Nested Coil Heat Exchanger for Compact Turbopump Exhaust
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Solution Overview
Problem
Existing heat exchangers face challenges in efficiently increasing the heat exchange surface area while maintaining a compact size, particularly in complex geometries like rocket engine turbopumps, where bending and shaping of coils are complex and resource-intensive.
Innovation Solution
A coil design with adjacent turns sharing a common wall portion, manufactured using additive manufacturing on a powder bed, allowing for reduced material usage and complex shapes without the need for supports, and enabling balanced pressure distribution for thinner common walls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the length of the coil circuit is increased to increase heat exchange surface area, then the heat exchange efficiency is improved, but the volume occupied by the coil increases
Solution Approach 1:
The coil is designed with adjacent turns that are nested or closely positioned, where each turn shares a portion of wall with adjacent turns. This nesting arrangement allows the coil to achieve a long heat exchange surface area within a compact volume, as the turns are stacked efficiently rather than extending linearly through space.
Solution Approach 2:
The coil transitions from a planar two-dimensional arrangement to a three-dimensional stacked configuration. By arranging turns in multiple layers with vertical stacking (where the y-coordinate of the lowest point of an upper turn is less than the y-coordinate of the highest point of a lower turn), the design achieves high heat exchange surface area density within a compact volume.
2Area of stationary object
If the coil is bent into complex shapes to increase heat exchange surface area in compact space, then the heat exchange efficiency is improved, but the manufacturing complexity increases
Solution Approach 1:
The coil is manufactured using additive manufacturing technology, which creates the complex three-dimensional shape with shared walls between turns in a single manufacturing process. This preliminary formation of the complex geometry eliminates the need for subsequent bending, shaping, or assembly operations that would otherwise be required to achieve the same compact configuration.
Solution Approach 2:
The traditional mechanical bending and shaping processes are replaced with additive manufacturing. The complex geometry with shared walls between adjacent turns, which would be difficult or impossible to create by bending tubes, is directly fabricated layer by layer, substituting mechanical forming with a digital manufacturing process.
3Loss of substance
If material is reduced to minimize resource usage, then the manufacturing cost is reduced, but the structural strength decreases
Solution Approach 1:
Adjacent turns of the coil share common wall portions, merging the structural material between turns. Instead of having separate, complete circular walls for each turn, the shared walls are utilized by multiple adjacent turns simultaneously. This merging of material resources reduces the total amount of material required while maintaining the structural integrity and pressure-containing capability of each turn.
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 design enhances heat exchange surface area while minimizing material usage and simplifying manufacturing, achieving efficient heat transfer in compact configurations, such as in rocket engine turbopumps, by allowing for complex geometries and reduced size without the complexity of traditional bending processes.
Implementation Method 1
heat exchangers, in particular heat exchangers comprising a coil in which a fluid circulates
Implementation Method 2
thermal energy is extracted from fluid A to raise the temperature of fluid B
Data Source
Figure 1
Figure 2~3A
Figure 3B~3C
AI summary
The invention relates to a coil (16, 18) for a heat exchanger, comprising at least a first and a second turn, the first and second turns being adjacent, each turn having, in a cross-sectional plane transverse to the direction of fluid flow in the coil (16, 18), a wall delimiting a fluid passage section within the turn, the passage section having a shape comprising a major axis and a minor axis, an orthogonal projection of one end of the major axis of the first turn onto a line comprising the major axis of the second turn lying on the major axis of the second turn, the first and second turns having a portion of wall in common. The invention also relates to a turbopump exhaust (10) comprising such a coil and a method for manufacturing such a coil.