Supercritical CO2 Propulsion System for Aircraft Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional gas turbine engines are thermodynamically inefficient, especially at high altitudes, due to low air density, leading to large and heavy components, high fuel consumption, and increased operational and maintenance costs, which can be mitigated by using a super-critical carbon dioxide (s-CO2) system for improved efficiency and reduced size.
Innovation Solution
A distributed propulsion system powered by a s-CO2 cycle, where carbon dioxide operates in a super-critical region, providing power to multiple propulsors through a closed-loop system, eliminating the need for conversion equipment and allowing for redundant and fault-tolerant operation by decoupling propulsors from the power shaft and integrating them with the air vehicle for aerodynamic benefits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If air is used as working fluid in conventional gas turbine engines, then the system can operate with simple structure, but thermodynamic efficiency deteriorates especially at high altitude due to low air density
Solution Approach 1:
The patent changes the working fluid from air to supercritical carbon dioxide (sCO2), fundamentally altering the thermodynamic parameters. sCO2 operates at higher densities and allows for more efficient heat transfer and expansion processes, directly improving thermodynamic efficiency while maintaining system operational capability
Solution Approach 2:
The system utilizes the unique properties of carbon dioxide at its critical point (31.1°C, 73.8 atm) to operate in the supercritical phase. This phase transition enables the working fluid to achieve both liquid-like density and gas-like compressibility, optimizing the thermodynamic cycle efficiency particularly in high-altitude conditions where air density is low
2Quantity of substance
If high pressure ratio compression is used to achieve needed combustor pressure and temperature, then adequate mass flow rate is achieved, but component size and weight increase significantly
Solution Approach 1:
By switching to sCO2 as the working fluid, the system achieves higher density compared to air at the same conditions. This density increase allows for adequate mass flow rates to be achieved with lower compression ratios, directly reducing the size and weight of compression components while maintaining the required mass flow for power generation
3Power
If high combustion temperatures are used to achieve adequate power output, then power generation is sufficient, but operational and maintenance expenses increase
Solution Approach 1:
The sCO2 cycle operates with controlled temperature profiles that optimize power generation while avoiding excessive combustion temperatures. The supercritical fluid's high heat capacity and efficient heat transfer properties allow for effective thermal management, reducing thermal stress on components and thereby lowering operational and maintenance costs while maintaining adequate power output
4Power
If propulsors are coupled to power shaft in conventional systems, then power transfer is direct, but conversion inefficiencies and additional mass occur due to speed mismatch
Solution Approach 1:
The patent replaces the conventional mechanical shaft coupling system with a fluidic power transmission system using sCO2. The working fluid directly drives distributed propulsors through fluid pressure and flow, eliminating the need for mechanical gearboxes and speed conversion mechanisms, thereby reducing conversion inefficiencies and system mass
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 enhances propulsion efficiency, reduces mass, and minimizes conversion inefficiencies by using the dense, non-toxic properties of carbon dioxide, resulting in a compact and high-power-density propulsion system with improved fault tolerance and reduced maintenance needs.
Implementation Method 1
carbon dioxide operated in super-critical cycle
Implementation Method 2
operating in a super-critical region (operating at a temperature and pressure that exceed the critical point)
Implementation Method 3
s-CO2 - based systems may be operated having very dense super-critical properties, such as approximately 460 kg/m3
Data Source
Figure 1~3
Figure 4
Figure 5
AI summary
A power and propulsion system (400, 500, 600, 700) includes an air compressor (712, 718), a combustor (724) positioned to receive compressed air from the air compressor (712, 718) as a core stream (726), and a closed-loop system (404, 504, 722) having carbon dioxide as a working fluid that receives heat from the combustor (724) and rejects heat to a cooling stream. The closed-loop system (404, 504, 722) configured to provide power to a fan (718, 732) that provides the cooling stream, and to one or more distributed propulsors (406, 506, 606, 608) that provide thrust to an aircraft.