Ammonia Tank Level Detection via Pressure Rise Measurement
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Solution Overview
Problem
Existing systems for reducing NOx emissions in diesel engines, particularly those using SCR catalysts with ammonia storage, face challenges in efficiently managing ammonia levels within storage tanks, necessitating frequent refilling and requiring accurate measurement of remaining ammonia to ensure optimal engine operation and compliance with emission regulations.
Innovation Solution
A method to determine the quantity of reducing agents, such as ammonia, in a tank by using a storage material that reversibly stores and releases ammonia, a heating device to control its release, and a control device to regulate pressure, measuring the time and derivative of pressure rise to calculate the ammonia level based on calibrated values and vehicle parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If periodic filling or replacement of the tank is used to limit tank size, then the tank size is reduced, but the frequency of maintenance operations increases
Solution Approach 1:
The patent replaces mechanical/physical tank size limitations with a measurement and control system. By using pressure sensors, temperature sensors, and a control unit to monitor ammonia levels and determine optimal refilling timing, the system allows the tank to be sized appropriately for the vehicle while eliminating the need for frequent manual intervention. The control system calculates refilling based on actual ammonia consumption patterns rather than fixed periodic schedules.
2Measurement precision
If accurate measurement of ammonia quantity is implemented, then NOx reduction efficiency is improved, but device complexity increases
Solution Approach 1:
The patent uses pressure and temperature as intermediary parameters to indirectly measure ammonia quantity. Instead of directly measuring ammonia concentration (which would require complex sensors), the system uses pressure sensors and temperature sensors to monitor the physical state of the ammonia storage material. The control unit then calculates ammonia levels based on these physical parameters and calibrated relationships, simplifying the measurement system while maintaining accuracy.
Solution Approach 2:
The patent replaces direct chemical measurement systems with a physical measurement approach. By using pressure and temperature sensors to monitor the storage material state and applying thermodynamic relationships, the system achieves accurate ammonia quantity measurement without requiring complex chemical sensors or analysis equipment.
3Speed
If heating device power is increased to accelerate ammonia release, then ammonia injection speed is improved, but energy consumption increases
Solution Approach 1:
The patent implements dynamic control of the heating device power based on real-time system conditions. The control unit adjusts heating power according to: (1) current ammonia levels in the tank, (2) vehicle operating conditions (engine load, temperature), and (3) desired ammonia injection rates. This allows the system to use higher heating power when needed (e.g., during high NOx emission conditions) and reduce power when ammonia levels are sufficient or vehicle conditions demand lower injection rates, optimizing the energy-speed trade-off.
Solution Approach 2:
The system uses feedback from pressure sensors, temperature sensors, and ammonia level calculations to continuously adjust heating device operation. The control unit monitors the actual ammonia release rate and compares it with target rates, modifying heating power accordingly to achieve optimal performance without excessive energy consumption.
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 method allows for precise determination of ammonia levels, enabling optimal ammonia injection and reducing the frequency of refilling, thus improving NOx reduction efficiency and compliance with emission regulations, while also considering the thermal conductivity and saturation rates of the storage material.
Implementation Method 1
a storage material arranged in the tank and capable of storing and of releasing the reducing agent reversibly according to the demand for reducing agent
Implementation Method 2
a storage material arranged in the tank and capable of storing and of releasing the reducing agent reversibly
Implementation Method 3
a heating device designed to supply heat for releasing the reducing agent from the storage material
Implementation Method 4
The injection of ammonia into the exhaust gases is driven by means of a heating device making it possible to heat the storage material in order to enable the reversible absorption/desorption ammonia reaction since this reaction is directly linked to the temperature within the storage material
Implementation Method 5
a control device for driving the heating device in order to release the reducing agent
Data Source
AI summary
A method for determining the quantity of reducing agent in a tank vehicle, including: a storage material in the tank for storing and releasing the reducing agent according to demand; a heating device to supply heat to release the reducing agent, and a control device for driving the heating device. After the motor vehicle is started, driving the heating device so that it delivers constant power during an initial phase over which the pressure inside the tank increases until it reaches a predetermined value. The heating device then regulating the pressure around a datum value; then measuring the time of the initial phase or the derivative of pressure with respect to time during this initial phase; and comparing the measured time against various calibrated values of the initial phase in order to determine the quantity of reducing agent in the tank.