Coolant Flow Control for Aftercooler Thermal Stress
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Solution Overview
Problem
Aftercoolers in internal combustion engines face thermal stress due to increased heat rejection and transient operation, leading to reduced lifespan, and existing solutions either compromise engine performance or increase size and cost.
Innovation Solution
A coolant flow control system that includes a fluid cooling device, a coolant bypass circuit, and a controller to manage coolant flow based on projected temperature gradient changes, using sensors to adjust the bypass valve position and minimize thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the overall temperature in the aftercooler is reduced to reduce thermal stresses, then thermal stress cycles decrease, but engine performance is negatively impacted or aftercooler size increases
Solution Approach 1:
The system dynamically adjusts coolant flow rate through the aftercooler based on real-time operating conditions (engine load, ambient temperature, aftercooler inlet temperature). The controller modulates the coolant flow to maintain optimal temperature gradients that minimize thermal stress cycles while ensuring adequate cooling for engine performance across varying operating conditions.
Solution Approach 2:
The system changes the coolant flow rate parameter dynamically based on operating conditions. By adjusting this parameter, the system optimizes the temperature gradient across the aftercooler core to reduce thermal stress cycles during transient operation while maintaining effective heat rejection when needed for engine performance.
2Reliability
If higher strength constituent materials are used to withstand thermal stresses, then aftercooler durability improves, but manufacturing cost increases and heat transfer properties may deteriorate
Solution Approach 1:
The system performs preliminary action by actively controlling coolant flow to prevent excessive thermal stress cycles before they can cause damage. By managing the thermal environment proactively, the system protects the standard-material aftercooler from conditions that would otherwise require higher-strength, more expensive materials.
Solution Approach 2:
The system converts the potential harm of thermal stress cycles into a manageable parameter through active control. By using sensors and a controller to monitor and adjust coolant flow, the system transforms what would be a material limitation into a controllable operational parameter, allowing standard materials to perform as if they were higher-strength materials.
3Productivity
If brazing process is used to assemble aftercooler components, then manufacturing efficiency improves, but joint fatigue characteristics deteriorate due to copper's low mechanical strength
Solution Approach 1:
The system takes preliminary action by controlling coolant flow to prevent thermal conditions that would cause fatigue in the brazed joints. By managing temperature gradients and avoiding rapid thermal transients, the system protects the inherently vulnerable brazed joints from fatigue damage throughout the aftercooler's service life.
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
The system reduces thermal stress cycles in aftercoolers, extending their lifespan and maintaining engine performance without increasing size or cost.
Implementation Method 1
the differences in Coefficient of Thermal Expansion (CTE) of the various materials within the core, induces stresses in the core. Changes in engine power and charge-air flow interrupt this balance resulting in a new temperature gradient and a new distribution of stress.
Implementation Method 2
aftercoolers on internal combustion engines are required to reject increased heat
Implementation Method 3
the aftercooler eventually reaches a steady state thermal condition characterized by a substantially constant temperature gradient through the depth of the aftercooler core
Data Source
AI summary
A coolant flow control system includes a fluid cooling device, a coolant bypass circuit, and a controller. The controller is configured to generate a control signal indicative of a desired flow of coolant through the coolant bypass circuit as a function of the projected rate of change in the cooling device temperature gradient.