Optical Fuel Coking Sensing for Gas Turbine Heat-Sink Control
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Solution Overview
Problem
Existing gas turbine engines face limitations in utilizing fuel as a heat sink due to the risk of coking at temperatures above 400°F, which restricts the amount of heat that can be added to the fuel, thereby limiting engine efficiency improvements.
Innovation Solution
Incorporation of optical coking sensors to monitor fuel thermal stress in real-time, using UV LEDs and light sensing elements to detect fuel darkening, allowing the controller to adjust heat transfer to prevent coking onset and optimize fuel temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If heat is added to fuel to improve engine efficiency, then fuel temperature increases and engine performance improves, but fuel coking occurs at temperatures above 400°F
Solution Approach 1:
The optical sensor performs preliminary detection of fuel thermal stress before coking actually occurs. By monitoring fuel color changes in real-time upstream of the fuel nozzles, the system identifies approaching coking conditions and triggers cooling action before deposits form, preventing the harmful effect while maintaining high fuel temperature for efficiency.
Solution Approach 2:
The system establishes a closed-loop feedback control where the optical sensor continuously monitors fuel thermal stress and sends signals to the controller, which adjusts the fuel cooling valve to modulate cooling flow. This feedback mechanism allows the system to dynamically maintain fuel temperature near the coking threshold without actually causing coking, resolving the contradiction between heat addition and coking prevention.
2Reliability
If real-time monitoring of fuel thermal stress is implemented, then coking prevention capability improves, but system complexity increases due to additional sensors and control mechanisms
Solution Approach 1:
The patent replaces complex mechanical temperature measurement and control systems with an optical detection system. Instead of using thermocouples and mechanical cooling control, the system uses UV-optical sensors to detect fuel thermal stress through color changes and controls cooling via optical feedback, simplifying the overall system while improving reliability.
Solution Approach 2:
The optical sensor acts as an intermediary that translates fuel thermal stress into detectable optical signals without direct contact with the fuel. This intermediary approach allows monitoring of fuel condition while isolating the sensing system from the harsh fuel environment, reducing complexity compared to direct measurement methods.
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
Enables real-time control of fuel temperature to prevent coking, maximizing heat sink potential and fuel burn efficiency by safely increasing fuel temperature, thereby improving engine performance and reducing emissions.
Implementation Method 1
The fuel/oil cooler transfers heat from the oil to the fuel to increase a temperature of the fuel
Implementation Method 2
a light sensing element configured to detect the light traveling through the fuel
Implementation Method 3
The light source includes a light emitting diode (LED), which emits light in the UV wavelength
Implementation Method 4
The fuel delivery subsystem delivers fuel to a gas turbine engine
Implementation Method 5
the oil cooling subsystem receives heated oil from the gas turbine engine
Data Source
AI summary
A gas turbine engine fuel system includes a fuel delivery system, an oil cooling subsystem, a fuel delivery conditioning system, and one or more optical coking sensors. The fuel delivery subsystem delivers fuel to a gas turbine engine and the oil cooling subsystem receives heated oil from the gas turbine engine. The fuel delivery conditioning system includes a fuel/oil cooler that is in fluid communication with the fuel delivery subsystem to receive the fuel and is in fluid communication with the oil cooling subsystem to receive the heated oil. The fuel/oil cooler transfers heat from the oil to the fuel to increase a temperature of the fuel, and the optical coking sensors output a signal indicating a thermal stress of the fuel that occurs with a changing temperature of the fuel. A controller receives the voltage signal determines an onset of coking in the fuel based on the signal.