Thermal Stress Management in Heat Exchanger Walls
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Solution Overview
Problem
Heat exchangers and pressure vessels face limitations in accommodating rapid transients in process temperatures, leading to high thermal stresses and potential mechanical failures due to thick walls that resist fast temperature changes.
Innovation Solution
Integration of flow passages within the walls of these structures to actively manage temperature gradients by circulating fluid, allowing for controlled heating or cooling during transients, thereby reducing thermal stresses and increasing ramp rate capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thick walls are used in heat exchangers and pressure vessels, then strength and pressure containment are improved, but thermal stress resistance during rapid temperature transients deteriorates
Solution Approach 1:
The patent segments the thick wall structure by introducing internal flow passages that divide the wall into multiple zones. These passages allow independent thermal management of different wall sections, enabling the inner and outer surfaces to experience more uniform temperature changes during transients, thereby reducing thermal gradients and associated stresses while maintaining the overall structural integrity provided by the thick wall.
Solution Approach 2:
The patent introduces a thermal management fluid as an intermediary substance circulating through the internal flow passages. This fluid acts as a heat transfer medium that actively regulates temperature distribution within the thick wall, absorbing or releasing heat as needed to minimize thermal gradients between the inner and outer surfaces during rapid temperature transients, thus protecting the structure from thermal fatigue.
2Strength
If thick walls are used in heat exchangers and pressure vessels, then pressure boundary strength is improved, but ramp rate capability deteriorates
Solution Approach 1:
The patent implements preliminary thermal action by circulating thermal management fluid through the flow passages before and during temperature transients. This pre-conditioning of the wall structure through active fluid circulation prepares the thermal field, reducing the thermal inertia effect and enabling faster ramp rates by anticipating and mitigating thermal gradients before they cause damaging stresses.
Solution Approach 2:
The patent transforms the static thick wall structure into a dynamically controllable thermal system. By introducing actively circulated fluid through the flow passages, the thermal properties of the wall can be dynamically adjusted during operation, allowing the structure to adapt its thermal response to varying operating conditions and achieve higher ramp rates while maintaining structural integrity.
3Reliability
If active thermal management with flow passages is implemented, then thermal stress resistance is improved, but device complexity increases
Solution Approach 1:
The patent merges the structural function of the pressure vessel wall with the thermal management function by integrating flow passages directly into the wall structure. This combination eliminates the need for separate external cooling/heating systems and complex mounting arrangements, as the thermal management channels are embedded within the load-bearing structure itself, thereby reducing overall system complexity while maintaining effective thermal stress control.
Solution Approach 2:
The patent creates a multi-functional wall structure where the same component serves both structural pressure containment and active thermal management purposes. The thick wall provides strength and pressure containment, while the integrated flow passages enable active thermal control, allowing a single structure to perform multiple functions that would traditionally require separate systems, thus reducing device complexity.
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 minimizes transient thermal stresses, enhancing the ability to handle rapid temperature changes without material limitations, thus improving the operational flexibility and reliability of heat exchangers and pressure vessels.
Implementation Method 1
The method uses flow passages in the walls to circulate fluid to actively manage temperature gradients
Implementation Method 2
This approach effectively minimizes transient thermal stresses, enhancing the ability to handle rapid temperature changes
Data Source
AI summary
A method of managing transient thermal stresses in a wall of a fluid-carrying or fluid-containing structure, the structure having a temperature ramp rate limit associated with its structure walls. The structure is provided with flow passages in the structure walls, and the temperature of the structure walls is monitored. If a rate of change of temperature of the structure walls becomes too high, fluid is circulated through the flow passages to heat or cool the structure wall during hot or cold transient thermal events, respectively.