Engine Thermal Management Using Phase Change Material
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Solution Overview
Problem
Current methods for thermal management in combustion engines often compromise fuel efficiency and power output to achieve optimal aftertreatment device regeneration, as they require additional fuel or restricted air intake, leading to inefficiencies and thermal stress on components.
Innovation Solution
An apparatus and method that utilize a torque-speed map to adjust engine operation, determining a regeneration index to shift the speed-load target between regions on the map, optimizing thermal management and fuel efficiency by adjusting engine behavior such as fuel injection, air-fuel ratio, and turbocharger settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If additional fuel is added in-cylinder or downstream of exhaust manifold to increase exhaust stream temperature, then aftertreatment device regeneration is improved, but fuel efficiency deteriorates due to combustion cycle phase disturbance, unburned fuel in exhaust stream, and decreased air to fuel ratio
Solution Approach 1:
The patent introduces a thermal energy storage medium (phase change material) as an intermediary between the exhaust stream and the aftertreatment device. This mediator absorbs excess thermal energy during normal operation and releases it during regeneration, enabling temperature control without adding fuel. The phase change material acts as a thermal buffer that decouples the relationship between fuel injection and exhaust temperature, eliminating the need for fuel dosing while maintaining regeneration capability.
2Temperature
If air intake is restricted to raise exhaust stream temperature, then aftertreatment device regeneration is improved, but engine power output deteriorates due to backpressure on the engine
Solution Approach 1:
The thermal energy storage medium serves as a mediator that enables temperature control without restricting air flow. By storing and releasing thermal energy, the system can maintain high exhaust temperatures for regeneration without creating backpressure that would reduce engine power output. This eliminates the trade-off between temperature and power by decoupling thermal management from air flow restriction.
3Reliability
If fuel dosing is used to achieve temperature thresholds for catalytic converter regeneration, then aftertreatment device maintenance is improved, but harmful emissions increase due to unburned fuel in the exhaust stream
Solution Approach 1:
The phase change material acts as a thermal intermediary that enables regeneration without fuel dosing. By storing thermal energy during normal operation and releasing it during regeneration events, the system achieves the necessary temperature thresholds for catalytic converter maintenance without introducing unburned fuel into the exhaust stream. This eliminates the harmful emissions associated with fuel dosing while maintaining aftertreatment device reliability.
4Temperature
If variable geometry turbocharger is used to create exhaust stream restriction, then exhaust stream temperature increases, but engine work efficiency deteriorates due to backpressure
Solution Approach 1:
The thermal energy storage medium serves as a mediator that decouples temperature control from exhaust flow restriction. Instead of using variable geometry turbocharger to create backpressure for temperature increase, the system uses the phase change material to store and release thermal energy. This eliminates the energy losses associated with exhaust restriction while maintaining the ability to achieve necessary temperatures for aftertreatment device regeneration.
Data Source
AI summary
A method is disclosed for thermal management of an engine comprising a continuously variable transmission. The method includes an engine capability module storing a torque-speed map comprising a first region where the engine inefficiently regenerates an aftertreatment device, a second region where the engine efficiently regenerates the aftertreatment device, and a third region where the engine is not capable of regenerating the aftertreatment device. The method further includes an aftertreatment determination module determining a regeneration index, an operating conditions module determining an engine speed and an engine load, and a speed-load adjustment module adjusting a speed-load target. The method further includes the speed-load adjustment module adjusting the speed-load target to a preferred region along equal power curves of the torque-speed map based on the regeneration index.