Engine NOx Estimation via Thermodynamic Modeling
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Solution Overview
Problem
Existing methods for monitoring and controlling NOx emissions in internal combustion engines are costly and prone to sensor failures under varying operating conditions, necessitating a more efficient and reliable approach to determine and manage NOx levels.
Innovation Solution
A method and system that determine NOx levels by measuring intake air and exhaust temperatures and pressures, engine speed, and heating losses, calculating enthalpy and humidity, and using these parameters to control engine operations, potentially without the need for additional NOx sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a NOx sensor is used to determine the amount of NOx, then the measurement precision is improved, but the device complexity and cost increase
Solution Approach 1:
The patent creates a virtual copy of the NOx sensing function through computational modeling. Instead of physically measuring NOx with a sensor, the system calculates equivalent NOx information by copying and processing data from existing sensors (temperature, pressure, humidity) through thermodynamic models, achieving the measurement function without the physical sensor
Solution Approach 2:
The patent replaces the mechanical/physical NOx sensor system with a computational/mathematical system. The physical measurement device is substituted by algorithms that process thermodynamic parameters to derive NOx equivalence, eliminating the need for complex sensor hardware while maintaining measurement capability
2Measurement precision
If a NOx sensor is used to determine the amount of NOx, then the measurement precision is improved, but the reliability deteriorates under varying operating conditions
Solution Approach 1:
The patent changes the measurement parameters from direct NOx concentration detection to fundamental thermodynamic parameters (temperature, pressure, humidity) that can be reliably measured across varying operating conditions. By measuring parameters that remain stable and predictable under different conditions, the system maintains reliability while deriving NOx information through calculation
Solution Approach 2:
The patent prepares for sensor failures and varying conditions by having pre-established thermodynamic models and alternative calculation methods ready. The system cushions against reliability issues by having multiple computational approaches and by using parameters that are less susceptible to failure, ensuring continuous operation even when conditions vary
3Device complexity
If thermodynamic parameters are used to estimate NOx, then the device complexity is reduced, but the measurement precision may deteriorate
Solution Approach 1:
The patent implements feedback mechanisms where the estimated NOx values are continuously refined based on actual engine performance data and emissions feedback. The system uses feedback loops to adjust and improve the accuracy of thermodynamic calculations, ensuring that precision is maintained while keeping the system simple
Solution Approach 2:
The patent makes the existing thermodynamic measurement system multi-functional by enabling it to serve both its original purpose (monitoring temperature, pressure, humidity) and the additional function of estimating NOx levels. This universal approach allows one set of sensors to perform multiple measurements, reducing overall system complexity while maintaining precision through sophisticated data utilization
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 accurate NOx monitoring and control, reducing reliance on costly sensors and enabling adaptive engine management to meet emission standards, while also detecting sensor faults and providing alternative NOx determination methods.
Implementation Method 1
determining an enthalpy of the intake air based at least on the work performed by the engine, the heating losses of the engine, a heating value of a fuel used for combustion within the engine, and the temperature and the pressure of the exhaust
Implementation Method 2
determining a humidity value of the intake air based on the enthalpy, temperature and pressure of the intake air
Data Source
AI summary
A method of operating an engine is provided. The method includes determining a temperature and a pressure of intake air, and a temperature and a pressure of exhaust generated by the engine. The method includes determining a work performed by the engine based at least on an engine speed of the engine, and determining heating losses of the engine. The method includes determining an enthalpy of the intake air based at least on the work, the heating losses, a heating value of a fuel used for combustion within the engine, and the temperature and the pressure of the exhaust. The method includes determining a humidity value of the intake air based on the enthalpy, temperature and pressure of the intake air and determining an amount of NOx based on the humidity value. The method further includes controlling an operation of the engine based on the determined amount of NOx.