Ammonia Sensor Mixed Potential Cell Formula Correction
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Solution Overview
Problem
Existing ammonia sensors using mixed potential-type cells fail to accurately derive ammonia concentration in target gases due to discrepancies between measured electromotive force and concentrations, as the relationship does not follow the conventional mixed-potential formula, leading to inaccurate ammonia concentration calculations.
Innovation Solution
An apparatus and method utilizing a mixed potential cell with a solid electrolyte body, detection, and reference electrodes, acquiring electromotive force and oxygen concentration data to derive ammonia concentration using a modified formula (EMF=α loga(pNH3)−β logb(pO2)+γ logc(pNH3)×logd(pO2)+B, which provides higher accuracy by accounting for specific constants and base values, and storing the relationship in a map for precise ammonia concentration measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the conventional mixed-potential formula (Formula 2) is used to calculate ammonia concentration, then the calculation process is simple, but the measurement precision deteriorates because the formula does not accurately represent the actual relationship between electromotive force and gas concentrations
Solution Approach 1:
The patent changes the parameters of the calculation formula by introducing a new empirical formula (Formula 1) with different mathematical relationships between electromotive force and gas concentrations. This new formula includes interaction terms and different exponents that better represent the actual physical chemistry of the mixed potential cell, thereby improving measurement accuracy while maintaining the overall simplicity of the calculation approach
Solution Approach 2:
The patent uses feedback by incorporating oxygen concentration measurements into the ammonia concentration calculation. The new formula utilizes both electromotive force and oxygen concentration data, creating a feedback mechanism where the measured oxygen level is used to correct and refine the ammonia concentration derivation, improving overall measurement accuracy
2Measurement precision
If the mixed potential cell is used to detect ammonia concentration, then the device structure is simple, but the measurement precision deteriorates because the electromotive force does not follow the conventional theoretical relationship with gas concentrations
Solution Approach 1:
The patent changes the mathematical parameters of the relationship formula to better match experimental observations. Formula (1) introduces new exponents and interaction terms that reflect the actual behavior of the mixed potential cell under various gas concentration conditions, making the formula reliably applicable to real-world measurements
Solution Approach 2:
The patent makes the calculation dynamic by incorporating multiple variables (electromotive force, oxygen concentration) and their interactions. The formula adapts to different operating conditions through the interaction term that accounts for the combined effect of ammonia and oxygen concentrations, improving reliability across varying environmental conditions
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 enables more accurate ammonia concentration derivation in target gases, improving measurement precision compared to conventional methods by using a modified formula that accounts for specific constants and base values, ensuring reliable data even at high temperatures.
Implementation Method 1
a sensor element including a mixed potential cell that includes a solid electrolyte body, a detection electrode arranged on the solid electrolyte body, and a reference electrode arranged on the solid electrolyte body
Implementation Method 2
EMF=α loga(pNH3)−β logb(pO2)+γ logc(pNH3)×logd(pO2)+B
Data Source
AI summary
An apparatus for measuring ammonia concentration measures ammonia concentration in a target gas with a sensor element including a mixed potential cell. The apparatus for measuring ammonia concentration includes an electromotive force acquisition section, an oxygen concentration acquisition section, and an ammonia concentration derivation section. The ammonia concentration derivation section derives the ammonia concentration in the target gas from the relationship represented by formula (1):EMF=α loga(pNH3)−β logb(pO2)+γ logc(pNH3)×logd(pO2)+B (1)(whereEMF: an electromotive force of the mixed potential cell,α, β, γ, and B: constants (provided that each of α, β, and γ≠0),a, b, c, and d: any base (provided that each of a, b, c, and d≠1, and each of a, b, c, and d>0),pNH3: the ammonia concentration in the target gas, andpO2: the oxygen concentration in the target gas).