Dual Fuel Engine System for Aircraft Range and Surge Control
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Solution Overview
Problem
The low effective specific energies of hydrogen and ammonia make them unsuitable for medium or long range journeys in aircraft or vehicles, due to the heavy storage tanks required for hydrogen and the higher fuel mass flow needed for ammonia.
Innovation Solution
A method of operating an engine system that uses a combination of two fuels, where the first fuel is provided at a first mass flow rate and the second fuel is provided at a second mass flow rate, with the relative fraction of the second fuel increased during engine acceleration to control the surge margin, and the second fuel is selected to have a higher specific energy and release more water per unit mass of fuel than the first fuel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If hydrogen is used as fuel, then high specific energy is achieved, but heavy storage tanks are required reducing effective specific energy
Solution Approach 1:
The fuel system is segmented into multiple fuel types (hydrogen/ammonia and hydrocarbon) stored in separate tanks, allowing the vehicle to leverage the high specific energy of hydrogen while using hydrocarbon fuel for extended range, thereby mitigating the weight penalty of hydrogen storage tanks
Solution Approach 2:
The system changes the fuel parameter by switching between different fuel types based on operational requirements, using hydrogen for high efficiency and hydrocarbon for range extension, optimizing the effective specific energy across different flight phases
2Ease of manufacture
If ammonia is used as fuel, then easier storage is achieved, but greater fuel mass flow is required reducing effective specific energy
Solution Approach 1:
The fuel system combines ammonia (easy to store) with hydrocarbon fuel, where ammonia provides storage advantages while hydrocarbon fuel compensates for the lower specific energy through blended combustion, maintaining effective specific energy levels
Solution Approach 2:
The system adjusts the fuel composition parameter by blending ammonia with hydrocarbon fuel in varying proportions, optimizing the balance between storage ease and effective specific energy based on operational conditions
3Length of moving object
If dual fuel system is used, then range is maximized, but device complexity increases
Solution Approach 1:
The fuel system is divided into separate storage and delivery systems for each fuel type, with individual control mechanisms that can be independently managed, reducing the complexity of coordinating multiple fuel systems compared to a fully integrated approach
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
This approach maximizes the range of vehicles powered by gas turbine engines while maintaining reduced carbon dioxide emissions, by optimizing fuel efficiency and surge margin control during engine acceleration.
Implementation Method 1
mechanical power is generated by combustion or oxidation of a fuel in an engine
Data Source
AI summary
A system comprises first and second first fuel stores, an engine arranged to produce mechanical power, a fuel distribution system arranged to deliver fuel from the first and second fuel stores to the engine, the first fuel delivered at a first mass flow rate, the second fuel delivered at a second mass flow rate, the first and second mass flow rates contributing to a total mass flow rate of fuel to the engine, and a control system arranged to increase the relative fraction of the total mass flow rate of fuel represented by the second mass flow rate during a period of acceleration of the engine, in order to control a surge margin of the engine. The second fuel is selected to have a higher specific energy than the first fuel and to release a greater mass of water per unit mass of fuel than the first fuel.