Ammonia Flow Measurement Using Critical Orifice
Solution Overview
Problem
Existing after-treatment systems for compression ignition engines face challenges in reducing nitrogen oxides (NOx) and particulates, with flow sensors being expensive, prone to durability and accuracy issues, and requiring additional components, which complicates the monitoring and control of ammonia injection for NOx conversion.
Innovation Solution
A flow manifold system that includes a supply cartridge for ammonia storage, a control valve, and a critical flow orifice to maintain a constant volumetric flow of ammonia into the exhaust gas, allowing the engine control unit to estimate the ammonia quantity based on flow duration without relying on flow sensors, thereby simplifying the system and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flow sensors are used to monitor NH3 flow, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent removes the flow sensor from the system entirely, extracting the measurement function and replacing it with a critical flow orifice that provides flow measurement through its physical design rather than electronic sensing. This eliminates the sensor, its associated electronics, and the complexity of interpreting sensor signals while maintaining the ability to monitor NH3 flow.
Solution Approach 2:
The patent replaces expensive, complex flow sensors with a simple, durable critical flow orifice that is inexpensive to manufacture and replace. The orifice is a passive component that provides flow measurement through its geometric design, eliminating the need for expensive electronic sensors and their associated maintenance and programming requirements.
2Measurement precision
If flow sensors are used to monitor NH3 flow, then measurement precision is improved, but reliability deteriorates due to harsh operating environment
Solution Approach 1:
The patent replaces expensive, complex flow sensors with a simple, durable critical flow orifice that is inexpensive to manufacture and replace. The orifice is a passive component that provides flow measurement through its geometric design, eliminating the need for expensive electronic sensors and their associated maintenance and programming requirements.
Solution Approach 2:
The patent removes the flow sensor from the system entirely, extracting the measurement function and replacing it with a critical flow orifice that provides flow measurement through its physical design rather than electronic sensing. This eliminates the sensor, its associated electronics, and the complexity of interpreting sensor signals while maintaining the ability to monitor NH3 flow.
3Measurement precision
If flow sensors are used to monitor NH3 flow, then measurement precision is improved, but installation expenses increase
Solution Approach 1:
The patent replaces expensive, complex flow sensors with a simple, durable critical flow orifice that is inexpensive to manufacture and replace. The orifice is a passive component that provides flow measurement through its geometric design, eliminating the need for expensive electronic sensors and their associated maintenance and programming requirements.
Solution Approach 2:
The patent removes the flow sensor from the system entirely, extracting the measurement function and replacing it with a critical flow orifice that provides flow measurement through its physical design rather than electronic sensing. This eliminates the sensor, its associated electronics, and the complexity of interpreting sensor signals while maintaining the ability to monitor NH3 flow.
4Measurement precision
If flow sensors are used to monitor NH3 flow, then measurement precision is improved, but ECU programming complexity increases
Solution Approach 1:
The patent removes the flow sensor from the system entirely, extracting the measurement function and replacing it with a critical flow orifice that provides flow measurement through its physical design rather than electronic sensing. This eliminates the sensor, its associated electronics, and the complexity of interpreting sensor signals while maintaining the ability to monitor NH3 flow.
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 solution enables efficient and cost-effective ammonia injection into the exhaust gas, reducing NOx conversion while eliminating the need for expensive flow sensors, enhancing system reliability and precision in estimating ammonia usage and depletion.
Implementation Method 1
The at least one critical flow orifice is configured to allow for a relatively constant volumetric flow of the first gas through the at least one critical flow orifice when the first gas attains a critical flow
Implementation Method 2
The NH3 may be injected into the exhaust gas in dosing amounts or rates for converting NOx in the exhaust gas into at least nitrogen, such as, for example, through a catalytic reaction in an selective catalytic reduction (SCR) system
Data Source
AI summary
A flow manifold system for injecting a first gas into a second gas, such as, for example, a system for injecting ammonia gas into the exhaust gas of an internal combustion engine. The first gas may be supplied to the system by one or more cartridges. The system may also include a control valve that is configured to control the delivery of the first gas to the least one critical flow orifice. The critical flow orifice is configured to allow for a relatively constant volumetric flow of the first gas through the critical flow orifice when the first gas attains a critical flow. Such critical flow may allow for an accurate estimation of the flow of the first gas through the critical orifice, and subsequently to the second gas, without the use of a flow sensor.