Real-Time Thermal Coking Sensor for Gas Turbine Fuel Heat Control
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Solution Overview
Problem
Gas turbine engines face limitations in utilizing fuel as a heat sink due to the risk of coking at temperatures around 400°F, restricting the amount of heat that can be added to the fuel, which affects engine efficiency and the use of Sustainable Aviation Fuels (SAFs) with higher coking temperatures.
Innovation Solution
A thermal coking sensor using two heated wires measures real-time fuel temperature to determine the onset of coking, allowing the system to actively control fuel temperature and prevent coking by adjusting heat transfer through a fuel/oil cooler, optimizing heat utilization.
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 efficiency improves, but fuel reaches coking temperature and coking occurs
Solution Approach 1:
The patent implements a feedback control system using a thermal coking sensor that continuously monitors fuel temperature and provides real-time feedback to the controller. When the sensor detects that fuel temperature approaches the coking threshold, the controller automatically adjusts the fuel/oil cooler operation to reduce heat transfer, preventing coking while maximizing efficient heat utilization. This closed-loop feedback mechanism enables dynamic balancing between heat recovery efficiency and coking prevention.
Solution Approach 2:
The system dynamically changes the heat transfer parameter by adjusting the fuel/oil cooler operation based on real-time fuel temperature conditions. The controller modulates the degree of heat extraction from fuel to the oil cooling system, varying the heat transfer coefficient and temperature differential to maintain fuel temperature below the coking threshold while maximizing heat recovery efficiency under different operating conditions.
2Reliability
If fuel temperature is limited to prevent coking, then coking is prevented, but the amount of heat that can be added to fuel is restricted
Solution Approach 1:
The patent employs dynamic control of the fuel/oil cooler system rather than static temperature limiting. The controller continuously adjusts the cooler operation based on real-time feedback from the thermal coking sensor, enabling the system to operate at maximum heat recovery efficiency when fuel temperature is safely below coking threshold, and automatically reduce heat transfer only when approaching the threshold. This dynamic approach replaces conservative static temperature limits with adaptive control that maximizes heat utilization while ensuring coking prevention.
3Measurement precision
If thermal coking sensor is added to monitor fuel temperature, then real-time coking detection is achieved, but system complexity increases
Solution Approach 1:
The thermal coking sensor acts as an intermediary element that indirectly measures fuel temperature by monitoring heat transfer characteristics rather than requiring direct contact thermocouples or complex temperature measurement systems. The sensor detects changes in thermal properties of fuel that indicate approaching coking conditions, providing reliable temperature monitoring through thermal field interaction rather than direct electrical measurement, thereby simplifying the overall sensing system while maintaining measurement precision.
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 the gas turbine engine to safely increase fuel temperature for improved efficiency, utilizing waste heat effectively and reducing fuel burn, while preventing coking and maintaining engine performance.
Implementation Method 1
a fuel/oil cooler configured to transfer heat from the heated oil to the fuel
Implementation Method 2
A thermal coking sensor...is configured to generate a signal in response to interacting with the fuel...determine a coking temperature indicating an onset of coking in the fuel based on the signal
Data Source
AI summary
A gas turbine engine fuel system includes a fuel delivery system, an oil cooling subsystem, and a fuel conditioning subsystem. 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 conditioning subsystem 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 configured to transfer heat from the heated oil to the fuel. A thermal coking sensor is in fluid communication with the fuel and is configured to generate a signal in response to interacting with the fuel. A controller is configured to determine a coking temperature indicating an onset of coking in the fuel based on the signal.