CAC Condensate Vaporization via EVAP Canister Heater
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Solution Overview
Problem
Condensate accumulation in charge air coolers (CACs) leads to engine misfires and mechanical wear due to ingestion during increased airflow, and existing solutions either increase system complexity or relocate condensate issues like freezing and corrosion.
Innovation Solution
Flowing heated air from a fuel vapor canister through the CAC using an electric booster to vaporize condensate, reducing accumulation and wear by routing heated air through the CAC, which is facilitated by operating the electric booster in reverse to generate vacuum and using existing engine components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If airflow through the CAC is increased to remove condensate, then condensate build-up is reduced, but system complexity increases due to additional valves and controls
Solution Approach 1:
The canister heater, originally designed solely for heating fuel vapors during EVAP purging, is repurposed to also heat air for condensate removal from the CAC. This multi-functional use eliminates the need for dedicated condensate heating equipment, reducing system complexity while maintaining effective condensate removal capability
Solution Approach 2:
The system uses its own existing components (canister heater, EVAP valves, electric booster) to perform condensate removal without requiring external or additional specialized equipment. The engine's intake system itself serves to draw heated air through the CAC, creating a self-service mechanism that avoids adding complexity
2Reliability
If condensate is trapped and drained from the CAC, then condensate levels in the CAC are reduced, but condensate is moved to an alternate location where freezing and corrosion problems occur
Solution Approach 1:
The system changes the temperature parameter of the air flowing through the CAC by heating it with the canister heater. This temperature change transforms condensate from liquid to vapor phase, preventing it from reaching locations where freezing and corrosion could occur. The heated air (typically 80-100°C from the canister heater) ensures condensate is vaporized before being moved
Solution Approach 2:
The system utilizes phase transition of water from liquid to vapor by heating air passing through the CAC. The canister heater raises air temperature above the dew point, causing liquid condensate to evaporate into vapor that can be safely transported through the intake system without freezing or causing corrosion
3Reliability
If a variable volume CAC is used to adjust airflow, then condensate build-up is reduced, but additional parts and controls are required
Solution Approach 1:
The existing EVAP canister heater and valve system, originally designed for emissions control, is repurposed to also control airflow for condensate removal. The canister purge valve and vent solenoid are used to regulate heated air flow through the CAC, eliminating the need for variable volume CAC mechanisms while achieving the same condensate management goal
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 effectively reduces engine misfires and mechanical wear by maintaining a dry CAC, improving engine operation and fuel efficiency while minimizing additional hardware costs and complexity.
Implementation Method 1
flowing heated air from a fuel vapor canister of an evaporative emissions control (EVAP) system through a charge air cooler (CAC) in an intake system to vaporize condensate in the CAC
Implementation Method 2
operating an electric booster coupled to the intake passage upstream of the CAC in a reverse direction to generate a vacuum in the intake passage
Data Source
AI summary
Methods and systems are provided for removing condensate form a charge air cooler coupled to an engine intake system. In one example, a method may include flowing heated air from a fuel vapor canister of an evaporative emissions control (EVAP) system through the charge air cooler to vaporize condensate in the CAC. The air is drawn in from atmosphere by operating an electric booster in a reverse direction and the air is heated at the canister by operating a canister heater.