Cryogenic Fuel Startup Using Two-Stage Thermal Vaporization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Cryogenic fuels stored in a liquid state require significant energy to vaporize without access to heat generated during engine operation, posing a challenge in starting gas turbine engines efficiently.
Innovation Solution
A two-stage thermal energy generation system is employed to vaporize cryogenic fuels, where a first stage generates a first quantity of thermal energy to heat a portion of fuel, and a second stage uses the heated fuel to generate a higher second quantity of thermal energy, which is then communicated to the core engine, supplemented by a bottoming cycle that recovers thermal energy from the core engine for further fuel heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cryogenic fuel is heated without access to engine-generated heat, then fuel vaporization can be achieved, but significant amounts of external energy are required
Solution Approach 1:
The system performs preliminary heating of a first portion of cryogenic fuel using an electric heater or blower before the engine is running. This preheated fuel is then used in the second stage to generate thermal energy that heats the second portion of fuel. This preliminary action reduces the total external energy required because the system leverages the preheated fuel to create a self-sustaining heating cycle once the engine starts.
Solution Approach 2:
The system transitions to self-service operation once the engine is running, where heat generated during engine operation is utilized to vaporize the liquid fuels. The two-stage system is designed so that the second stage uses heated fuel to generate thermal energy, creating a self-sustaining cycle that reduces dependence on external energy sources during normal operation.
2Use of energy by moving object
If a two-stage thermal energy generation system is used to vaporize fuel, then energy efficiency is improved, but system complexity increases
Solution Approach 1:
The heating system is divided into two distinct stages: a first stage that generates a first quantity of thermal energy to heat a first portion of fuel, and a second stage that uses the heated first portion to generate a second quantity of thermal energy to heat a second portion of fuel. This segmentation allows each stage to be optimized for its specific function, improving overall energy efficiency while maintaining manageable complexity through modular design.
Solution Approach 2:
The system recovers thermal energy by using the heated first portion of fuel to generate additional thermal energy in the second stage. Instead of discarding the heated fuel, the system recovers its thermal energy content and amplifies it, creating a cascading thermal energy generation process that improves efficiency without requiring proportionally more complex equipment.
3Reliability
If significant thermal energy is required for fuel vaporization, then complete vaporization can be achieved, but engine start-up time and energy resource requirements increase
Solution Approach 1:
The system performs preliminary heating of a first portion of cryogenic fuel using an electric heater or blower before the engine is running. This preheated fuel is then used in the second stage to generate thermal energy that heats the second portion of fuel. This preliminary action reduces the total external energy required because the system leverages the preheated fuel to create a self-sustaining heating cycle once the engine starts.
Solution Approach 2:
The system uses periodic action by operating the first stage (electric heater/blower) only during the start-up phase, then transitioning to the second stage that uses the heated fuel to generate thermal energy. This periodic operation pattern allows complete vaporization during the critical start-up period while reducing energy requirements during sustained operation, thereby improving reliability without permanently increasing start-up time.
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
Efficient vaporization of cryogenic fuels is achieved, reducing energy consumption and enabling reliable engine start-up, with the system transitioning to core engine heat for steady-state operation.
Implementation Method 1
a first stage that generates a first quantity of thermal energy for heating a first portion of fuel
Implementation Method 2
a second stage that utilizes the heated first portion of fuel to generate a second quantity of thermal energy for heating a second portion of fuel
Implementation Method 3
a combustor where a fuel (a cryogenic fuel) is mixed with compressed air and ignited to generate an exhaust gas flow
Implementation Method 4
a bottoming cycle where thermal energy from the core engine is recovered and utilized to heat a portion of fuel flow within the primary fuel path
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An aircraft propulsion system (20) includes a core engine (25) that includes a combustor (26) where a cryogenic fuel is mixed with compressed air and ignited to generate an exhaust gas flow (74), a propulsive fan (22) that is driven by shaft power generated by the core engine, a cryogenic fuel system (62) that includes a cryogenic fuel storage tank (78) and a fuel flow path (82) for routing fuel to the combustor of the core engine, an engine start system (60) that includes a first stage (92) that generates a first quantity of thermal energy (106) for heating a first portion of fuel (102) and a second stage (94) that utilizes the heated first portion of fuel to generate a second quantity of thermal energy (108) for heating a second portion of fuel (104), wherein the second quantity of thermal energy is greater than the first quantity of thermal energy and the second portion of fuel is communicated to the core engine.