Fuel Cell Power Generator for Unmanned Air Systems
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Solution Overview
Problem
Unmanned air systems (UAS) are limited by the short flight times of their power sources, specifically lithium ion/polymer batteries, and existing hydrogen generators for fuel cells are either too heavy or unable to generate hydrogen at a high enough rate for extended flight applications.
Innovation Solution
A fuel cell based power generator system using lithium aluminum hydride (LAH) that recirculates hydrogen and eliminates the need for a water fuel reservoir, incorporating a hydrogen generator and a recirculating hydrogen path to enhance energy efficiency and extend flight times, with a controller managing temperature and fluid flow to optimize power generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If commercially available hydrogen sources (metal hydrides, compressed hydrogen cylinders, catalytic waterborohydride generators) are used, then high rate hydrogen generation is achieved, but weight and size increase significantly
Solution Approach 1:
The patent extracts the water reservoir function from the hydrogen generation system by using ambient air as the water source. The lithium aluminum hydride reacts with water extracted from ambient air through a water extraction element, eliminating the need for carrying heavy water fuel reservoirs while maintaining high-rate hydrogen generation capability
Solution Approach 2:
The patent introduces a water extraction element as an intermediary component that extracts water from ambient air and transfers it to the lithium aluminum hydride. This mediator enables the system to obtain water from the environment rather than carrying it, significantly reducing system weight while maintaining hydrogen generation functionality
2Weight of moving object
If light-weight and small-size hydrogen generators are used, then weight and size are reduced, but hydrogen generation rate becomes insufficient for extended flight applications
Solution Approach 1:
The patent implements dynamic control of the hydrogen generation system through a controller that monitors flight conditions and adjusts the hydrogen generation rate accordingly. The controller regulates the water extraction rate and hydrogen flow to match the fuel cell's instantaneous power demands, enabling the compact system to deliver variable high-rate hydrogen generation when needed
Solution Approach 2:
The patent establishes continuous hydrogen generation and recirculation through a closed-loop system. Hydrogen generated from lithium aluminum hydride reacts with oxygen from ambient air in the fuel cell, and the product water is continuously extracted from ambient air and fed back to generate more hydrogen, creating an uninterrupted cycle that sustains high-rate generation without interruption
3Duration of action of moving object
If lithium ion/polymer batteries are used for power storage, then flight time is limited to 20-60 minutes, but extending flight time requires heavier or bulkier energy storage systems
Solution Approach 1:
The patent fundamentally changes the energy storage parameter from chemical energy in batteries to chemical energy in lithium aluminum hydride combined with ambient oxygen. This parameter change enables extended flight times of six to twelve hours or more while maintaining light weight, as the fuel cell system converts chemical energy to electrical energy continuously without the weight penalties of extended battery capacity
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 provides four to twelve times the flight time of state-of-the-art lithium batteries, achieving six to twelve hours of flight time while being lighter and having lower lifecycle costs, with improved energy efficiency and temperature control for extended operation.
Implementation Method 1
A fuel cell based power generator system uses lithium aluminum hydride (LAH) and converts the chemical energy into electrical energy
Implementation Method 2
uses lithium aluminum hydride (LAH) and converts the chemical energy into electrical energy
Data Source
AI summary
A fuel cell based power generator includes a fuel cell element, an ambient air path configured to receive ambient air and provide the ambient air across a cathode side of the fuel cell element, receive water from the fuel cell element and provide wet air to the water exchanger element, and a fuel cell cooling mechanism associated with the fuel cell element, separate from the ambient air path and configured to cool the fuel cell element.