Aircraft Emergency Power Unit With Fuel Cell Start-Up Storage
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Solution Overview
Problem
Existing emergency power units in aircraft, such as those using ram air turbines or fuel cells, face challenges in rapid start-up times due to the response time of turbomachines needed to supply air and fuel, which can exceed the required emergency response duration.
Innovation Solution
An emergency power unit system that includes a fuel cell system and an electrical storage system, where the electrical storage instantaneously provides power to the aircraft electrical bus and the fuel cell starter motor, allowing for rapid start-up of the fuel cell system, and transitions to parallel operation with the fuel cell system once operational, ensuring quick and reliable power delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fuel cell system with turbomachine is used to generate emergency power, then power can be supplied to the aircraft electrical bus, but the response time to reach design pressure lags behind the required emergency response time
Solution Approach 1:
The electrical storage device is pre-charged and ready to provide instantaneous power during emergency start-up, enabling the fuel cell system to begin operation immediately without waiting for the turbomachine to reach design pressure. This preliminary energy storage resolves the time lag by having power available before the fuel cell system is fully operational.
2Loss of time
If electrical storage is added to provide instantaneous power, then start-up time is reduced, but system complexity increases
Solution Approach 1:
The electrical storage device is directly connected to both the aircraft electrical bus and the fuel cell system, merging its output with the fuel cell power supply. This combination allows the system to draw from both sources simultaneously or sequentially, reducing start-up time while managing complexity through integrated connection architecture.
Solution Approach 2:
The electrical storage device serves multiple functions: providing instantaneous power during start-up, supplementing power during operation, and potentially providing backup power. This multi-functionality justifies the added complexity by delivering multiple benefits from a single component addition.
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 enables instantaneous power delivery to critical aircraft systems during emergencies, meeting safety regulations by starting the fuel cell system within a few seconds and providing sustained power, thereby addressing the lag in turbomachine response times.
Implementation Method 1
a fuel cell system configured to generate power using a fuel and an oxidizer and to supply electrical power to an aircraft electrical bus
Implementation Method 2
An electrical storage is operatively connected to the aircraft electrical bus and directly connected to the fuel cell system to provide electrical power to the aircraft electrical bus and to the fuel cell system
Implementation Method 3
The starter motor of the fuel cell system can be operatively connected to the compressor to drive the compressor for a first duration. The first duration can be a duration for the compressor to start and reach operational speed.
Data Source
Figure 1
AI summary
In accordance with at least one aspect of this disclosure, an emergency power unit system for an aircraft includes, a fuel cell system (102) configured to generate power using a fuel and an oxidizer and to supply electrical power to an aircraft electrical bus in at least a fuel cell operational mode. An electrical storage (130) is operatively connected to the aircraft electrical bus (110) and directly connected to the fuel cell system to provide electrical power to the aircraft electrical bus and to the fuel cell system in a fuel cell start up mode.