Flash-Boil Doser Virtual Temperature Control
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Solution Overview
Problem
Existing exhaust aftertreatment systems face challenges in accurately controlling the temperature of reducing agents, such as urea solutions, injected into exhaust streams to reduce NOx emissions, due to difficulties in manufacturing reliable temperature sensors and potential leak paths within the flash-boil doser.
Innovation Solution
A heating system with a virtual temperature sensor and controller that determines the temperature of the reducing agent based on external parameters, allowing for selective heat application to maintain optimal conditions without physical sensors inside the doser, thereby improving control, durability, and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If physical temperature sensors are installed inside the flash-boil doser to measure reducing agent temperature, then temperature measurement accuracy is improved, but device complexity increases and potential leak paths are created
Solution Approach 1:
The patent uses an intermediary approach by measuring temperature outside the flash-boil doser (in the supply line or exhaust stream) and using that external measurement to control the heating system, thereby avoiding the need to install sensors inside the doser chamber which would create leak paths and increase complexity
Solution Approach 2:
The patent replaces the mechanical/physical temperature sensor installation inside the doser with a virtual sensing approach using external temperature measurements and control algorithms to determine the reducing agent temperature indirectly, eliminating the need for physical sensor penetration into the doser
2Measurement precision
If physical temperature sensors are installed inside the flash-boil doser to measure reducing agent temperature, then temperature measurement accuracy is improved, but reliability decreases due to potential leak paths
Solution Approach 1:
The patent uses an intermediary approach by measuring temperature outside the flash-boil doser (in the supply line or exhaust stream) and using that external measurement to control the heating system, thereby avoiding the need to install sensors inside the doser chamber which would create leak paths and increase complexity
Solution Approach 2:
The patent creates a virtual copy of the temperature measurement function by using external sensors and control algorithms to determine the reducing agent temperature indirectly, rather than physically placing a sensor inside the doser, thus eliminating leak paths while maintaining measurement capability
3Measurement precision
If physical temperature sensors are installed inside the flash-boil doser to measure reducing agent temperature, then temperature measurement accuracy is improved, but manufacturing costs increase
Solution Approach 1:
The patent uses an intermediary approach by measuring temperature outside the flash-boil doser (in the supply line or exhaust stream) and using that external measurement to control the heating system, thereby avoiding the need to install sensors inside the doser chamber which would create leak paths and increase complexity
Solution Approach 2:
The patent creates a virtual copy of the temperature measurement function by using external sensors and control algorithms to determine the reducing agent temperature indirectly, rather than physically placing a sensor inside the doser, thus eliminating leak paths while maintaining measurement capability
4Measurement precision
If physical temperature sensors are installed inside the flash-boil doser to measure reducing agent temperature, then temperature measurement accuracy is improved, but durability decreases
Solution Approach 1:
The patent uses an intermediary approach by measuring temperature outside the flash-boil doser (in the supply line or exhaust stream) and using that external measurement to control the heating system, thereby avoiding the need to install sensors inside the doser chamber which would create leak paths and increase complexity
Solution Approach 2:
The patent creates a virtual copy of the temperature measurement function by using external sensors and control algorithms to determine the reducing agent temperature indirectly, rather than physically placing a sensor inside the doser, thus eliminating leak paths while maintaining measurement capability
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 enhances the accuracy and reliability of reducing agent injection, effectively controlling the flow rate and temperature, which leads to improved NOx reduction efficiency and system durability while minimizing costs.
Implementation Method 1
The heater is configured to heat the reducing agent in the flash-boil doser
Implementation Method 2
The flash-boil doser is configured to inject reducing agent into the mixing can through an injection aperture formed in the mixing can at a predetermined flow rate with each injection pulse
Implementation Method 3
mixing can that defines at least a portion of an exhaust passageway for receiving the exhaust gases and a flash-boil doser mounted to the mixing can
Implementation Method 4
chemical reaction between the reducing agent and exhaust gases reduces Nitrous Oxides (NOx) in the exhaust gas
Data Source
AI summary
An exhaust aftertreatment system for use with over-the-road vehicle is disclosed. The exhaust aftertreatment system includes a reducing agent mixer with a mixing can and a flash-boil doser configured to inject heated and pressurized reducing agent into the mixing can for distribution throughout exhaust gases passed through the mixing can.