Internally Diffusing Heat Exchanger for Low Pressure Loss
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Solution Overview
Problem
High velocities within heat exchangers in gas turbine engines lead to significant pressure losses, which can outweigh the efficiency gains provided by the heat exchanger, resulting in a net reduction in system efficiency.
Innovation Solution
The use of an internally diffusing heat exchanger with annular fins featuring undulated surfaces and staggered leading and trailing edges, which reduce air-side pressure drop by diffusing air radially and minimizing entrance and exit blockage, combined with optional serrations or chevrons to further reduce nozzle losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a heat exchanger is introduced into a gas turbine engine flowpath, then heat transfer efficiency is improved, but pressure losses increase due to high velocities
Solution Approach 1:
The patent employs curved or annular fin surfaces instead of flat surfaces, creating a curved flow path that reduces flow separation and turbulence. The curved geometry allows for smoother fluid passage through the heat exchanger, reducing pressure losses while maintaining effective heat transfer area.
Solution Approach 2:
The patent transitions from conventional planar heat exchanger designs to three-dimensional annular or curved fin structures. This dimensional change enables the heat exchanger to better accommodate the radial flow pattern in gas turbine engines, reducing flow resistance and pressure drops while maintaining heat transfer effectiveness.
2Area of stationary object
If conventional heat exchanger fins are used, then heat transfer area is increased, but entrance and exit blockage increases pressure drop
Solution Approach 1:
The patent employs asymmetric fin configurations where the fin spacing, thickness, or shape varies along the flow direction. This asymmetry allows for optimized flow distribution, reducing blockage effects at entrances and exits while maintaining adequate heat transfer area. The varying geometry adapts to local flow conditions to minimize pressure drops.
Solution Approach 2:
The heat exchanger is divided into multiple sections or zones with different fin configurations. By segmenting the heat exchanger, each zone can be optimized for its specific function (e.g., entrance region with lower blockage, middle section with maximum heat transfer, exit region with flow recovery), thereby reducing overall pressure drop while maintaining total heat transfer area.
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 achieves maximum heat transfer with minimal air-side pressure drop, enhancing the overall efficiency of the gas turbine engine by reducing flow losses and maintaining optimal fluid dynamics.
Implementation Method 1
The plurality of annular fins is configured such that the flow passage, the plurality of annular fins, and the outer body diverge along a centerline axis of the heat exchanger downstream from an inlet of the heat exchanger
Implementation Method 2
a heat transfer assembly disposed within the flow passage, the heat transfer assembly including a plurality of annular fins
Data Source
AI summary
A heat exchanger includes an outer body defining a centerline axis and a flow passage extending from an inlet to an outlet of the heat exchanger. A first annular fin is disposed within the flow passage, wherein the first annular fin is concentrically aligned with the centerline axis and defines a first undulating surface. A second annular fin is disposed within the flow passage. The second annular fin is concentrically aligned with the centerline axis and defines a second undulating surface. The second annular fin is radially spaced from the first annular fin to define a flow channel therebetween. The flow passage, the first annular fin, and the second annular fin diverge along the centerline axis downstream from the inlet.