Hydrogen Fuel Vaporization Before Pumping in Aircraft Engines
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Solution Overview
Problem
Efficient heating of liquid hydrogen fuel for aircraft propulsion systems, such as gas turbine engines and hydrogen fuel cells, poses significant challenges due to the high energy requirements and difficulties in pumping cryogenic liquids.
Innovation Solution
A fuel system that vaporizes cryogenically-stored hydrogen using burner exhaust heat, followed by further heating to propulsion system delivery temperature, minimizing pumping work and energy input by utilizing a single heat source for vaporization and heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If liquid hydrogen fuel is pumped directly to the engine, then the fuel delivery system is simplified, but the pumping work and energy requirements increase significantly due to the cryogenic temperature and low density
Solution Approach 1:
The patent changes the physical state parameter of hydrogen fuel from liquid to gaseous/supercritical phase before pumping. This parameter change increases the density and reduces viscosity, making the fuel more suitable for pumping while reducing the energy required by the pump. The vaporizer heats the liquid hydrogen to convert it to a gaseous or supercritical state, which is then pumped with significantly lower energy consumption.
Solution Approach 2:
The patent applies preliminary heating action through the vaporizer before the fuel enters the pump. By pre-heating the liquid hydrogen to convert it to a gaseous or supercritical state, the system prepares the fuel in an optimal state for pumping, reducing the workload and energy consumption of the subsequent pumping operation.
2Temperature
If the hydrogen fuel is heated to propulsion system delivery temperature before pumping, then the fuel meets engine requirements, but the energy input and system complexity increase
Solution Approach 1:
The system uses the fuel itself as the heating medium. A portion of the hydrogen fuel is diverted to the vaporizer where it is burned to generate heat, and this heat is then used to vaporize and heat the main fuel stream. The fuel serves dual purposes: as a combustion source and as the material being heated, eliminating the need for external heating systems and reducing overall energy input requirements.
Solution Approach 2:
The patent converts the potentially wasteful exhaust heat from the burner into a useful resource for heating the fuel. The exhaust gases from the hydrogen burner, which would otherwise be discarded, are used as the heat source in the heat exchanger to vaporize and heat the main fuel stream, turning a waste product into a beneficial heating source.
3Loss of energy
If a single heat source is used for both vaporization and heating, then energy efficiency improves, but the system design becomes more complex
Solution Approach 1:
The burner exhaust heat exchanger performs multiple functions within a single component: it vaporizes liquid hydrogen, heats the gaseous fuel to delivery temperature, and utilizes the exhaust heat that would otherwise be wasted. This multi-functional design achieves high energy efficiency by cascading the thermal energy utilization through different stages of fuel preparation.
4Weight of moving object
If hydrogen fuel is pumped in liquid state, then pump size can be smaller, but the pumping becomes highly inefficient and energy-consuming
Solution Approach 1:
The patent changes the physical parameters of the hydrogen fuel (temperature and phase) before pumping. By heating the liquid hydrogen to convert it to a gaseous or supercritical state, the fuel achieves optimal temperature and density characteristics for efficient pumping, resolving the contradiction between pump size and pumping efficiency.
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
Reduces the energy and power requirements for hydrogen fuel delivery, minimizing pump size and weight, and enhances system efficiency by pumping hydrogen in a gaseous or supercritical state, avoiding the inefficiencies of liquid hydrogen pumping.
Implementation Method 1
the vaporizer comprises a burner configured to burn a portion of the hydrogen fuel from the fuel line
Implementation Method 2
a first burner exhaust heat exchanger configured to exchange exhaust heat from the burner exhaust with hydrogen fuel in the fuel line
Implementation Method 3
configured to vaporize liquid hydrogen fuel from the fuel line to generate a supercritical or gaseous fuel
Implementation Method 4
a second heat exchanger provided downstream of the main fuel pump in fuel flow, the second heat exchanger being configured to exchange exhaust heat from the burner exhaust downstream of the first heat exchanger in exhaust flow, with gaseous hydrogen downstream of the main fuel pump in main fuel flow
Data Source
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AI summary
An aircraft propulsion system fuel system (224) comprises a fuel line (217) configured to receive liquid hydrogen fuel from a fuel tank (104), a vaporizer (612) configured to vaporize liquid hydrogen fuel from the fuel line to generate a supercritical or gaseous fuel, a main fuel pump (618) configured to receive and to pump the gaseous or supercritical fuel from the vaporizer during operation of the propulsion system, and a heater (620) provided downstream in fuel flow to the main fuel pump (618), and configured to raise the temperature of the gaseous or supercritical fuel to a propulsion system delivery temperature.