Aircraft Recuperative Closed-Cycle Powerplant Heat Recovery
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Solution Overview
Problem
Current aircraft engines face inefficiencies due to wasted heat and non-optimal sub-systems, particularly in transient phases and power extraction, with existing recuperative solutions facing integration challenges and low power ratings.
Innovation Solution
A closed-cycle powerplant arrangement that recovers heat from gas turbine engines using a working fluid undergoing a thermodynamic cycle, with components like primary heat exchangers, expanding elements, and power conversion systems housed within the aircraft's airframe structure, enhancing power distribution and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If heat is released to the atmosphere through the nozzle after turbine passage, then the engine structure is simple, but heat energy is wasted and efficiency is reduced
Solution Approach 1:
The patent captures the previously wasted hot exhaust gases from the turbine nozzle and redirects them into a closed-cycle heat recovery system. The thermal energy that would have been discarded is now used to heat a working fluid, drive an expander for power generation, and provide thermal energy to aircraft systems, thereby converting harmful waste heat into useful energy resources.
Solution Approach 2:
The patent implements a heat recovery system that captures and recovers thermal energy from the exhaust gases. The closed-cycle arrangement includes heat exchangers that transfer heat from the exhaust gases to a working fluid, and the recovered thermal energy is utilized for power generation and aircraft system heating, preventing the energy from being discarded to the atmosphere.
2Power
If power is extracted from engine core shafts through complex gearboxes, then power can be supplied to aircraft systems, but the engine design becomes more complex and space is constrained
Solution Approach 1:
The patent extracts the power generation function from the engine core shaft system and relocates it to an independent closed-cycle arrangement. The expander and generator are positioned separately from the engine core, connected via exhaust gas heat transfer rather than direct mechanical coupling, thereby simplifying engine design while maintaining power supply capability.
Solution Approach 2:
The patent introduces exhaust gases as an intermediary medium to transfer energy from the engine to the power generation system. Instead of direct mechanical coupling through gearboxes, the exhaust gases serve as the energy carrier, heating the working fluid in the closed-cycle system, which then drives the expander to generate power.
3Temperature
If compressed air is used to cool turbine components, then high temperatures are resisted, but engine efficiency is reduced due to air consumption
Solution Approach 1:
The exhaust gases serve multiple functions simultaneously: they drive the expander for power generation and provide thermal energy for cooling turbine components through heat exchangers. This multi-functional use of the exhaust gas thermal energy improves overall engine efficiency by eliminating the need for separate compressed air cooling systems.
Solution Approach 2:
The exhaust gases, which would otherwise be wasted, serve to cool the turbine components themselves by transferring their thermal energy to the working fluid in the closed-cycle system. The system uses its own waste heat resource to maintain component temperatures, reducing dependence on external compressed air cooling.
4Object-generated harmful factors
If low carbon fuels like Liquid Hydrogen are used, then emissions are reduced, but volumetric energy density decreases requiring much larger fuel tanks
Solution Approach 1:
The patent converts the low volumetric energy density characteristic of hydrogen into an advantage by implementing a closed-cycle heat recovery system. The exhaust gases from hydrogen combustion, which would be wasted in conventional systems, are captured and used to drive power generation and provide thermal energy, effectively utilizing the chemical energy stored in the hydrogen and offsetting the larger tank volume requirement.
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 configuration significantly improves powerplant efficiency by effectively transferring high power levels within the aircraft, reducing engine complexity, and enhancing transient performance while minimizing structural and aerodynamic penalties.
Implementation Method 1
at least two primary heat exchangers, each one configured to transfer heat from a respective gas turbine engine to the working fluid
Implementation Method 2
at least one expanding element configured to drive a gearbox and an output shaft by the expansion of the working fluid
Implementation Method 3
at least one pre-cooler configured to transfer heat from the working fluid to a heat sink; the heat sink in thermal communication with the pre-cooler, the heat sink being a fuel tank and/or an airframe surface
Implementation Method 4
at least one pumping element configured to move the working fluid through the closed circuit
Data Source
AI summary
The disclosure provides a powerplant for an aircraft comprising: at least two gas turbine engines, and at least one closed-cycle arrangement for recuperating heat from the at least two gas turbine engines and supplying power to at least one power-demanding system, wherein the closed-cycle arrangement comprises: a closed circuit channeling a working fluid subjected to a thermodynamic cycle; at least one pre-cooler configured to transfer heat from the working fluid to a heat sink; the heat sink in thermal communication with the pre-cooler, the heat sink being a fuel tank and/or an airframe surface; at least one pumping element configured to move the working fluid through the closed circuit; at least two primary heat exchangers, each one configured to transfer heat from a respective gas turbine engine to the working fluid; at least one expanding element configured to drive a gearbox and an output shaft by the expansion of the working fluid; wherein the output shaft driven by the expanding element is connected to at least one electrical generator configured to generate electrical power; a power conversion system configured to receive the generated electrical power by the electrical generator and to accommodate and supply it to the at least one power-demanding system; wherein the closed-cycle arrangement is adapted to be partially housed within the airframe structure of the aircraft, so that at least the pumping element, the expanding element, the electrical generator, and the power conversion system are housed in said airframe structure.