Hydrogen Fuel Heat Exchanger Thermal Buffer Design
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Solution Overview
Problem
Hydrogen fuel heat exchangers for aircraft engines face challenges in maintaining structural integrity and thermal performance due to water and air freezing at the outer surface, while minimizing connection points to prevent hydrogen leakage, resulting in bulky and heavy designs that are not ideal for aircraft applications.
Innovation Solution
A compact heat exchanger with anti-freezing capability using heat transfer fins and a thermal buffer around each tube of a tube bank, featuring single-run inner-tubes that meander to form multiple parallel rows, with varying thermal buffer thickness and material conductivity along the tube length to manage thermal gradients and minimize pressure drop, and an optional recirculated tertiary fluid for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If hydrogen fuel is stored at extremely cold temperatures and heated to gaseous state, then the fuel can be combusted by aircraft engines, but water and air freeze at the outer surface of the heat exchanger, compromising structural integrity
Solution Approach 1:
The patent applies preliminary action by providing thermal insulation around the heat exchanger tubes before the freezing issue occurs. The insulation layer is pre-installed to prevent water and air from freezing on the outer surface, thereby maintaining structural integrity throughout the heating process of the hydrogen fuel.
Solution Approach 2:
The patent introduces thermal insulation as an intermediary layer between the cold hydrogen fuel pipes and the external environment (water and air). This intermediary prevents direct contact between the cold surface and moisture in the air, eliminating the freezing problem while allowing the hydrogen to be heated to the required temperature.
2Strength
If the heat exchanger design is made bulky to ensure structural integrity, then structural strength is improved, but the device becomes heavy and unsuitable for aircraft applications
Solution Approach 1:
The patent employs thin film thermal insulation layers instead of bulky structural reinforcements. These thin insulation films provide sufficient protection against freezing while adding minimal weight, allowing the heat exchanger to maintain structural integrity without becoming too heavy for aircraft applications.
Solution Approach 2:
The patent uses composite material structures combining the heat exchanger tubes with thermal insulation layers. This composite design provides both the necessary structural integrity and thermal protection, achieving strength requirements without the excessive weight that would result from traditional bulky designs.
3Use of energy by moving object
If multiple connection points are used in the heat exchanger, then thermal performance is improved, but hydrogen leakage risk increases
Solution Approach 1:
The patent merges multiple connection points into fewer, more reliable connections by using continuous tubing designs or welded joints throughout the heat exchanger. This reduces the total number of potential leakage points while maintaining effective thermal contact between components, thus improving reliability without sacrificing heat transfer efficiency.
Solution Approach 2:
The patent replaces mechanical connection points (which are prone to leakage) with alternative joining methods such as welding or brazing. This substitution eliminates the need for multiple discrete connection points, reducing hydrogen leakage risk while maintaining the thermal performance necessary for effective heat exchange.
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 solution provides a compact, efficient, and structurally robust heat exchanger that maintains thermal performance while minimizing hydrogen leakage risks, optimizing heat transfer, and ensuring structural integrity, suitable for aircraft applications.
Implementation Method 1
a thermal buffer least partially surrounding the inner-tube... with varying thermal buffer thickness and material conductivity along the tube length to manage thermal gradients
Implementation Method 2
thermal energy from the hot-side-fluid is transferred to the H2 hydrogen fuel
Implementation Method 3
a plurality of fins disposed along the inner-tube and extending radially outwardly from an outer surface of the thermal buffer
Implementation Method 4
a plurality of fins disposed along the inner-tube and extending radially outwardly from an outer surface of the thermal buffer
Data Source
AI summary
A heat exchanger for a hydrogen fuel delivery system includes a tube bank including an inner-tube where a first portion of the inner-tube extends through an inlet region of the tube bank, a second portion of the inner-tube extends through a mid-region of the tube bank, and a third portion of the inner-tube extends through an outlet region of the tube bank. A thermal buffer at least partially surrounds the inner-tube. A first portion of the thermal buffer extends along the first portion of the inner-tube, a second portion of the thermal buffer extends along the second portion of the inner-tube, and a third portion of the thermal buffer extends along the third portion of the inner-tube. A plurality of fins is disposed along the inner-tube and extends radially outwardly from an outer surface of the thermal buffer.