Bimetallic Fin Heat Exchanger for Passive Flow Regulation
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Solution Overview
Problem
Existing tube-fin heat exchangers are heavy, require complex control systems, and introduce additional failure modes due to their design and manufacturing limitations, which hinder efficient heat transfer and regulation.
Innovation Solution
A bimetallic fin heat exchanger that passively regulates the flow of cooling fluids by utilizing fins with different thermal expansion coefficients to alter the flow passages' area, allowing for passive control of heat transfer based on temperature changes, thereby optimizing cooling capacity without the need for active control systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If active control systems (control loops, blocker doors) are used to control heat transfer, then heat transfer regulation is achieved, but device complexity and weight increase
Solution Approach 1:
The heat exchanger fins are designed with bimetallic construction that automatically adjusts flow passages in response to temperature changes, eliminating the need for external control systems. The system self-regulates heat transfer based on thermal conditions without requiring control loops or blocker doors
Solution Approach 2:
The bimetallic fin structure utilizes differential thermal expansion between two metals with different expansion coefficients. As temperature changes, the fins expand or contract at different rates, passively opening or closing flow passages to regulate cooling fluid flow and control heat transfer
2Power
If traditional tube-fin heat exchanger structures are used, then heat transfer function is achieved, but weight increases
Solution Approach 1:
The heat exchanger employs bimetallic composite fins combining two different metals, each selected for specific properties. This composite structure achieves the desired heat transfer function while optimizing weight by selecting materials with appropriate strength-to-weight ratios and thermal conductivities
Solution Approach 2:
The differential thermal expansion property of the bimetallic fins enables passive flow regulation without adding heavy control mechanisms. The inherent material property is exploited to achieve control functionality while maintaining lightweight construction
3Ease of manufacture
If traditional heat exchanger designs are used, then manufacturing is achieved, but additional failure modes are introduced
Solution Approach 1:
By eliminating control loops, sensors, and blocker doors, the design removes multiple potential failure points. The passive bimetallic fin structure has no moving parts or electronic components that could fail, significantly improving system reliability while remaining manufacturable
Solution Approach 2:
The invention extracts and removes the control system components (control loops, blocker doors, actuators) from the heat exchanger design. This simplification eliminates the failure modes associated with these components while maintaining the essential heat transfer function through passive thermal regulation
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 bimetallic fin design enhances heat transfer efficiency by dynamically adjusting the flow area and surface area, reducing weight and complexity while maintaining reliable operation across varying temperature ranges.
Implementation Method 1
Each fin of the plurality of fins is bimetallic and can be configured passively to regulate the flow of the cooling fluid across the fins of the heat exchanger
Implementation Method 2
heat exchangers may be used to transfer heat between a relatively hot air source (e.g., bleed air from a gas turbine engine) and a relatively cool air source (e.g., ram air)
Data Source
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AI summary
A heat exchanger (10) is configured to adjust a flow restriction of flow passages through the heat exchanger in response to changes in temperature of elements that define at least a portion of the flow passages. The elements include a first material having a first coefficient of thermal expansion, and a second material having a second coefficient of thermal expansion that is different from the first coefficient of thermal expansion.