Exhaust Gas Treatment Heater Temperature Control
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Solution Overview
Problem
Exhaust gas treatment devices for lean-burn internal combustion engines face challenges in efficiently reducing nitrogen oxide compounds due to low exhaust gas temperatures, which hinder the effective conversion of pollutants and require energy-intensive heating to evaporate liquid reducing agents.
Innovation Solution
A method that sets two distinct limit temperatures for heating in the exhaust gas treatment device, allowing for energy-saving operation by optimizing heating based on the specific conversion processes required for reducing agents and pollutant conversion, with the option to store reducing agents temporarily and supply them in either liquid or gaseous form to maintain effective pollutant reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid reducing agent is supplied to exhaust gas in lean-burn internal combustion engines, then nitrogen oxide compounds can be reduced through selective catalytic reduction, but exhaust gas temperature decreases due to evaporative cooling
Solution Approach 1:
The control device predicts future exhaust gas temperature based on current operating conditions and reducing agent supply plans. This allows the system to prepare heating actions in advance to compensate for the cooling effect of liquid reducing agent injection, ensuring temperature remains sufficient for effective SCR conversion.
Solution Approach 2:
The heating control is dynamically adjusted based on predicted temperature trajectories and actual temperature measurements. The control device continuously modifies heating power to maintain optimal temperature for nitrogen oxide reduction while accounting for the variable cooling effect of reducing agent supply.
2Reliability
If exhaust gas temperature is increased through heating to enable reducing agent evaporation and pollutant conversion, then conversion efficiency improves, but energy consumption increases
Solution Approach 1:
Instead of continuously heating to maintain a fixed temperature, the system applies heating only partially - specifically when and where needed to reach minimum conversion temperatures. The control device calculates the exact heating required based on predicted temperature and reducing agent supply, avoiding excessive energy consumption while ensuring sufficient conversion efficiency.
Solution Approach 2:
The system dynamically changes temperature parameters based on operating conditions, reducing agent supply rate, and conversion requirements. Rather than maintaining a constant high temperature, the control device adjusts temperature targets and heating power to match actual needs, optimizing the balance between conversion efficiency and energy consumption.
3Volume of stationary object
If heating is applied to maintain sufficient temperature for reducing agent evaporation, then reducing agent can be supplied in liquid form saving space, but energy consumption increases
Solution Approach 1:
The control device predicts whether future exhaust gas temperature will be sufficient for reducing agent evaporation based on current operating conditions. This allows the system to plan reducing agent supply timing and associated heating actions in advance, optimizing the balance between liquid storage benefits and heating energy requirements.
Solution Approach 2:
The system dynamically changes the state of reducing agent supply between liquid and gaseous forms based on predicted temperature conditions and energy availability. When temperature and energy conditions are favorable, liquid supply is used for space efficiency; when conditions are unfavorable, gaseous supply or enhanced heating is employed to maintain conversion efficiency.
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 ensures efficient conversion of pollutants while minimizing energy consumption by tailoring heating to the specific temperature requirements of different conversion processes and utilizing stored reducing agents, ensuring effective nitrogen oxide reduction even at low exhaust gas temperatures.
Implementation Method 1
Liquid reducing agent must usually first be evaporated before it can be supplied in gaseous form to an exhaust gas treatment device
Implementation Method 2
Sufficiently high exhaust gas temperatures are necessary for this
Implementation Method 3
Ammonia is converted with the nitrogen oxide compounds in the exhaust gas into harmless components, namely nitrogen as well as water and carbon dioxide
Implementation Method 4
Ammonia, for example, can be used as a reducing agent. Ammonia is converted with the nitrogen oxide compounds in the exhaust gas into harmless components
Implementation Method 5
electrically heatable honeycomb bodies, in which packages made of several at least partially structured metallic foils have an electrical current flowing through them
Implementation Method 6
electrically heatable honeycomb bodies have the advantage that they have a significantly larger surface area through which they can release the heat generated into the exhaust gas
Data Source
Figure 1~2
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Figure 5~6
AI summary
The invention relates to a method for operating an exhaust gas treatment device (1) comprising at least one heater (3) and at least one supplying device (4) for a reducing agent. According to the method, a test is initially carried out in order to determine whether the reducing agent is to be supplied, and different heating strategies are subsequently implemented in each case. In the event that the reducing agent is to be supplied, the exhaust gas treatment device is heated with the heater (3) until a first threshold temperature (8) is reached, if a first temperature (7) lies below the first threshold temperature (8).In the case that no reducing agent is to be fed, the exhaust gas treatment device is heated with the heater (3) until a second threshold temperature (10) is reached, if a second temperature (9) lies below the second threshold temperature (10).