Gas Turbine Oil-to-Fuel Heat Exchange for Low-Viscosity Combustion
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Solution Overview
Problem
The aviation industry's transition to fuels different from traditional kerosene-based jet fuels necessitates adjustments in gas turbine engine operation to account for varying fuel properties, particularly to optimize fuel temperatures and viscosities for improved combustion efficiency and oil cooling.
Innovation Solution
A method and apparatus involving a heat exchange system that raises fuel temperature to at least 135°C and controls fuel viscosity by transferring heat from the oil loop system to the fuel, utilizing multiple heat exchangers and bypass pipes to manage oil and fuel flow, allowing for efficient combustion and oil cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional kerosene-based jet fuels are used, then the engine operates with standard fuel properties, but the transition to new fuels requires adjustments to fuel temperature and viscosity to optimize combustion efficiency
Solution Approach 1:
The patent applies parameter changes by adjusting fuel temperature (raising to at least 135°C) and controlling fuel viscosity through heat exchange with the oil loop system. This allows the engine to adapt to different fuel types (including sustainable aviation fuels) by modifying physical parameters to optimize combustion efficiency while maintaining compatibility with existing engine systems.
2Productivity
If fuel temperature is raised to at least 135°C, then fuel burn efficiency is enhanced, but the oil loop system must be cooled to maintain effective lubrication
Solution Approach 1:
The patent converts the harmful effect of heat into a beneficial one by using the oil loop system's excess heat to pre-heat the fuel before combustion. The heat that would otherwise be waste heat is now utilized to raise fuel temperature to 135°C or higher, improving combustion efficiency while simultaneously cooling the oil system to maintain effective lubrication.
Solution Approach 2:
The patent merges the fuel heating function with the oil cooling function into a single heat exchange system. The heat exchange system transfers heat from the oil loop to the fuel stream, simultaneously achieving both fuel temperature increase (for improved burn efficiency) and oil temperature control (for maintained lubrication).
3Productivity
If heat exchange system is used to transfer heat from oil to fuel, then fuel temperature and viscosity are optimized, but the system complexity increases
Solution Approach 1:
The patent applies multi-functionality by designing the heat exchange system to serve multiple purposes: it cools the oil loop system, heats the fuel stream, and simultaneously optimizes both temperature and viscosity parameters for improved engine performance. This multi-functional approach justifies the added system complexity by delivering multiple benefits from a single integrated system.
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 fuel burn efficiency and improves oil cooling by raising fuel temperature and adjusting viscosity, thereby optimizing engine performance with non-traditional fuels.
Implementation Method 1
a heat exchange system arranged to transfer heat between the oil and the fuel, the oil having an average temperature of at least 180° C. on entry to the heat exchange system at cruise conditions, wherein the method comprises controlling the heat exchange system so as to raise the fuel temperature to at least 135° C. on entry to the combustor at cruise conditions
Data Source
AI summary
A gas turbine includes an engine core with a turbine, a compressor, a combustor to combust a fuel, and a core shaft connecting the turbine to the compressor; a fan located upstream of the engine core; a fan shaft; a main gearbox that receives an input from the core shaft and outputs drive to the fan via the fan shaft; a primary oil loop system arranged to supply oil to lubricate the main gearbox; and a heat exchange system arranged to transfer heat between the oil and the fuel, the oil having an average temperature of at least 180° C. on entry to the heat exchange system at cruise conditions. A method of operating the turbine includes transferring heat from the oil to the fuel so as to lower the fuel viscosity to a value of less than or equal to 0.58 mm2/s on entry to the combustor at cruise conditions.