Lean-Burn Fuel Heating for Viscosity-Controlled Combustion
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Solution Overview
Problem
The use of fuels different from traditional kerosene-based jet fuels in gas turbine engines poses challenges related to fuel viscosity and lubricity, which affect delivery and combustion efficiency, potentially leading to pump wear and inefficiencies.
Innovation Solution
A method and system involving a fuel-oil heat exchanger to transfer heat from lubricating oil to fuel before combustion, adjusting fuel viscosity to 0.58 mm2/s or lower and temperature to 135°C or higher to optimize combustion in a lean burn staged combustion system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If heat is transferred from oil to fuel to lower fuel viscosity, then fuel burn efficiency is improved, but pump wear increases due to reduced lubricity
Solution Approach 1:
The patent applies parameter changes by precisely controlling fuel temperature and viscosity within specific ranges (temperature: 135-170°C, viscosity: 0.35-0.58 mm²/s) to optimize both combustion efficiency and pump lubrication. This resolves the contradiction by finding the optimal parameter window where both benefits are achieved simultaneously.
Solution Approach 2:
The system uses feedback control through sensors that monitor fuel temperature and viscosity, adjusting the heat exchanger operation accordingly. This ensures fuel remains within the optimal viscosity range for combustion while maintaining sufficient lubricity for pump operation, resolving the trade-off between efficiency and reliability.
2Productivity
If fuel temperature is raised to lower viscosity, then combustion efficiency is improved, but coking risk increases
Solution Approach 1:
The patent specifies a maximum fuel temperature of 170°C to lower viscosity sufficiently for efficient combustion while preventing temperature excursions that would cause coking. This parameter boundary resolves the contradiction between combustion efficiency and coking prevention.
3Productivity
If fuel viscosity is lowered for better atomisation, then burn efficiency is improved, but fuel pump lubrication deteriorates
Solution Approach 1:
The patent establishes a minimum viscosity threshold of 0.35 mm²/s to ensure adequate pump lubrication while allowing sufficient reduction (down to 0.58 mm²/s) for efficient atomisation and combustion. This parameter range resolves the contradiction between burn efficiency and pump lubrication.
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
Improves fuel delivery and combustion efficiency, reducing pump wear and enhancing engine performance by controlling fuel viscosity and temperature, suitable for aircraft gas turbine engines using alternative fuels.
Implementation Method 1
a fuel-oil heat exchanger arranged to transfer heat between oil and fuel that is provided to the combustor
Implementation Method 2
Transferring heat from the oil to the fuel before the fuel enters the combustor so as to lower the fuel viscosity to 0.58 mm2/s or lower on entry to the combustor at cruise conditions
Data Source
AI summary
A method of operating a gas turbine engine having a lean burn staged combustion system having a combustor in which fuel is combusted. The gas turbine engine includes a fuel-oil heat exchanger arranged to transfer heat between oil and fuel that is provided to the combustor. The method includes transferring heat from the oil to the fuel before the fuel enters the combustor so as to lower the fuel viscosity to 0.58 mm2/s or lower on entry to the combustor at cruise conditions.