Fluid Temperature Determination via Boundary Layer Thermal Resistance
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Solution Overview
Problem
Existing methods for determining the temperature of a fluid flowing through a pipe section fail to accurately account for the finite thermal conductivity of the fluid boundary layer, leading to significant differences between estimated inner wall temperatures and actual average fluid temperatures, especially when the thermal resistance of the fluid boundary layer is higher than that of the pipe section.
Innovation Solution
A method that determines the temperature of a fluid by calculating the heat transfer behavior of the boundary layer, including its thermal resistance, based on material properties and state variables, and combining this with the heat transfer behavior of the pipe section and measured temperatures to provide an accurate average fluid temperature across a pipe cross-section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the finite thermal conductivity of the fluid boundary layer is not taken into account, then the measurement method is simpler, but the temperature estimation accuracy deteriorates significantly
Solution Approach 1:
The invention changes the thermal parameters model by introducing the boundary layer thermal resistance as a distinct parameter. Instead of assuming infinite thermal conductivity, the method calculates the boundary layer thermal resistance based on fluid properties (density, viscosity, thermal conductivity) and flow conditions (Reynolds number), thereby improving temperature estimation accuracy while maintaining computational feasibility.
2Measurement precision
If the thermal resistance of the fluid boundary layer is considered, then the temperature measurement accuracy improves, but the calculation complexity increases
Solution Approach 1:
The invention performs preliminary calculations by determining fluid properties and flow conditions before calculating the boundary layer thermal resistance. By pre-establishing the relationship between Reynolds number, Prandtl number, and Nusselt number, the method prepares the necessary parameters in advance, reducing the complexity of the final temperature calculation while maintaining high accuracy.
Solution Approach 2:
The invention introduces the Nusselt number as an intermediary parameter that connects the fluid flow characteristics with the thermal boundary layer properties. This intermediary allows the complex thermal conductivity relationship to be expressed through a dimensionless number that can be calculated from standard flow parameters, simplifying the overall calculation process.
3Reliability
If the boundary layer thermal resistance is higher than the pipe section thermal resistance, then the conventional method fails to provide accurate results, but the present method maintains accuracy
Solution Approach 1:
The invention converts the harmful effect of high boundary layer thermal resistance (which causes temperature estimation errors in conventional methods) into a beneficial factor. By explicitly calculating and incorporating the boundary layer thermal resistance into the heat transfer model, the method transforms the source of error into a corrected parameter, improving accuracy in scenarios where the boundary layer resistance dominates the thermal resistance.
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
This approach allows for a more precise estimation of the average fluid temperature by incorporating the thermal resistance of the boundary layer, improving accuracy and aligning with practical application scenarios where the fluid boundary layer's resistance is higher than the pipe section's.
Implementation Method 1
determining a heat transfer behavior, comprising a thermal resistance, of a boundary layer of the fluid on an inner wall of the pipe section
Implementation Method 2
determining a heat transfer behavior, comprising a thermal resistance, of a boundary layer of the fluid
Implementation Method 3
determining a heat transfer behavior, comprising a thermal resistance, of the pipe section
Data Source
AI summary
A method for determining a temperature of a fluid flowing through a pipe section includes: determining a temperature of the pipe section; obtaining a reference temperature at a distance from a surface of the pipe section; determining a heat transfer behaviour, in particular a thermal resistance, of a boundary layer of the fluid on an inner wall of the pipe section based on at least one material property and/or at least one value of a state variable of the fluid; and determining the temperature of the fluid based on the heat transfer behaviour of the boundary layer, a heat transfer behavior, in particular a thermal resistance, of the pipe section, the temperature of the pipe section, and the reference temperature.