Split Exhaust Recuperator Layout for Gas Turbine Fuel Heating
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Solution Overview
Problem
Existing gas turbine engines with recuperators face reduced propulsive efficiency and increased back-pressure due to restricted exhaust gas flow, which also increases the risk of foreign object damage and poses fire/explosion hazards from high-temperature exhaust gases.
Innovation Solution
A gas turbine engine design with separate exhaust paths and a heat-exchange system using a buffer fluid, such as nitrogen, to transfer heat from the exhaust to fuel, reducing the direct exposure of high-temperature gases to flammable fuels, and incorporating a recuperator system within one exhaust path to enhance thermal efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a recuperator is used to transfer heat from exhaust gases to compressed air, then thermal efficiency is improved, but propulsive efficiency is reduced due to restriction of exhaust gas flow
Solution Approach 1:
The exhaust gas flow is segmented into two separate paths: a first exhaust path that passes through the recuperator for heat recovery, and a second exhaust path that provides a direct exhaust route. This segmentation allows the system to simultaneously achieve thermal efficiency improvement through heat recovery while maintaining propulsive efficiency through the direct exhaust path that avoids flow restriction.
2Use of energy by moving object
If a recuperator is used to transfer heat from exhaust gases, then thermal efficiency is improved, but back-pressure increases reducing power extraction
Solution Approach 1:
The exhaust system is segmented into two independent paths, allowing the second exhaust path to maintain low back-pressure for effective power extraction while the first path handles heat recovery operations.
Solution Approach 2:
The second exhaust path acts as an intermediary that provides a dedicated low-resistance exhaust route, preventing the recuperator from causing excessive back-pressure that would reduce turbine power extraction.
3Use of energy by moving object
If a recuperator is located within the core engine gas path, then heat recovery is achieved, but vulnerability to foreign or domestic object damage increases
Solution Approach 1:
The exhaust system is divided into two paths, with the first path containing the recuperator for heat recovery and the second path providing a separate exhaust route. This segmentation isolates the recuperator within a dedicated path, reducing its exposure to foreign objects while maintaining heat recovery functionality.
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
Enhances thermal efficiency while minimizing propulsive efficiency loss and reducing the risk of fire/explosion, with improved engine power density and protection against foreign object damage.
Implementation Method 1
a recuperator system disposed within the first engine core exhaust path and arranged to transfer heat from the first portion of the mass flow of the engine core exhaust to a buffer fluid
Implementation Method 2
a heat exchanger arranged to transfer heat from the buffer fluid to fuel within a fuel path arranged to convey fuel to a combustor
Data Source
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AI summary
A gas turbine engine 108A comprises an engine core 201 having first 222 and second 224 engine core exhaust paths arranged to pass first and second portions respectively of the mass flow of the engine's core exhaust mass. A heat-exchange system comprises a recuperator system 230A-D disposed within the first engine core exhaust path and arranged to transfer heat from said first portion to a buffer fluid, and a heat exchanger arranged to transfer heat from the buffer fluid to fuel within a fuel path arranged to convey fuel to the engine's combustor 208. The engine provides for heat to be recovered from the engine's core exhaust flow to the engine's fuel supply, thus improving thermal efficiency, but without significantly impeding the engine core exhaust flow or presenting the significant fire or explosion risk associated with a recuperator arranged to heat fuel directly.