Offset Core Nacelle Heat Recovery for Steam-Injected Propulsion
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Solution Overview
Problem
Existing aircraft propulsion systems lose significant heat energy in exhaust gas flows, and existing heat exchangers are inefficient due to small flow facing areas relative to engine size, limiting the recovery of heat energy for steam generation and increasing engine efficiency.
Innovation Solution
An aircraft propulsion system with an offset gas generating core engine and nacelle-mounted heat exchangers, including a condenser and evaporator assembly, where water in the gas flow is condensed into liquid form and subsequently heated to generate steam, which is injected back into the core engine, enhancing efficiency by increasing mass flow without additional compressor work.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If heat exchangers are designed with large flow facing areas to improve heat recovery efficiency, then heat energy recovery is improved, but the device size and complexity increase
Solution Approach 1:
The condenser and evaporator heat exchangers are nested within the nacelle structure, utilizing the available internal volume. The offset core engine configuration creates space within the nacelle to accommodate these heat exchangers without significantly increasing the overall engine footprint, thereby achieving large heat exchange areas while controlling device complexity.
Solution Approach 2:
The heat exchangers are arranged in a three-dimensional configuration within the nacelle, utilizing vertical and radial spaces rather than only linear extensions. This dimensional arrangement allows for large flow facing areas to be achieved within the constrained nacelle volume, improving heat recovery without proportionally increasing device complexity.
2Productivity
If steam injection is used to increase mass flow and engine efficiency, then engine efficiency is improved, but the system complexity increases due to additional heat exchangers
Solution Approach 1:
The condenser and evaporator are integrated into a unified water recovery and steam generation system within the nacelle. The offset core engine configuration allows these components to be merged with the exhaust ducting and nacelle structure, reducing the number of separate systems and simplifying the overall architecture while maintaining the steam injection function for improved engine efficiency.
Solution Approach 2:
The system uses the waste heat from the exhaust gas flow to drive the entire steam generation process. The exhaust gas itself provides the heating medium for the evaporator and the cooling medium for the condenser, making the system self-sufficient and reducing the need for additional external energy sources or complex control systems.
3Ease of manufacture
If the core engine is offset from the fan axis to accommodate heat exchangers, then heat exchanger installation is enabled, but the engine configuration complexity increases
Solution Approach 1:
The core engine is deliberately positioned asymmetrically with its axis offset from the fan axis, creating an asymmetric engine configuration. This asymmetric arrangement generates the necessary space within the nacelle for heat exchanger installation while maintaining a manageable configuration through systematic ducting and component layout that adapts to the offset geometry rather than requiring symmetric complexity.
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
The system achieves increased engine efficiency and power output by recovering heat energy for steam generation, utilizing large flow facing areas within the nacelle for heat exchangers, and maintaining compatibility with traditional engine mounting locations.
Implementation Method 1
a condenser where water in the gas flow is condensed into a liquid form
Implementation Method 2
an evaporator assembly that is in thermal communication with the exhaust duct where water recovered by the condenser is heated to generate a steam flow
Implementation Method 3
an ejector duct where a portion of a bypass airflow is thermally communicated with the condenser to cool the gas flow
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A propulsion system (20) for an aircraft includes a fan (22), a core engine (24) configured for generating a gas flow (36) utilized to generate shaft power for driving the fan (22), a nacelle (48) that surrounds the core engine (24) and the fan (22), a condenser (58) where water in the gas flow (36) is condensed into a liquid form, an exhaust duct assembly (52) where the gas flow (36) is directed to the condenser (58), an ejector duct (60) where a portion of a bypass airflow (38) is thermally communicated with the condenser (58) to cool the gas flow (36), and an evaporator assembly (54), that is in thermal communication with the exhaust duct (60), where water recovered by the condenser (58) is heated to generate a steam flow (56) that is subsequently communicated to the core engine (24).