Water Hardness Conversion via Conductivity Segmentation
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Solution Overview
Problem
Existing methods for determining the concentration of components removable from fluid by a fluid treatment device, such as water hardness, are insufficiently accurate due to the presence of additional ion species in mains water, which affect conductivity measurements.
Innovation Solution
A method that uses at least two measurement values of a parameter like electrical conductivity at different ratios of untreated to treated fluid, converting the difference into an output value representative of component concentration, with improved accuracy by approximating absolute values within the fluid treatment apparatus, using a factor dependent on the average conductivity values upstream and downstream of the treatment part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conductivity measurements are used to determine water hardness, then the measurement process is simple and fast, but the measurement precision is insufficient due to interference from additional ion species in mains water
Solution Approach 1:
The measurement process is segmented into multiple steps: first measuring conductivity of untreated water, then measuring conductivity after treatment, and finally calculating hardness from the difference. This segmentation allows the method to maintain simplicity while improving accuracy by isolating the effect of removable components.
Solution Approach 2:
The method extracts the contribution of removable components (like calcium and magnesium ions) from the total conductivity measurement by comparing treated and untreated water. This extraction isolates the specific parameter of interest from interfering substances, resolving the accuracy problem while keeping the measurement process simple.
2Measurement precision
If a conversion factor based on average conductivity values is used, then the measurement precision improves by accounting for activity coefficients, but the computational complexity increases
Solution Approach 1:
The method changes the conversion approach from using fixed conversion factors to using conversion factors that vary with the average conductivity value. This parameter change allows the system to account for concentration-dependent activity coefficients, improving accuracy while requiring only simple arithmetic operations that maintain low computational complexity.
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 provides a more accurate measure of component concentration, specifically temporary hardness, by accounting for concentration-dependent activity coefficients and temperature variations, suitable for existing fluid treatment apparatuses and reducing sensor drift and computational resources.
Implementation Method 1
determining the electrical conductivity of the raw, softened or blended water by means of a conductivity sensor
Implementation Method 2
The ion exchanger exchanges calcium ions against sodium ions, wherein the electrical conductivity of the water is changed
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
Method and apparatus for determining the hardness of water. Water is separated into two portions. One portion is treated in an ion exchanger while the other portion bypasses the treatment unit. Both portions are mixed together again to obtain water of defined hardness. The conductivity of the water for different blending ratios is determined and the change of conductivity with the blending ratio is used to determine a conversion factor for the conversion of conductivity values into hardness values.