Optical heat exchanger and associated method
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Solution Overview
Problem
Existing optical heat exchangers for spacecraft and aircraft face challenges in achieving a high thrust-to-weight ratio due to conflicting requirements for material strength, heat conductivity, and propellant containment, leading to increased weight and cost.
Innovation Solution
An optical heat exchanger with a support structure featuring tapered openings and convex lenses that concentrate electromagnetic energy to heat the propellant, combined with an absorber surface and optional window plugs, to efficiently transfer energy while minimizing material thickness and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the tube material is made thin to reduce temperature difference and improve heat transfer efficiency, then heat transfer efficiency is improved, but the ability to contain propellant under high pressure deteriorates
Solution Approach 1:
The heat exchanger is divided into multiple separate tubes instead of using a single thick structure. Each tube can be made thin-walled to improve heat transfer efficiency while the collective array of tubes maintains the required structural strength and propellant containment capability through distributed load bearing.
Solution Approach 2:
The patent employs composite material structures for the tubes, combining materials with high strength-to-weight ratios and good thermal conductivity. This allows the tubes to be thin-walled for efficient heat transfer while maintaining the mechanical strength required to contain propellant under high pressure.
2Strength
If the tube material is selected for high strength at high temperatures, then propellant containment is improved, but heat conductivity deteriorates
Solution Approach 1:
Composite material structures are used for the tubes, combining materials that provide both high-temperature strength and adequate heat conductivity. This allows the tubes to withstand high operating temperatures while maintaining efficient heat transfer from the outer surfaces to the propellant.
Solution Approach 2:
Different regions of the heat exchanger structure may use different materials optimized for their specific functions. The tube walls use materials optimized for heat conduction, while support structures and regions requiring high-temperature strength use appropriately selected materials, allowing each component to perform its function efficiently.
3Device complexity
If a single large transparent window plate is used to admit electromagnetic energy and confine propellant, then device simplicity is improved, but weight increases due to required thickness
Solution Approach 1:
The window structure is divided into multiple smaller transparent window elements arranged in an array, corresponding to the tube arrangement. This segmentation allows each window element to be thin and lightweight while collectively providing the required electromagnetic energy admission and propellant confinement functions across the entire heat exchanger surface.
Solution Approach 2:
The window structure transitions from a single large two-dimensional plate to a three-dimensional array of smaller window elements integrated with the tube structure. This dimensional reorganization allows for reduced material usage and weight while maintaining the required functional performance.
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 solution enhances the thrust-to-weight ratio by allowing for a higher exhaust speed and specific impulse, enabling more payload delivery at a lower cost by optimizing energy transfer and structural strength.
Implementation Method 1
Each lens is configured to receive an electromagnetic energy beam and concentrate the majority of the electromagnetic energy beam through the inwardly facing end of the respective tapered opening so as to heat the propellant
Implementation Method 2
concentrate the majority of the electromagnetic energy beam through the inwardly facing end of the respective tapered opening so as to heat the propellant
Implementation Method 3
The inwardly facing end of each tapered opening may be configured to absorb at least a portion of the electromagnetic energy beam
Data Source
AI summary
An optical heat exchanger and an associated system and method are provided to allow a vehicle, such as an unmanned air vehicle, a rocket or the like, to deliver more payload at a lower cost. The optical heat exchanger includes a support surface defining a plurality of tapered openings. Each tapered opening tapers from the first size proximate an outwardly facing end of the opening to a second smaller size proximate an inwardly facing end of the opening. The inwardly facing end of each tapered opening is in communication with the propellant. The optical heat exchanger also includes a plurality of lenses with each lens positioned proximate the outwardly facing end of a respective opening. Each lens is configured to receive an electromagnetic energy beam and concentrate the majority of the electromagnetic energy beam through the inwardly facing end of the respective tapered opening, thereby heating the propellant.