforms a source of measurement error into a quantifiable correction term that improves accuracy.
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
Precisely determines the core temperature of a flowing substance with an error of less than 3K, even at high flow velocities and Reynolds numbers, by accounting for friction-induced heating near the pipe wall.
Implementation Method 1
a temperature sensor (21) thermally coupled to a lateral surface of the wall for generating a temperature measurement signal following a change of a temperature Tw of the wall
Implementation Method 2
Friction processes within the measured substance flowing through the line, or also between the flowing measured substance and the wall of the line, lead to the fact that kinetic energy of the flowing measured substance is converted into thermal energy, and therefore, by dissipation, (additional) heating is generated
Data Source
AI summary
A method includes: determining a wall temperature of a wall enclosing a lumen of a flow line; determining a density, a viscosity, a thermal conductivity, a thermal capacity, and a pressure differential of a medium to be measured flowing in the line; determining a characteristic number value for the medium, which characterizes a heating of the medium flowing in the line as a result of dissipation and is a function of an Eckert number, a Prandtl number, and a pressure loss coefficient of the line as well as line-specific first, second and third exponents; and determining a temperature of the medium using the characteristic number value and the wall temperature. A measuring system for the method includes: a temperature sensor thermally coupled to a lateral surface of the wall and configured to generate a temperature measurement signal; and an operating electronic system electrically connected to the temperature sensor.