Transient Control of Thermal Transport Bus in Turbomachines
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Solution Overview
Problem
The thermal transport bus of a turbomachine faces challenges in maintaining optimal working fluid conditions during engine starting, throttle push to takeoff, and throttle chop, leading to large transients in temperature, pressure, or flow rate, which can compromise its operation and the turbomachine's performance, especially when the working fluid is carbon dioxide.
Innovation Solution
A method and system for transient control of the thermal transport bus, involving measurement of temperature and pressure, selection of desired operating conditions based on the turbomachine's run state, and modulation of control parameters such as pump speed, inlet guide vanes, and bypass valves to maintain the working fluid within desired ranges, ensuring the fluid remains gaseous or supercritical.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If individual heat exchangers are used for each accessory system, then heat removal capability is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple individual heat exchangers into a single thermal transport bus that serves multiple accessory systems. The thermal transport bus includes a working fluid that circulates through the bus and removes heat from multiple heat sources (such as bearings and gear meshes) simultaneously, eliminating the need for separate heat exchangers for each accessory system while maintaining effective heat removal capability.
2Temperature
If thermal transport bus operates during transient conditions, then heat removal is improved, but working fluid stability deteriorates
Solution Approach 1:
The patent implements dynamic control of the thermal transport bus during transient operating conditions. The system monitors the state of the working fluid (such as carbon dioxide) and adjusts operational parameters to maintain the fluid in the desired supercritical or gaseous state. This dynamic adjustment ensures stable working fluid composition while maintaining effective heat removal during engine starting, throttle push to takeoff, and throttle chop conditions.
3Speed
If working fluid transients are allowed, then system responsiveness is improved, but operational reliability deteriorates
Solution Approach 1:
The patent implements a feedback control system that continuously monitors temperature, pressure, and flow rate of the working fluid in the thermal transport bus. When transients are detected that could compromise operational reliability, the system responds by adjusting operational parameters to maintain the working fluid within safe operating limits. This feedback mechanism prevents harmful transients while preserving necessary system responsiveness during normal transient conditions such as engine starting and throttle changes.
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
This approach effectively stabilizes the working fluid's state, protecting hardware components and preventing issues like fuel coking, while optimizing the turbomachine's efficiency and reducing the need for multiple heat exchangers, thereby enhancing overall engine performance and reducing fuel consumption.
Implementation Method 1
a first heat source exchanger in thermal communication with the heat exchange fluid in the thermal transport bus and configured to receive heat from a main lubrication system of the turbofan jet engine; a second heat source exchanger in thermal communication with the heat exchange fluid in the thermal transport bus and configured to receive heat from a gas generator portion of the turbofan jet engine; at least one heat sink exchanger in thermal communication with the heat exchange fluid in the thermal transport bus
Data Source
AI summary
A method of transient control of a thermal transport bus of a turbomachine includes measuring a measured temperature and a measured pressure of a working fluid; determining a selected run state of a turbomachine, wherein the selected run state is one of a plurality of run states; selecting a desired operating condition comprising a desired temperature range and a desired pressure range as a function of a desired state of the working fluid; comparing the measured temperature with the desired temperature range, and comparing the measured pressure with the desired pressure range; and modulating control of the thermal transport bus as a function of the comparing of the measured temperature with the desired temperature range and the comparing of the measured pressure with the desired pressure range.