Heat Pipe Fuel Cell Cooling for Flooding Risk and Weight Reduction
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Solution Overview
Problem
The existing fuel cell systems for aircraft face challenges in weight reduction due to the large size of pre-warmers or recuperators required to manage the steep temperature gradient in two-phase cooling systems, which can lead to flooding and other risks.
Innovation Solution
A fuel cell system with a two-phase cooling system that incorporates a thermally conductive element between the coolant inlet and outlet to efficiently transfer heat from the coolant outlet to the inlet, reducing the need for pre-warmers and enhancing weight reduction opportunities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a preheater or recuperator is used upstream of the evaporator to mitigate the steep temperature gradient, then the risk of condensation and flooding is reduced, but the system weight increases significantly
Solution Approach 1:
The patent extracts and eliminates the preheater/recuperator component from the two-phase cooling system. By redesigning the coolant flow path and thermal management architecture, the system achieves reliable operation without this heavy component, directly resolving the contradiction between reliability and weight.
Solution Approach 2:
The cooling system is designed to self-regulate temperature gradients through passive thermal management features integrated into the evaporator and coolant channels. The system uses its own operational characteristics (phase change, heat transfer) to mitigate condensation risks without requiring external preheating equipment.
2Loss of energy
If liquid cooling is used in commercial fuel cell stacks, then heat dissipation is achieved, but the system weight is high
Solution Approach 1:
The patent employs two-phase cooling where the coolant undergoes phase transition from liquid to vapor and back, utilizing latent heat of vaporization for highly efficient heat dissipation. This eliminates the need for heavy liquid cooling systems while achieving superior thermal management performance.
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 implementation of a thermally conductive element between the coolant inlet and outlet in the fuel cell system improves heat transfer efficiency, reduces weight, and mitigates risks associated with temperature gradients, thereby enhancing the overall performance and reliability of the cooling system.
Implementation Method 1
a thermally conductive element (28) is provided between the coolant inlet (14) and the coolant outlet (16), wherein the thermally conductive element (28) is configured to transfer heat from the coolant outlet (16) to the coolant inlet (14)
Implementation Method 2
Two-phase cooling relies on phase transitions in the evaporator (fuel cells) and in the heat exchanger with the environment (condenser). To pump the coolant to the fuel cell, it is necessary for the coolant to be supercooled, i.e., in a liquid state (to prevent pump cavitation).
Implementation Method 3
This utilizes the latent heat of vaporization to dissipate large amounts of heat from the fuel cells.
Implementation Method 4
To pump the coolant to the fuel cell, it is necessary for the coolant to be supercooled, i.e., in a liquid state (to prevent pump cavitation). Supercooling refers to the temperature range below the coolant's boiling point.
Data Source
Figure 1~2
AI summary
A fuel cell system (10) with a two-phase cooling system is specified, comprising: at least one fuel cell (12) with a coolant inlet (14) and a coolant outlet (16), a collector (18) wherein the collector (18) is in fluid communication with the fuel cell (12) and is configured to contain coolant (20) flowing from the fuel cell (12) in a gas phase in a first section (22) and a liquid phase in a second section (24), a condenser (26) wherein the condenser (26) is in fluid communication with the collector (18) and is configured to condense and subcool the coolant, wherein a thermally conductive element (28) is provided between the coolant inlet (14) and the coolant outlet (16), the thermally conductive element (28) being configured to transfer heat from the coolant outlet to the coolant inlet.