NOx Adsorbent Preheating for Cold Start Emission Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In internal combustion engines, the adsorption capacity of NOx adsorbents is reduced by adsorbed moisture, leading to increased NOx release into the atmosphere before the NOx purifying catalyst reaches its activation temperature, as existing solutions only initiate moisture release when the adsorbed moisture exceeds a threshold.
Innovation Solution
An exhaust purification device with an NOx adsorbent that desorbs moisture when heated to a moisture desorption temperature and NOx when heated to an NOx desorption temperature, using an electric heater to preheat the NOx adsorbent before engine startup, maintaining its adsorption capacity and suppressing NOx release until the NOx purifying catalyst reaches its activation temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the NOx adsorbent is used to adsorb NOx in exhaust gas, then NOx release is suppressed, but the adsorption capacity is reduced by adsorbed moisture
Solution Approach 1:
The electric heater preheats the NOx adsorbent before engine operation to desorb moisture in advance, so that when the engine starts and NOx needs to be adsorbed, the adsorbent has already recovered its adsorption capacity and is not blocked by moisture
2Reliability
If the electric heater is operated to raise the temperature of the NOx adsorbent, then moisture is desorbed, but energy is consumed
Solution Approach 1:
The electric heater is operated during the period before engine operation (when no exhaust gas is flowing) to desorb moisture, utilizing this idle time to restore adsorption capacity without interfering with engine operation and minimizing energy consumption to essential levels
3Quantity of substance
If the temperature of the NOx adsorbent is raised above the NOx desorption temperature, then moisture is desorbed, but NOx is also desorbed prematurely
Solution Approach 1:
The heating process is precisely controlled to maintain the NOx adsorbent temperature within a specific range (above moisture desorption temperature but below NOx desorption temperature), creating different thermal conditions for different adsorption processes - moisture desorbs at lower temperatures while NOx remains adsorbed until higher temperatures are reached
Solution Approach 2:
The temperature parameter of the NOx adsorbent is carefully controlled to fall within a specific window between the moisture desorption temperature and NOx desorption temperature, enabling selective desorption of moisture while preserving NOx adsorption
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 effectively maintains the NOx adsorbent's absorption capacity while reducing NOx emissions into the atmosphere until the NOx purifying catalyst is fully activated, by preheating the NOx adsorbent to desorb moisture and allowing NOx adsorption without premature NOx release.
Implementation Method 1
an electric heater for raising the temperature of the NOx adsorbent
Implementation Method 2
the gas which is present in the engine exhaust passage contains moisture. This moisture is adsorbed at the NOx adsorbent before the engine is restarted
Implementation Method 3
the NOx adsorbent having the property of the adsorbed moisture starting to be desorbed when raising the temperature of the NOx adsorbent and the temperature of the NOx adsorbent reaches a moisture desorption temperature
Implementation Method 4
an NOx purifying catalyst for purifying NOx in the exhaust gas
Data Source
AI summary
An exhaust purification device for an internal combustion engine is provided with an NOx adsorbent for adsorbing NOx in exhaust gas and an NOx purifying catalyst for purifying NOx in exhaust gas, which are arranged in an engine exhaust passage. An electric heater is provided for raising the temperature of the NOx adsorbent. When a signal requesting startup of an internal combustion engine is issued, the device starts to supply electric power to the electric heater before the internal combustion engine completely warms up, and supplies the electric heater with a quantity of electric power making the temperature of the NOx adsorbent equal to or higher than the moisture desorption temperature but lower than the NOx desorption temperature.